Project on Concrete Mix Design for various grades of Concrete

MIX DESIGN OF M35 GRADE CONCRETE WITH FLY ASH

Aim- To calculate mix design ratio of M35 grade concrete by adding fly ash

Introduction

• Concrete mix design is a process of finding the accurate quantities of cement,sand,aggregates and other materials to achieve the desired strength.
• It is a systematic process that produces a cohesive concrete of desired workability in fresh state and desired strength,durability in hardened state.
• Accurate concrete design mix makes construction economical.

Test data for materials:

a)Cement=opc43 grade

b)Specific gravity=3.15

c)Specific gravity coarse aggregate=2.74

d)Specific grsvity of fine aggregate=2.74

e)Water absorbtion 0f coarse aggregate=0.55% and fine aggregate=1%

f) Free surface moisture of coarse and fine aggregates are nill

Step1:

Target mean strength F'ck=fck+1.65s

s=5N/mm2

Ts =35+1.65x5=43.25N/mm2

Step2: Water content = 186+6/100*186 =197litres

=197x0.71=139.8liters

Step3: Cement content

W/c ratio =0.4

cement content139.8/0.4= 349.6kg/m3

Step4:

Adding fly ash

cementatious content of fly ash (cement +fly ash)=349.8x1.1

=384kg

water cement ratio=140kg/m3

water cement ratio =140/384 =0.36

fly ash 30%total cementatiousmaterial content=384x30/100=115kg/m3

=384-115=269kg/m3

cement while using fly ash=349.8-269=80.8kg/m3

fly ash being utilized =115kg/m3

Step5:

volume of coarse aggregate =0.62*0.9 =0.56

volume of fine aggregate =1-0.56 =0.44

Step 6: mix calculation

• volume of concrete=1m3
• volume of cement =0.087m3
• volume of fly ash =0.014m3
• volume of water =0.16m3
• volume of super plasticzers =0.0002m3
• volume of total aggregate =0.71m3

coarse aggregate =0.71x0.63x2.74x1000= 1225kg

fine aggregate =0.71x0.37x2.74x1000= 719.8kg

Step7 : Mix properties

• cement=275kg
• fly ash =115kg
• fine aggregate =720kg
• coarse aggregate =1226kg
• water=160liters
• superplasticizers=2L

Result: M35 grade concrete mix design

cement:fly ash: Fine aggregate: coarse aggregate:water=1:0.4:2.6:4.46:0.58

MIX DESIGN of M50 GRADE CONCRETE WITHOUT FLY ASH

Aim: To calculate mix design ratio of M50 grade concrete without fly ash.

Introduction

• Concrete mix design is a process of finding the accurate quantities of cement,sand,aggregates and other materials to achieve the desired strength.
• Accurate concrete design mix makes construction economical.
• It is a systematic process that produces a cohesive concrete of desired workability in fresh state and desired strength,durability in hardened state.

Stipulation for proportioning

a)Grade designation=M50

b)cement opc=43grade confirming to IS 8112

c)maximum sixe of aggregate=20mm

d)minimum cement content=350kg/m3

e)maximum water cement ratio=0.4

f)workability=100mm

g)exposure condition=extreme

h)method of concrete placing=pumping

i)degree of supervision =good

j)type of aggregate=crushed angular aggregate

k)maximum cement content =450kg/m3

l)chemical admixture used=superplasticizers

Test data for materials

• cement cement used =43 grade conforming to IS 8112
• specific gravity of cement=3.15
• chemical admicture=superplasticizers confirming to IS 9103
• specific gravity of coarse aggregate =2.74; fine aggregate=2.74
• water absorption of coarse aggregate=0.5% and fine aggregate=1%
• free surface moisture of coarse aggregate=nill and fine aggregate =nill
• sieve analysis of coarse aggregate=confirming to table 2 of IS 383 and fine aggregate=confirming to garding zone 1 of table 4 of IS383.

Mix proportioning

a) target mean strength of concrete ft=fck+1.65s =50+1.65x 5= 58.25N/mm2

b)selection of water cement ratio = from table 5 of IS456:2000, maximum w/c ratio for extreme exposure condition is 0.40,then adopt w/c ratio as 0.35,

c) selection of water content = from table2 IS 10262:2009 maximum water content corresponding to 20mm nominal size of aggregate 186liters for slump value of 25-50mm.

The slump value is 100mm,thus additional slump is present, from closure 4.2 of IS 10262:2009, water content may be increased by 3% for every additional 25mm slump.

Hence water content =186+186x(6/100) =197liters.

then superplasticizers are used as admixture, the water contentcan be reduced upto 30%.

let water be reduced upto29% i.e water content=197x((100-29)/100) =40liters

d) calculation of cement content w/c ratio=0.35

Hence water cement content=140/0.35=400kgm3.

From table 5 of IS456:2000, for extreme exposure condition minimum cement is 360kg/m3, which is less than 400kg/m3

e)volume of coarse aggregate and fine aggregate

From table 3 of IS10262:2009, volume of coarse aggregate per unit volume total aggregate corresponding to fine aggregate zone-1 =0.6 (w/c ratio 0.5)

Hence the water cement ratio is 0.35, which is lower by0.15. Hence coarse aggregate needs to be increased to decrease the fine aggregate content. So increase coarse aggregate content by 0.03%

Corrected volume of coarse aggregate for w.c ratio of 0.35=0.63

For pumpable concrete values are reduced by 10%,hence volme of coarse aggregate=0.63x0.9=0.567

volume of fine aggregate =1-0.567 =0.433

f) Mix calculations

• volume of concrete=1m3
• volume of cement=(400/3.15)x(1/1000)=0.127m3
• volume of water=(140/1)x(1/1000)=0.14m3
• volume of chemical admixture=(7.6/1.145)x(1/1000)=0.006m3
• volume of aggregate =1-(0.127+0.14+0.006)=0.727m3
• mass of coarse aggregate=0.727x0.567x2.74x1000=1129kg/m3
• mass of fine aggregate =0.727x0.433x2.74x1000=862kg/m3

g) Mix proportion

• cement =400g/m3
• water content =140kg/m3
• coarse aggregate =1129kg/m3
• Fine aggregate=862kg/m3
• chemical admixture=7kg/m3
• w/c ratio=0.35

Result

Mix ratio of M50 concrete is 1:2.82:2.15.