METHOD STATEMENT OF THERMOPLASTIC

 

1.0 Scope

2.0 General

3.0 Materials

4.0 Procedure

5.0 Precaution

6.0  Opening to traffic

1.0 Scope

The work shall consist of providing and laying of pavement marking with hot applied thermoplastic paints (type-2) as per Clause 803 of MORT&H.

2.0 General

This method statement covers providing and laying of pavement marking with hot applied thermoplastic paints as Per IRC: 35 code of practice for road marking and specified in drawing of as directed by the Engineer.

3.0 Materials

Materials of road marking shall be hot applied thermoplastic compound and the same shall meet the requirements as specified in clause 803.2 of MORT&H.

Composition: The pigment, beads, and aggregate shall be uniformly dispersed in the resin. The material shall be free from all skins, dirt and foreign objects and shall comply with requirements indicated following table.

Proportions of constituents of Material (% by weight)

Note: Amount of calcium carbonate and inert fillers shall be at the option of the manufacturer, provided all other requirements of this specification are met.

3.1 Properties: The properties of thermoplastic material, when tested in accordance with ASTM D36/BS-3262-(Part I) shall be as below;

a. Luminance :

 b. White: Daylight luminance at 45 degrees – 65 percent min as per AASHTOM 249.

 c. Drying time:  when applied at a temperature specified by the manufacturer and to the required thickness, the material shall set to bear traffic in   not more than 15 minutes.

d. Skid resistance: not less than 45 as per BS 6044.

e. Cracking resistance at low temperature: The material shall show no cracks on application to concrete blocks.

f. Softening point: 102.5+/- 9.5ºC as per ASTM D 36.

g. Flow resistance: Not more than 25 per cent as per AASHTO M 249.

h. Yellowness index (for white thermoplastic paint: not more than 0.12 as per AASHTO M 249.

i. Storage life: The material shall meet the requirements of these specifications for a period of one year. The thermoplastic material must also melt uniformly with no evidence of skins or un-melted particles for the one year storage period. Any material not meeting the above requirements shall be replaced by the manufacture/supplier/Contractor.

j. Reflectorisation  : shall be achieved by incorporation of beads, the grading and other properties of the beads shall be as specified in clause 803.4.3 of MSRT&H.    

3.2 Marking: each container of the thermoplastic material shall be clearly and indelibly marked with following information.

The name, trade mark or other means of identification of manufacturer.

Batch number

Date of manufacture.

Colour (white or yellow)

Maximum application temperature and maximum safe heating temperature.

3.3 Sampling and Testing: The thermoplastic material shall be sampled and tested in accordance with the appropriate ASTM/BS method. The Contractor shall furnish to the Employer a copy of certified test reports from the manufacturer of the thermoplastic material showing results of all tests specified herein and shall certify that  the material meets all requirements of this specification

3.3.1 Reflective glass beads

The glass beads shall be transparent, Colourless and free from milkiness, dark particles and excessive air inclusions. These shall conform to the requirements spelt out in Clause 803.4.2.3 of MORT&H.

Gradation: The glass beads shall meet the graduation requirements for the two types as given in the following table Table 800-10

Roundness: The glass beads shall have a minimum of 70 per cent true spheres

Refractive index: The glass beads shall have a minimum refractive index of 1.50.

Free flowing properties: The glass beads shall be free of hard lumps and clusters and shall dispense readily under any condition suitable for paint stripping. They shall pass the free – Flow test.

Before taking up of laying markings, program for the diversion of traffic shall be drawn up and got it approved by the Engineers as per 112 of MOSRT&H and as per IRC: SP-55.

Temporary sign boards, barricading, flags, lights and flagmen will be provided at working area as per approval of the Engineer.

On both sides, suitable regulatory/warning signs as approved by the Engineer shall be installed for the guidance or roads users.

4.0  Procedure

4.1  Equipment to be used

  1. Pre-Melter
  2. Pram-applicator
  3. Mechanical Broom
  4. Air compressor
  5. Truck
  6. Water tanker with pipe attachment
  7. Survey kit / instrument

4.2 Construction operation

4.2.1 Preparation (as per MORT&H Clause:803.4.4):

The material shall be melted in accordance with the manufacturer’s instructions in a heater fitted with a mechanical stirrer to give a smooth consistency to the thermoplastic material to avoid local overheating. The temperature of the mass shall be within the range specified by the manufacturer, and shall on no account be allowed to exceed the maximum temperature stated by the manufacturer. The molten material should be used as expeditiously as possible and for thermoplastic material which has natural binders or is otherwise sensitive to prolonged heating the material shall not be maintained in a molten condition for more than 4 hours.

After transfer to the laying equipment, the material shall be maintained within the temperature range specified by the manufacture for achieving the desired consistency for laying.

4.2.2 Cleaning: The surface of the flexible road pavement shall be thoroughly cleaned form all of dust any other material, grease, oil etc. at the area where the material shall be applied to mark the pavement with the help of broom and air compressor.

4.2.3 Pre- Marking: The reference centre – line ( Pre-Marking) of the lane marking as per the drawing shall be made to have temporary marking with chalk powder/long thin rope ,so that the applicator machine pointer in the front of the machine can be guided to move along this pre-Marked line while material is being applied on the road . This ensures accurate alignment of the markings when laid on the road surface.

4.2.4 Heating of the Material: The material shall be heated in the pre-Melter as well as pram-applicator machine fitted with mechanical stirrer to give smooth consistency to the material and to avoid local heating of the material. For heating, LPG with suitable burner system shall be used to achieve temperature of 180+/-10º C which is the specified application temperature. The temperature Gauge fitted on the machine as well as the pre-Melter displays the material temperatures continuously for monitoring the application temperature.

4.2.5 Lane Markings: The lane marking shall be made as per the approved drawing for width; length and thickness shall be made with the help of the Screed- Box attached to the Applicator Machine. The thermoplastic paint shall be applied in intermittent of continuous lines of uniform thickens of at least 2.5 mm. where arrows or letters are to be provided. Thermoplastic compound may be hand sprayed. The tolerances of the width, position alignment and length of segment of broken lines shall be as per Technical specification sub clause 803.6.6.

4.2.6 Drop-On Glass Beads Application: The approved glass beads shall be placed in position from the bead dispenser attached to the machine and the dispersion is by forced –feed mechanism which works while the machine is applying the markings with the screed –Box., simultaneously and before the thermo plastic material (which is hot applied) becomes dry and cold while achieving road surface temperature. The type-2 glass beads conforming to the above noted specification shall be sprayed uniformly into a mono-layer on to the paint line at the rate of 250 grams per square meter area.

5.Precaution:

1.The strip shall not be slippery when wet.

2 .The marking shall not lift from the pavement in freezing weather.

3.After application and proper drying, the stripe shall shown no appreciable deformation or discoloration under traffic and under road temperatures up to 60º C.

4.The marking shall not deteriorate by contact with sodium chloride or oil drippings from traffic.

5.The stripe or marking shall maintain its original dimension and position. Cold ductility of the material shall be such as to permit normal movement with surface without chopping or cracking.

6.The marking shall be done with approved Material ONLY on dry pavement surfaces of minimum Temperature of 10º C.

7.The arrow marking shall be made using the approved material with specifically made stencils of shape and size.

6.Opening to traffic: Traffic will be opened after 24 hours.

 

 

 

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CONCRETE KERB CASTING METHOD STATEMENT

This Method Statement provides detail procedure for the laying of concrete Kerb as per the approved drawing.

  • Scope

This work consists of constructing cement concrete kerb in the central median and /or along the footpaths in conformity with the lines, levels and dimensions as specified in the drawings.

  • Responsibility

Section In charge will be responsible for quality control of the section for the construction of Kerb. Further field engineers, surveyors, supervisors and lab technicians will assist him.

  • Equipment

A continuous kerb casting equipment will be deployed capable of laying the kerb in required cross-sections and producing a well-compacted mass of concrete.

Where continuous casting with Equipment is not practicable, manual construction with suitable shutter will be done with the approval of the Engineer.

