Collaborative design of cement-based composites incorporated with cooper slag in considerations of engineering properties and microwave-absorbing characters

Abstract

“Waste materials” possess “new utilization” for that the application of copper slag (CS) instead of natural sand can impart excellent engineering properties and exceptional microwave absorption characters to cement-based composites. In this work, natural sand was replaced in volume by copper slag to design and prepare cement mortars with different copper slag contents (10%, 30%, 50%, 70% and 100%). The mechanical properties, workability, durability and microwave-absorbing characters of mortars were tested and evaluated by the response surface methodology (RSM) and grey entropy correlation analysis to perform a collaborative analysis; and finally, optimal copper slag content was recommended. The prediction model constructed by RSM shows that mechanical properties can be mostly optimized when the conditions were set to water/cement ratio of 0.6, copper slag content of 46% and copper slag fineness modulus of 2.77. Copper slag can obviously affect workability and durability of mortars, which can be mainly due to its irregular shape and low water absorption rate. Furthermore, the microwave-absorbing characters of mortars can vary with copper slag content. The mortar with 50% copper slag content achieves the minimum reflectivity and the maximum effective bandwidth. The roughness, water absorption and content of copper slag should be given priority when applied in microwave-absorbing building engineering. Copper slag makes a dominant contribution to mortars when its content reached 50%, which can be recommended as the optimal copper slag content incorporating into cement-based composites.