Flexural Fatigue Performance Of High-Flexural Strength Slag Calcium Sulfoaluminate Cement Concrete For Pavement

Cement concrete is widely used in pavement engineering,but as a result of its own problems such as low tensile strength and brittleness,in today’s "big traffic" and "heavy traffic" environment background,the degradation of easy cracking of cement concrete road,and poor fatigue resistance,causing most of the road can’t meet the design service life and affects the application and development of cement concrete pavement.Under traffic load,the bottom of cement concrete pavement is mainly subjected to flexural stress,so the flexural strength of cement concrete is very important for pavement bearing capacity and service life.Slag calcium sulfoaluminate cement is a new type of lowcarbon waste cement with high flexural strength.The slag calcium sulfoaluminate cement can be used to prepare high-flexural strength slag calcium sulfoaluminate cement concrete.This material not only has higher flexural strength,but also has a longer flexural fatigue life than ordinary Portland cement concrete.The application of high-flexural strength slag calcium sulfoaluminate cement concrete to cement concrete pavement can solve the problem of poor quality of existing cement concrete pavement.Based on the uniaxial compression test,three point flexural strength test,free shrinkage test,the fracture energy test,abrasion test and three point flexural fatigue test for highflexural strength slag calcium sulfoaluminate cement concrete pavement performance and fatigue performance is studied,and combining with pilot application for cracking analysis of high-flexural strength slag calcium sulfoaluminate cement concrete provide theoretical basis and guidance to engineering application.The results show that :(1)The compressive strength,flexural strength and flexural to compressive ratio of high-flexural strength slag calcium sulfoaluminate cement concrete are higher than that of ordinary Portland cement concrete;(2)Compared with ordinary Portland cement concrete,the fracture energy of high-flexural strength slag calcium sulfoaluminate cement concrete is higher,and more energy can be absorbed before the failure of concrete;(3)Compared with ordinary Portland cement,the abrasion resistance of high-flexural strength slag calcium sulfoaluminate cement is better,and the abrasion rate per unit is nearly twice as low;(4)The free shrinkage rate of high-flexural strength slag calcium sulfoaluminate cement concrete is similar to that of ordinary Portland cement concrete,and the early shrinkage rate can be reduced by adding fly ash;(5)In the three-point bending fatigue test,the fatigue resistance of high-flexural strength slag calcium sulfoaluminate cement concrete is significantly better than that of ordinary Portland cement concrete,and the fatigue life is significantly longer.In addition,high-flexural strength slag calcium sulfoaluminate cement concrete has more coarse aggregate being pulled during the fatigue failure process.(6)The fatigue life obtained in the fatigue test was tested by using Weibull distribution.The logarithmic fatigue equation with different survival rates was obtained,and the fatigue life of concrete can be predicted more accurately with this equation;(7)Acoustic emission signals in the fatigue test were collected by acoustic emission device for processing and analysis,to explore the fatigue failure mechanism of high-flexural strength slag calcium sulfoaluminate cement concrete,and to explain the reason why its fatigue life is longer than that of ordinary Portland cement concrete.At the same time,combining with the b value method in seismology,the equation of predicting the fatigue life of concrete is proposed.(8)In the high-traffic environment,the high-flexural strength slag calcium sulfoaluminate cement concrete pavement with the same service time has fewer cracks and longer service life than ordinary Portland cement concrete pavement.