Properties and composition of recycled aggregates from construction and demolition waste suitable for concrete production

Construction and demolition waste generation and properties of recycled aggregate concrete: A global perspective

Recycling of waste concrete has become an important issue worldwide due to the continued increase of construction wastes. Also, the growing global construction activities urge to find sustainable resources to replace natural materials for the production of concrete. In the past few decades, many researches have been carried out on the use of recycled aggregate (RA) derived from construction and demolition wastes to produce concrete products. This paper reviews the previous findings on the effects of use of RA on durability of concrete. In general, the amount of adhered mortar and the quality of the original concrete have a significant effect on the properties of resulting concrete. The increase of RA content and w/c ratio results in poorer durability of concrete. In comparison, the negative effect of recycled fine aggregate is more obvious than that of recycled coarse aggregate. The use of pozzolanic materials either for surface coating of RA or intermixed within the concrete are effective and feasible to improve the overall durability of concrete. Recent researches on CO2 treatment indicate that it can enhance the properties of RA and durability of concrete significantly.

Durability of recycled aggregate concrete – A review

A critical review and assessment for usage of recycled aggregate as sustainable construction material

Mechanical performance of concrete made with aggregates from construction and demolition waste recycling plants

Durability performance of concrete with recycled aggregates from construction and demolition waste plants

Chloride migration in structural lightweight aggregate concrete produced with different binders

Pozzolanicity is a very interesting issue regarding building materials, as a way to enhance mortars and concrete durability. This property results from the reaction between calcium hydroxide and silica and alumina based materials. Different types of natural and artificial pozzolans show pozzolanic activities that differ depending on the materials characteristics. Therefore, the study of this property, namely its reactivity with calcium hydroxide, reveals itself to be important in the selection of the type and content of these materials. This paper presents the results of several pozzolanic reactivity methods, applied to different pozzolanic materials. The selected pozzolanic methods include Chapelle method, Fratinni method and Strength Activity Index. Those tests have been applied to evaluate the reactivity of various kinds of artificial pozzolans. The correlation between the test methods are presented and discussed.

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Evaluation of Pozzolanic Reactivity of Artificial Pozzolans

This research analyses the shrinkage and creep performance of concrete with recycled aggregates from various Portuguese construction and demolition waste recycling plants, studying the influence of the properties and composition of each recycled aggregate source on the characteristics of concrete produced with them. Recycled aggregates from four plants were used in the concrete mixes produced in this research, of which two were coarse recycled aggregates and two were fine recycled aggregates. During this experimental campaign, the behaviour of the mixes with recycled aggregates was evaluated by three fresh-state concrete tests (slump using the Abrams cone, density, and air content) and two hardened-state concrete tests (shrinkage and creep). It was found that the incorporation of recycled aggregates caused a qualitative drop in the concrete's properties. The properties of the concrete mixes were significantly dependent on the source (and composition) of the recycled aggregates.

Jorge Pontes

Papers

Mechanical performance of concrete made with aggregates from construction and demolition waste recycling plants

Durability performance of concrete with recycled aggregates from construction and demolition waste plants

Chloride migration in structural lightweight aggregate concrete produced with different binders

Evaluation of Pozzolanic Reactivity of Artificial Pozzolans

Shrinkage and creep performance of concrete with recycled aggregates from CDW plants