Sustainable self-compacting concrete containing high-amount industrial by-product fly ash as supplementary cementitious materials.

Abstract

Nowadays, utilizing large amount industrial by-product fly ash (FA) as the alternatives for cement in self-compacting concrete (SCC) had attracted more attention. In this study, FA was employed in SCC at five levels (0 %, 20 %, 30 %, 40 %, 50 %). The mechanical behaviors, the water porosities, the transport properties, and the sustainability of FA series SCC were investigated. At the initial curing stage (3 days), the use of FA in SCC reduces mechanical properties and increases water porosity, water absorption and water absorption coefficient (sorptivity) of SCC. FA series SCC have the lower resistance against carbon dioxide attack and chloride ion penetration than cement-based SCC. The prolonging curing time is beneficial to improve the long-term behaviors of FA- blended SCC. After SCC made by 20 %, 30 %, and 40 % FA water-curing for 90 days, there are the reduction of 0.44-2.09 % in the mechanical behaviors and the increase of 0.082-0.41 % in the water porosity, compared to pure-cement SCC. Beyond the content of FA (40 %), the difference s of the mechanical properties and the water porosity between SCC with 50 % FA and fully cement SCC are below the value of 2.5 %. With the progress in the curing time, the largest reduction rates of the water absorption and the sorptivity in all SCC mixtures were found in 50 % FA-blended SCC. Utilizing 50 % FA in SCC reduces the total charge passed values of SCC. The manufacture of 50 % FA-blended SCC has the lowest energy consumption and released amounts of CO2, NOx, and SOx in all series SCC mixtures. The application of high-level FA to SCC is the positive assistance to prepare sustainable SCC with satisfying long-term behaviors.