Study On Foamed Magnesium Oxychloride Cement Filled With Wood Raw Materials

Foamed cement is a porous material that is often used for external wall insulation.It has many advantages such as light weight,flame retardancy,and thermal insulation,but also has the disadvantages of poor toughness,low mechanical strength,and high water absorption.This topic explored the effects of material composition and process parameters on the performance of foamed magnesium oxychloride cement,and then filled the foamed magnesium oxychloride cement with industrial waste wood powder to improve its performance,and then added foam stabilizers and fibers to optimize performance.The purpose is to prepare lightweight foamed magnesium oxychloride cement with excellent comprehensive performance,so as to expand its application in the future.The main findings are as follows:(1)The best mixing ratio of magnesium oxychloride cement was obtained by the single factor control variable method:the brine concentration was 28° Be,and the mass ratio of MgO to brine was 1.1.The performance of foamed magnesium oxychloride cement after adding different proportions of thickener sodium carboxymethylcellulose(CMC)and foaming agent hydrogen peroxide was analyzed,and it was found that the performance of the samples with 1%CMC and 4%hydrogen peroxide mixed was the best.And discuss the best process parameters:the slurry temperature is between 30?-40?,the stirring rate is 1400 r/min,and the stirring time is 30 s.(2)After mixing with wood powder,the mechanical properties of the sample increase,the toughness increases,and the thermal conductivity decreases,but the volumetric water absorption increases.The sample with 3%wood powder mixed had the best comprehensive performance:the compressive strength was 1.12 Mpa,the flexural strength was 1.02 Mpa,the volumetric water absorption was 22.2%,and the thermal conductivity was 0.067 W.(m·K)-1.(3)Adding a foam stabilizer to the wood flour-foam magnesium oxychloride cement mixture can make the bubbles more closed and stable,reducing the volumetric water absorption rate and thermal conductivity.When adding 1%hydroxypropyl methylcellulose(HPMC),the volumetric water absorption of the sample is 17.1%,the thermal conductivity is 0.052 W·(m·K)-1,the compressive strength is 1.13 Mpa;adding 0.02%vinyl for alcohol(PVA),the volumetric water absorption of the sample is 13.8%,the thermal conductivity is 0.054 W·(m·K)-1,and the compressive strength is 1.05 Mpa.(4)Incorporating fibers can improve the physical and mechanical properties of wood flour-foam magnesium oxychloride cement mixture.When 0.4%long and short mixed fibers are mixed,the comprehensive performance of the sample is the best,the apparent density is 275 kgm-3,compressive strength is 1.28 Mpa,the flexural strength is 1.29 Mpa,the compression ratio is about 1,and the pore size distribution is relatively uniform.