Study On The P Reparation And Properties Of Surface Layer Mortar Of Flexible Pervious Concrete

Pervious concrete is an environment-friendly building material,which has the characteristics of water permeability,air permeability,light weight,high heat dissipation,and low noise.The existing pervious concrete is generally double-layer structure:surface layer mortar and bottom of concrete.Pervious concrete surface layer mortar has the problems of poor mechanical property,poor flexibility,easy fading and poor wear resistance in the use process.the regenerated rubber particle aggregate can provide a flexible framework for the pervious concrete;In this paper,the influence of emulsified asphalt and recycled rubber aggregate on the properties of pervious concrete surface layer mortar is studied,and the influence of PVA and fiber on the wear resistance and color retention properties of the pervious concrete surface layer mortar is investigated.The mechanism of action is explored by means of XRD,SEM,FTIR,hydration heat and rheomete.The main conclusions are as follows:(1)With the increase of the paste-aggregate-ratio,the compressive strength of pervious concrete mortar increases gradually,but the porosity and permeability coefficient decrease,and the compressive strength of surface mortar increases first and then decreases with the increase of the flowing degree of mortar.The porosity and permeability decreased with the increase of paste fluidity.when the paste fluidity is 192mm and the ratio of slurry to bone is 0.26,the compressive strength of surface mortar is 16.3 MPa for 3 days and 33.5 MPa for 28 days,and the permeability coefficient is 8.1 mm/s.(2)Emulsified asphalt as superfine filler can effectively improve the mechanical properties of surface mortar,but the porosity and permeability coefficient will decrease.When the emulsified asphalt content is 15%,the compressive strength of emulsified asphalt at 3 and28 days was 18.3 MPa and 34.2 MPa respectively,which was 36.1%and 47.3%higher than that of the blank sample,respectively.The mechanical properties of surface mortar can be reduced by emulsified asphalt instead of cement cement,but the influence of emulsified asphalt on permeability and porosity is small.When the emulsified asphalt content is 10%,the compressive strength decreases 38.5%compared with the blank sample.(3)Emulsified asphalt as superfine filler can effectively improve elastic modulus and flexibility of surface mortar.When the content of emulsified asphalt is 15%,the elastic modulus of surface mortar is 5×10~4 MPa,which is 37.6%lower than that of blank sample.The effect of emulsified asphalt instead of cement mortar on the elastic modulus is small.When the substitution of emulsified asphalt is 15%,the elastic modulus of permeable concrete mortar is 8×10 ~4 MPa,which is 11.2%lower than that of blank sample.(4)The addition of coupling agent can effectively improve the mechanical properties of pervious concrete mortar and has little effect on porosity and permeability coefficient.When the content of coupling agent is 3%,the compressive strength of surface mortar is increased by53.3%compared with the blank sample.(5)Recycled rubber aggregate has a great influence on elastic modulus of permeable concrete mortar.When the amount of recycled rubber particles was 5%,the elastic modulus of permeable concrete mortar was 2.4×10~4 MPa.Compared with the sample without emulsified asphalt,the elastic modulus was reduced by 43.4%.The flexibility of surface mortar is greatly improved.(6)PVA can effectively improve the color retention performance of permeable concrete mortar.When the content of PVA is 3%,the wear of surface mortar is 1.8%,which is 69.5%lower than that of blank sample,and the value of color difference is 13.9,which increases12.2%compared with blank sample.At this time,the total porosity and connectivity porosity of the surface mortar are 16.1%and 13.9%respectively,which are reduced by 25.1%and27.2%than the blank sample,and the permeability coefficient of the surface mortar is 0.78mm/s and 24.3%lower than that of the blank sample.Permeability has declined to some extent.(7)The addition of steel fiber can effectively improve the mechanical properties and wear resistance of surface mortar.When the steel fiber content is 1%,the compressive strength of the surface mortar is 39.6 MPa,which is 19.3%higher than that of the blank sample,and the wear capacity of the surface mortar is 2.5%and 57.6%lower than that of the blank sample.(8)Blending of polypropylene fiber can effectively improve the color retention property of surface mortar.When the fiber content is 3%,the wear loss of surface mortar is 1.96%,which is 67.5%lower than that of blank sample,and the chromatic difference of surface mortar is 14.3,which increases 15.3%compared with blank sample.