Experimental Investigation On Shrinkage And Cracking Property In Glass Fiber-mortar

GRC?Glass Fiber Reinforced Cement?as a new type of composite material has been continuously researched and developed since it came out,and GRC has been widely applied to various fields.The durability of glass fiber mortar has been highly valued by researchers at home and abroad.The shrinkage and cracking of glass fiber mortar both are important factors which are affecting the durability and limiting the scope of application.Therefore,the experts and scholars focus on the shrinkage and cracking of mortar for many years.This paper focuses on the subject of shrinkage and cracking resistance of glass fiber reinforced mortar,and conducts in depth research and discussion according to experimental research and mechanism.The main research work and results are as follows:?1?The autogenous shrinkage and drying shrinkage of glass fiber,carbon fiber,steel fiber,basalt fiber and lignin fiber mixing in mortar individually were studied.Studies show that inhibition of shrinkage and stability of drying shrinkage and wet expansion of mortar with glass fiber is the best comparing to mortar with other fibers.The lignin fiber has a good inhibitory effect on the early shrinkage of the mortar,but the ability of long-term shrinkage inhibition of the mortar is worse.The age of day 90 shrinkage phenomenon of different mortar with mortar is:mortar with lignin fiber>fiber-free reference mortar>mortar with steel fiber>mortar with basalt fiber>mortar with carbon fiber>mortar with glass fiber.Shrinkage rate of age day 90 of mortar with glass fiber reduces by 10.7%compared with the reference mortar,shrinkage rate of age day 90 of mortar with lignin fiber increases by 9.4%compared with the reference mortar.?2?With the other performance of glass fiber unchanging,the ability of shrinkage inhibition of mortar becomes better with the increasing content of glass fiber.The mortar with50kg/m³ content of glass fiber has the best volume stability of drying shrinkage and wet expansion.With the increasing length of glass fiber,the ability of the shrinkage inhibition of mortar increases first and then decreases.The mortar with the length of 12mm glass fiber has the lowest shrinkage in the age day 90 and the best volume stability.It has the lowest wet expansion rate at the same water absorption rate.The phenomenon for the shrinkage rate of mortar with different length of glass fiber for the age day 90:the drying shrinkage of the mortar decreases with the increasing length of glass fiber at 6mm¹2mm,and the drying shrinkage of the mortar increases with the increasing length of glass fiber at 12mm³5mm..?3?Through orthogonal experimental design,the results show that the drying shrinkage of mortar decreases with the amount of the metakaolin,fly ash and arylic emulsion increasing individually.The drying shrinkage of GRC increases with the water-cement ratio increasing.The range analysis shows that the most important factors on drying shrinkage of GRC is water-cement ratio.The autogenous shrinkage of GRC decreases with the amount of fly ash,acrylic emulsion and water-cement ration increasing individually.The autogenous shrinkage of GRC increases with the amount of metakaolin increasing.The range analysis shows that the most important factor on autogenous shrinkage of GRC is water-cement ratio.According to the all experimental results,GRC with the optimal mix proportion metakaolin 10%,fly ash20%,arylic emulsion 5%,water-cement ratio 0.36 is selected.?4?Among five kinds of fibers,glass fiber mortar has the best improvement in plastic crack resistance.with the increasing of the content of glass fiber,the early plastic crack resistance of mortar increases compared to the fiber-free reference mortar.When the content of glass fiber reaches 6kg/m³,the total crack area is reduced by 94.9%,the evaluation index of crack resistance reaches 95%,and the crack of mortar can be almost suppressed.With the length of the glass fiber increasing,the total crack area of the mortar is continuously reduced,the evaluation index of crack resistance is increased,and the mortar with glass fiber of volume content of 2kg/m³ and length of 35mm the crack suppression effect is better,the evaluation index of crack resistance is 91%.Considering the performance of the glass fiber such as content and length of fiber,the product of the aspect ratio of fiber and the content of fiber percentage is simplified to the parameter D×L_df,and the curve equation with higher correlation coefficient is fitted with the corresponding crack area of mortar specimens,which can comprehensively evaluate the effect of different parameters of glass fiber on plastic shrinkage crack suppression.