  • Procedure
  1. Lines and levels will be marked and the sensor of the kerb-casting machine will be adjusted accordingly. Pegs will be put at every 10 meters interval indicating the levels. These pegs will be joined with a metal wire.
  2. The concrete of Grade M20 to be used for kerb will be produced at the batching plant as per the approved mix formula.
  3. The concrete will be loaded on to the transit mixer directly from the batching plant and transported to the kerb location.
  4. Kerb casting will be laid on firm foundation of minimum 150 mm thickness of cement concrete of M10 grade cast-in-situ and extending 50mm beyond the kerb stone or over WMM surface as per site condition.
  5. Before laying the foundation with lean concrete, the base will be leveled and lightly watered to make it damp.
  6. The cast – in – situ kerb will be constructed in all situations except at location where continuous casting with Equipment is not practicable, manual construction with suitable shutter with the approval of the Engineer.
  7. In the median portions in the straight reaches, the kerb will be cast in continuous lengths. In the portions where footpaths are provided and /or the slope of the carriageway is towards median gap/recess will be provided in the kerb by cutting to facilitate drainage openings.
  8. After laying the kerbs and just prior to 6 to 8 hours after laying of the concrete, saw cut grooves will be provided at 5m intervals or as specified by the engineer.
  9. Curing of kerb will be done by applying curing compound / or any other suitable method
  10. Vertical and horizontal tolerances with respect to true line and level will be + 6mm.
  11. Saw joint groove mechanically cut to 3mm to 5mm wide.
  • Quality Control Testing and Acceptance

Quality control tests shall be done as per Quality Control Tests and Acceptance Criteria

 

 

 

 

 

 

 

 

 

 

 

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METHODOLOGY FOR WET MIX MACADAM

Wet Mix Macadam consist of laying spreading and compacting of clean, crushed, well-graded granular materials on a prepared and approved Granular sub-Base. The material is well mixed with water and rolled to a dense mass. It shall be laid on one or more layers as per line and level, grade and cross section shown in the drawing or as directed by the Engineer. The thickness of single compacted Wet Mixed Macadam (WMM) Base shall not be less than 75 mm. Maximum thickness of single compacted layer base can be up to 250 mm upon approval of Engineer.

1. Reference

2. Setting Out.

3. Selection of Material.

4. Equipments.

5. Methods of Operation.

6. Quality Control.

7. Work Safety.

8. Environmental Safety.


1.0 Reference

Reference Documents:-
I) Ministry of Road Transport& Highways Specifications
II) Technical Specifications
III) Relevant Drawings.
IV) IS 2720 Codes.

2.0 Setting Out

After the layer of GSB Sub-Base has been approved, then line and level are carried out to fix the Wet Mix Macadam base layer (herein after called WMM Base). Pegs are fixed at regular intervals on the safe side of the road edge where blade of grader should not disturb the peg while blending of the Base materials. On each peg’s top level of Base layer is marked. The chainage boards and working bench mark shall be set out side the limits of construction areas.

3.0 Selection of Material

3.1 Aggregate

Coarse aggregate shall be crushed stone or crusher run as per IRC 109 or clause 406.2.1 of MORT&H specification.

3.2 Physical requirement

The constituents of the aggregates shall be produced by integrated crushing and screening plant (Impact or Cone type) and, unless otherwise instructed by the Engineer, crushing shall be carried out in at least two stages. The fraction of material passing through 4.75mm sieve shall also be crusher run screening only. The aggregate shall conform to the physical requirements set forth in Table 400-12 of MORT&H. or IRC 109 clause 3.1.1
If the water absorption value test of coarse aggregate is greater than 2 per cent, the soundness test shall be carried out on the materials delivered to site.
3.3 Grading Requirement

The aggregate shall conform to the grading given in table 406.2.1.2 of technical specification or IRC 109 -2015. Material finer than 425 micron, shall have Plasticity Index (PI) less than 6. The final gradation approved within these limits shall be well graded from coarse to fine and shall not vary from low limit on one sieve to high limit of adjacent sieve or vice versa.

4.0 Equipments

The following equipments shall be carried out for the WMM

1. Wet Mix Macadam Plant

2. Dumper / Tippers.

3. Vibro Roller (80 to 100 KN)

4. Water Tanker

5. Paver capable of paving more than 9 meter width.

6. Survey kit / instrument

5.0 Method of Operation

5.1 Preparation of WMM Base (As per clause 406.3.1):

5.1.a Provision of lateral confinement of aggregates

Proper arrangement shall be made for the lateral confinement of wet mix during laying. This shall be done by laying materials on adjoining shoulder along with that of WMM layer. The preparation of mix, spreading of mix and compaction are done sequentially.
The sequence of operation shall be followed as described in clause: 406.3.3 of MORT&H.

5.2 Preparation of mix

Wet mix Macadam shall be prepared in an approved WMM mixing plant having provision for controlled addition of water and forced/positive mixing arrangement. Optimum moisture for mixing shall be determined in accordance with IS: 2720 (Part 8) after replacing the aggregate fraction retained on 22.4 mm sieve with materials of passing from 22.4 and retained on 4.75 mm. While adding water, evaporation loss shall also be taken into account. The mixed material should be uniformly wet and no segregation shall be permitted.

5.3 Spreading of mix

Immediately after mixing, the aggregate shall be spread uniformly and evenly upon the approved GSB layer. Materials should neither be dumped in heap nor their hauling over a partly completed stretch. The first layer will be laid by motor grader and the second layer mix shall be spread by a WMM paver finisher capable of paving minimum 4.5m to 9.0m width. The layer may be tested by depth block during construction. No segregation of materials are allowed. The aggregates should be of uniform gradation with no pockets of fine materials.

5.4 Compaction

After the mix has been laid on site to the required thickness, grade and camber, then compaction is carried out with suitable roller to the full depth. For a thickness up to 200mm in a single layer, compaction shall be done with vibratory roller of 80 to 100 KN static weights with plain drum or equivalent capacity roller. Rolling is done from lower edge towards upper edge longitudinally for the portion having unidirectional cross fall and super elevation.
Each pass of the roller shall uniformly overlap not less than one third of the track made in the previous pass. During rolling, grade and cross fall shall be checked and any high spot or depressions, which become apparent, corrected by adding or removing fresh materials. The speed of roller shall not exceed 5km/h. Rolling shall be continued till the density of the layer is achieved 98% of the Maximum Dry Density.
Rolling should not be done when the WMM layer is soft or yielding or when it causes a wave like motion. If level difference or irregularities develop during rolling which exceeds 12 mm when tested with 3 metre straight edge, the surface should be loosened and premixed materials added or removed as required before rolling again. In no case the unmixed material be permitted to make up the depressions.

5.5 Opening to traffic

After testing the compaction & level of WMM course the road shall be allowed to dry for 24 hours. Preferably no vehicular traffic should be allowed on the finished WMM surface till it has dried and covered with wearing course.

6.0 Quality Control

Table 400-12 Physical Requirement of coarse aggregate for Wet Mix Macadam for Sub-base /Base Courses

 406 WET MIX MACADAM SUB BASE /BASE

     Table 400- 13: Grading Requirement of Aggregate for Wet Mix Macadam

  1. Control Tests for Granular WMM Base: Post Construction
  2. Tolerance in Surface Level                                             : +10 mm
  3. permissible undulation (with 3 m straight edge) : 8 mm
  4. no. of undulations permitted in any 300 m length, exceeding 12 mm: 20
  5. Control on quality of materials and works shall be in accordance to section 900 of MORT&H.

7.0     Work Safety

 1.Safety will be provided location specific safety plan.

8.0   Environmental Safety

1.Nearby Streams, water courses, lakes, reservoir shall be protected from contamination by the soil erosion from areas exposed during excavation by constructing temporary berms, dykes, sediment Basins, slopes, drains & by the use of temporary mulches, seeding or other control devices.

2.Vehicles tracks shall be kept moist to prevent flying of dust particles with the vehicle movement.

