Effect of Modification Treatment on Properties of Coal Gangue Ceramsite Concrete

Abstract In engineering, prewetting treatment is often used to deal with the high water absorption of ceramsite. However, prewetting treatment will reduce the mechanical properties and frost resistance of ceramsite concrete. In order to solve this problem, this study considers the use of organic silicon and ash modification to reduce the water absorption rate of the aggregate. The mechanical properties, frost resistance, pore structure, and microstructure of ceramsite concrete treated by organic silicon and a cement-ground granulated blast furnace slag-silica fume (OPC-SG-SF) ternary system were studied. The results showed that when the silicone content was 6% and the dipping time was 10 s, the compressive strength of ceramsite concrete reached 39.2 MPa. Compared with the prewetted ceramsite concrete, the compressive strength increased by 21.4%. When the content of SG in the OPC-SG-SF ternary system was 30%, the strength of modified ceramsite concrete was the highest, reaching 42.7 MPa. At the same time, under this modification method, the modified ceramsite concrete has the best frost resistance. After 100 freeze–thaw cycles, the mass loss rate is 50% lower than that of prewetted ceramsite concrete, and the relative dynamic elastic modulus is 3.6% higher than that of prewetted ceramsite concrete. The results of pore structure and backscattered scanning electron microscopy (BSEM) showed that when the content of SG in OPC-SG-SF was 30%, the porosity of modified ceramsite concrete was at a low level, and the interface transition zone (ITZ) was uniform and dense.