Recycled concrete aggregates consist of adhered mortar in addition to what natural aggregate has. Meaning that, depending on the quality of the adhered mortar, the mechanical properties of the aggregate, and later in the recycled aggregate concrete would vary (It has been discussed so far in the field of research). So, if we quantify the quality thresholds, which of the factors are more significant?
Dear researcher
-Bulk density
-Water absorption
-Porosity
-Specific gravity
- Water resistance
-Durability
- Shrinkage
-Efflorescence
-Thermal conductivity
- Abrasion
- TCLP tests
further information can be found by ASTM Test procedures for concrete aggregates.
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The recycled concrete aggregate can be sufficient in many respect as concrete aggregate if it is not contaminated with other weak waste materials such as brick, plaster etc. However, its high water absorption values can make some workability problems and later compressive strength and durability problem in concrete mixtures produced with the aggregate. So last studies have been focused on decreasing of its water absorption levels to make it more suitable for concrete production. Of course many aggregate properties can also be check according related aggregate standards for concrete.
Particle size, shape and surface textures of recycled aggregates are different than normal coarse aggregates. This will affect work-ability of concrete and water demand for concrete mix design. The quality of adhered mortar will affect strength of concrete made from recycled aggregate. Rich mortar adhered aggregates will give higher strength as compared to aggregate with poor mortar quality. Percentage of broken brick aggregates as compared to crushed concrete aggregate will affect strength and durability of concrete made from recycled aggregates.
Water absorption and abrasion resistance are two key factors related to quality of RA.
RA might exhibit large variability in their physical and mechanical properties and this might reflect in concretes with strength characterized by larger statistical dispersion. In one word, recycled concretes might be less reliable than normal concretes and this might motivate the use of larger partial safety factors.
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