Study On Preparation And Mechanical Properties Fibre Of Polypropylene Recycled Fine Aggregate Mortar

In the process of urban construction,China consumes a lot of natural building resources and produces a large amount of construction waste.At the same time,modern buildings put forward higher quality and functional requirements for mortar.Therefore,it is imperative to strengthen the performance of mortar with composite materials.In this paper,the application of polypropylene fiber in recycled concrete fine aggregate mortar and recycled brick fine aggregate mortar is studied.The following research work has been carried out in this paper:(1)Two kinds of recycled fine aggregates are prepared from waste clay bricks and waste concrete,and the basic physical properties of the two kinds of recycled fine aggregates are measured and analyzed;the influence of the two kinds of recycled fine aggregates on the water consumption of recycled fine aggregate mortar is studied by adopting the principle of single variable analysis and controlling the consistency of the two kinds of recycled fine aggregates;and the influence of the two kinds of recycled fine aggregates on the recycled fine aggregate mortar water consumption is studied by controlling the water-binder The influence of the content and length of polypropylene fibers on the mechanical properties and durability of recycled fine aggregate mortar was studied,and the effect of polypropylene fibers on the mechanical properties and durability of recycled fine aggregate mortar was determined by comparing the performance of two kinds of recycled fine aggregate mortar with that of ordinary mortar.The optimum content of aggregate mortar.The test results show that:(1)There are some differences in physical properties between recycled concrete fine aggregate and recycled brick fine aggregate and natural sand.The content of fine powder in recycled brick fine aggregate is more,the particle size below 0.63 mm accounts for 49.82%,and the particle size of recycled concrete fine aggregate is more than 2.36-4.75 mm.The apparent density and bulk density of recycled brick fine aggregate and recycled concrete fine aggregate are less than natural sand;the 24-hour water absorption rate of recycled concrete fine aggregate and recycled brick fine aggregate are 4.21 times and 4.81 times of natural fine aggregate respectively;the mud content of recycled brick fine aggregate is 5.73%,so it is necessary to wash recycled brick fine aggregate before use.(2)When two kinds of recycled fine aggregate mortar with the same consistency are prepared,the water consumption increases with the increase of recycled fine aggregate content;under the same water-binder ratio,the compressive strength,flexural strength and frost resistance of recycled fine aggregate mortar decrease with the increase of the two kinds of recycled fineaggregate content;the drying shrinkage rate increases with the increase of the two kinds of recycled fine aggregate content;Comparing the raw and fine aggregate mortar,it is found that the performance of recycled concrete fine aggregate mortar with the same content is better than that of recycled brick fine aggregate mortar with the same content.(3)Polypropylene fibers can not enhance the compressive strength of recycled fine aggregate mortar,and may reduce the compressive strength of recycled fine aggregate mortar slightly,but can significantly improve the flexural strength,drying shrinkage and freezing resistance of recycled fine aggregate mortar.Under the experimental conditions,the optimum type,content,length and length of recycled fine aggregate are recycled concrete fine aggregate,25% content,0.4% volume content of polypropylene fiber and 9 mm length of polypropylene fiber.