Construction Technology_Concrete Mix Design_Project 1
1. Concrete Mix Design for M35 grade concrete with fly ash : Type of cement = OPC 43 grade , specific gravity = 3.15, slump = 100, Type of coarse aggregate = crushed angular aggregate 20 mm with specific gravity =2.74 Type of fine aggergate = zone -1-sand with specific gravity of 2.74, exposure severe. method of concreting = pumping. Type of mieran admixture = flyash , specific gravity = 2.2, type of chemical admixture = superplasticizer.
for comcrete mix design first of all we have to calculate Target mean compressive strength :
(a) Target mean compressive strength : formula is fm=fck+1.65xσ , where, fm =Target mean compressive strength at 28 days (N/mm^2) fck = characteristic compressive strength at 28 days. (N/mm^2) σ = standard deviation. (N/mm^2) For M35, fck = 35 N/mm^2, σ = 5 from table 1 of IS 10262:2009,
fm = 35+1.65x5=43.25 N/mm^2
(b) Calculation for w/c ratio : for severe condition max, free w/c ratio is .45 form Tbale 2 of IS 456. now, we are adopting w/c ratio = .40 , .40 < .45 Hence ok.
(c) Calculation for water (w) quantity : from table 2 of IS 10262 , max water content per cubic meter for nomial 20 mm max, size of aggregate for slump 25 to 50 mm , taken is 186 Kg/m^3 ,
Here add add 3% water for every additional 25 mm slump. Hence for slump value 100mm. Water to be added is 6%.
quantity of water = 186+(186x6)/100 = 197 kg/m^3
due to superplasticizer , water quantity can be reduced above 20% , so based of trails water reduction is taken as 29 %,
so quantity of water = 197x(100-29)/100 = 140 Kg/m^3.
(d) Calculation cementitious quantity :
weight of ( cement + fly ash ) = 140/.40 = 350 Kg/m^3. but minimun cement content for severe exposre condition is 320 kg/m^3. hence, 350 kg/m^3 > 320 kg/m^3. ok.
Now, decide the percentage of fly ash based on project requirement and quantity of materials.Now based on trials increase cementitious material by 10%,
so, cementitious quantity = 350*1.10 = 385 kg/m^3. water content = 140 Kg/m^3 so, water ratio = 140/385 = .364 now, add 30% fly ash of total cementitious materials = 385*.3 = 115 Kg/m^3. cement quantity = 350-115 = 270 kg/m^3. saving of cement after using fly ash = 350-270 = 80 kg/m^3.
(e) Calculation of Volume of cement , water , super plasticiser and fly ash :
Volume of cement = 270/(3.15*1000) = .086 m^3 volume of water = 140/1000 = 0.140 m^3. volume of fly ash = 115/(2.2*1000) = 0.052 m^3. volume of superplasticizer 2% of cementitious materials = 7.7/(1.145*1000)=0.006 m^3.
(f) finding the volume of coarse aggregate for zone 1 of fine aggregate :
now, volume of aggregates is = 1-.086-.140-.052-.006=0.716 m^3. which is occupied by coarse and fine aggregate.
from tabel 3 of IS 10262:2009 the % of coarse aggretgate for 20 mm size for w/c ratio 0.50 in zone 1 = .60.
but water cement ratio = .364 , hence we have to increase % of coarse aggregate by 0.01 for every decrease of 0.05
so % of coarse aggregate = 0.60 +0.01+0.01 = 0.62.
but for givem pumpable concrete volume of coarse aggregate is reduced by 10 %.
so final % volume of coarse aggregate= 0.62*(100-10)/100 = .56
volume of coarse aggregate = 0.716*0.56 =0.4 m^3 volume of fine aggregate = 0.716-0.4 = 0.316 m^3
(g)finding the mix proportion for 1 m^3 of concrete :
Volume of cement = .086 m^3 volume of water = 0.140 m^3. weight of fly ash = 115 kg/m^3. weight of superplasticizer = 7.7 Kg/m^3 weight of coarse aggregate =0.4*2.74*1000=1096 kg/m^3 weight of fine aggregate =0.316*2.74*1000=865 kg/^3.
2. Concrete Mix Design for M50 grade concrete with fly ash : Type of cement = OPC 43 grade , specific gravity = 3.15, slump = 50, Type of coarse aggregate = crushed angular aggregate 20 mm with specific gravity =2.74 Type of fine aggergate = zone -1-sand with specific gravity of 2.74, exposure severe. method of concreting = pumping. , type of chemical admixture = superplasticizer.
for comcrete mix design first of all we have to calculate Target mean compressive strength :
(a) Target mean compressive strength : formula is fm=fck+1.65xσ , where, fm =Target mean compressive strength at 28 days (N/mm^2) fck = characteristic compressive strength at 28 days. (N/mm^2) σ = standard deviation. (N/mm^2) For M35, fck = 50 N/mm^2, σ = 5 from table 1 of IS 10262:2009,
fm = 50+1.65x5=58.25 N/mm^2
(b) Calculation for w/c ratio : for severe condition max, free w/c ratio is .45 form Tbale 2 of IS 456. now, we are adopting w/c ratio = .40 , .40 < .45 Hence ok.
(c) Calculation for water (w) quantity : from table 2 of IS 10262 , max water content per cubic meter for nomial 20 mm max, size of aggregate for slump 25 to 50 mm , taken is 186 Kg/m^3 ,
.
quantity of water = 186 kg/m^3
due to superplasticizer , water quantity can be reduced above 20% , so based of trails water reduction is taken as 29 %,
so quantity of water = 186x(100-29)/100 = 132 Kg/m^3.
(d) Calculation cementitious quantity :
weight of cement = 132/.40 = 330 Kg/m^3. but minimun cement content for severe exposre condition is 320 kg/m^3. hence, 330 kg/m^3 > 320 kg/m^3. ok.
(e) Calculation of Volume of cement , water , super plasticiser and fly ash :
Volume of cement = 330/(3.15*1000) = 0.1047 m^3 volume of water = 132/1000 = 0.132 m^3. volume of superplasticizer 2% of cementitious materials = 6.6/(1.145*1000)=0.0057m^3.
(f) finding the volume of coarse aggregate for zone 1 of fine aggregate :
now, volume of aggregates is = 1-0.1047-0.132-0.0057=0.757 m^3. which is occupied by coarse and fine aggregate.
from tabel 3 of IS 10262:2009 the % of coarse aggretgate for 20 mm size for w/c ratio 0.50 in zone 1 = .60.
but water cement ratio = 0.40 , hence we have to increase % of coarse aggregate by 0.01 for every decrease of 0.05
so % of coarse aggregate = 0.60 +0.01+0.01 = 0.62.
but for givem pumpable concrete volume of coarse aggregate is reduced by 10 %.
so final % volume of coarse aggregate= 0.62*(100-10)/100 = .56
volume of coarse aggregate = 0.757*0.56 =0.4239 m^3 volume of fine aggregate = 0.757-0.4239 = 0.333 m^3
(g)finding the mix proportion for 1 m^3 of concrete :
Volume of cement = 0.1047 m^3 volume of water = 0.132 m^3. weight of superplasticizer = 6.6 Kg/m^3 weight of coarse aggregate =0.4239*2.74*1000=1161 kg/m^3 weight of fine aggregate =0.316*2.74*1000=912 kg/^3.