Preparation and performance influencing factors of sludge-based non-sintering ceramsite foam concrete block

Abstract

In this study, the preparation of ceramsite foam block using Sludge-based Non-sintering Ceramsite (SNSC) was investigated through orthogonal test and performance optimization test to investigate the effects of different coal fly ash addition, volume ratio of SNSC, water binder ratio and sodium silicate concentration on the performance of the concrete block, and the optimal material mixing ratios were obtained as follows: cement was 400 kg/m3, coal fly ash was 100 kg/m3, SNSC was 371 kg/m3, water binder ratio was 0.43, CaCl2 was 10 kg/m3, and Na2SO4 was 5 kg/m3. The performance of Sludge-based Non-sintering Ceramsite Foam Concrete Block under these conditions meets the specification requirements of GB/T 36534–2018 "Ceramsite Foam Concrete Block". Its compressive strength was 7.76 MPa, dry bulk density was 948.7 kg/m3, the water absorption was 20.75 %, and the softening coefficient was 0.861. XRD and SEM analyses revealed that the internal physical phase of the concrete blocks under the optimal conditions was tightly bonded, with fewer and uniformly distributed pores, and that the hydration generated C-S-H, C-A-H gel-like substances, calcium alumina (AFt), and hydrated calcium chloroaluminate generated by hydration could significantly improve the physical and mechanical properties of concrete blocks.