Testing & Sampling - Kalokhe RMC

Why Proper Testing Matters

Concrete testing ensures that the supplied concrete meets the specified strength and quality requirements. Proper sampling and testing procedures are critical for reliable results and project success.

Quality Assurance

Verifies concrete meets design specifications

Compliance

Ensures adherence to IS codes and standards

Documentation

Provides permanent record for quality verification

Sampling Procedures (IS 1199:2018)

Step-by-Step Sampling Guide

When to Sample

1
After discharge begins
Not from the first 0.3 m³ or last 0.3 m³ of the load
2
Middle portion of load
Sample from the middle third of the discharge
3
Within 15 minutes
Complete sampling within 15 minutes of discharge start

Sampling Frequency

Quantity (m³)	Min. Samples
1-5	1 sample
6-15	2 samples
16-30	3 samples
31-50	4 samples
>50	4 + (1 per add'l 50m³)

Important Sampling Guidelines

Use clean sampling equipment free from previous concrete
Ensure representative samples from different portions of the batch
Protect samples from sun, wind, and contamination
Transport samples to testing location immediately

Cube Testing Procedure (IS 516:2021)

Mould Preparation

Clean 150mm cube moulds, oil lightly

Clean moulds thoroughly
Apply light coat of oil
Ensure tight assembly

Filling Moulds

Fill in three layers, compacting each

Fill in 3 equal layers
35 strokes per layer
Level top surface

Initial Curing

Store at 27±2°C for 24 hours

Cover with wet burlap
Maintain temperature
Label clearly

Water Curing

Demould and cure in water tank

Remove after 24h
Cure in clean water
Until testing day

Compressive Strength Testing

Testing Procedure

Remove cube from water - Wipe excess water from surface
Measure dimensions - Ensure 150mm ± 2mm on each side
Place in testing machine - Center cube, apply load uniformly
Apply load gradually - 140 kg/cm²/min (14 MPa/min)
Record failure load - Note the maximum load at failure

Testing Ages

Age	Expected Strength	Purpose
7 Days	~65% of f_ck	Early strength check
28 Days	100% of f_ck	Design strength verification
56/90 Days	>100% of f_ck	Long-term strength gain

Calculation: Compressive Strength = Load at Failure / Cross-sectional Area
For 150mm cube: Strength (MPa) = Load (kN) / 22,500 mm²

Slump Test for Workability

Slump Test Procedure (IS 1199)

Steps:

Dampen the slump cone
Place on flat, non-absorbent surface
Fill in 4 equal layers
Rod each layer 25 times
Strike off excess concrete
Lift cone vertically in 5-10 seconds
Measure vertical settlement

Slump Values:

Slump (mm)	Workability
0-25	Very Low
25-50	Low
50-100	Medium
100-175	High

Concrete Testing & Sampling