The NTP
400,011 defines crushed stone as coarse aggregate obtained by artificial crushing of rocks or gravel.
coarse aggregates must meet the following specifications:
- It shall be composed of particles clean, preferably angular profile of , hard, compact , resistant, and preferably texture rough.
- particles should be chemically stable and must be free of scale, dirt, dust, silt, humus, surface deposits, subject organic salts or other harmful substances.
- It is advisable to take into consideration the following: According NTP400.037 or ASTM C33
1) The particle size selected should preferably be continuous.
2) The particle size selected should allow the highest density of concrete with adequate workability and consistency in terms of placement of the mix.
3) The selected particle size should not exceed 5% of the aggregate retained on the mesh of 11 / 2 "and no more than 6% of the aggregate passing the mesh of ¼".
- Design Standards Structural recommend that the maximum nominal size of coarse aggregate is the highest that can be economically available, provided that it is compatible with the dimensions and characteristics of the structure. It is considered that in any case the nominal maximum aggregate size should not be greater than:
- particles should be chemically stable and must be free of scale, dirt, dust, silt, humus, surface deposits, subject organic salts or other harmful substances.
- It is advisable to take into consideration the following: According NTP400.037 or ASTM C33
1) The particle size selected should preferably be continuous.
2) The particle size selected should allow the highest density of concrete with adequate workability and consistency in terms of placement of the mix.
3) The selected particle size should not exceed 5% of the aggregate retained on the mesh of 11 / 2 "and no more than 6% of the aggregate passing the mesh of ¼".
- Design Standards Structural recommend that the maximum nominal size of coarse aggregate is the highest that can be economically available, provided that it is compatible with the dimensions and characteristics of the structure. It is considered that in any case the nominal maximum aggregate size should not be greater than:
1) One-fifth of the smallest dimension across flats of formwork, or
2) One third of the depth of slabs, or
3 ) Three-fourths of the minimum space between individual bars or wire reinforcements bar packages, strands, or prestressed pipeline.
In items reduced thickness, or in the presence of large amounts of armor; may be authorized by the Inspectorate to reduce the nominal maximum size of coarse aggregate, while retaining adequate workability and required to comply with the settlement, and to obtain the properties specified for concrete.
- The percentage of particles in the coarse aggregate disadvantages must not exceed the following values:
· Clay ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... 0.25%
· Particles despicable ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. ... .5.00% thinner
· Material passing No. 200 mesh ... ... ... ... ... ... ... ... ... ... ... ... ... ... .. 1.00%
· Coal and lignite:
1) When the concrete surface finish is important. ... ... ... ... .. 0.50%
2) Other concrete ... ... ... ... ... ... ... ... ... ... .. ... ... ... ... ... ... ... ... ... ... .. ... ... ... ... 1.00%
The coarse aggregate particles whose harmful exceed limits specified above, may be accepted provided that a concrete made with aggregate from the same source, has given satisfactory service that has been exposed in a manner similar to the study, or in the absence a record of services provided that the concrete prepared with the addition has characteristics satisfactory when tested in the laboratory.
- The coarse aggregate used in concrete pavements, structures subjected to erosion, abrasion or cavitation, it should have a greater than 50% loss in the abrasion test conducted according to NTP 400,019 NTP or 400,020, or to the Standard ASTM C 131.
- Washing of the coarse aggregate particles should preferably be done with potable water. Otherwise, water must be free of salts, organic matter or suspended solids.
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