Study On Mix Design And Thermal Properties Of Lightweight Concrete Blocks

With the development of the country's wall materials,clay solid bricks will be gradually canceled and restricted.The development and application of insulation and energy-saving wall materials are imperative.Judging from the current situation,the most likely wall material to replace clay solid bricks is concrete blocks.Although ordinary concrete small blocks can replace clay solid bricks,they are heavy and difficult to construct,and their thermal insulation is far from meeting the national energy saving requirement of 50%.At present,lightweight aggregate concrete blocks on the market cannot be used for load-bearing buildings.Therefore,it is of great significance to study lightweight lightweight thermal insulation blocks or concrete.Shale ceramsite is used as a coarse concrete aggregate,which has the advantages of light weight and saving stone.However,the improvement of the thermal insulation performance of the building is not obvious,and there is a floating phenomenon of ceramic particles during the mixing process,which affects the stability of its mechanical properties.Although foamed concrete has a light weight and good thermal insulation performance,it has poor mechanical properties and is easy to crack.Currently,it is mostly used for non-load-bearing structures with low requirements for material strength.The ceramsite foamed concrete studied in this paper is a combination of both.The shale ceramsite is used as a light aggregate,and a foaming agent is introduced into the cement slurry for foaming.To make it not only ensure light-weight insulation,but also ensure its mechanical strength as a building wall in villages and towns.The mix ratio design adopts the orthogonal test method.Through controlling the four factors of the dosage of ceramsite,the content of expanded perlite,the content of fly ash and the amount of foaming agent,the mechanical properties and thermal insulation of ceramic foam concrete are explored respectively.The law of the influence of performance,resulting in the optimal mix ratio of the test.According to the optimal mix ratio,the lightweight concrete block was made and its thermal performance was studied.First,a systematic understanding of ceramsite concrete and foamed concrete was conducted by consulting the literature.Through the literature review,the physical properties of the two types of concrete and the preparation methods were understood.Compared with the ordinary concrete,the characteristics of the lightweight concrete were summarized;the lightweight concrete was tested and the preparation method of the lightweight concrete was mastered.Test preparation.Secondly,the amount of each component in the lightweight concrete was explored through experiments to prepare for the later orthogonal test.That is,experiments were conducted on single-doped shale ceramsite,expanded perlite,foaming agent and fly ash,and the range of the amount of each test material in the orthogonal test was determined by analyzing the test results.Third,through the orthogonal test,the basic mix ratio of ceramic foam concrete was determined and optimized.The analysis of orthogonal test results compared the influence of shale ceramsite,foaming agent,fly ash,and expanded perlite on the dry density,compressive strength,thermal conductivity,and softening coefficient of ceramsite foam concrete,combined with the test results.The basic mix ratio was obtained from the specification;the results of the orthogonal test were analyzed,and the related literature was referenced.The strength of the single-mixed silica fume was optimized for the basic mix proportion of the ceramic foam concrete,and the properties of the ceramic foam concrete after optimization were measured.Finally,the thermal performance of lightweight concrete blocks was experimentally studied.A control group experiment was set up with the magnesium cement mortar developed by the research group,and the heat transfer coefficient and internal node temperature of the block masonry were measured.The finite element analysis software ADINA and the thermal-moisture coupling analysis software HMCT1.0 were used to simulate the wall.The simulation results were in good agreement with the experimental results.Through experimental research,the following conclusions have been drawn:When the shale ceramsite dosage is 35%of the cement content,the average dry density is about1410kg/m~3,which has a significant effect on reducing the dry density of the concrete.The foaming agent has a significant influence on the dry density and thermal conductivity of concrete.When used as a lightweight concrete and its products,the amount of foaming agent should not exceed 3%of the cement content.Fly ash replaces part of the cement for environmental protection,but the amount should not exceed 20%of cement content.Expanded perlite can improve the thermal insulation properties of lightweight concrete.When the amount of cement added is 0.14%,the compressive effect is best.When the silica fume content is 10%,the mechanical properties of the concrete products can be significantly improved.The masonry heat transfer coefficient of the block formed by the combination of the lightweight concrete block and the wheat compressed straw block can reach 0.78W/(m~2·K),and the thermal insulation performance is good.Combining ceramsite concrete with foamed concrete and optimizing the mix ratio through orthogonal tests,it is necessary to ensure light-weight insulation while ensuring its mechanical strength as a building material for villages and towns.Secondly,the hot and cold box-heat flow meter method used to study the thermal performance of the block wall is affected by the environment,the test stability is good,and the test data is accurate.