**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)**

**M****aximum ****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 ****m³**

**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 ****m³**

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

**= ****154/{****1 x 1000} = ****0.154 ****m³**

**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 ****m³**

**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 ****m³**

**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.

What water cement ratio used if Mix design of grade M25 and cement is OPC 53 ?

Water cement ration is not fixed , it depends upon so many things.

Very nice,thanks for explanatory note on m30 mix design as I am lecturer in applied mechanics in govt.polytechnic,dhule maharashtra and I am teaching concrete technology for diploma students take practicals on design mix proportions as per is 10262

Thanks for appreciation.

Sir i saw your video and Google search this is very important for the civil thanks such type of video

Thanks for appreciation.

Can take water cement ratio 0.43 & Cement 350 kg

Sir,

I am a retired structural engineer. I went through the mix design a per latest code IS10262-2019.

Can you list out the difference to the present code to the old versions so that it can be clearly have good idea.