Experimental Study On Properties Of Bentonite And Basalt Fiber Modified Cement Mortar

With the implementation of the rural revitalization strategy,agricultural infrastructure construction has become the key to solving the "three rural problems".Farmland irrigation channels have largely solved the problem of inefficient agricultural irrigation water and alleviated the contradiction between supply and demand of agricultural irrigation water.However,there are also some shortcomings in farmland irrigation channels,many channels have problems such as poor anti-seepage and crack resistance,easy aging failure,difficult maintenance in the later stage and limited adaptation range.In this paper,a cement mortar material resistant to seepage resistance cracking is developed for the problems of easy aging failure,cracking and leakage of irrigation channels in rural areas of China at this stage.The working,mechanical properties,impermeability and crack resistance properties of cement mortar were studied by the doping of bentonite and basalt fibers,and the mechanism of action of cement mortar was explained by scanning electron microscopy,energy spectroscopy,X-ray diffraction and spectral analysis,and finally the engineering application was analyzed.The main research contents and conclusions of this paper are as follows:(1)Different blends of bentonite and basalt fiber cement mortar were prepared and tested for their working properties,compressive strength and flexural strength,respectively.The test results show that the mixture of bentonite and fiber significantly reduces the fluidity of the mortar,and the greater the mixture of the two,the greater the decrease in fluidity.The mixture of bentonite and fiber can significantly improve the water retention of mortar,when the mixture of bentonite and fiber is 8% and 0.4%respectively,the water retention rate is improved the best,compared with the ordinary mortar(control group)increased by 4.69%.The early compressive strength of mortar was affected by mixing bentonite and fiber;with the increase of bentonite and fiber,the compressive strength and flexural strength of mortar showed a trend of increasing first and then decreasing,and the 28 d compressive strength reached the maximum when the dosing of bentonite and fiber was 4% and 0.2%,respectively,and increased by 15.05%compared with the control group.The 28 d flexural strength was maximum when the doping amounts of bentonite and fiber were 6% and 0.2%,respectively,and increased by21.93% compared with the control group.(2)The impermeability and crack resistance of bentonite and basalt fiber cement mortar with different admixtures were tested.The test results showed that: the impermeability of the mortar with single bentonite and bentonite dosing showed a linear growth relationship,single fiber can also improve the impermeability,but the improvement effect is not as obvious as bentonite;when mixed with bentonite and fiber,with the increase of the dosing of the two,the impermeability of the mortar showed a trend of first increase and then decrease,when bentonite and fiber dosing of 4% and 0.4%respectively,the impermeability pressure value is the largest,compared with the control group When the bentonite and fiber dose was 4% and 0.4% respectively,the impermeability pressure value was the largest,which was 62.26% higher than the control group,and the impermeability grade reached P8.Single bentonite on the mortar to improve the crack resistance performance is not obvious,mixed bentonite and fiber to improve the crack resistance performance is obvious,with the increase in the amount of both,the crack resistance performance shows a trend of first increase and then decrease in the amount of bentonite and fiber,respectively,4% and 0.4%,the crack reduction coefficient can reach more than 80%,the crack limit grade Ⅰ,the crack characteristics of"less The crack characteristics are "less,fine,short".The study proved that the bentonite and fiber on the mortar impermeability,crack resistance performance of the most suitable amount of bentonite 4%-6%,fiber 0.4%.(3)The microstructures of single-doped bentonite,mixed bentonite and basalt fiber mortar were analyzed.Scanning electron microscope analysis showed that the mixed bentonite and fiber could improve the compactness of the mortar and reduce the cracks and pores of the mortar.The incompletely hydrated bentonite is wrapped around the surface of the fiber,which increases the adhesion between the fiber and mortar,and the cracks and holes are interlaced by the fiber,which plays a role in dispersing and transferring the load when subjected to external load;if the bentonite and fiber are mixed too much,the fiber and the matrix are prone to agglomeration and the fiber mesh crosslinking is weakened,which leads to the reduction of mechanical properties and antiseepage and anti-cracking properties.The physical phase analysis and spectral analysis show that the admixture of bentonite and fiber does not change the type of hydration products of mortar,but reduces the crystallinity of calcium hydroxide and promotes the generation of hydrated calcium silicate gel,which is conducive to improving the mechanical properties,seepage resistance and crack resistance of mortar.(4)The application of bentonite and basalt fiber cement mortar in practical engineering is discussed in the engineering context of agricultural irrigation channels in a certain area,and the construction technology points of the mortar are summarized,and the economic and socio-ecological benefits of the mortar and the common mortar are compared and analyzed.The analysis results show that although the preparation cost of this mortar is slightly higher than that of ordinary mortar,it has higher economic benefits in the whole life cycle.Compared with ordinary mortar,this cement mortar can save 101.3yuan/m3.In addition,the application in farmland irrigation channels also has higher social,ecological and environmental benefits.