Preparation Parameter Design And Road Performance Study Of Basalt Fiber Permeable Concrete

As a green and environment-friendly material,pervious concrete is widely used in sponge city construction.Its unique porous structure can quickly drain surface water,which can effectively alleviate serious natural disasters such as urban waterlogging and underground water level.At present,pervious concrete pavement is widely used in parks,parking lots and other light pavement with small load demand.If pervious concrete is to be popularized and applied in the construction of pervious pavement in sponge cities,on the one hand,it needs to meet the requirements of the material’s own pervious performance,on the other hand,it needs to enhance its strength and frost resistance.However,the enhancement of water permeability of pervious concrete will be accompanied by the decrease of mechanical properties and frost resistance.In view of this contradiction,a certain proportion of short cut basalt fiber is mixed into pervious concrete.Compared with other fibers,basalt fiber has higher mechanical properties,high temperature resistance and other advantages,and is a good concrete reinforcement material.Therefore,this paper explores the preparation parameter design of basalt fiber pervious concrete material and its road performance,and finds out the optimal material preparation parameters to make the material performance reach the optimal.The main research results are as follows:(1)The single factor control variable method is adopted to conduct the test of fiber permeable concrete,to study the influence rule of basalt fiber diameter,length and dosage on mechanical properties,water permeability and frost resistance of pervious concrete,and to determine the optimal index of basalt fiber in pervious concrete.1)With the increase of fiber diameter,the compressive strength of pervious concrete decreases,the splitting tensile strength increases first and then decreases,the permeability coefficient and porosity both increase significantly,and the mass loss rate and compressive strength loss rate also increase gradually.2)With the increase of fiber length,the compressive strength of pervious concrete decreases,the splitting tensile strength increases first and then decreases,the permeability coefficient and porosity both show an upward trend,the mass loss rate also increases gradually,and the compressive strength loss rate decreases significantly.3)With the increase of fiber content,the compressive strength of pervious concrete decreases gradually,the splitting tensile strength increases gradually,the permeability coefficient and porosity show a downward trend,and the mass loss rate and compressive strength loss rate also decrease gradually.4)when the mechanical properties of basalt fiber are optimal under single factor variable,the optimal incorporation indexes of basalt fiber are 17μm in diameter,18 mm in length and 4kg/ m2 in dosage.When the water permeability is optimal,the fiber incorporation index is 20μm in diameter,24 mm in length and 2kg/ m2 in dosage.When the anti-freezing performance is the best,the fiber incorporation index is 14μm in diameter,18 mm in length and 6kg/ m2 in dosage.(2)The road performance of basalt fiber permeable concrete under compound factors was studied by orthogonal test.Six factors and three levels orthogonal design table of water-cement ratio,target porosity,aggregate particle size,fiber diameter,fiber length and fiber dosage were used to study and determine the primary and secondary factors affecting the mechanical properties,water permeability and frost resistance of basalt fiber pervious concrete by range analysis method.The test results show that:The primary order of factors affecting mechanical properties of basalt fiber pervious concrete is target porosity > aggregate size > fiber length > water-cement ratio > fiber content > fiber diameter.The main order of factors influencing the permeability of basalt fiber pervious concrete is target porosity > aggregate size > fiber content > water-cement ratio > fiber length > fiber diameter.The main order of factors affecting the frost resistance of basalt fiber pervious concrete is aggregate size > target porosity >water-cement ratio > fiber content > fiber length > fiber diameter.(3)Based on the fuzzy grey matter-element theory,the optimal material preparation parameters of fiber permeable concrete are determined as follows: water cement ratio 0.28,target porosity 10%,aggregate particle size 2.5mm,fiber diameter 17μm,fiber length24 mm,fiber dosage 4kg/ m2.After recalculating the material mix ratio,the test results show that the compressive strength and splitting tensile strength of basalt fiber pervious concrete increase by 72.55% and 86.8% respectively,and the permeability coefficient increases by 552%.After 25 freeze-thaw cycles,the relative dynamic elastic modulus increases by 61.07%,the mass loss rate decreases by 97.6%,and the compressive strength loss rate decreases by 92.35%.After 50 freeze-thaw cycles,the relative dynamic elastic modulus increases by 58.47%,the mass loss rate decreases by 96%,and the compressive strength loss rate decreases by 84.15%.