 

 

 

 

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Method Statement of Longitudinal Drain

The Scope of this work covers the following activities:
The excavation necessary for construction of Longitudinal Drain as per Section 300 MORT&H Specifications.
The selection of various construction materials, testing of materials, approvals and quarry selection, testing and approval of various grades of materials etc. conforming to section 1000 MORT&H Specifications
The construction of Longitudinal Drain with reference to, Section 300, Section 1000, Section 1500, Section 1600 and Section 1700 of MORT&H Specifications.

1.0 Materials
2.0 Plant, Equipment and Machinery
3.0 Construction Operations
3.1 Survey and Setting Out Works
3.2 Shop Drawing submission
3.3 Construction of Longitudinal Drain
3.3.1 Excavation
3.3.2 Bedding for Longitudinal Drain
3.3.3 Construction of Longitudinal Drain Base slab (Raft) by Cast-in-Situ Method
3.3.4 Construction of Longitudinal Drain walls – Stage 2
3.3.5 Construction of Longitudinal Drain by Precast Drain Method
3.3.6 Spreading, Compaction and Testing for Backfilling Material on both sides of Longitudinal Drain Backfilling behind Structure
4.0 Work Safety
5.0 Records

1.0 Materials:

• Ordinary Portland 43 Grade conforming to IS 8112, or 53 Grade Cement conforming to IS 12269.
• Coarse Aggregates, Sand / Fine Aggregates as per IS 383 and the tests shall be carried out as per IS 2386.
• The formwork material shall comply with IRC 87.
• Reinforcement steel bar shall be Fe 500 grade and conforming to IS: 1786.
• Water conforming to section 1010 MORT&H Specifications

2.0 Plant, Equipment and Machinery:

The following plant and equipment are necessary for the planned progress: –
a) Batching Plant.
b) Transit Mixers.
c) Needle Vibrators.
d) Slump cone and concrete test cube moulds.
e) Concrete Pump and Crane bucket.
f) JCB/Excavator.
g) Tippers/Dumpers.
h) Steel Shutters as formwork.

3.0 Construction operations.

3.1 Survey & Setting out Works

The limits for excavations shall be set out true to lines, curves, slopes, grades and sections as shown on the drawings or as directed by the Engineer and using established Bench Marks / Co-ordinates. All the Survey Instruments used shall be calibrated periodically as per the Calibration Plan. Survey Check Reports and other relevant data shall be maintained in relevant inspection formats.

3.2 Drain drawing submission

The  drawing for the Longitudinal Drain shall be made with the Invert levels shown with the indication of type of bedding as specified on the working drawing.
Before any construction work is being carried out, the Contractor must submit an elevation of the Invert Level showing the length to be constructed and the following details to be incorporated on the shop drawing:-
• The existing ground profile.
• Founding levels at the base.
• Invert levels of Longitudinal drain from one point at downstream to upstream.
• The invert levels of the longitudinal drain intersecting the box culvert
• The Longitudinal drain bar bending schedule should be submitted together the shop drawing.
• The Engineer’s approval for the shop drawing and bar bending schedule should be obtained well in advance of the scheduled start date of the Longitudinal Drain.

3.3 Construction of Longitudinal Drain

3.3.1 Excavation

The foundation bed for the Longitudinal Drain shall be excavated true to the lines and grade as set out. It shall be executed to provide sufficient room for steel shutters.

3.3.2 Bedding for Longitudinal Drain

The bedding surface of filling area must be a firm ground of uniform density throughout the length of the drain. It shall be compacted and tested so that it is good for the PCC to be laid on it.
The bedding surface of cutting area shall be clean and free from loose materials. Then lay the PCC to required thickness and dimensions. The finished surface should be uniform in thickness.

3.3.3 Construction of Longitudinal Drain Base slab (Raft) by Cast-in-Situ Method

The base slab dimensions shall be marked on the PCC.
After the above step is satisfactorily completed, fix the base slab reinforcement which were cut and bend in conformity with the bar bending schedule. Concrete covers shall be uniformly spaced at the bottom to support the reinforcement.
Clean up any debris in the PCC by blowing out any foreign materials not permitted.
All temporary shuttering shall be checked so that they are securely fixed.
When the approval to go ahead with concreting is obtained from the Engineer, order the calculated quantity of concrete for the pour.
The concrete should be uniformly vibrated with a needle. Conduct the routine slump checks and make test cubes as directed by the Engineer.
25mm Expansion joint gap to be provided at every 40 m interval to be filled with Salutex board and filler material (water proof).
Upon completing the concreting it is essential to cure the concrete with potable water on the next day and regularly do so for the next 7 days.

3.3.4 Construction of Longitudinal Drain walls – Stage 2

1.Tie the wall reinforcement which were cut and bend as per the bar bending schedule. When the Contractor is satisfied that the preparation is ready for inspection, submit a request to the Engineer for reinforcement inspection by raising a RFI.

2.Fix the steel shutters forms for the walls for stage 2 concrete after obtaining approval from the Engineer on the wall reinforcement. The steel shutters must be properly fixed and fastened together. Attention must be given to external lateral bracings are sufficient and would prevent bulging of concrete. Check that all gaps between steel shutters are properly plugged to prevent leaking of concrete slurry during vibration of the concrete. Next, when the Contractor is satisfied that the preparation is ready for inspection, submit a request to the Engineer for inspection by raising a RFI.

3.The Engineer carries out his inspection and approval given to proceed. Order, pour and vibrate the concrete in an acceptable manner specified by MORT&H Specifications. The concrete should be uniformly vibrated with a needle. Conduct the routine slump check and make test cubes as directed by the Engineer.

4.Upon completing the concreting it is essential to cure the concrete with water the next day regularly and continuously for the next 7 days.

3.3.5 Construction of Longitudinal Drain by Precast Drain Method

1.The base of the drain shall be formed with sand compacted to the required gradient.The drain centre line shall be maintained with the use of a string tied to wooden pegs from the downstream end to the upstream end.

2.The precast drain already lined up along the edge of the trench shall then be lifted by a JCB, equip with two steel rope (or acceptable slings) for lifting, and put in place in the trench.

3.The string shall be the guide in installing the precast drain unit from downstream to upstream.

4.The joints between drains shall be sealed with cement/sand mortar.

5.The next step is to construct the upper part where the reinforcement has been left for overcoming variation in depth of the Longitudinal Drain. This portion of work shall be constructed by the cast-in-situ method described in 3.3.3.

3.3.6 Spreading, Compaction and Testing for Backfilling Material on both sides of Longitudinal Drain

1.Back filling behind the drain shall be carried out as per the Clause 305 in MORT&H.

2.Back fill materials from approved Borrow areas will be spread in Layers to get 150 mm compacted thicknesses for the required length and width.

3.The required Cross Slope and Gradient shall be maintained as per drawings.

4.In areas where using vibratory rollers is not possible to carry out the compaction, suitable means like mechanical tamper, rammer, plate vibrator etc. shall be used for the compaction.

5.The frequency of testing and the type of tests to be conducted on compacted Backfill behind structures shall be as per MORT&H Specifications.

4.Work Safety Plan

The construction area occupied by the longitudinal drain shall be cordoned off from other earth moving plant working in the vicinity with warning tape. The contractor’s site safety team must conduct regular checks to see that the safety put up is in working condition at all times.

If concrete pouring has to continue beyond daylight, proper lighting should be organized ahead and standby for use when necessary.

Safety will be provided as per location specific safety plan.

6.Records

All records should be carefully documented and kept on all items of works so that when making payment to the Contract it is in order.

 

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METHOD STATEMENT FOR DENSE BITUMINOUS MACADAM (DBM)

This work shall consist of laying in a single course a 50 to 100 mm – thick layer of DBM on a previously primed and approved Wet Mix Macadam Layer, as per specified lines & grades and in accordance with clause 507 of MORT&H specification or project specification.

1. REFERENCE DOCUMENTS.

2. MATERIALS.

3. MIX DESIGN.

4. PLANTS & EQUIPMENTS.

5. CONSTRUCTION OPERATIONS.

6. ARRANGEMENT FOR TRAFFIC.

7. QUALITY CONTROL

1. REFERENCE

Reference Documents:-
1. Ministry of Road Transport & Highway Specifications.
2. Technical Specifications
3. Relevant Drawings.

