This article covers mix design calculations of M30 Grade Concrete with Fly ash admixture and Poly Carboxylite super plasticizer according to IS10262-2009. All high-strength concrete requires super plasticizers to achieve good workability and strength in concrete.
I. STIPULATIONS FOR PROPORTIONING OF M30 GRADE CONCRETE
Minimum cement content is selected based on the grade of concrete. Water content is selected based on the size of the aggregate and exposure contitions.
| A | Grade Designation | M30 | |
| B | Type of Cement | OPC 53 | |
| C | Type of Admixture | Fly Ash | |
| D | Maximum Nominal Size of Aggregate | 20mm | |
| E | Minimum Cement Content | 320kg | Table 5-IS456 As per code |
| F | Maximum Cement Content | 450kg | As per code |
| G | Partial replacement of cement by Fly Ash | 30% | as per requirement |
| H | Maximum W/C ratio | 0.45 | Table 5-IS456 As per code |
| I | Workability | 50mm | as per requirement |
| J | Chemical Admixture | Polycarboxylate Superplasticizers | as per requirement |
II. TEST DATA FOR MATERIALS
Materials should be tested to check their quality and to find their different physical and chemical properties.
| A | Cement Used | OPC 53 | Confirming to IS8112 |
| B | Specific Gravity of Cement | 3.15 | Test – IS: 2720 |
| C | Mineral Admixture | Fly Ash | Confirming to IS12089 |
| D | Specific Gravity of Fly Ash | 2.90 | |
| E | Chemical Admixture | @0.6% | IS9103 |
| F | Specific Gravity of | Test – IS 2386 | |
| Coarse Aggregate | 2.74 | ||
| Fine Aggregate | 2.74 | ||
| Admixture PCE based | 1.12 | ||
| G | Water Absorption | Test – IS 2386 | |
| Coarse aggregate | 0.5 % | ||
| Fine aggregate | 1 % | ||
| H | Sieve Analysis | Test – IS 2386 | |
| Coarse aggregate | Confirming to Table 2-IS383 | ||
| Fine aggregate | Zone II | Confirming to Table 4-IS383 |
III. TARGET STRENGTH FOR MIX PROPORTIONS OF M30 GRADE CONCRETE
Strength of the concrete may be affected by quality of the materials, mixing method and other factors not considered in the Mix Design. Therefore Target mean strength (Fck) of the concrete should be equal to the characteristic strength plus 1.65 times of standard deviation (IS456 Clause 9.2.2). The value of Standard deviation (S) for different grades of concrete is given in Table 1 of IS456.
| Fck | = fck+1.65s | “S” from Table1-IS10262 |
| Fck | = 30+(1.65 x 5) | |
| Fck | = 38.25 N/mm2 |
IV. SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio for different grades of concrete is given in Table 5-IS456. Water-cement ratio directly affects the strength of the concrete hence change in the water-cement ratio should be based on experience and research.
| Maximum W/C ratio | =0.45 | Table 5-IS456 |
| Adopted W/C ratio | =0.45 |
V. SELECTION OF WATER CONTENT
| Maximum Water Content | =186 L | Table 2-IS1026 for 25 to 50mm slump range |
With the help of Since superplasticizers, water content can be reduced to reduce the void ratio in concrete and increase the density of concrete. The percentage of reduction of water-content depends on the type of superplasticizer.
| Percentage of Reduction in water content | =15% |
| Water content requirement after SP | =186 – (0.15*186) |
| =158.1 | |
| Adopted Water Content | =160 L |
VI. CALCULATION OF CEMENT AND FLYASH CONTENT
| Adopted Water Cement Ratio | =0.45 |
| Total Cementitious (Cement +Flyash) requirement | = Water Content / WaterCement ratio |
| =160/0.45 | |
| =355.55 kg |
Since we are using fly ash the cementitious content (Cement+Fly ash) should be increased. We have increased the cementitious content here by 10 % based on research and experience.
| Final Cementitious Content (Cement+ Fly ash ) | = 356+(356*0.10) | |
| =391.6 kg | ||
| Minimum Cement Content required for ‘severe’ exposure | =320kg | Table 5-IS456 |
| Adopted Cementious content | =391.6 kg | > 320kg |
| Fly ash content requirement | = 391.6 * 0.30 | 30% replacement |
| = 117.48 ~ 118 kg | ||
| Cement Content requirement | =Cementious content – Fly ash | |
| =391.6-117.48 | ||
| = 274.12 ~ 274 kg |
Calculation of Super Plasticiers @ 0.6 percent to the mass of cementitious content = 391.6*(0.6/100) = 2.35 kg
VII COARSE AND FINE AGGREGATE
The standard coarse aggregate ratio is given in table 3 but this should be adjusted based on the water-cement ratio.
| Coarse Aggregate ratio | =0.62 | Table3-IS10262 (For W/C =0.5) |
| Coarse Aggregate ratio for 0.45 w/c ratio | =0.63 | |
| Final Fine Aggregate ratio | =0.37 | (1-0.63) = 0.37 |
VIII MIX CALCULATIONS OF M30 GRADE CONCRETE
| A | Volume of Concrete | = 1 cu.m |
| B | Volume of Cement | = Cement weight/(S.G*1000) |
| = 274/(3.15*1000) | ||
| = 0.086 cu.m | ||
| C | Total Volume of Fly ash | = Fly ash weight /(S.G*1000) |
| = 118/(2.9*1000) | ||
| = 0.041 cu.m | ||
| D | Volume of Water | = Water /(S.G*1000) |
| = 160/(1*1000) | ||
| = 0.160 cu.m | ||
| E | Volume of Superplasticizers | = S.P/(S.G*1000) |
| = 2.35/(1.12*1000) | ||
| = 0.002 cu.m | ||
| F | Total Aggregates requirement | = A – (B+C+D+E) |
| = 1 -(0.086 +0.041+0.160+0.002) | ||
| =0.71 cu.m | ||
| G | Coarse Aggregate (C.A) | = F * C.A ratio * S.G * 1000 |
| = 0.71*0.63 *2.74 *1000 | ||
| = 1225 kg | ||
| I | Fine Aggregate (F.A) | = F * F.A ratio * S.G * 1000 |
| = 720 kg |
Cement Fly ash Sand Aggregate Water and Superplasticizer needed for M30 grade concrete
| S.No. | MATERIALS | QUANTITY |
| 1 | Cement | 274 kg |
| 2 | Flyash | 118 kg |
| 3 | Fine Aggregate | 720 kg |
| 4 | Coarse Aggregate (20mm) | 1225 kg |
| 5 | WATER | 160 L |
| 6 | SuperPlasticizer | 2 L |
Mix Ratio of M30 Grade concrete by weight with fly ash admixture is Cement : Flyash: F.A : C.A : Water = 1: 0.43 : 2.6 : 4.47: 0.58
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