Project on Concrete Mix Design for various grades of Concrete
Develop the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash.
Aim: To develop a concrete mix design for M35 grade concrete incorporating fly ash and M50 grade concrete without fly ash, ensuring the desired strength and durability as per the relevant standards and guidelines.
Introduction: To achieve the required strength, workability, and durability, concrete mix design entails choosing the proper quantities of cement, water, aggregates, and additives. We're going to create two distinct mixes for this exercise:
- M35 Grade Concrete with Fly Ash: M35 is a medium-grade concrete with moderate strength that is employed in structural applications. As an additional cementitious ingredient, fly ash a by-product of burning coal in power plants improves workability and durability.
- M50
Grade Concrete without Fly Ash: High-strength structural parts and
applications use M50, a high-grade concrete. Fly ash is not included in
this mix; instead, the direct application of cement and other ingredients
is the main strategy for achieving high strength.
Procedure:
1. Determine the Design Parameters:
- Grade of Concrete:
- M35 Concrete (with Fly Ash)
- M50 Concrete (without Fly Ash)
- Target Mean Strength:
- For M35: 35 MPa
- For M50: 50 MPa
- Standard Conditions:
- Environmental conditions as per IS 456:2000
- Concrete density approximately 2400 kg/m³
- Assumed Properties:
- Cement: Ordinary Portland Cement (OPC)
- Coarse Aggregate: 20 mm maximum size
- Fine Aggregate: Natural sand
2. Concrete Mix Design for M35 Grade Concrete with Fly Ash
a. Select the Mix Proportions:
- Water-Cement Ratio (W/C Ratio): As per IS 456:2000, for M35 grade, a W/C ratio of approximately 0.45 is commonly used.
- Target Strength: 35 MPa
- Fly Ash Replacement: 20% of the cement weight
b. Calculate the Cement Content:
- Assumed Cement Content: 350 kg/m³ (based on trial mixes)
c. Calculate the Total Water Requirement:
- Water-Cement Ratio: 0.45
- Water Content: W= W/C×C = 0.45 × 350 = 157.5 kg/m³
d. Aggregate Proportions:
- Fine Aggregate (Sand): 35% to 40% of total aggregate weight
- Coarse Aggregate: Balance of total aggregate weight
Assuming a total aggregate content of 1850 kg/m³:
- Fine Aggregate = 35% of 1850 = 647.5 kg/m³
- Coarse Aggregate = 65% of 1850 = 1202.5 kg/m³
e. Mix Calculation:
Cement Content: 350 kg/m³
Fly Ash Content: 20% of 350 = 70 kg/m³
Total Cementitious Material: 350 + 70 = 420 kg/m³
Water Content: 157.5 kg/m³
Fine Aggregate: 647.5 kg/m³
Coarse Aggregate: 1202.5 kg/m³
Mix Proportion: 1:1.85:3.43 (Cement: fine Aggregate: Coarse Aggregate)
3. Concrete Mix Design for M50 Grade Concrete without Fly Ash
a. Select the Mix Proportions:
- Water-Cement Ratio (W/C Ratio): Approximately 0.40 for high-strength concrete.
b. Calculate the Cement Content:
- Assumed Cement Content: 450 kg/m³ (based on trial mixes)
c. Calculate the Total Water Requirement:
- Water-Cement Ratio: 0.40
- Water Content: W =W/C×C = 0.40 × 450 = 180 kg/m³
d. Aggregate Proportions:
- Fine Aggregate: 30% to 35% of total aggregate weight
- Coarse Aggregate: Balance of total aggregate weight
Assuming a total aggregate content of 1800 kg/m³:
- Fine Aggregate = 35% of 1800 = 630 kg/m³
- Coarse Aggregate = 65% of 1800 = 1170 kg/m³
e. Mix Calculation:
Cement Content: 450 kg/m³
Water Content: 180 kg/m³
Fine Aggregate: 630 kg/m³
Coarse Aggregate: 1170 kg/m³
Mix Proportion: 1:1.4:2.6
Results
1. M35 Grade Concrete with Fly Ash:
- Mix Proportion: 1:1.85:3.43
- Cement Content: 350 kg/m³
- Fly Ash Content: 70 kg/m³
- Water Content: 157.5 kg/m³
- Fine Aggregate: 647.5 kg/m³
- Coarse Aggregate: 1202.5 kg/m³
2. M50 Grade Concrete without Fly Ash:
- Mix Proportion: 1:1.4:2.6
- Cement Content: 450 kg/m³
- Water Content: 180 kg/m³
- Fine Aggregate: 630 kg/m³
- Coarse Aggregate: 1170 kg/m³
Result shows:-
The concrete mix designs for M35 and M50 grades were developed considering the appropriate cement content, water-cement ratio, and aggregate proportions. Fly ash was incorporated in the M35 mix to enhance workability and durability, while the M50 mix, designed for high strength, did not include fly ash but required a higher cement content and lower water-cement ratio to achieve the desired performance.