Study On Anti-salt And Mechanical Properties Of Polypropylene Fiber Reinforced Cement Composites

In recent years,concrete has become the most widely used and widely used material in engineering.The performance and types of concrete have been diversified with the advancement of science and technology,such as high-performance concrete,fiber concrete,geopolymer concrete,recycled concrete,and also derived inventions.A variety of composite materials with excellent properties,such as fiber cement-based engineering composites.In the past two decades,domestic and foreign scholars have carried out a lot of research work on polypropylene fiber engineering cement-based composite materials(PP-ECC),mainly focusing on the selection and production of high-performance materials,the optimization of the process of mixing production process,and pulling Constitutive model under conditions such as bending and bending,durability in special environments(such as permeability resistance,wet and dry cycle,sulfate attack,etc.),workability,microscopic pore structure distribution,etc.,and PP-ECC compounding ratio There are relatively few studies on optimization,mechanical toughness,and mechanical and antifreeze properties after freeze-thaw cycles.In this paper,we mainly studied the optimization of PP-ECC mix ratio,the antifreeze performance and mechanical properties of PP-ECC under the salt-freeze coupling environment,and explained the mechanism of PP-ECC antifreeze and tensile toughness.The main research contents and conclusions are as follows:(1).Based on the traditional method and grey correlation method,the PP-ECC material mix ratio optimization was comprehensively selected.Based on the superior deformation ability and tensile toughness design test of PP-ECC,the optimal mix ratio was determined as the optimal decision value.(2).Using the rapid freeze-thaw test method,the PP-ECC test piece was placed in a 3.5% sodium chloride solution for testing.The anti-freeze performance of PP-ECC was analyzed by measuring the mass loss rate and compressive strength.The solution is more resistant to PP-ECC than ordinary concrete.(3).The PP-ECC specimens after freeze-thaw cycles were used for compressive and flexural tests.The mechanical properties of PP-ECC after freeze-thaw cycles were analyzed by measuring the compressive strength and flexural strength of PP-ECC.It shows that with the increase of the number of freeze-thaw cycles,the compressive strength,the fracture bearing capacity and the deformability of PP-ECC are gradually reduced,and the test piece is more likely to be damaged.(4).The uniaxial tensile test was carried out by using PP-ECC specimens after freeze-thaw cycles.The tensile properties of PP-ECC after freeze-thaw cycles were analyzed by measuring the stress and strain of PP-ECC.The results showed that PP-As the number of freeze-thaw cycles increases,the ultimate tensile strength decreases,but still exhibits pseudo-strain hardening behavior.This paper has a certain theory for the correct evaluation of the anti-freeze and mechanical properties of PP-ECC materials in chloride and frozen environments,and to solve the practical problems of salt-cold damage,premature failure of materials and shortened service life of pavement structural materials in alpine regions.Based on the reference,the research results can provide reference for the application of pavement materials in the cold zone.