Experimental Study On Mid-Long Term Effects Of Polypropylene Fiber On Non-Load Crack Resistance Of Cast-In-Place Concrete Floor

Concrete cracking is ubiquitous, which seriously affects concrete quality and causes concrete durability decreasing in particular. Now the building industry has become a pillar industry of national economy. However, cracking and leaking of cast-in-place concrete floor has become one of the serious problems and a hot problem of engineering quality complaints.To discuss solution to the problem of mid-long term non-load crack resistance of cast-in-place concrete floor, the paper analyzes the cause of mid-long term cracking of cast-in-place concrete floor and discusses the formation mechanism of concrete structure cracking, and studies the effects and formation mechanism of concrete mid-long crack resistance and permeation resistance improved by polypropylene fiber based on the experimental analysis on slab mid-long crack resistance and permeation resistance and uniaxial tensile test of polypropylene fiber concrete. That the research achievement is put into practical engineering has practical significance, which can improve both economic and social benefits by means of solving the cracking and leaking problem of cast-in-place concrete floor.The research work of the paper focuses on three basic aspects. The one is experimental research, including the effects polypropylene fiber has on concrete mid-long term non-load crack resistance, concrete permeation resistance and concrete uniaxial tension. The other is engineering application concerning three case studies on polypropylene fiber concrete floor. Another is economic and social benefit analysis on application of polypropylene fiber concrete floor. The research results of the paper show as follows: one is polypropylene fiber has better inhibition action on concrete mid-long cracking and greater contribution to improving concrete mid-long crack resistance. Polypropylene fiber concrete, which can effectively solve the problem of cracking and leaking of cast-in-place concrete floor, is a type of material with good performance. Two is polypropylene fiber can effectively improve concrete permeation resistance. Three is polypropylene fiber enhances concrete tensile strength, limit tensile stain and maximum crack width of critical fracture. Four is the successful application of polypropylene fiber concrete to the three practical projects such as employees' residential building shows that crack resistance and permeation resistance of polypropylene fiber concrete floor experiences general increase and achieves good application effects. Five is the application of polypropylene fiber concrete floor has coMParatively remarkable economic and social benefits.