Carbonation of recycled aggregate and its effect on properties of recycled aggregate concrete: A review

Abstract

The over exploitation of stone quarries, the generation of construction and demolition (C&D) waste, and the steady increase in the cost of preparing additional landfill space have caused great challenges to the environment and economy. Recycled aggregate concrete (RAC), as one of the sustainable construction material, has become a research hotspot and has received widespread attention. However, the formation of weak interface transition zone (ITZ) which caused by the existence of residual old mortar will exert a negative impact on the performance of RAC. Therefore, various treatments have been proposed to enhance the properties of the residual old mortar, including mechanical treatment, soaking, carbonation and so on. And it has been proved that carbonation is an effective and sustainable way to both improve the water absorption of RA and strengthen the ITZ of RAC. So, firstly, this article is devoted to reviewing the current research on the application of carbonized RA to RAC, focusing on two parts: (1) RA: the changes of physical properties under different conditions; (2) RAC: the microstructure, workability, mechanical properties and durability of the concrete with carbonized RA. Thereafter, it is known from the summarized literatures that carbonation can improve physical properties of RA and the optimal effect can be achieved by adjusting carbonation conditions. RAC with carbonized RA has denser both new and old ITZs, the microstructure, performance of it are also improved. Finally, this work may provide a reference for the research of carbonation and the application of RA in engineering in the future.

CO2 Mineralization Methods in Cement and Concrete Industry

“…Among them, the carbonation was evaluated as an efficient and feasible method [126,128]. Indeed, the carbonation treatment of recycled concrete aggregates has recently gained much attention due to its RCA performance enhancement and environmental benefits [129][130][131][132][133].…”

“…The carbonation treatment effect is strongly influenced by the carbonation conditions and the characteristics of the recycled aggregates. The CO 2 pressure, ambient temperature and relative humidity, carbonation duration, and aggregate moisture condition appear to be the governing carbonation factors [130][131][132]. However, there are no established general rules and relationships.…”

“…Proper recycling of the concrete enables the reuse of recycled concrete paste and aggregates, preserving virgin resources [170,221]. The recycled aggregate's properties can be improved by accelerated carbonation enabling the application of this material for new concrete production [129][130][131][132][133]. The recycled concrete paste can be valorized by means of carbonation and used for new cement production [196,197,200,211].…”

Compression stress-strain curve of lithium slag recycled fine aggregate concrete

“…Therefore, to make up for the shortcomings of RFA. Some researchers have tried to reprocess RFA [36][37][38][39], use fibers [40], mineral admixtures [33], and other methods [41] to improve the mechanical properties of concrete, and have achieved good results. Gao et al [42] found that the incorporation of mineral admixture can reduce the porosity, average pore size, and maximum pore size of recycled aggregate concrete (RAC).…”

Shear Behavior of Recycled Fine Aggregate Reinforced by Nano-MgO Modified Cement

“…Recycled aggregate is a building material in construction waste that can be recycled through various processing techniques. Its recycling can not only alleviate the shortage of natural aggregate, but also help to manage construction waste [ 6 , 7 ]. In the treatment and application of recycled aggregates, different curing materials are usually added to improve their mechanical properties [ 8 , 9 , 10 ], among which nanomaterials have been widely used due to their excellent properties [ 11 , 12 , 13 ].…”