Mechanical Properties And Mix Propertion Of Cement-based Silt Foamed Concrete Considering

Foamed concrete is widely used in burnping at bridge-head treatment,highway reconstruction,pipeline backfilling and construction of special foundation based on the characteristics of light weight,high strength,strong self-reliance and convenient construction.However,the conventional foamed concrete has a large amount of cement,high cost and poor environmental impact.In order to solve this problem,scholars at home and abroad put forward the matching method of replacing part of cement with equal amount of admixture.The silt widely distributed in Shandong province is suitable to be used as admixture of foamed concrete due to its characteristics of uniform particle size,low clay content and high roundness.Based on the early stage of the research,in order to further expand engineering applications of silt-based foamed concrete,the effect of high silt content on physical and mechanical properties of foamed concrete with different density ranges were studied.Taking the data of foamed concrete with low silt content in consideration,the relationship between mechanical properties,silt content and wet density was established.At the same time,in order to reveal the influence of the actual construction environment temperature on the mechanical properties of foamed concrete,this paper focused on the study of the physical and mechanical properties of foamed concrete under different construction temperatures,and made the construction technical requirements explicit.Based on more than 2000 groups of experiment data of silt-based foamed concrete,the compressive strength was developed by machine learning algorithm,which could be used to determine the mix proportion under different engineering application conditions.The research results of this paper can be used to guide the proportion design and construction organization of silt-based foamed concrete,which has important theoretical significance and engineering practical value for greatly reducing the cost of foamed concrete and improving the construction quality.According to the research results,the main conclusions are as follows.1.For high-content silt-based foamed concrete,with the increase of silt content,the compressive strength,flexural strength and elastic modulus of foamed concrete all decrease,and the water stability becomes worse,which is suitable for filling of non-bearing structure.The key mechanical properties of foamed concrete with a wet density of 600≤ρ≤800kg/m3 and silt content of 0≤α≤70%were obtained by fitting.2.According to the ambient temperature influence test of silt-based foamed concrete,for the specimen of 28 d,it is shown that the variation trend of the key mechanical indexes under each initial temperature condition is basically the same,but the values are different.Specifically,in the range of 0℃～20℃,the mechanical indexes gradually increase with the increase of temperature.However,it is opposite in the range of 20℃～50℃.3.By comparing the attenuation amplitude of compressive strength under standard curing conditions,the construction environment temperature of foamed concrete can be divided into four temperature ranges which named freezing,low temperature,suitable and high temperature.Based on the analysis of the research results,it is suggested that the construction of the important load-bearing parts of the project should not be carried out in the freezing or the high temperature area,and the insulation measures should be taken.For the non-load-bearing project,under the premise of satisfying the design minimum strength requirements and reasonable insulation measures,construction can be carried out in the freezing or high temperature area as appropriate.4.Combined with the existing test data of silt-based foamed concrete,taking the wet density,silt content,coarse particle content,silt plasticity index,temperature into consideration,a program for predicting the compressive strength of silt-based foamed concrete at 28 days is developed by using machine learning algorithm,which can be used in different mix proportion design of engineering application.