Early-Age Performance Analysis of Sludge Water Incorporation in High-Temperature Steam Cured Green High-Performance Concrete

Sludge water (SW) with abundant sulfate ions (SO(4)(2−)) was utilized in this work to replace freshwater (FW) to prepare green high performance concrete (GHPC). A comprehensive investigation was conducted to evaluate the early-age performance of GHPC specimen mixed with SW incorporation (GHPC-SW). High temperature steam curing (HTS) has been presented to prepare GHPC-SW specimens. The compressive strength of the GHPC-SW specimen cured by HTS curing for 2 days is 85.2 MPa, which is 34% higher than the compressive strength of the GHPC-SW specimen cured by 3 days standard curing as the reference. The mechanical property results reveal that the incorporation of SW makes no harmful effects on the strength formation of HPC specimens, compared with FW added specimens under the same curing methods. Moreover, XRD and TG analyses indicate that HTS curing can effectively improve the hydration degree of GHPC-SW specimens. MIP analysis has been conducted and the specimens cured by HTS curing exhibit a more refined pore structure with fewer harmful pores. This work lays a solid foundation for the utilization of SW in the concrete construction industry, which is resource saving and environmentally friendly.