Abstract:

Blast furnace slag（BFS），as an industrial solid waste，is considered as an ideal raw material for the preparation of green and low-carbon foam concrete.In this paper，BFS was used to prepare foam concrete by efficiently replacing cement and combing it with an animal protein blowing agent to enhance the material properties.The pore structure was optimized by adjusting the replacement rate of BFS and the blowing agent dosage.The effects of BFS and blowing agent admixture on the properties of foam concrete，such as compressive strength，dry density，and thermal conductivity，were investigated.Additionally，pore structure parameters were obtained through image analysis.The results of the study showed that the appropriate amount of BFS could improve compressive strength and reduce dry density.When the substitution rate reached 80%，the 28 d compressive strength was 5.1 MPa，and the dry density was 1 057.06 kg/m³.The dry density and thermal conductivity of foam concrete were decreased with an increase in amount of the blowing agent，with the maximum reduction reaching 17.1% and 37.0% respectively.The optimal dosage of foaming agent was 3%，the pore size distribution was the most uniform，the pore shape factor was 1.182，the pores were close to spherical，and the adhesion phenomenon was minimized.The thermal conductivity of the prepared foam concrete was ranged from 0.094 2~0.059 3 W/（m·K），which showed the excellent thermal insulation performance.This study provided technical support for carbon emission reduction in building materials and enabled the integration of efficient thermal insulation and green low-carbon development.

Key words: foam concrete, blast furnace slag, pore structure, thermal conductivity, mechanical properties