Property Analysis Of Basalt Fiber Fast Setting And Hardening Cement Reinforced Concrete

To restore or repair quickly some industrial and civilian projects like airport runway, highway and underground pipeline, fast setting and hardening cement reinforced concrete (FCRC) with its characteristics of fast setting, fast hardening and high strength in early time can be used. Without appropriate maintenance this concrete can easily cause drying shrinkage because tensile strength development of this type of concrete is low. Many papers and research indicates that basalt fibers (BF) can improve the toughness of concrete, reduce the contraction, restrain the crack generation, and maintain the durability of concrete. The aim of this work is to study two basic mechanical properties of FCRC by different volumetric fractions (0%,0.1%, 0.2%,0.3% and 0.4%) and different length (6mm,18mm) of BF as well as the effects of chloride ion impermeability and frost resistance under low temperature of basalt fibers fast setting and hardening cement reinforced concrete (BFFCRC). Main works and important results are as follow:1- For BF of the 6mm length, the compressive strength of BFFCRC after one day and twenty-eight day's strength firstly increase and then decrease as the increase of the volumetric fraction of BF. The maximum compressive strength is obtained when the volumetric fraction is 0.1%.2- BF can strengthen the toughness of fast setting and hardening cement reinforced concrete3- The ductility of FCRC is greatly improved because of added BF, and the added BF has delayed the appearance of crack, which has a great effect on cracking resistance. Besides, the flexural strength of BFFCRC has increased compared to FSHRC without BF. The enhancement effect of BFFCRC varies depending on the different volumetric fraction of BF.4- The test results show that FCRC has a good performance on chloride ion impermeability concrete specimens, and the length of BF can influence the chloride ion impermeability.5- Relative dynamic elasticity modulus of BFFCRC is gradually strengthened as the increasing volumetric fraction of BF. That is, the ability of concrete's antifreeze is improved after adding BF. Furthermore, basalt fiber can effectively improve the trend of falling strength of the concrete specimens, which is under constant low temperature.Besides, this thesis simply analyzes the strengthening and toughening mechanism of BFFCRC and elaborates its durability mechanism. In addition to the excellent impermeability, adding BF has greatly improved the concrete structure, which decreases internal crevices of the concrete, thus strengthening the impermeability of the concrete. Moreover, this thesis also analyzes the antifreeze mechanism of BFFCRC in two different stages (one day and twenty-eight day) under constant low temperature.