Utilization of Treated Recycled Aggregate by Using Carbonation Incorporated with Highly Alkaline Slurry Technique for ProducingHigh Strength Concrete

Information from the abstract

This paper investigated the utilization of recycled concrete aggregate (RCA) treated by carbonation and high alkaline slurry technique for producing high strength concrete (HSC). High alkaline slurry including high calcium fly ash (HFA), ground calcium carbide residue (GCR), and CO 2 curing was used to improve physical properties of RCA. As observed, after being treated, the water absorption of RCA was decreased, while the specific gravity and Los Angles abrasion resistance, particularly at the treatment of 7 days in CO 2 curing were increased. The treated RCA was soaked in calcium carbide residue mixed with fly ash slurry and cured with CO 2 method showed the best performance after being modified. Considering the mechanical properties and durability HSC fully containing RCA, the treatment of RCA helped to enhance all properties of HSC. It is important to note that concrete utilized the treated RCA by combining HFA and GCR with the CO 2 curing (RCGCF concrete) had compressive strength close to the control concrete (CT) made with natural coarse aggregate (NCA) at 28 and 90 days. The modulus of elasticity strongly depended on the aggregate types, which indicated that the regression coefficient of NCA concrete group (Ec = 3,079√fʻc + 8,546 MPa) was higher than that of treated RCA concrete group (Ec = 2,519√fʻc + 8,263 MPa). The treated RCA in concrete had lower total shrinkage than the concrete containing untreated RCA (RA concrete): RCGCF concrete (505 με) exhibited 25.9% lower total shrinkage, and RC concrete (562 με) exhibited 17.7% lower total shrinkage than RA concrete (684 με) at 91 days. Moreover, the higher is the compressive strength of HSC, the lower is the compression creep strain deformation; the specific creep of RCGCF concrete (21.82 × 10⁻⁶/MPa) was 22.4% lower than that of RA concrete (28.10 × 10⁻⁶/MPa). Since the lower absorption and higher density of treated RCA than untreated RCA, the RCGCF concrete had lower rapid chloride migration than that of the RA concrete.

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Related topics: Recycled Aggregate Concrete Performance · Concrete and Cement Materials Research · Innovative concrete reinforcement materials