Study On Fresh And Mechanical Properties Of Basalt Fibre Reinforced Mortar

Basalt fibre can not only improve the toughness but also have significant effects on the fresh properties of mortar.However,there has been little research on the key factors affecting the fresh properties of basalt fibre mortar.In this paper,the fresh and mechanical properties of basalt fibre mortar were tested.Based on film thickness theory and fibre factor theory,the influence mechanism and key factors of fresh properties of basalt fibre mortar were studied.The research results are of great significance to the understanding of rheology of fibre reinforced cement-based materials,and to the production and application of basalt fibre reinforced mortar.In this paper,by taking basalt fibre content,fibre length and W/C ratio as control variables,64 mortar mixes were designed to carry out fresh properties test and packing density test to evaluate their fresh properties.Two mechianical test were also carried out to evaluate the compressive strength and flexural strength of the mortar mixes.Meanwhile,the water film thickness(WFT)of mortar for each mortar mix was calculated,and the fibre factor was tried to integrate.Lastly,the combined effects of WFT and basalt fibre factors on the mortar performance was investigated.The main tasks are presented as follows:(1)Investigate the effect of the additions of basalt fibre,fibre content,fibre length and W/C ratio on the fresh properties and mechanical properties of mortar by carrying out mini slump-flow test,mini V funnel test,sieve segregation test,stone rod adhesion test and the flexural strength test and compressive strength test of mortar.The results show that:with the increase of W/C,the static flowability and dynamic flowability of mortar increase,while the cohesiveness decreases,and the adhesiveness increases first and then decreases;with the increase of basalt fibre content or fibre length,the static flowability,dynamic flowability and adhesiveness decrases,but the cohesiveness increases.Overall,the influence degree of each factor on fresh properties of mortar is in the order of W/C>basalt fibre content>basalt fibre length.On the other hand,the flexural strength and compressive strength of mortar decrease with the increase of W/C.With the increase of basalt fibre content or fibre length,the flexural strength and the flexural strength to compressive strength ratio(F/C ratio)increase to a certain extent,but the compressive strength decreases.(2)Measure the packing density of mortar mix by wet packing test;investigate the effect of basalt fibre content and fibre length on the packing density,total specific surface area and water-solid ratio of mortar.Meanwhile,the WFT of mortar was calculated.And the WFT was used to evaluate the effects of fibre addition on the packing density,total specific surface area and water-solid ratio of mortar mixture.The results show that,with the increase of basalt fibre content,the packing density of mortar mix increases first and then decreases.The packing density of mortar mix reaches the peak value when the basalt fibre content is about 0.20%.With the increase of basalt fibre length,the packing density of mortar mix decreases.For the WFT of the fresh mortar,with the increase of W/C,the WFT of fresh mortar increases,with the increase of basalt fibre content,the WFT of fresh mortar increases first and then decreases,with the increase of basalt fibre length,the WFT of fresh mortar decreases.(3)Investigate the combined effects of WFT and basalt fibre content or fibre length on fresh properties of mortar by using regression analysis.The results show that WFT,fibre content and fibre length are the key factors affecting the fresh properties of basalt fibre reinforced mortar.And based on the model,the combined effects of WFT and fibre content or fibre length on fresh properties of mortar have been quantified.(4)Last but not the least,integrate the basalt fibre content and fibre length into a fibre factor of(V_f(L/D),V_f denotes fibre volume,L/D denotes the fibre length to fibre diameter ratio),and establish models to evaluate the combined effects of the WFT and fibre factor on the fresh properties of mortar by using regression analysis method.The analysical results show that the WFT and fibre factor can well reflect the changing rule of fresh properties of basalt reinforced mortar,which has certain guiding significance.