2. MATERIALS

The source and test report of all material will be submitted to the Engineer for approval before using the material as per clause 505.2 of MORT&H.

2.1 Bitumen

Bitumen shall be Viscosity grade or as per specified in the contract .

2.2 Coarse Aggregates

Coarse aggregate shall be obtained from the approved quarry. One cone crusher shall be installed at the quarry site. This crusher shall produce aggregates cubical / angular type so that flakiness and elongation indices are contained within the specified limit. The coarse aggregate shall satisfy specification as per Table 500-8

2.3 Fine Aggregate

Fine aggregates shall be of the fraction passing 2.36 mm sieve and retained on 75 micron sieve, consisting of crusher run screening, sand or a mixture of both. Natural sand is not allowed as a fine aggregate in bituminous mix.

2.4 Filler
Filler shall consisting of crusher dust, hydrated lime, or cement and shall satisfy the grading limit set in Table 500-9.The PI should not be more than 4.However, It is not applicable in case , if filler is Lime or Cement.
Where aggregate fails to comply the water sensitivity test then 2% by weight of aggregate lime or cement is required.

3. MIX DESIGN

3.1 Requirement of Mix

Apart from conformity with grading and quality requirements of individual ingredients, the mix shall meet the requirements set out in Table-500-11, MORT&H specifications. .Job mix formula shall be submitted 21 days in advance when going to start the bituminous work.

3.2 Binder Content

The binder content shall be determined to achieve the requirements set out in Table-500-10, MORT&H specifications and traffic volume specified in the contract. The Marshal method for determining the optimum binder content shall be adopted as described in the Asphalt Institute Manual MS-2.If the specific gravity of aggregate is more than 2.7 ◦C The minimum bitumen content can be reduced subsequently. Where the maximum size of aggregate is more than 26.5 mm , the modified marshal test by using 150 mm diameter mould as specified in MS-2 and ASTM D 5581 shall be used. When the modified procedure is used. The minimum stability should be multiplied by 2.25 and minimum flow should not be less than 3mm.

3.3 JOB MIX FORMULA

Job mix formula should be as per clause. 505.3.3 The .Job Mix formula should be true representative of material used and satisfy all the criteria set forth in Table 500-10 & 500-11.

3.4 Plant Trials

After the job mix formula approved plant trial should be done to confirm the bituminous mix design. The formula should be within limit as per set forth in Table 500-13 and shall satisfy the quality control criteria as per section 900. or project specification

4. PLANTS & EQUIPMENTS

1. Crusher of required capacity
2. Hot Mix Plant
3. Paver with sensor arrangement and capable of paving 9 meter width of mat.
4. Steel Tandem Rollers with required weight
5. Pneumatic Roller with required weight
6. Bitumen Sprayer
7. Dumpers
8. Air compressor
9. Pegs for putting levels
10. Mechanical broom
11. Straight edge
12. Camber plate
13. Thermometer
14. Gauge for checking thickness
15. Survey Kit / instrument.

5. CONSTRUCTION OPERATIONS

5.1 Weather and Seasonal Limitations

The work of laying shall not be taken up during rainy or foggy weather/ the base course is damp or wet or during dust storm or when the atmospheric temperature in shade is 10 deg. or less as specified in clause 504.3.1 0f the MORT&H specifications.

5.2 Preparation of Base

The WMM surface already prepared to the specified lines, grades and cross sections shall be swept clean free from dust and foreign matters using mechanical broom or blown off by compressed air as specified in the MORT&H specifications.

5.3 Tack Coat
The binder for tack coat shall be RS-I Grade Emulsion and shall be applied as per clause 503 of the MORT&H specifications.

5.4 Preparation and Transportation of Mix
DBM should be produced on batch basis by weight in Hot Mix Plant. The mixing will be done in a twin shaft pug-mill, which will produce a homogeneous mix.
The mixture shall be transported from the batching plant in tippers covered with tarpaulin (if required) so as to maintain the temperature and dust.

5.5 Spreading

The mix shall be transported to the site by the dumpers, which shall slowly discharge the mix in the paver hopper, while both the tipper and paver will move forward steadily and slowly. The automatic sensor shall ensure that the mix is being laid to the proper line and grade and level. The direction of the paver will be guided by the string lines fixed with the stack
& arms on both sides of the edges 0.5 m away from the edge. The paving will be done in one go for the full width of 9 meter. The minimum temperature of the mix at the time of laying shall be VG30/VG40——- 140°C/160 °C .
Transverse joints shall be cut vertically with asphalt cutter and a coat of hot bitumen shall be applied before placing materials.

5.6 Compaction

As soon as the mix has been laid to the paver, compaction shall be done with the help of a set of rollers moving at a speed not exceeding 5 km/hour following close to the paver. Rolling sequence will be as under or as established during laying trial stretch.
Compaction subsequently completed before the temperature falls below the minimum rolling temperatures VG30/VG40——90°C/100 °C.
Longitudinal joints shall be rolled immediately behind the paving operation. After this, rolling shall commence at the edges and progress towards the centre longitudinally except that on super elevated and unidirectional cambered portions, it should be started from the lower edge to the upper edge & parallel to the centre line of the pavement. Rolling shall be done continuously until all roller marks have been removed from the bituminous surface.
i) Initial or breakdown rolling shall be done with 80-100 KN dead weight smooth wheeled rollers.
ii) Intermediate rolling shall be done by 8-10 tons dead weight or vibratory roller or with a pneumatic tire roller of 12 to 15 tons weight having nine wheels, with a tyre pressure of at least 5.6 kg/sqcm. The finish rolling shall be done with 6 to 8 tons smooth wheeled tandem rollers and the no. of passes required shall be decided after laying a trial bed.
During rolling, wheels of rollers shall be kept moist by sprinkling water from the water storage fitted with the roller to prevent the mix from adhering to the wheels. The roller shall proceed on the fresh material with rear or fixed wheel leading so as to minimize the pushing of the mix.
In portions in camber, rolling should begin at the edge with the roller forward and backward until the edges have been firmly compacted. The roller shall then progress gradually towards the center parallel to the center line uniformly overlapping each of the preceding tracks by one-third width until the entire surface has been rolled.
Along forms, kerb and walls where rolling cannot be done by rollers, shall be compacted with mechanical tampers or a plate compactor or rammers as may be feasible.
Any undulations / displacement found as a result of reversing of the direction of a roller or due to some other reasons shall be rectified as specified or removed and made good to the satisfaction of the Engineer.
All the field tests such as checking of compaction by core cutting, surface irregularity by using a straight edge and checking of cross slope by camber plate and level, rate of spray of tack coat / prime coat using trays, temperature of mix using digital thermometer. Depth of the layer using thickness gauge etc. shall be carried out as per the requirements.

6. ARRANGEMENT FOR TRAFFIC

The works shall be so executed that there is a minimum disturbance to the traffic. The traffic shall be diverted by making proper diversions at suitable locations and in accordance with clause 112 of MORT&H. Signboards indicating the locations of these diversions shall be fixed at desired positions.

7. QUALITY CONTROL

Following are the list of Control Tests to be carried out in the laboratory prior construction on DBM Materials:

Pre -construction activities of aggregates

Pre-Construction test for Filler

B) Frequency of tests to be performed during Construction of DBM

C) Allowable surface finish level Dense Graded Bituminous Macadam base layer: Post Construction:

Tolerance in Surface Level                                                                    : +6 mm

Max. Permissible undulation (with 3 m straight edge)            : 6 mm

Max. no. of undulations permitted in any 300 m length, exceeding  10 : 20 mm

Control on quality of materials and works shall be exercised by the Engineer in accordance with section – 900 of MORT&H.

 

 

 

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WORKING METHOD STATEMENT OF GRANULAR SUB BASE (GSB)

Granular-Sub-base is often used as subbase layer of the pavement . The main role of this layer is to spread evenly the load over the subgrade .The subbase shall consist of a uniform mixture of granular material placed on a subgrade, uniformly moistened, shaped, and compacted, all in accordance with the contract documents.The work shall consist of laying and compacting of well-graded materials on a prepared and approved sub-grade. Materials shall be laid in one or more layers as per line and level, grade and cross section shown in the drawing and as per clause 401 of MORT&H specification.In the following sequence we had to carry out the work:   

 1. Reference

2. Setting Out.

3. Selection of Material.

4. Equipments.

5.Methods of Operation.

