Study On Performance And Meso Mechanism Of Slag Polypropylene Permeable Concrete

Since the concept of“Sponge City”was first proposed in 2012,China has successively issued guidance and implementation methods for promoting the construction of Sponge City.Changing the traditional hardened pavement into a water-permeable pavement is an important part of the construction of a sponge city.Although pervious concrete is currently the most widely used pervious pavement material,its pore structure itself has a declining performance compared with traditional hardened pavement.Therefore,how to study It is necessary to improve the comprehensive application performance of pervious concrete to better serve the construction of“sponge city”.In this paper,by using granulated blast furnace slag and polypropylene fiber to modify the pervious concrete,slag polypropylene permeable concrete specimens were prepared according to the orthogonal test method,and the mechanical properties and durability performance tests of different proportions of the specimens were conducted respectively.At the same time,using scanning electron microscopy to study its microstructure.The main research contents and analysis results are as follows:1.Can use extensibility and slump flow to control it workability,the slump should be controlled between 160mm²00mm,extensibility should be controlled between 160mm¹80mm,if not it is easy to produce after winding and conglobation,and not conducive to the dispersion;using statistical method to establish the mathematical model between porosity and permeability the coefficient.2.Analysis test data by means of Intuitive analysis and variance,found that:granulated blast furnace slag has significant influence on the compressive strength and tensile strength of the specimen at the later stage.Using scanning electron microscopy observation,it is found that the incorporation of granulated blast furnace slag can improve the interfacial transition zone defect caused by pervious concrete configuration process;The incorporation of polypropylene steel fiber can significantly improve the compressive strength,tensile strength and flexural strength of the test piece,and at the same time improve the brittleness and change the damage shape of the test piece;However,the effect of polypropylene bundle fibers on the mechanical properties of the permeable concrete specimens was not significant.3.A rapid freeze-thaw cycle test was conducted to study the durability of different mix ratio specimens.It was found that the polypropylene bundle fiber can better limit the rate of mass loss due to spalling of cement paste,and it is better to control the frost heaving cracks of cement stone;Polypropylene plastic steel fibers have a significant effect on suppression of cracks in macroscopic cracks;Assuming that the strength loss rate is the slag polypropylene permeable concrete damage evaluation index,the relationship between the strength loss rate and the mass loss rate and the relative dynamic elastic modulus under the freeze-thaw cycle is studied by regression analysis,and established a freeze-thaw damage models about the slag polypropylene permeable concrete,It can be expressed as:??_c= 6.209 + 6.76?W_ni-0.192?W_ni²、??_c= 63.07-61.14e^-?W_ni/5.22和??_c= 103.53-0.994P_i.The results of the study have found that the simultaneous incorporation of granulated blast furnace slag,polypropylene steel and bundle fibers is highly feasible for the modification of primed permeable concrete,and that it can be applied in the construction of actual permeable pavement in the future.