Picture this: three quarters of the concrete holding up your building is neither cement nor water — it is sand and gravel. Aggregate occupies 60% to 80% of any mix volume, yet it usually gets the least attention. Any defect in its grading, cleanliness, or hardness transfers straight into the structure's strength and lifespan.
This guide walks through the tests we run in the aggregate testing section at TECHNO Soil Lab, the standard governing each one, and what the results mean for your project in practice.
Aggregate in Two Lines
By size, aggregate splits into two types that work together inside the mix:
- Fine aggregate (sand): fills the voids and gives the mix its body and cohesion.
- Coarse aggregate (gravel/crushed stone): the load-bearing skeleton inside concrete, asphalt layers, and fills.
Why We Never Pour Before Testing
- Wrong grading means more voids, weaker concrete, and higher cement consumption.
- Excess silt and dust cut the bond between aggregate and cement paste.
- Organic matter and salts attack concrete from within over time.
- Fixing a mix after placement costs many times the price of testing before it.
Sand (Fine Aggregate) Tests
Sieve Analysis — ASTM C136
The sand passes through a stack of standard sieves to plot its grading curve against specification limits; well-graded sand produces a denser, stronger mix.
Material Finer Than the #200 Sieve — ASTM C117
Determines silt and dust content by washing; exceeding the limit weakens cohesion and raises the mix's water demand.
Specific Gravity & Absorption — ASTM C128
Two numbers that feed directly into mix design: particle density and how much water the sand soaks up.
Gravel (Coarse Aggregate) Tests
Coarse Sieve Analysis — ASTM C136
Verifies the size distribution against the nominal size the specification calls for.
Los Angeles Abrasion — ASTM C131
The sample tumbles in a drum with steel spheres and the loss is measured; the lower the loss, the harder the gravel and the fitter it is for roads and heavily loaded concrete.
Specific Gravity & Absorption — ASTM C127
Assesses gravel density and absorption to control the actual water content of the mix.
Deleterious Materials — ASTM C40
A chemical check for organic and clayey materials that spoil setting and bond.
Quick Reference Table
| Test | Standard | The question it answers |
|---|---|---|
| Sieve analysis | ASTM C136 | Is the grading inside specification limits? |
| Finer than #200 | ASTM C117 | How much silt and dust is present? |
| Specific gravity & absorption | ASTM C127 / C128 | How dense are the particles, and how much water do they absorb? |
| Los Angeles abrasion | ASTM C131 | Will the gravel withstand wear and impact? |
| Organic impurities | ASTM C40 | Are harmful materials present? |
The Aggregate We Sign Off On
- Grading within standard specification limits.
- Fines and impurities within allowance.
- Low Los Angeles loss (high hardness).
- Low water absorption.
- Free of organic matter and harmful salts.
Golden rule: qualify the aggregate source once, then test deliveries periodically — quarry strata change, and today's truckload is not necessarily the qualification sample.
How We Run These Tests at TECHNO Soil Lab
With periodically calibrated equipment and specialized technicians at our branches in Makkah, Jeddah, Madinah, Riyadh, and Qassim — issuing accredited technical reports accepted by consultants and government authorities.
Have aggregate deliveries waiting for approval? Order aggregate, sand and gravel testing from an accredited lab and settle the quality question before the pour.