Study On Mechanical Properties Of GRC

Glass fiber reinforced cement(GRC)is a new type of composite material for modern buildings.It is generally made of spray method,premixing method,mesh laying method,winding method(GRC pipe)and pressing method.Alkali resistant glass fiber is mixed into cement mortar or cement paste.GRC,as a new type of building composite material,has many advantages,such as high strength,good toughness,low water absorption,green environmental protection,not easy to fade,low cost and light weight.It has the same service life as the main building and so on.Since its birth,GRC has been favored by a large number of researchers and has been widely used in many fields.Because of the long-term nature and poor mechanical properties of GRC in engineering application,it can not act on load-bearing components,which greatly limits the development and promotion of GRC materials.The mechanical properties of glass fiber mortar have been highly valued by domestic and foreign researchers,and glass fiber,cement matrix,molding process are important factors affecting its mechanical properties,so for many years,the impact of glass fiber,cement matrix,molding process on its mechanical properties is the focus of experts and scholars.Focusing on the research of GRC mechanical behavior under bending load,this paper makes a more in-depth study on the influence of glass fiber,cement matrix,molding process and other factors on GRC mechanical behavior.The main contents of this paper are as follows:(1)the influence of the properties of glass fiber on the mechanical behavior of GRC under bending load.The effects of glass fiber length,glass fiber content,water binder ratio and sand binder ratio on the mechanical behavior of GRC were studied.(2)The effect of cement matrix on the mechanical behavior of GRC under bending load.The effects of water binder ratio and sand binder ratio on the mechanical behavior of GRC were studied.(3)The effect of forming process on the mechanical behavior of GRC under bending load.The effects of forming pressure,water binder ratio and holding time on the mechanical behavior of GRC were studied.The experimental results show that the bending strength of GRC is strengthened with the increase of the length of short cut glass fiber,but too long is not good for the strength;the length of glass fiber is not obvious for the toughening effect;when the length of glass fiber is 20 mm,GRC has higher fracture energy.The amount of glass fiber has little contribution to GRC strength,but with the increase of the amount of glass fiber,the toughness of GRC is obviously improved;a small amount of glass fiber can increase the fracture energy of GRC,and the increase range is obvious.When the water binder ratio is 0.32,0.4 and 0.5,the toughness of GRC is obviously improved with the increase of glass fiber content;the fracture energy of GRC is generally on the rise;when the water binder ratio is 0.32 and 0.4,the bending strength of GRC fluctuates slightly;when the water binder ratio is 0.5,the bending strength of GRC is generally on the rise.When the sand binder ratio is 0.75,1 and 1.25,the toughness of GRC is obviously improved with the increase of glass fiber content,and the bending strength and fracture energy data of GRC fluctuate greatly without obvious rules.The experimental results of the influence of cement matrix on the mechanical behavior of GRC under bending load show that the water binder ratio increases from 0.32 to 0.50,the bending strength of GRC decreases and the toughness gets better and better,and the fracture energy of GRC increases by 227%.When the sand binder ratio increases from 0.75 to 1.75,the bending strength of GRC decreases generally;when the sand binder ratio is 1 and 1.25,the decline section of bending stress deflection curve is the most gentle,which indicates that too high or too low sand binder ratio is unfavorable to toughening;GRC fracture energy decreases from 535n/m to 223n/m.The experimental results show that when the glass fiber content is 1.5%,2.5% and 3.5%,the bending strength and toughness of GRC increase with the increase of forming pressure,and the fracture energy of GRC decreases.At the same forming pressure,with the increase of water binder ratio,the bending strength of GRC changes less,the toughness of GRC is improved and the fracture energy is increased significantly.Under the same forming pressure,the effect of holding time on the bending strength of GRC is less and its effect on the fracture energy is not obvious;the longer holding time is,the more obvious the brittle failure characteristics of GRC are.