Research On The Relationship Between Micro-Structure And Macro-Performance Of High Performance Foam Concrete With Fiber

Foamed concrete has excellent properties such as light weight,heat insulation,sound insulation and earthquake resistance.It is a new type of environmental protection building material that is increasingly widely used.It is commonly used in foamed concrete blocks,foamed concrete lightweight partition boards,cast-in-place roof foamed concrete insulation layers,etc.However,its shortcomings of poor crack resistance and low strength limit its wide application.At present,most of the research is focused on the effect of matrix materials on properties,and less on pore structure.Starting from the mechanism,this paper studies several important parameters porosity,average pore diameter,roundness value and pore diameter distribution of the pore structure of foamed concrete mixed with polyvinyl alcohol fibers,and explores the relationship between the pore structure parameters and macro-performance.This paper aims to improve the characteristics of low strength and poor crack resistance of foam concrete,expand the application scope of foam concrete,and provide theoretical support for the regulation of foam concrete pore structure.In this paper,three factors(foaming agent,water-binder ratio and fiber content)and four-level orthogonal tests are used to explore the influence of different factors on the macro-performance(dry density,compressive strength and crack resistance)of foamed concrete mixed with polyvinyl alcohol fiber.On this basis,the relationship between the micro-structure and macro-performance of foamed concrete is studied by image processing and numerical analysis.The following conclusions are drawn:Synthesizing the shortcomings of the existing research,this subject systematically studies the relationship between the microstructure and macroscopic properties of foamed concrete with polyvinyl alcohol fibers based on the pore structure mechanism of foamed concrete.The main research contents are:(1)Through orthogonal tests of three factors(foaming agent,water-binder ratio and fiber content)and four levels of foam concrete,the influence of composition materials on the macro-performance of foam concrete is investigated.It is found that the dry density and compressive strength of foam concrete decrease with the increase of foaming agent content,and increase first and then decrease with the increase of water-binder ratio and fiber content.However,the two indexes of crack resistance(dry shrinkage and splitting tensile strength)are obviously improved when the fiber content is 1kg/m~3.(2)The pore structure parameters are obtained by image processing method,and the porosity,average pore diameter and roundness value increase with the increase of foaming agent and water-binder ratio,and decrease with the increase of fiber content.(3)Analyzing the influence of pore structure parameters on macro-performance,it is concluded that the dry density increases with the increase of porosity,while the compressive strength and splitting tensile strength decrease with the increase of porosity and average pore diameter.The innovation of this research lies in:when exploring the crack resistance of foamed concrete,two indicators of dry shrinkage and splitting tensile strength are taken into consideration;through the method of adding polyvinyl alcohol fibers,the improvement of foamed concrete pores is studied from the mechanism.Structural approach.By completing the above studies,the effect of pore structure parameters on the macro performance of foamed concrete is determined,and the relationship between the microstructure and macro performance of foamed concrete is improved.