6.Quality Control.

7.Work Safety.

8.Environmental Safety. 

1.0 Reference

Reference Documents:-

I) Ministry of Road Transport& Highways Specifications

II) Technical Specifications

III)   Relevant contract drawings.

IV) IS 2386 Codes.

2.0 Setting Out

After the layer of Sub-grade has been approved, then line and level are carried out to fix the granular sub-base layer (herein after called GSB layer). Pegs are fixed at regular intervals on the safe side of the road edge where blade of grade will not disturb the peg while blending of the GSB materials. On each pegs top level of GSB layer is marked. The chainage boards and working bench mark shall be set outside the limits of construction areas.

3.0 Selection of Material

3.1 Material

The material used in GSB shall be mixture of natural sand, moorum, gravel, crushed stone in specified grading given in Table 400‑1.Crushed slag, crushed concrete, brick ballast and kankar can also be used on the prior approval of the Engineer or competent authority. It shall be free from organic or other deleterious materials. The material for GSB shall be obtained from the approved source and shall be in accordance with clause 401 of MORT&H specification.

3.2 Physical requirement

The material shall have Impact Value 40% Maximum when tested in compliance with IS: 2386(Part 4) or IS 5640. The water absorption value of coarse aggregate shall be determined as per IS: 2386 (Part 3); if the value is greater than 2%, the aggregate shall be tested for wet Impact value (IS 5640).

The Contractor shall before the commencement of the construction of the sub-base course, submit to the Engineer, the results for approval of the laboratory testing on the physical properties defined above. The construction of the sub-base course shall be taken up only upon the Engineer’s approval of the material.

3.3 Strength of GSB

Prior to actual execution, it shall be ensured the material to be used in sub-base satisfies the requirement of CBR and other physical requirements when compacted and finished as per table 400-2.The minimum CBR 30% is required.

4. Equipments

The following equipments shall be carried out for the Sub grade Construction:

  1. Excavator
  2. Dumper
  3. Motor Grader
  4. Vibro Roller (80 to 100 KN) and pneumatic tire roller (200 to 300 KN weight with minimum tire pressure of 0.7 Mpa)
  5. Water Tanker
  6. Tractor trolleys
  7. Survey Kit / instrument

5.0      Method of Operation

5.1       Preparation of GSB

Prior to laying of GSB material, the sub-grade already finished to clause: 301 or 305 of MORT&H as applicable shall be prepared. Approved sub-grade layer is rolled with two passes by smooth wheel roller with slight sprinkle of water.

5.2       Spreading and compacting

The GSB Material is spread with the help of motor grader on the approved layer of Sub-grade in single layer of 200 mm with Grading either IV or V. During spreading and mixing by grader in site, water is sprinkled over the material by water browser mounted on water tanker. Sufficient water is added, taken into account of evaporation losses so that Moisture content of the materials should lie in between 1% to 2% of below optimum moisture content. Immediately rolling starts with vibratory roller of 80 to 100 KN static weight with plain drum or with pneumatic tire rollers of 200 to 300 KN weight having tire pressure of minimum 0.7 Mpa. Rolling is done from lower edge towards upper edge longitudinally for the portion having unidirectional cross fall and super elevation.

Each pass of the roller shall uniformly overlap not less than one third of the track made in the previous pass. During rolling, grade and cross fall shall be checked and any high spot or depressions, which become apparent, corrected by adding or removing fresh materials. The speed of roller shall not exceed 5km/h. Rolling shall be continued till the density of the layer is achieved at 98% of the Maximum Dry Density.

5.3       Arrangement of traffic

During the period of construction, arrangement of traffic shall be maintained as per clause 112.

6.0 Quality Control

Control Tests for Granular Sub-Base: Post Construction

  1. Tolerance in Surface Level                                              : +10 mm, -20 mm
  2. permissible undulation (with 3 m straight edge) : 8 mm
  3. no. of undulations permitted in any 300 m length, exceeding 16 mm:20

Control on the quality of materials and works shall be exercised by the Engineer in accordance with section 900 of MORT&H.

7.0     Work Safety :  Safety will be provided as per location specific safety plan.  Following safety point should be kept in mind when using Motor Grader

1.Drive at a slow speed in congested areas.

2.Give the right-of-way to loaded vehicles. Watch for    overhead dangers.

3.Know your work area: check weight limitations, types of surfaces, and clearances.

4.Report defective equipment immediately Select a safe parking area.

5.Remove ignition key when leaving grader.

6.Ground the blade when leaving grader unattended.

7.Use colored flags at each end of mould board when blading

8.0     Environmental Safety

1.Nearby Streams, water courses, lakes, reservoir shall be protected from contamination by the soil erosion from areas exposed during excavation by constructing temporary berms, dykes, sediment Basins, slopes, drains & by the use of temporary mulches, seeding or other control devices.

2.Vehicles / tracks shall be kept moist to prevent flying of dust particles with the vehicle movement.

 

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METHODOLOGY FOR SUBGRADE CONSTRUCTION

Subgrade is the main part of the any  earth work .They are widely used in  road, railway and airport runway construction but here we will discuss sequence wise working methodology for the earthwork in subgrade for any highway work. 

  1. Scope of Work
  2. Reference Documents.
  3. Setting Out.
  4. Selection of Material & Borrow areas.
  5. Equipments.
  6. Methods of Operation.
  7. Quality Control.
  8. Work Safety
  9. Environmental Safety

 1.0 Scope of Work:-

The work shall consist of Construction of Sub-grade with approved and specified materials obtained from approved borrow areas or suitable material obtained from roadway excavation and drain excavation and in accordance with clause 305 of MORT&H specification.

2.0 Reference: –

Reference Documents:-

  1. Ministry of Road Transport & Highway Specifications.     
  2. Technical Specifications
  3. Relevant contract drawings.
  4. IS 2720 Codes.

3.0 Setting Out:

After completion of site clearance/embankment the limits of sub-grade shall be marked by fixing pegs on both sides at regular intervals. The chainage boards and working bench mark shall be set outside the limits of construction areas.

4.0 Selection of Material and Borrow areas: –

4.1 Material:                              

The material used in Sub-grade shall be soil, moorum, gravel, a mixture of these or any other material approved by the Engineer. It shall be free from logs, stumps, roots, rubbish & any other material detrimental to the stability of structure. The material for sub-grade shall be obtained from the approved source with preference to the material becoming available from nearby roadway excavation or any other excavation under the contract. The material requirements shall be in accordance with clause 305.2 of MORT&H.

4.2 Borrow Material:

Samples should be taken from the known borrow area & to be tested as per IS 2720 for the suitability in use in embankment as per project specification. On confirmation of the suitability material the area shall be properly demarcated and satisfy the clause 305.2.2.2 or project specification

5.0 Equipments: –

The following equipments shall be carried out for the Sub-grade Construction. If desired the contractor shall demonstrate the efficacy of the type of equipment to be used, before commencement of work.

