Project on Concrete Mix Design for various grades of Concrete
AIM:
To calculate the concrete mix design for M35 grade concrete with fly ash and M50 grade concrete without fly ash.
INTRODUCTION:
It is the method of finding the proportion of cement, sand and aggregates for concrete to achieve the strength. It is based on the relationship between properties and concrete composition include durability, permeability, early strength, 28 day compressive strength. This project consists of two parts, design of M35 grade with fly ash and M50 grade without fly ash.
OBJECTIVE:
To produce a mix design for M35 grade concrete containing fly ash and M50 grade concrete. Concrete mix proportioning guidelines from IS 10262:2009 and recommended guidelines from IS 10262:1982.
STEP 1: STIPULATION FOR PROPORTIONING OF M35 CONCRETE
- Grade designation : M35
- Type of cement : OPC 53
- Type of admixture : Fly ash
- Maximum nominal Size of aggregate : 20mm
- Minimum cement Content : 320kg table 5-IS456
- Maximum cement Content : 450kg as per code
- Maximum w/c ratio : 45
- Workability : 100mm
- Chemical admixture : super plasticizer
STEP 2: TEST DATA FOR MATERIALS
- Cement used : OPC 53
- Specific gravity of Cement : 3.15
- Mineral admixture : Fly ash
- Specific gravity of Fly ash : 2.2
- Chemical admixture : super plasticizer conforming to IS 9103
- Specific gravity of
- Coarse aggregate : 74
- Fine aggregate : 74
7.Water absorption
- Coarse aggregate : 5%
- Fine aggregate : 1%
8.Sieve analysis
- Coarse aggregate : conforming table 2-IS383
- Fine aggregate : Zone II table 4-IS383
STEP 3: TARGET STRENGTH FOR MIX PROPORTIONS
Fck = fck + 1.65s
Where,
Fck = target average compressive strength at 28 days
fck = characteristic compressive strength at 28 days
s = standard deviation
from table 1, standard deviation, s = 5N/mm2.
Therefore, target strength = 35+ 1.65*5 = 43.25N/mm2.
STEP 4: SELECTION OF WATER-CEMENT RATIO
- Maximum w/c ratio : 45
- Adopted w/c ratio : 44
STEP 5: SELECTION OF WATER CONTENT
Maximum water content = 186L (for 25 to 50mm slump range)
Estimated water content for
100mm slump = 186+ (0.06*186)
= 197.16L
As super plasticizer is used, the water content can be reduced up to 20 percent and above.
Percentage of reduction in water content = 20%
Water content requirement after sp = 198- (0.20*198)
= 157.73
Adopted water content = 158L
STEP 6: CALCULATION OF CEMENT AND FLY ASH CONTENT
Adopted w/c ratio = 0.45
Total cementitious
(cement+flyash)requirement = water content/water cement ratio
= 158/0.45
= 359kg/m3
Fly ash is used the amount of cementitious content shall be increased to get good workability and strength. The percentage of increased cementitious content by 1%.
Final cementitious content
(cement + fly ash) = 359*1.1
= 395kg
Minimum cement content
Required for severe exposure = 320kg table 5-IS456
Adopted cementitious content = 395kg less than 320kg
Fly ash content requirement = 395*0.30
= 118.5kg
Cement content requirement = cementitious content – fly ash
= 395 – 118.5
= 277kg/m3
STEP 7: COARSE AND FINE AGGREGATE
Coarse aggregate ratio = 0.62
Coarse aggregate ratio
For 0.44w/c ratio = 0.632
For pumpable concrete these values should be reduced up to 10% = 0.632*0.9 = 0.568
Final fine aggregate ratio = 1-0.568 = 0.431
STEP 8: MIX CALCULATIONS
- Volume of concrete = 1cu.m
- Total volume of cement = cement/(S.G*1000)
= 277/(3.15*1000)
= 0.087cu.m
- Total volume of fly ash = fly ash/(S.G*1000)
= 118/(2.2*1000)
= 0.053cu.m
- Volume of water = water/(S.G*1000)
= 158/(1*1000)
= 0.158cu.m
- Volume of super plasticizers = super plasticizers/(S.G*1000)
= 7.6/(1.145*1000)
= 0.006cu.m
-
Total aggregatesRequirement = a-(b+c+d+e)
=1-(0.087+0.053+0.158+ 0.006)
= 0.696cu.m
- Coarse aggregate = f*C.A ratio*S.G*1000
= 0.696*0.568*0.74*1000
= 1077kg/m3
- Fine aggregate = f*F.A ratio*S.G*1000
= 0.696*0.431*0.74*1000
= 822kg/m3
CEMENT FLYASH SAND AGGREGATE WATER AND SUPER PLASTICIZER NEEDED FOR M35 CONCRETE
|
S.No. |
Materials |
Quantity |
|
1 |
Cement |
277kg/m3 |
|
2 |
Flyash |
118kg/m3 |
|
3 |
Fine aggregate |
822kg/m3 |
|
4 |
Coarse aggregate (20mm) |
1077kg/m3 |
|
5 |
Water |
158L |
|
6 |
Chemical admixtute |
7.18kg/m3 |
Therefore, mix ratio of M35 grade concrete by weight is 1:2.08:2.72.
