Presentation -----------------------------.pptx

applicable to all civil

1. EFFECTS OF TWO STAGE MIXING APPROACH ON HARDENED CONCRETE-

2. INTRODUCTION- Concrete is widely used in construction but needs to be strong and durable.
The Two-Stage Mixing Approach (TSMA) is a modern method that can improve concrete properties. Instead of mixing all materials at once, TSMA involves two steps- 1. First, cement and water are mixed to form a paste.
2. Then, sand and aggregates are added gradually.
This method ensures better bonding and uniformity, leading to improved strength and durability.

3. WHY THIS STUDY- In conventional mixing, all ingredients are mixed at once. This can lead to uneven cement distribution, affecting concrete quality. Problems in conventional mixing- 1) Poor bonding between cement paste and aggregates.
2) Weak Interfacial Transition Zone (ITZ) (the contact zone between cement and aggregates).
3) More voids → lower strength and durability.
TSMA overcomes these issues by improving paste formation and aggregate bonding.

4. OBJECTIVES OF THIS STUDY- 1.Strength Evaluation: Test compressive, tensile, and flexural strength of TSMA concrete. 2. Durability Analysis: Check water absorption, permeability, and chemical resistance. 3. Comparison with Conventional Mixing :
Compare TSMA results with traditional mixing methods.

5. MATERIALS REQUIRED- Cement: OPC 43/53 Grade. Fine Aggregate (Sand): Well-graded river sand. Coarse Aggregate : Gravel or crushed stone (size: 10mm to 20mm). Water : Clean, potable water (as per IS standards). Admixtures (Optional) : Superplasticizers (to improve workability) Air-entraining agents (for better durability).

6. EQUIPMENT REQUIREMENT- Concrete Mixer – Ensures uniform mixing. Moulds - Cubes (150x150x150mm) → Compressive strength test.
Cylinders (150mm x 300mm) → Tensile strength test.
Beams (100x100x500mm) → Flexural strength test.

Curing Tank – Keeps concrete hydrated.

7. Testing Machines:
Compression Testing Machine (CTM) – Measures compressive strength.
Universal Testing Machine (UTM) – Tests tensile and flexural strength.

Permeability Testing Apparatus – Measures water penetration.
Chemical Resistance Setup – Tests for acid/salt effects.

8. WHAT WE WILL DO IN FUTURE- How TSMA PROCEDURE WILL BE CARFIED OUT-

9. STEP-1 PREPARATION OF MATERIAL- Cement: Ensure it is fresh and has no lumps. Fine & Coarse Aggregates- Wash and sieve to remove dust and oversized particles.

Water: Measure accurately based on the water-cement ratio (W/C ratio).

10. STEP-2-TWO STAGE MIXING PROCESS- Stage 1: Mixing Cement and Water
Mix cement and water thoroughly for 2-3 minutes to form a paste.
Ensures proper hydration and even cement particle distribution.

Stage 2: Adding Aggregates
Gradually add fine aggregate (sand) and mix for 2 minutes.
Add coarse aggregate (gravel) and mix for 3-5 minutes.
Results in better bonding and uniform mix.

11. STEP 3-CASTING OF SPECIMEN- Cube specimens (150mm x 150mm x 150mm) → Compressive strength test.

Cylinder specimens (150mm x 300mm) → Tensile strength test.

Beam specimens (100mm x 100mm x 500mm) → Flexural strength test.

Cover specimens with a plastic sheet for 24 hours before demolding .

12. STEP 4-CURING OF CONCRETE- Why Curing?
Prevents moisture loss, ensuring complete hydration.
Increases strength and durability.

Curing Periods:
7 days → Early strength.
14 days → Intermediate strength.
28 days → Full strength.

13. STEP 5-COMPRESSIVE STRENGTH TEST- Why? To measure how much load concrete can bear before breaking.

How?
Place cube specimen in Compression Testing Machine (CTM).
Apply gradual load until failure.

Test at: 7, 14, and 28 days.

14. STEP 6-TENSILE STRENGTH TEST- Why? To measure concrete’s ability to resist cracking under tension.
How? Place cylinder specimen in Universal Testing Machine (UTM).
Apply load until failure.

Test at: 28 days.

15. STEP 7-FLEXURAL STRENGTH TEST-(IF) Why? To measure how well concrete resists bending forces.

How?
Use beam specimen in UTM under three-point bending test.

Test at: 28 days.

16. STEP 8-DURABILITY TEST- 1. Water Absorption Test:
Measure weight before and after immersion in water.
Lower absorption = More durable concrete.

2. Permeability Test:
Measures how easily water passes through concrete.
Less permeability = Higher durability. 3. Chemical Resistance Test:
Immerse specimens in acid/salt solutions and observe changes.

17. DATA COLLECTION AND ANALYSIS- Compressive Strength: 7, 14, 28-day results.

Tensile & Flexural Strength: 28-day results.

Durability: Water absorption, permeability, and chemical resistance data.

18. COMPARISON WITH CONVENTIONAL MIXING- Strength and durability differences between TSMA and traditional mixing=...............................

19. WHY TWO STAGE MIXING APPROACH IS BETTER?- Better Cement Paste Formation → Stronger bond.

Stronger Interfacial Transition Zone (ITZ) → Less cracking.

Improved Durability → Less water absorption & permeability.

20. FUTURE SCOPE/WORK- Effect of different cement types & admixtures.

Study with various water-cement ratios.

Long-term durability testing (years instead of months).