  1. Hydraulic Excavator
  2. Dozer
  3. Dumper (Tipper Trucks)
  4. Motor Grader
  5. Vibratory Roller
  6. Water Tanker
  7. Tractor Trolleys
  8. Survey Kit

6.0 Method of Operation: –

  • After completion of embankment, the limits of sub-grade shall be marked by fixing pegs at regular intervals  before commencing the earthwork. Construction toe line shall be more than the design toe line for proper construction of the edges.
  • The Embankment top shall be levelled to facilitate placement of first layer of Sub-grade, scarified, mixed with water and then compacted by rolling so as to achieve minimum dry density as specified in the modified Technical specification. Sub-grade treatment specified for Sub-grade shall be carried out as per approved drawing. Unsuitable material occurring in sub-grade foundation shall be removed as per direction and approval of the Engineer and replaced by approved materials laid in layers and suitably compacted to the required and specified degree of compaction. Excavation at approved borrow areas shall be carried out with excavator and transportation of excavated material shall be done by dumpers/ tractor trolley.
  • Maximum Dry density of borrow area soil shall be determined, and the soil shall be tested for dry density, if found less than 97% of M.D.D., the layer shall be scarified mixed with required quantity of water and compacted with soil vibratory roller to achieve minimum required specified dry density.
  • For construction adjacent to the existing embankment a continued, horizontal benching 300 mm wide or as per drawing shall be provided in the existing embankment.
  • The sub-grade material shall then be spread in layers not exceeding 250 mm compacted thicknesses or as per direction of the Engineer over the entire area with the dozer and finished by a motor grader. When the existing embankment to be widened continuous horizontal benches shall be cut out into the old slope to ensure adequate bond. Where water is required to be added the same shall be sprinkled from a water tanker fitted with sprinkler, uniformly on the surface but without flooding and shall be mixed thoroughly in soil by blending or harrowing until uniform moisture content is obtained throughout the depth of the layer. If the material delivered to the roadbed is too wet, it shall be dried by aeration and exposure to the sun till the moisture content is accepted for compaction.
  • The compaction shall be done with the help of Vibratory Roller of 8 – 10 Ton static weight with plain or pad foot drum or heavy pneumatic tyred roller of adequate capacity capable to achieve required compaction. Compaction trial shall be carried out on a suitable stretch to determine the no. of passes required for particular type of soil, dumped for sub-grade, to achieve densities specified in the table 300-2 of the Technical specification. Based on the trial actual compaction will be carried out with required no. of passes of Vibratory Roller until the specified density is achieved. Rolling shall progress parallel to the centerline of the road uniformly overlapping each preceding track by one-third width. Rolling shall be continued till the specified density is achieved as per table 300-2. In case specific compaction is not achieved the material in the soft area shall be removed and replaced with approved material. Densities shall be tested by sand replacement method / nuclear density gauge.
  • Subsequent layers shall be placed only after the finished layer has been tested as per the clause 903.2.2 and accepted. The top levels of the sub-grade shall be checked with reference to the longitudinal and cross profile of the road as per drawing to keep the variation within tolerance limit as per table 900-1. or as per standard specification.

7.0 Quality Control:-

Minimum compaction for sub-grade layers is 97% of modified proctor value of project specification.

8.0    Work Safety:-                   

8.1  During construction of widening works, adequate safety and traffic signs shall be installed adjacent to the road shoulders to protect the ongoing works as per location specific safety plan.

8.2  For locations where the dumping of embankment  materials by tippers are performed from the road shoulder, a minimum of 2 flagmen with reflective vests and holding a red  flag each be deployed to control the traffic which may be affected by the  unloading operation.

8.3  All locations adjacent to existing road where embankment construction is in progress shall be provided with safety and road signs.

8.4  No machines or equipment’s shall be permitted to remain on the existing road or shoulder unattended at all times unless it is properly protected and secured in a safe manner.              

8.5  The Safety Officer shall make frequent patrols along the highway to ensure that the safety equipment and signs are operational at all time.

8.6  Trucks sometimes fall over a tip head because the driver backs over the edge or the edge collapses under the weight of the truck. A protective berm or timber baulk should be used. Alternatively,  a signalman should be deployed in order to avoid this possibility.

8.7  When excavating trenches, place the excavated material at least 600 mm clear of the edge, where there is no danger of it falling back into or collapsing the side of the trench.

9.Environmental Safety: –

a.Nearby streams, water courses, lakes, reservoir shall be protected from contamination by the soil erosion from areas exposed during excavation by constructing temporary berms, dykes, sediment Basins, slopes, drains & by the use of temporary mulches, seeding or other control devices.

b.Vehicles tracks shall be kept moist to prevent flying of dust particles with the vehicle movement.

 

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CONCRETE MIX DESIGN OF M25 GRADE – AS PER IS 10262:2019

1.STIPULATIONS FOR PROPORTIONING

a) Grade designation : M 25 RCC

b) Type of cement : 43 grade Ordinary Portland Cement conforming IS 8112

c) Maximum nominal size of coarse aggregate : 20 mm

d) Minimum amount of cement  : 300 kg/m³ as per IS 456

e) Maximum water-cement ratio : 50 as per Table 5 of IS 456:2000

f) Workability : 75-125 mm slump

g) Exposure condition : Moderate (For Reinforced Concrete)

h) Method of concrete placing : Pumping

j) Degree of supervision : Good

k) Type of aggregate : Crushed Angular Aggregates

l) Chemical admixture type : Super Plasticizer Normet

2.TEST DATA FOR MATERIALS

a) Cement used : Sagar 43 grade Ordinary Portland cement conforming IS 8112

b) Specific gravity of cement : 3.14

c) Chemical admixture : Super Plasticizer conforming to IS 9103 

d) Specific gravity of

1) Coarse aggregate 20 mm : 2.799

2) Coarse aggregate 10 mm: 2.789

3)Combined Specific Gravity of aggregate ( 20 mm- 60% & 10 mm 40 % )=2.795

4) Fine aggregate : 2.517

e) Water absorption:

1) Coarse aggregate 20 mm : 0.41 %

2) Coarse aggregate 10 mm  : 0.59 %

3) Fine aggregate           : 1.87 %

f) Aggregate Impact Value : 20.52%

g) Combined Flakiness & Elongation Index : 27.57 %

h) Sieve analysis:

1) Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383

2) Fine aggregate : Conforming to Grading Zone III of Table 4 of IS 383

3 TARGET STRENGTH FOR MIX PROPORTIONING

f’ck =fck + 1.65 s   Or  f’ck = fck + X  where

f’ck = average target compressive strength of concrete at 28 days,

fck = characteristics compressive strength of concrete at 28 days,

X   = Factor based on grade of concrete

S = standard deviation. From table 2 of IS 10262-2019  S = 4 N/mm² & from table 1 , X=5.5

Therefore target strength of concrete using both equation

.

a) f’ck= fck+ 1.65 S  = 25 + 1.65 x 4 = 31.60 N/mm²

b) f’ck = fck+ X        = 25 +  5.5 =  30.5 N/mm².

The higher value to be adopted , therefore target strength will be 31.60 N/mm². Can adopt  this value while doing the concrete mix design those who are working other than highway project.

But as per MORT&H Table 1700.5 required target mean compressive strength = 25 + 11 = 36.00 N/mm²  where 11 is the current margin. Adopt this value those who are working in highway project.

4. APPROXIMATE AIR CONTENT

From Table 3, the approximate amount of entrapped air to be expected in normal (non-air-entrained) concrete is 1.0 percent for 20 mm nominal maximum size of aggregate.

5 SELECTION OF WATER-CEMENT RATIO

From Fig. 1 of IS 10262 -2019, the free water-cement ratio required for  the target strength  of  31.60 N /mm²  is 0.48 may be used for OPC 43 grade curve. (For other than MORT&H)

Maximum water cement ratio required for the target strength of 36.00 N /mm²(As per MORT&H requirement)  is 0.44  from figure 1 of IS 10262-2019.

My suggestion & experience , never adopt higher water cement ratio  because it is the main reason for cube failure at site. In IS code , suggestion has been given for adopting the water cement ratio but concrete designer has to take the decision what to keep water cement ratio.

Based on trial & experience adopted 0.44 water cement ratio.

 This is lower than the maximum value of 0.50 prescribed for from the Table 3 of IS 456 maximum Water Cement Ratio for moderate condition

As per MORT&H, maximum water cement ratio is 0.45 for moderate condition  so 0.44 is satisfying  all codal provision  whether it is  IS 456 or MORT&H

0.44 < 0.50 < 0.45 hence ok.

6. SELECTION OF WATER CONTENT

From Table 4 of IS 10262:2019, maximum water content for 20 mm aggregate = 186 liter (for 25 to 50 mm slump range)

but for an increase by about 3 percent for every additional 25 mm slump so here estimated water content for 125 mm slump

= 186+(9/100) x 186

= 202 liter.       

Based on trials with Super plasticizer water content reduction of 23.76 % has been achieved . How it comes ,

We will see the back calculation

(Water requirement , if  we intended to keep cement 350 kg  &  w/c ratio 0.44 for our concrete mix design  calculated water will be 154 liter ,  so required reduction in water when using superplaticizer  = 100 – (154/202 x 100) = 23.76 %.)

