Aggregate Terms Definition [Sand / Stone / Gravel]

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Maybe many new friends have doubts about some basic terms of the industry. Understanding the aggregates terms is crucial for understanding the properties, characteristics, and applications of sand, gravel and aggregates. Let’s introduce some appellations of aggregate industry briefly to help you better understand and communicate.

Material TypeDefinition
Aggregategranular loose material that plays the role of skeleton, filling and volume stabilization in concrete. According to the particle size, it can be divided into coarse aggregate and fine aggregate.
High Performance ConcreteThe concrete is made by selecting high-quality conventional raw materials, adding admixtures and mineral admixtures reasonably, using a lower water cement ratio and optimizing the mix proportion, and having excellent mixing performance, mechanical performance, long-term performance, and durability.
Coarse Aggregaterock particles larger than 4.75mm, including pebbles and crushed stone:
Pebblerock particles > 4.75mm formed by natural weathering, water transportation, sorting and accumulation.
Crushed Stonerock particles > 4.75mm made from rock, pebble and tailings without chemical treatment by desoiling, crushing, shaping, screening, powder control and other processes.
Fine Aggregaterocks and particles with particle size < 4.75mm. Including natural sand and artificial sand.
Irregular Particle in Coarse AggregatePebble and crushed stone particles are particles with an average particle size less than 0.5 times the corresponding particle size.
Natural Sandrock particles < 4.75mm formed naturally, mined and screened manually include river sand, Lake sand, mountain sand and desalinated sea sand
Artificial SandIncluding machine-made sand and mixed sand.
Machine-Made Sandrock particles < 4.75mm made from rock, pebble and tailings without chemical treatment by desoiling, crushing, shaping, screening, powder control and other processes.
Mixed Sandsand formed by mixing natural sand and machine-made sand in proportion
Crushed StoneRock particles with a nominal particle size greater than 5.00mm obtained by crushing and screening natural rocks or pebbles.
Flaky Particle in Artificial SandArtificial sand particles with a particle size of 1.18mm or more have a one-dimensional size smaller than the average particle size of 0.45 times the corresponding particle size.
Fineness ModuleAn indicator for measuring the fineness of sand.
Dust ContentThe nominal particle size in the aggregate is less than 80 μ The content of m particles, including clay, silt, and fine particles.
Clay lump Content in SandsThe content of particles with a nominal particle size greater than 1.25mm in sand that have been washed and pinched by hand to become particles smaller than 0.63mm.
Clay lump Content in StonesThe content of particles with a nominal particle size greater than 5.00mm in the stone that have been washed and pinched by hand to become particles smaller than 2.50mm.
Crusher Dust ContentThe nominal particle size of artificial sand is less than 0.08mm, and its mineral composition has the same particle content as the processed parent rock.
Methylene Blue ValueAn indicator used to determine the adsorption performance of particles with a particle size less than 0.08mm in artificial sand.
Apparent DensityThe mass per unit volume of aggregate particles (including enclosed pores).
Tight DensityThe mass per unit volume of aggregate after being compacted according to the prescribed method.
Bulk DensityThe mass per unit volume of aggregate in a naturally accumulated state.
SoundnessThe ability of aggregates to resist cracking under natural weathering or other physical and chemical factors.
Light MaterialSubstances with an apparent density of less than 2000kg/m3 in sand.
Elongated ParticleAny rock particle with a length greater than 2.4 times the average particle size of the particle size is considered a needle shaped particle.
Flaky ParticlesA particle with a thickness less than 0.4 times the average particle size is considered a sheet-like particle. The average particle size refers to the average value of the upper and lower particle sizes of the particle size.
Crushing Value IndexThe ability of artificial sand, gravel, or pebbles to resist crushing.
Alkali Aggregate ReactionThe chemical reaction between alkali in hardened concrete and alkali active minerals in aggregates occurs slowly in humid environments, leading to concrete expansion, cracking, and even damage.
Alkali Active Aggregate in OrthopedicsAggregates that can react chemically with alkalis in concrete under certain conditions, causing expansion, cracking, and even damage to the concrete.
Alkali Silica Reactive AggregateAggregates containing amorphous or incompletely crystalline silica that may undergo alkali aggregate reactions under appropriate conditions.
Alkali Carbonate Reactive AggregateMicrocrystalline dolomite containing specific structural structures may produce aggregates that undergo alkali aggregate reactions under appropriate conditions.
Fluidity Ratio of Rock Fines (FF)The ratio of the flowability of the sand mixed with stone powder to the reference cement sand under the conditions of adding additives and a water cement ratio of 0.4 is used as an indicator to determine the adsorption performance of stone powder on water reducing agents.
Water Requirement of Artificial Sand (X)The ratio of water consumption between artificial sand and ISO standard sand under the specified deviation of cement mortar flowability is used to comprehensively determine the indicators of artificial sand gradation, particle type, water absorption rate, and stone powder adsorption performance.

In the mining industry, the particle size of gravel is usually between 5mm-31.5mm, and 1-2 / 1-3 gravels are generally collectively referred to as paving gravels. The specific sizes of gravel are as follows:

Gravel TypeParticle Size
0-5sand with particle size of 0-5mm
5-1gravel with a particle size of 5-10 mm
2-41/4-1/2 inch, 10-15mm gravel
1-2gravel with particle size of 10-20mm
4-61/2-3/4 inch, 15-20mm gravel
1-3gravel with particle size of 16-31.5mm

According to the fineness modulus (MX), the specifications of machine-made sand can be divided into 4 types: coarse, medium, fine and extra fine:

sand fineness modulus

  • 1. Coarse Sand: the fineness modulus is 3.7-3.1, and the content of particles larger than 0.5mm exceeds 50% of the total weight, and the average particle size is 1mm-0.5mm.
  • 2. Medium Sand: sand with fineness modulus of 3.0-2.3, particle size greater than 0.25 mm and average particle size of 0.5-0.25 mm.
  • 3. Fine Sand: the fineness modulus is 2.2-1.6, and the particles with particle size greater than 0.075mm exceed 85% of the total weight, and the average particle size is 0.25mm-0.125mm.
  • 4. Ultra Fine Sand: the fineness modulus is 1.5-0.7, and the average particle size is less than 0.25mm.
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