AGGREGATES Flashcards
_____ means a mass of crushed stone, gravel, sand, etc, predominantly composed of individual particles, but in some cases including clays and silts.
Aggregates.
Due to the differences in the size of the aggregate particles, four terms are defined to facilitate the discussion of the general size characteristics of aggregates: _____ and ______.
Coarse aggregates and Fine craggregates.
Aggregate particles that are retained on a 4.75 mm sieve (No. 4). A 4.75 mm sieve has openings equal to 4.75 mm between the sieve wires. A No. 4 sieve has four openings per linear inch. The 4.75 mm sieve is the metric equivalent to a No. 4 sieve.
Coarse aggregates.
Aggregate particles that pass a 4.75 mm sieve (No. 4).
Fine aggregates.
The smallest sieve through which 100% of the aggregates pass.
Maximum aggregate size.
The largest sieve that retains any of the aggregate, but generally not more than 10%.
Nominal maximum aggregate size.
Natural sources for aggregates include ______.
Gravel pits, river run deposits, and rock quarries.
_______ can use slag waste from iron and steel mills and expanded shale and clays to produce lightweight aggregates.
Manufactured aggregates.
It used for radiation shields, can use steel slag and bearings for the aggregate.
Heavyweight concrete.
It can be used as an aggregate in lightweight concrete used for insulation. Natural lightweight aggregates include pumice, scoria, volcanic cinders, tuff, and diatomite.
Styrofoam beads.
Aggregates are used primarily as an underlying material for foundations and pavements as ______ for erosion control, and as _____ in portland cement and asphalt concretes.
Rip-rap, ingredients.
It can add stability to a structure, provide a drainage layer, and protect the structure from frost damage.
Aggregate underlying materials, or base courses.
It is a function of the interparticle friction between the aggregates and the amount of clay and silt “binder” material in the voids between the aggregate particles.
Stability.
In ______, 60% to 75% of the volume and 79% to 85% of the weight are made up of aggregates.
The ______ act as a filler to reduce the amount of cement paste needed in the mix. In addition, having it has a greate volume stability than the cement paste.
Portland cement concrete.
Aggregates.
In _____, aggregates constitute 75% to 85% of the volume and 92% to 96% of the mass.
The acts as a binder to hold the aggregates together, but does not have enough strength to lock the aggregate particles into position.
As a result, the strength and stability of it depends mostly on interparticle friction between the aggregates and, to a limited extent, on the binder.
Asphalt cement.
The shape and surface texture of the individual aggregate particles determine how the material will pack into a dense configuration and also determines the mobility of the stones within a mix.
There are two considerations in the shape of the material:
Angularity and flakiness.
These produce bulk materials with higher stability than rounded, smooth-textured.However, the angular aggregates will be more difficult to work into place than rounded aggregates, since their shapes make it difficult for them to slide across each other.
Regular and rough-textured aggregates.
This improves bonding and increases interparticle friction. In general, natural gravel and sand have a smooth texture, whereas crushed aggregates have a rough texture.
Aggregates with a rough texture.
The ability of aggregate to withstand weathering is defined as ______
Soundness or durability.
The soundness test.
ASTM C88.
The ability of aggregates to resist the damaging effect of loads is related to the hardness of the aggregate particles and is described as the _______ or _____.
Toughness or abrasion resistance.
The bulk unit weight of aggregate is needed for the proportioning of portland cement concrete mixtures.
According to ASTM ____ procedure, a rigid container of known volume is filled with aggregate, which is compacted either by rodding, jigging, or shoveling.
Bulk Unit Weight and Voids in Aggregate, and ASTM C29.
_______ describes the particle size distribution of the aggregate. The particle size distribution is an important attribute of the aggregates.
Gradation.
______ is evaluated by passing the aggregates through a series of sieves.
The sieve retains particles larger than the opening, while smaller ones pass through.
Sieve Analysis Gradation, ASTM C136, 11.
A _______ is any material that adversely affects the quality of portland cement or asphalt concrete made with the aggregate.
Deleterious substance.
The ______ results in excessive expansion, cracking, or popouts in concrete, as shown.
Alkali–silica reaction.
The _____ is affected by the amount, type, and particle size of the reactive material, as well as by the soluble alkali and water content of the concrete.
alkali–aggregate reactivity