Net required water = 202 (202 x 23.76) % = 202 – 48 = 154.0 litre

Note :For 75 mm slump increase 3% , for 100 mm increase 6% , increase 9 % for 125 mm slump, increase 12 % for 150 mm slump & increase 15 % for 175 mm slump

7 CALCULATION OF CEMENT CONTENT

As discuss earlier adopted  based on trial w/c Ratio = 0.44

Cement Content = 154/0.44 = 350 kg/m³

,from Table 5 of IS 456, minimum cement content for ‘moderate’ exposure conditions is 300 kg/m³  but taken  350 kg/m³ > 300 kg/m³ hence ok.

As per MORT&H 5th revision for moderate exposure  with reference to Table number 1700-2  maximum water cement ratio 0.45 & minimum cement 340 kg/m³ is specified but we had taken 350 kg/m³ , hence ok

but we had taken 350 kg/m³ > 340 kg/m³ hence ok. 

8 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

As per table number 5 of IS 10262:2019 volume of coarse aggregate for 20 mm nominal size aggregate and fine aggregate (Zone III) for having water-cement ratio of 0.50 =0.64 (a)

20 mm aggregate and fine aggregate (Zone III) for having water-cement ratio of 0.50 =0.64 (a)

In the present case water-cement ratio is 0.44. Therefore. volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. the proportion of volume of coarse aggregate is increased by 0.012 (at the rate of -/+ 0.01 for every ± 0.05 change in water-cement ratio).

= (0.06/0.05) = 1.2 times of 0.01 so  0.01 x 1.2 = 0.012 (b)

a+b = 0.64 + 0.012 =0.65  (at the rate of -/+ 0.01 for every ± 0.05 change in w/c ratio).

Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.44 = 0.65

For pumpable concrete these values should be reduced up to 10%. Therefore, volume of coarse aggregate =0.65 x 0.9 =0.585 or say 0.59

Volume of fine aggregate content = 1 – 0.59 = 0.41

9 MIX CALCULATIONS

The mix calculations per unit volume of concrete shall be as follows:

a)Volume of concrete = 1

b)Volume of the entrapped air in wet concrete =0.01m³ 

c) Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}

= 350/{3.15 x 1000} = 0.111

d) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}

= 154/{1 x 1000} = 0.154

e) Base on trial we had kept admixture 50 percentage by weight of cement(You can increase % admixture dosage as per requirement)

 Volume of admixture  = [Mass of admixture ] / {[Specific Gravity of admixture ] x 1000}

= 1.75 /{1.090 x 1000}

= 0.0016

f) Volume of all in aggregate = [(a-b)-(c+d+e)]

= [(1-0.01)-(0.111+0.154+0.0016)]= 0.99-0.250

= 0.723

g) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of coarse Aggregate x 1000

= 0.723 x 0.59 x 2.795 x 1000

= 1192.26 kg/m³

h) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.723 x 0.41 x 2.517 x 1000

= 746.11 kg/m³

10  MIX proportion

Cement = 350 kg/m³

Water = 154 l/m³

Fine aggregate = 746.11 kg/m³

Coarse aggregate 20 mm = 1192.26 x 60 %= 715.36 kg/m³

Coarse aggregate 10 mm  = 1192.26 x 40 %= 476.90 kg/m³

Chemical admixture = 1.75 kg/m³ 

Water-cement ratio = 0.44

11 CALCULATION

1.Aggregate 20 mm  = 715.26/ (1+(0.41/100)}           = 712.0 kg

2. Aggregate 10 mm = 476.90/ (1+(0.59/100)}         = 474.0 kg       

3.Sand                            = 746.11/ (1+(1.87/100)}           = 732.0 kg

4.Water                        = 2444 – 350 – 1.75 -732 -712 – 474  = 174.25 kg 

Can  say 174 kg  alternatively can calculate in the following manner.

 154+(746.11-732.0) +(715.26-712) +(476.90-474) = 154 + 14.11 + 3.26 + 2.90 = 174.27  or say 174 kg

Note 1.Do the trial in dry position as in practical in batching plant you can cot use aggregate in SSD condition.

2.Do the number of trials with variation of ± 10 percent of water-cement ratio & different cement content,

3.Do the surface moisture correction whenever required.

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EMBANKMENT CONSTRUCTION METHODOLOGY

Embankment are the main part of the any  earth work .They are widely used, e.g. as embankment dams for reservoirs,  as road, railway and airport runway embankments in transportation but here we are discussing sequence wise working methodology for the earthwork in embankment for highway work.

  1. Scope of Work 
  1. Reference Documents. 
  1. Setting Out. 
  1. Selection of Material & Borrow areas. 
  1. Equipments. 
  1. Methods of Operation. 
  1. Quality Control. 
  1. Work Safety 
  1. Environmental Safety 

1.0 Scope of Work:

The work shall consist of Construction of embankment with approved and specified materials obtained from approved borrow areas or suitable material obtained from roadway excavation and drain excavation and in accordance with clause 305 of MORT&H specification.

2.0 Reference: 

Reference Documents:

  1. Ministry of Road Transport & Highway Specifications for Road & Bridges.5th Revision
  2. IRC SP-87
  3. Technical Specification
  4. Relevant contract drawings.
  5. IS 2720 Codes

3.0  Setting Out: 

After completion of site clearance, the limits of embankment shall be marked by fixing pegs on both sides at regular intervals. The chainage boards and working bench mark shall be set outside the limits of construction areas.

4.0  Selection of Material and Borrow areas: 

4.1  Material:                                

The material used in Embankment shall be soil, moorum, gravel, a mixture of these or any other material approved by the Engineer. It shall be free from logs, stumps, roots, rubbish & any other material detrimental to the stability of structure. The material for embankment shall be obtained from the approved source with preference to the material becoming available from nearby roadway excavation or any other excavation under the contract. The material requirements shall be in accordance with clause 305.2 of MORT&H.

4.2  Borrow Material:

Samples should be taken from the known borrow area & to be tested as per IS 2720 for the suitability in use in embankment as per project specification. On confirmation of the suitability material the area shall be properly demarcated and satisfy the clause 305.2.2.2

5.0  Equipments: 

The following equipments shall be carried out for the Embankment Construction. If desired the contractor shall demonstrate the efficacy of the type of equipment to be used, before commencement of work.

  1. Hydraulic Excavator
  2. Dozer
  3. Dumper (Tipper Trucks)
  4. Motor Grader
  5. Soil Compactor
  6. Water Tanker
  7. Tractor Trolleys
  8. Survey Kit / instrument