CALCULATE THE CONCRETE MIX DESIGN FOR M50 GRADE CONCRETE WITHOUT FLYASH
STEP 1: STIPULATIONS FOR CONCRETE MIX
- Grade designation = M50
- Type of cement = OPC 53 grade conforming to IS BIS 12269-1987
- Maximum nominal size Of aggregate =20mm
- Minimum cement content = 320kg/m3 (table 5 of IS 456:2000- exposure condition)
- Minimum water-cement Ratio = 0.45 table 5 of IS456:2000
- Workability =100mm (slump value from pumpable concrete)
- Exposure condition = severe (for reinforced concrete)
- Method of concrete placing = pumping
- Type of aggregate = crushed
- Maximum cement content = 450kg/m3
- Chemical admixture type = super plasticizer
STEP 2: TEST FOR MATERIALS
1. Cement used = OPC 53 grade
2. Specific gravity Of cement =3.15
3. Chemical admixture = super plasticizer conforming to IS 9103
4. Specific gravity Of coarse aggregate = 2.74
5. Specific gravity Of fine aggregate = 2.64
6. Water absorption of
(i) Coarse aggregate 0.5%
(ii) Fine aggregate 1.0%
7. Sieve analysis of
(i) Coarse aggregate conforming to table 2 of IS 383
(ii) Fine aggregate zone II table 4 of IS 383
STEP 3: TARGET STRENGTH FOR MIX PROPORTIONING
f’ck = fck + 1.65s
Where,
f’ck = target average compressive strength at 28 days
fck = characteristics compressive strength at 28 days and
S = standard deviation
From table1, standard deviation = 5N/mm2
= 50+1.65*5
= 58.25N/mm2.
STEP 4: SELECTION OF WATER CEMENT RATIO
Maximum water cement ratio = 0.45
Based on experienced adopted water cement ratio is 0.44
0.44 less than 0.45, hence ok
Adopted w/c ratio = 0.44
STEP 5: SELECTION OF WATER CONTENT
Maximum water content = 186L ( 20 to 25mm slump range)
Estimated water content
For 100mm slump = 186+(6/100)*186
= 197L
As super plasticizers is used the water content can be reduced upto 20%
= 197*0.8
= 158L
STEP 6: CALCULATION OF CEMENT REQUIRED
Adopted w/c ratio = 0.44
Cement content = 158/0.44
= 359kg/m3
Minimum cement content = 320kg/m3
359kg/m3 less than 320kg/m3 hence ok.
STEP 7: VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
Coarse aggregate ratio = 0.62
Therefore, corrected proportion of coarse aggregate for the w/c ratio is 0.44 = 0.632
For pumpable concrete these values should be reduced upto 10% = 0.632*0.9 = 0.568
Volume of fine aggregate content = 1-0.576
= 0.431
STEP 8: MIX CALCULATIONS
- Volume of concrete = 1cu.m
- Volume of cement = cement/(S.G*1000)
= 359/(3.15*1000)
= 0.114cu.m
- Volume of water = water/(S.G*1000)
= 158/(1*1000)
= 0.158cu.m
-
Volume of chemical Admixture = admixture/(S.G*1000)
= 7.6/(1.145*1000)
= 0.006cu.m
- Volume of all aggregates = a-(b+c+d+e)
=(0.114+0.158+0.006)
= 0.722cu.m
- Coarse aggregate = f*C.A ratio*S.G*1000
= 0.722*0.568*2.74*1000
= 1123kg/m3
- Fine aggregate = f*F.A ratio*S.G*1000
=0.722*0.431*2.64*1000
= 821kg/m3
MIX PROPORTIONS
|
S.No. |
Materials |
Quantity |
|
1 |
Cement |
359kg/m3 |
|
2 |
Water |
158L |
|
3 |
Fine aggregate |
821kg/m3 |
|
4 |
Coarse aggregate(20mm) |
1123kg/m3 |
|
5 |
Chemical admixture |
7.18 |
|
6 |
Water cement ratio |
0.44 |
|
7 |
Mix proportion by weight |
1:2.28:3.12 |