Study On Mechanical Properties Of Basalt Fiber Reinforced Magnesium Phosphate Cement Based Composites

Magnesium phosphate cement(MPC)is a kind of inorganic cementing material obtained by the acid-base reaction and hydration reaction of heavy-burning MgO and phosphate in contact with water at the same time.It has the advantages of fast hardness,early strength,wear resistance and good volume stability,but in the meantime,magnesium phosphate cement based composite material(MPCC)has the disadvantages of high brittleness and poor deformation ability.Basalt fiber(BF),as an environmentally friendly fiber,is suitable for MPCC reinforcement due to its excellent tensile strength,acid and alkaline resistance and high temperature resistance.However,there are few researches on the application of basalt fiber in MPCC at home and abroad.Therefore,it is of great significance to incorporate basalt fiber into MPCC to improve their mechanical properties and develop MPCC with high performance and environmental friendliness.Therefore,this thesis firstly explored the influence of various factors on MPC based materials through experiments and determined the mix ratio of subsequent tests in order to obtain a higher performance MPC matrix.Secondly,BF-MPC was manufactured by combining it with basalt fiber,and its mechanical properties were studied.Finally,the influence of mineral admixture on the performance of BF-MPC was explored and the age test was conducted,and the enhancement mechanism of BF-MPCC was analyzed in combination with macro and micro.The main contents of this thesis are as follows:(1)The effects of incorporation of basalt fibers of different lengths and doping amounts on the properties(fluidity,compressive strength,flexural strength and toughness)of MPC were investigated.The results showed that the fluidity of MPC decreased with the increase of basalt fiber admixture,but the admixture of basalt fiber can enhance the above other performance of MPC.(2)The effects of incorporation of basalt fibers of different lengths and doping amounts on the impact resistance of MPC were investigated.The results showed that the incorporation of basalt fibers,especially the large amount of short fibers,had the most significant effect on the impact resistance of MPC.The times of initial crack and final crack of the specimen containing 1.5% basalt fiber with the length of 6mm are 3 times and 3.37 times of those without basalt fiber,respectively.The probability distribution of the number of initial and final cracks of BF-MPC obeyed the Weibull distribution well,and the number of damage raised with the increase of failure probability.(3)The effects of different amounts of mineral admixtures(fly ash,silica fume and metakaolin)and different lengths of basalt fibers on the properties(setting time,fluidity,compressive strength and flexural strength)of BF-MPCC were investigated.The results showed that the incorporation of mineral admixtures could prolong the setting time of BFMPCC and improve the fluidity and mechanical properties of BF-MPCC due to the morphological effect,microaggregate effect and activity effect of mineral admixtures.(4)The strength development of BF-MPCC under long curing age was studied.The results showed that the strength of BF-MPCC was still greatly improved after curing for more than 28 days,and the compressive strength and flexural strength of the group with the largest strength improvement increased by 79% and 71% respectively after curing for 120 days compared with 28 days.