6.0  Method of Operation: 

  • After completion of site clearance, the limits of embankment shall be marked by fixing pegs at regular intervals before commencing the earthwork. Construction toe line shall be more than the design toe line for proper construction of the edges .
  • The original ground shall be levelled to facilitate placement of first layer of embankment, scarified, mixed with water and then compacted by rolling so as to achieve minimum dry density as specified in the modified Technical specification. Foundation treatment specified for embankments shall be carried out as per approved drawing. Unsuitable material occurring in embankment foundation shall be removed as per direction and approval of the Engineer and replaced by approved materials laid in layers and suitably compacted to the required and specified degree of compaction.  Excavation at approved borrow areas as per clause 305.2.2.2 shall be carried out with excavator and transportation of excavated material shall be done by dumpers/ tractor trolley.
  • Natural ground soil shall be tested for its suitability. If found unsuitable it shall be replaced with the permission of the Engineer.
  • Dry Density of natural ground soil shall be determined, and natural ground shall be tested for dry density, if found less than 95% of M.D.D., the original ground shall be scarified and mixed with the required quantity of water and then compacted by vibratory roller to achieve minimum specified dry density.
  • For construction adjacent to the existing embankment, a continuous horizontal benching 300 mm wide or as per drawing shall be provided in the existing embankment.
  • The embankment material shall then be spread in layers not exceeding 250 mm compacted thicknesses when using vibratory roller over the entire area with the dozer and finished by a motor grader. When the existing embankment to be widened continuous horizontal benches shall be cut out into the old slope to ensure adequate bond. Where water is required to be added the same shall be sprinkled from a water tanker fitted with sprinkler, uniformly on the surface but without flooding and shall be mixed thoroughly in soil by harrowing until uniform moisture content is obtained throughout the depth of the layer. If the material delivered to the roadbed is too wet, it shall be dried by aeration and exposure to the sun till the moisture content is accepted for compaction. At the time of compaction the moisture content should be in the range of +/- ½ of OMC.
  • The compaction shall be done with the help of Vibratory Roller of 8 – 10 Tonne static weight. Compaction trial shall be carried out on a suitable stretch to determine the no. of passes required for particular type of soil, dumped for embankment, to achieve densities specified in the table 300-2 of the Technical specification. Based on the trial actual compaction will be carried out with required no. of passes of Soil Compactor until the specified density is achieved. Rolling shall progress parallel to the center line of the road uniformly overlapping each preceding track by one-third width. Rolling shall be continued till the specified density is achieved as per table 300-2.  In case specific compaction is not achieved the material in the soft area shall be removed and replaced with approved material. Densities shall be tested by sand replacement method / nuclear density gauge.
  • Subsequent layers shall be placed only after the finished layer has been tested as per the clause 903.2.2 and accepted. The top levels of the embankment shall be checked with reference to the longitudinal and cross profile of the road as per drawing to keep the variation within tolerance limit as per table 900-1.
  • Different layers of embankment will be marked on pillars fixed outside the toe-line.

7.0 Quality Control:

Minimum compaction for embankment layers is 95% of modified proctor value.

8.0    Work Safety:                

8.1   During construction of widening works, adequate safety and traffic signs shall be installed adjacent to the road shoulders to protect the ongoing works as per location specific safety plan.

8.2   For locations where the dumping of embankment  materials by tippers are performed from the road shoulder, a minimum of 2 flagmen with reflective vests and holding a red  flag each be deployed to control the traffic which may be affected by the  unloading operation.

8.3 All locations adjacent to existing road where embankment construction is in progress shall be provided with safety and road signs.

8.4 No machines or equipment’s shall be permitted to remain on the existing road or shoulder unattended at all times unless it is properly protected and secured in a safe manner.   

8.5 The Safety Officer shall make frequent patrols along the highway to ensure that the safety equipment and signs are operational at all time.

8.9  Trucks sometimes fall over a tip head because the driver backs over the edge or the edge collapses under the weight of the truck. A protective berm or timber baulk should be used. Alternatively,  a signalman should be deployed in order to avoid this possibility.

8.10  When excavating trenches, place the excavated material at least 600 mm clear of the edge, where there is no danger of it falling back into or collapsing the side of the trench.

9.Environmental Safety: 

a.Nearby streams, water courses, lakes, reservoir shall be protected from contamination by the soil erosion from areas exposed during excavation by constructing temporary berms, dykes, sediment Basins, slopes, drains & by the use of temporary mulches, seeding or other control devices.

b.Vehicles tracks shall be kept moist to prevent flying of dust particles with the vehicle movement.

 

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Methodology For Clearing & Grubbing

Clearing means the removal of all vegetation, while grubbing is the removal of roots that may remain in the soil.
This includes the removal of all logs, brush, and debris, further as grinding and removal of stumps.

We can divide all work sequence wise into 8 sections and discuss one by one:

  1. Scope of Work 
  1. Reference 
  1. Preservation of Property / Amenities 
  1. Equipment 
  1. Method Statement 
  1. Disposal of Material 
  1. Work Safety 
  1. Environment Safety 
  1. Scope of Work

The work shall consist of cutting, excavation, removing and disposing of all materials such as trees of girth up to 300 mm, bushes, shrubs, stumps, roots, grass weeds, rubbish etc. and top soil up to 150mm declared unsuitable by the Engineer, including draining out stagnant water if any from the area of road land, drain, cross drainage structure and other area as specified in the drawing or instructed by Engineer. It shall include necessary excavation & back filling of the pits, by suitable soil, resulting from uprooting of trees & stumps and making the surface levelled by suitable equipment and compacted by the power roller to required compaction as per Clause 305.3.4 of the Technical specification.  The work also includes handling, salvaging and disposal of cleared material. Clearing and grubbing shall be done well before starting the   earthwork operation and in accordance with requirement of project specification.

2. Reference

Reference Documents:-

I) Ministry of Road Transport & Highway Specifications

II) Technical Specifications.

3. Preservation of Property / Amenities

Suitable safeguards shall be ensured with the approval of Engineer to protect the road side amenities, erosion & water pollution by the exposed surface of slopes & cut formed during the clearing & grubbing operations, shall be prevented through the use of berms, dykes, sediment basins, slope drains, grasses or other suitable devices as per Clause 201.2 of MORT&H.

4. Equipments

The following equipments shall be used to carry out the Clearing & Grubbing operation.

  1. Grader
  2. Excavator / J.C.B.
  3. Tipper / Tractor Trolley.
  4. Rollers
  5. Water tankers
  6. Survey Kit / Instrument
  7. Dozer with all attachments.
5.0 Method of Operation

5.1 The toe line shall be jointly (both by contractor & consultant) established, with reference to the alignment based on the levels taken earlier. The area for clearing & grubbing shall be jointly identified, covering areas of road embankment, drains, cross drainage structures and such other areas as specified.

5.1 a.  Enumeration of Trees girth more than 300 mm falling within the Toe line shall be prepared and got approved for measurement prior to cut. Modes of measurement shall be done according to clause 201.5.

5.2   Trees up to 300 mm in girth and stumps and roots shall be removed by the suitable equipment or by manual labour means.

5.3   The Grader / Excavator / Dozer shall be deployed to remove all shrubs, bushes, vegetation, grass, weeds, rubbish and top organic soil not exceeding 150 mm in thickness, which in the opinion of Engineer is unsuitable for  incorporation in the work.

5.4.  The above machines & tools shall be deployed to carry out the Clearing & Grubbing operation and the bushes, stumps falling with in the excavation and fill lines shall be cut to the depth below ground level that in no case these fall within 500 mm of the sub grade, also all vegetation and deleterious matters unsuitable for use in the embankment & sub -grade should be removed between fill lines .

5.5  All branches of the trees extending above the highway shall be trimmed.

5.6  All excavation below the general ground level done to remove the trees shall be filled with suitable approved material and compacted to the density as required by the contract specification.

5.7   The existing soil of natural ground shall be tested for its suitability. In the event of the material nonconforming to the MORT&H specifications, it shall be removed and replaced with the approved material & compacted with Vibratory Roller to achieve the required density of 95%. In case where ground level is less than 0.5 M required density shall be 97%.

5.8  OGL will be taken after clearing and grubbing and compaction.

 6.Disposal of the Materials

6.1   Materials collected from Clearing and Grubbing is disposed off to the specified places as per the Engineer’s instruction.

6.2   Stacking of cleared stumps, branches & boulders shall be done neatly at the approved location up to a lead of 1000 M.

7. Work Safety

Safety aids shall be mobilized in required number to take care of the workers & of the adjoining road users.

7.1     Minimum of two flagmen with reflective vests holding a red flag each shall be deployed to control the traffic which may be affected by clearing & grubbing operations.

7.2   All locations adjacent to the existing road where clearing & grubbing is progressing shall be provided with visible safety & road signs.

7.3   No machines or equipments shall be permitted to remain on the existing road or shoulder unattended at all times unless it is properly protected & secured in a safe manner.

7.4  The safety Officer shall make frequent patrols along the highway to ensure the safety of equipment & signs are operational at all time.

7.5  Borrow pits shall not be dug in the right-of-way of the road. Also it has to be ensured that the borrow area is being placed in the prescribed zone at the site and also ensure about the soil characteristics of the borrow area like slope, ground water level etc.

8.Environmental Safety

1.Deleterious matters detrimental to the environment shall be disposed off at the designated locations as per direction of the Engineer.

2.Vehicles tracks shall be kept moist to prevent flying of dust particles with the vehicle movement.

 

 

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