Research On The Application Of Precast Concrete Bricks Prepared From Rice Husk In Slope Protection Project

As a kind of agricultural waste,rice husk has the characteristics of light weight,porous,low density and low thermal conductivity,etc.If combined with the mechanical properties and durability performance indexes required by traditional precast concrete blocks for slope protection,it will be of great engineering application value to use rice husk to replace part of the coarse aggregate to prepare light weight and green precast concrete blocks.In this thesis,we have conducted experimental research on rice husk concrete for slope protection projects and carried out the design and application of precast bricks,and achieved the following results.(1)The influence of the following factors on the mechanical properties of rice husk concrete was investigated through orthogonal tests,and it was obtained that the maximum size of coarse aggregate has a significant influence on the 28d compressive strength of rice husk concrete,and the order of importance of the influence of each factor is:maximum size of coarse aggregate>rice husk admixture>water-cement ratio>fly ash admixture;it was obtained that the admixture of rice husk has a significant influence on the 28d flexural strength of rice husk concrete,and the order of importance of the influence of each factor is:rice husk The degree of importance of each factor is:rice husk admixture>water-cement ratio>fly ash admixture>maximum size of coarse aggregate;the density of rice husk concrete is significantly lower than that of conventional concrete.(2)A series of optimization of the ratio design of rice husk concrete were carried out with the forming process,light weight target and economic efficiency as the optimization directions respectively,and the mechanical property indexes of rice husk concrete under mechanical vibratory forming process were obtained to be better than those of mechanical static pressing forming process;the 28d compressive strength of rice husk concrete was20.5MPa,28d flexural strength was 3.12MPa,and the density was 19.5MPa when the maximum rice husk admixture amount reached 38%.The 28d compressive strength and 28d flexural strength of rice husk concrete were 20.5MPa,3.12MPa,and 1943 kg/m~3,achieving the goal of light aggregate concrete;two groups of rice husk concrete ratios were obtained to meet the requirements of slope protection project design and have better economic benefits,among which the 28d compressive strength of 24%rice husk concrete reached34.2MPa,28d flexural strength reached 4.42MPa,and the density was 2101 kg/m~3,and the cost per cubic meter was lower than that of ordinary fine stone concrete.The construction cost is lower than that of ordinary fine stone concrete.(3)Freeze-thaw cycle test and sulfate solution erosion test were designed to investigate the durability performance of rice husk concrete,and the strength loss rate of 24%rice husk concrete after 50 freeze-thaw cycles was 8.5%,which was significantly higher than that of ordinary concrete at the same factor level;the erosion resistance coefficient of 24%rice husk concrete after 56d sulfate solution immersion test was 0.87 The corrosion resistance coefficient of 24%rice husk concrete after 30 dry and wet cycles of sulfate test is 0.74,which is lower than 0.84 of ordinary concrete,it is obtained that the blending of fly ash is beneficial to improve the frost resistance and sulfate erosion resistance of rice husk concrete.(4)The appearance and connection methods of four types of rice husk concrete precast bricks were designed,and the finite element software was used to verify and optimize the connection methods of precast bricks;the practical application of rice husk concrete precast bricks was carried out,including the field preparation of rice husk concrete,the production and maintenance of precast bricks,and the laying of test sections.