Preparation And Properties Of Recycled Micro Powder Foam Concrete

Currently,the annual production of construction waste in China has exceeded 2 billion tons,with a significant amount of construction waste being improperly disposed of,resulting in adverse environmental impacts.The"14th Five-Year Plan for the development of a circular economy"proposes that the comprehensive utilization rate of construction waste should reach60%by 2025.Recycled fine powder from construction waste exhibits some level of activity and potential application value.Foam concrete,as a new type of lightweight thermal insulation building material,can be prepared using recycled fine powder as an auxiliary cementitious material to replace part of the cement,which has feasibility in research.This not only provides reference direction for solid waste utilization but also actively responds to the national dual-carbon policy,reducing CO₂ emissions and energy consumption,and has important social and environmental effects.Therefore,based on the premise of selecting high-quality foam agent,this experiment mainly focuses on preparing foam concrete using recycled fine powder and incorporating fiber-reinforced recycled fine powder foam concrete,and analyzing the pore structure of recycled fine powder foam concrete as a whole.The following conclusions were drawn:（1）Under the experimental conditions,it was found through comparison of foam agent performance that when 1.0%sodium dodecyl sulfate（K12）and 1.0%alpha-olefin sulfonate sodium（AOS）are compounded with animal protein,the maximum foaming multiple is 60times,settling distance is 7.7mm,water content is 79.3g,and overall performance is the best,which can be better applied in the preparation of recycled fine powder foam concrete.（2）The strength of recycled fine powder foam concrete increases first and then decreases as the micro-powder content increases.The compressive strength at 28 days for a micro-powder content of 5%is the highest.When the micro-powder content exceeds 5%,the water absorption rate of recycled fine powder foam concrete gradually increases with the increase of micro-powder content.For foam concrete with design bulk densities of 600kg/m³ and 800kg/m³,the thermal conductivity decreases with the increase of recycled fine powder content.（3）When the fixed recycled fine powder content was 5%,and foam concrete with low bulk densities of 400kg/m³ and 300kg/m³ was prepared,the compressive strength of recycled fine powder foam concrete increased first and then decreased as the fiber content increased,reaching the highest point at a fiber content of 0.6%.The water absorption rate and thermal conductivity decreased first and then increased as the fiber content increased.（4）When the bulk density of foam concrete is 600kg/m³,the average pore size decreases and then increases as the water-cement ratio rises,while the average roundness value increases and then decreases with an increase in the water-cement ratio.As the micro-powder content increases,the average pore size gradually decreases,and the average roundness value increases as the content increases within 10%.The average pore size first decreases and then increases as the fiber content increases,while the average roundness value first increases and then decreases as the content increases.Compressive strength gradually decreases as the porosity and average pore size increase,and gradually increases as the average roundness value increases.The water absorption rate gradually increases as the porosity and average pore size increase,and gradually decreases as the average roundness value increases.