MixDesignCalc 2026 β Complete IS 10262:2019 Mix Proportioning Procedure: Every Step from Material Testing Through to Mix Design Report Documentation, with Formula Boxes, Decision Points, Adjustment Protocols and Full Example Calculations
IS 10262:2019 is India's primary standard for concrete mix design, specifying the Absolute Volume Method. The procedure consists of 11 sequential steps β each dependent on the results of the preceding steps. Shortcuts, reversals, or skipped steps produce incorrect proportions that cannot be verified by trial mix.
This page provides the complete proportioning procedure with full explanations at each step, the IS code references, formula boxes, decision protocols, and a running example (M30, Severe exposure, 100mm slump, 20mm crushed granite, OPC 53, PCE SP) throughout so you can follow a real calculation from start to finish.
Before any calculation can begin, the following data must be assembled. Some items come from IS 10262 tables (assumed values for preliminary design); others must be tested on the actual site materials before the final design is confirmed.
The single most common mix design error β using OPC Sg (3.15) for PPC or PSC cement β understates the cement volume by 8β9%, which shifts the aggregate proportion and voids the volume sum. PPC Sg β 2.89; PSC Sg β 2.90. Always test with IS 4031 Pt.11 (Le Chatelier flask) using actual site cement. If using silica fume: Sg β 2.20 (test by helium pycnometry per IS 15388 β water flask method underestimates by 10β15% for SF).
Concrete must be designed to a mean strength higher than the characteristic strength fck, because individual test results are variable. The design is based on achieving the mean such that 95% of results exceed fck β which requires the mean to exceed fck by 1.65 standard deviations (from normal distribution statistics).
| Grade of Concrete | Standard Deviation S (MPa) | Remarks |
|---|---|---|
| M10, M15 | 3.5 | Lean / plain concrete β lower variability expected |
| M20 | 4.0 | Residential RCC β moderate QC |
| M25, M30, M35 | 5.0 | Standard structural β assumed value before actual plant data |
| M40, M45, M50, M55 | 5.5 | Higher strength β tighter QC assumed |
| M60, M70, M80 | 6.5 | Very high strength β specialist production |
IS 10262 Table 1 values are for preliminary design when production data is unavailable. Once a batching plant has produced at least 30 cube results, the actual standard deviation should be calculated (IS 10262 Annex B) and used in place of Table 1. If actual S > assumed S, fcm increases β more cement required. If actual S < assumed S (better QC), fcm decreases β less cement needed β this is the economic incentive for better QC systems at concrete plants.
The design w/c is determined from two independent sources and the lower (more restrictive) value governs. The strength-based w/c comes from the w/cβstrength relationship for the specific cement type being used. The durability-based maximum comes from IS 456:2000 Table 5 for the exposure class.
Free water content (W) is the mass of water per mΒ³ of concrete that participates in the mix β it excludes water absorbed within aggregate pores (SSD condition). It is determined from IS 10262:2019 Table 2, which gives values for crushed angular aggregate as a function of MSA and target slump.
| MSA (mm) | 25β50mm slump | 51β75mm | 76β100mm | 101β125mm | 126β150mm | 151β175mm |
|---|---|---|---|---|---|---|
| 10mm | 208 | 215 | 222 | 228 | 234 | 240 |
| 12.5mm | 200 | 207 | 213 | 219 | 225 | 231 |
| 16mm | 196 | 200 | 206 | 212 | 218 | 223 |
| 20mm | 190 | 196 | 202 | 208 | 213 | 217 |
| 25mm | 184 | 188 | 193 | 199 | 204 | 208 |
| 40mm | 168 | 172 | 176 | 181 | 185 | 189 |
IS 10262 Table 2 gives water content for target slump at the point of placement β inside the formwork. For ready-mix concrete transported 30β45 minutes, slump at plant must be 25β40mm higher than placement target to account for transit slump loss. In hot weather (>35Β°C), add 10β20 L/mΒ³ more water to the Table 2 value, or use a slump-retention PCE formulation. Design the mix for placement slump, but dispatch from plant at higher slump.
Cement content is calculated from the design free water and the design w/c, then checked against two IS 456 limits. The governing (design) cement content is the maximum of the calculated value and the IS 456 minimum β then checked not to exceed the IS 456 maximum.
Before calculating aggregate volume, the volumes of superplasticizer and air must be established. This step is frequently skipped in manual calculations β but omitting it produces a mix that doesn't sum to 1.0 mΒ³ and overstates aggregate content. Both SP and air displace aggregate.
