Challenge

Project on Concrete Mix Design for various grades of Concrete

SSmriti Gupta15 Sept 2021

# CONCRETE MIX DESIGN for M35 grade concrete with FLY ASH.

STEP 1: STIPULATIONS FOR PROPORTIONING
Grade designation Type of cement Type of mineral admixture Maximum nominal size of aggregate Minimum cement content Maximum water-cement ratio Workability Exposure condition Method of concrete placing Degree of supervision Type of aggregate Maximum (OPC) cement content Chemical admixture type	M35 OPC 43 grade conforming to IS 8112 Fly ash conforming to IS 3812(Part 1) 20mm 340 kg/m^3 0.45 100mm(slump) Very severe(for reinforced concrete) pumping good Crushed angualr aggregate 450 kg/m^3 Superplasticizer
STEP 2: TEST DATA FOR MATERIALS
Cement used Specific gravity of cement Fly ash Specific gravity of fly ash Chemical admixture Specific gravity of: Coarse aggregate Fine aggregate Water absorption Coarse aggregate Fine aggregate Free(surface)moisture Coarse aggregate Fine aggregate Sieve analysis Coarse aggregate Fine aggregate	OPC 43 grade conforming to IS 8112 3.15 Conforming to IS 3812(Part 1) 2.2 Superplasticizers conforming to IS 9103 2.74 2.74 0.5% 1.0% nil nil Table 4 of IS 383 of IS 10262:2009 Conforming to grading Zone I of IS 383

STEP 3:TARGET STRENGTH FOR MIX PROPORTIONING:

f'ck=fck+(1.65*s)
f'ck=35+(1.65*5)=43.25 N/mm^2

STEP 4:WATER-CEMENT RATIO

From Table 5 of IS 456:2000;maximum water-cement ratio=0.45;
Based on experience;water-cement ratio=0.40;
Thus,0.40<0.45=> o.k.

STEP 5:WATER CONTENT

Maximum water content for 20mm aggregate=186 litre(for 25-50 mm slump);
Estimated water content for 100mm slump=[186+{(6/100)*186}]=197 litre;
Water content to be reduced upto 29% based on trials i.e. =197*0.71=140 litre.

STEP 6:CALCULATION OF FLY ASH and CEMENT content

Water-cement ratio=0.40;
Cementitious material(cement+flyash)content=(140/0.40)=350 kg/m^3;

# According to Table 5 of IS 456:2000;

Minimum cement content for "very severe" exposure condition=340 kg/m^3;
Cementitious material content=350*1.10=385 kg/m^3;
Water-content = 140kg/m^3;
Water-cement ratio={(140/385)}=0.364;
Fly ash @ 30% of total cementitious material content=385*30%=115 kg/m^3;
Cement(OPC)=385-115=270 kg/m^3;
Saving of cement using flyash=350-270=80 kg/m^3;
Fly ash being utilized=115 kg/m^3.

STEP 7:VOLUME OF COARSE AGGREGATE and FINE AGGREGATE

Volume of coarse aggregate corresponding to 20mm aggregate and fine aggregate for water-cement ratio of 0.50=0.60;

# NOTE- In present case water-cement ratio=0.40; thus volume of coarse aggregate is required to be increased to decrease the fine aggregate content;As water-cement ratio is lowered by 0.10;

Volume of coarse aggregate is increased by 0.02;

Thus Volume of coarse aggregate for water-cement ratio of 0.40=0.62;

For pumpable concrete value is to be reduced by 0.10;
Volume of coarse aggregate =0.62*0.9=0.56;
Volume of fine aggregate=1-0.56=0.44.

STEP 8:MIX CALCULATIONS

Volume of concrete=1m^3;
Volume of cement={(270/3.15)*(1/1000)}=0.086 m^3;
Volume of fly-ash={(115/1)*(1/1000)}=0.052 m^3;
Volume of water={(140/1)*(1/1000)}=0.140 m^3;
Volume of chemical admixture @ 2% by mass of cementitious material={(7/1.145)*(1/1000)}=0.007 m^3;
Volume of all in aggregate={a-(b+c+d+e)}=0.715 m^3;
Mass of coarse aggregate=f*volume of coarse aggregate*specific gravity of coarse aggregate*1000=1097 kg;
Mass of fine aggregate=f*volume of fine aggregate*specific gravity of fine aggregate*1000=862 kg.

STEP 9:MIX PROPORTIONS FOR TRIAL NO. 1:

Cement
Fly-ash
water
Fine aggregate
Coarse aggregate
Chemical admixture
Water-cement ratio

270 kg/m^3
115 kg/m^3
140 kg/m^3
862 kg/m^3
1097 kg/m^3
0.364

# CONCRETE MIX DESIGN for M50 grade concrete without FLY ASH.

STEP 1: STIPULATIONS FOR PROPORTIONING
Grade designation Type of cement Type of mineral admixture Maximum nominal size of aggregate Minimum cement content Maximum water-cement ratio Workability Exposure condition Method of concrete placing Degree of supervision Type of aggregate Maximum (OPC) cement content Chemical admixture type	M50 OPC 43 grade conforming to IS 8112 Fly ash conforming to IS 3812(Part 1) 20mm 320 kg/m^3 0.45 100mm(slump) Severe(for reinforced concrete) pumping good Crushed angualr aggregate 450 kg/m^3 Superplasticizer
STEP 2: TEST DATA FOR MATERIALS
Cement used Specific gravity of cement Chemical admixture Specific gravity of: Coarse aggregate Fine aggregate Water absorption Coarse aggregate Fine aggregate Free(surface)moisture Coarse aggregate Fine aggregate Sieve analysis Coarse aggregate Fine aggregate	OPC 43 grade conforming to IS 8112 3.15 Superplasticizers conforming to IS 9103 2.74 2.74 0.5% 1.0% nil nil Table 4 of IS 383 of IS 10262:2009 Conforming to grading Zone I of IS 383