Performance Analysis of New Fine-Grained Biochar Concrete Prepared from Ultrafine Sand

Abstract

Biochar concrete has good application prospects, and the research and analysis of its performance is an important basis for large-scale application. In this paper, using cement as the main cementitious material, biochar concrete was prepared by replacing equal weight of cement with different proportions of biochar and mixing with water, sand and gravel according to the mix ratio design, respectively. The biochar was crushed and sieved to a cement fineness of 400 mesh. The basic chemical properties of the waste carbon were determined by weight method and chemical method. Elemental analyzers were used to determine the content of non-metallic elements such as C, O and H, and X-ray fluorescence spectroscopy analysis was used to determine the remaining elements. The effects of biochar on the mechanical properties of concrete such as slump and compressive and tensile strength were investigated through controlled tests. The water absorption performance and frost resistance of biochar concrete were analyzed in combination with ecological functional tests. The 1-week compressive strength of concrete increased by 13.7% and 19.1 % compared with the control group at substitution rates of 1% and 2.5%, and the 4-week compressive strength increased by 7.9% and 13.4% compared with the control group. The concrete basically showed some mass loss after 300 freeze-thaw cycles, but did not exceed 5%. This study provides theoretical support for the promotion and application of biochar concrete.