PCE SP in liquid form is typically 40% polycarboxylate solid dissolved in 60% water. When you add 3.31 L/mΒ³ of SP liquid, you are also adding 1.99 L/mΒ³ of water β beyond the design free water W. To maintain the design w/c, the batch water must be reduced by this amount. Failing to correct for SP water content raises effective w/c by approximately 0.005β0.012 units β significant for M30 (target w/c 0.45) and critical for M60 (target w/c 0.28).
In the Absolute Volume Method, each ingredient's volume = mass / (specific gravity Γ 1000). The sum of all ingredient volumes must equal 1.0 mΒ³ β this is the mathematical constraint that uniquely determines the aggregate content once cement, water, air, and SP are fixed.
Calculate V_paste = V_cem + V_water + V_air + V_SP. Normal range for standard structural concrete: 0.27β0.35 mΒ³/mΒ³ (27β35%). Below 0.27: likely too lean β workability problems, potential honeycombing. Above 0.35 for normal concrete: excessive shrinkage risk and heat generation. HSC with SF can accept 0.33β0.38 because the denser SF paste has different shrinkage characteristics. If your V_paste falls outside 0.27β0.38, recheck all specific gravity inputs β wrong Sg is almost always the cause.
The total aggregate volume from Step 6 must be divided into fine aggregate (FA, <4.75mm) and coarse aggregate (CA, >4.75mm). IS 10262:2019 Table 3 gives the percentage of FA by volume as a function of MSA and FA zone per IS 383:2016.
| MSA (mm) | Zone I FA% | Zone II FA% | Zone III FA% | Zone IV FA% |
|---|---|---|---|---|
| 10mm | 40 | 44 | 48 | 52 |
| 12.5mm | 36 | 40 | 44 | 48 |
| 16mm | 34 | 38 | 42 | 46 |
| 20mm | 32 | 36 | 40 | 44 |
| 25mm | 30 | 34 | 38 | 42 |
| 40mm | 28 | 32 | 36 | 40 |
Increase FA% by 2β4% if: mix is harsh or stiff despite meeting target slump; pumping problems; Zone III/IV sand being used.
Decrease FA% by 2β4% if: excessive bleeding; segregation of CA; mix appears "fatty" (sticky, over-cohesive).
Pump mixes: add 3β5% to Table 3 FA% for reliable pumpability β more paste and fines reduce pipe friction.
Round gravel: reduce FA% by 2β3% (rounder particles need less fine material to achieve cohesion).
IS 10262 Table 2 water contents assume SSD (Saturated Surface-Dry) aggregate condition β pores full of water but surface dry. In practice, aggregates are almost never at SSD during production. They may be wet (surface moisture above SSD) or air-dry (below SSD). The batch water must be corrected, and aggregate masses adjusted correspondingly. This step is performed in the mix design report AND at every batching plant batch throughout production.
A FA surface moisture of 2.5% on a 675 kg/mΒ³ FA content adds 16.9 kg/mΒ³ of water to the mix if uncorrected β raising effective w/c from 0.45 to 0.50 for M30. Over a year of monsoon season production at 5000 mΒ³/year, this means thousands of mΒ³ of under-strength, over-permeable concrete placed in structures. Moisture correction must happen at every batching cycle β modern batching plants use microwave moisture meters on aggregate belts for continuous real-time correction. Manual correction requires moisture tests per shift using IS 2386 Pt.3 method.
The theoretical fresh density of the concrete mix provides a final design check and a quality control benchmark for production. In trial mixes, the measured density should match the theoretical density within Β±30β50 kg/mΒ³. Significant deviations indicate batching errors or wrong specific gravity assumptions.
Fresh density (measured by IS 1199 Part 6 β density pot method) is the fastest and cheapest QC test available at every truck. Once the design fresh density is known (Β±20 kg/mΒ³), density measurement on every truck takes 2 minutes and provides immediate feedback on batching consistency. A density 40+ kg/mΒ³ below target suggests excess water (high w/c β reject truck). A density 40+ kg/mΒ³ above target suggests under-water (may be workable but check slump). Density combined with slump gives a two-parameter QC check achievable in under 5 minutes per truck.
IS 10262:2019 Clause 7 mandates a minimum of three trial batches using the calculated proportions. No mix design is complete β or legally compliant β without this verification step. Trial mixes must be made using the actual site materials, in the actual proportions, under conditions representative of production.
A Mix Design Report is the formal document that records every step of the design procedure, the material test data used, the calculated proportions, and the trial mix verification results. It is the legal basis for production and must be retained as a quality record. The following template shows all required contents per IS 10262:2019.
IS 456:2000 Cl.17.1 requires that records of concrete production (including mix design reports, cube test results, and delivery records) be retained for a minimum of 5 years from the date of completion of the structure. For infrastructure projects (bridges, dams, tunnels), best practice is to retain mix design documentation for the entire design service life of the structure. Mix design reports should be stored in both physical and digital form.