Study On The Strength And Chlorine Resistance Of Modified Sugarcane Bagasse Asd(SCBA) Cement Mortar

The demand for Portland cement is increasing rapidly.This has caused great pressure on China’s increasingly tense energy and resources,and seriously polluted the living environment of human beings.Therefore,in the production and application of cement,it has become one of the goals of human beings to make high-performance concrete by using industrial wastes and biomass agricultural products discharged from human social activities.It has been proven that sugarcane bagasse ash(SCBA)can be used as supplementary cementitious material to improve the performance of concrete in construction industry.So far,most of the researches on SCBA concrete are focused on the improvement of basic mechanical properties and durability,but the properties of SCBA materials will be significantly affected by the modification methods and then the properties of SCBA concrete will be affected.Therefore,it is necessary to study the influence of different modified SCBA on the strength and chloride resistance of SCBA concrete.In this paper,different quality of modified SCBA was obtained through different modification treatments.The microstructure and physicochemical properties of modified SCBA were further characterized,and the strength test and rapid chloride ion migration test of SCBA mortar were carried out.At the same time,by means of SEM,XRD and MIP etc,the mechanism of strength and chloride resistance of modified SCBA mortar was studied.The main research and conclusions of this paper are given as follows:(1)The physical modification scheme was designed based on the influence factors of grinding fineness,calcination temperature and calcination time,and the chemical modification scheme was designed based on the influence factors of the dosages of chemical reagents and types of chemical reagents.The modified SCBA of different quality was obtained through physical modification and chemical modification,and the microstructure and physicochemical properties of the modified SCBA were further characterized.The analysis showed that the activity of SCBA could be improved to a certain extent by reasonably controlling the physical and chemical modification methods.The results of XRD showed that,among the physical modification methods,calcination at 600℃ for 90min(T90)has the most significant effect on improving the activity of SCBA.However,active silica began to crystallize at 800℃ and transformed into inert cristobalite,which led to the decrease of SCBA activity.Compared with the physical modification,the area of diffuse reflection peak in XRD spectrum of SCBA treated with five chemical reagents increased in different degrees,which indicated that the activity of SCBA could be further improved by chemical modification.The results of XRF showed that the carbon and volatile impurities in SCBA could be effectively removed by calcination,and the content of amorphous silica was increased,and the pozzolanic activity of SCBA was improved.(2)The strength test of SCBA cement mortar with different modification methods was carried out.The results showed that the strength of physical modified SCBA mortar increased first and then decreased with the increase of calcination temperature,and the strength increased significantly at 600℃.The strength of SCBA mortar increased with the increase of calcination temperature,and the strength increased by 18% after 90 minutes of calcination.The results show that calcination at 600℃ for 90 min is the best physical modification method for SCBA,and the strength of T90 cement mortar is improved most significantly.At the same time,the strength of chemically modified SCBA cement mortar had been effectively improved to a certain extent.Among them,the By cement mortar had excellent chemical modification effects,and the compressive strength was increased by 41%.The results showed that the compressive strength of SCBA mortar was improved by five chemical reagents: B>E>A>D>C,and the best chemical modification method to enhance the strength of SCBA is to use reagent B at the dosage of y,and the strength of By cement mortar is improved most significantly.(3)Rapid chloride migration coefficient(RCM)method was used to test the chloride corrosion resistance of SCBA cement mortar with different modification methods.The results showed that the chloride salt corrosion resistance and strength of physical modified SCBA mortar showed similar changes.Among them,the chloride diffusion coefficient of SCBA cement mortar was effectively reduced to a certain extent.The best physical modification method was calcination at 600℃for 90 min and the chloride diffusion coefficient of T90 cement mortar decreased by 43%.At the same time,the SCBA cement mortar treated with further chemical modification showed different degrees of improvement and decrease in the resistance to chloride salt erosion.The chloride corrosion resistance of Az cement mortar was also significantly improved,and the chloride diffusion coefficient decreased by 64%.The improvement degree of chloride resistance of SCBA cement mortar by five chemical reagents: D>A>E>B>C.(4)The micro-indices of SCBA cement mortar were obtained through a series of micro experiments,such as SEM,XRD and MIP.The influence mechanism of SCBA modification methods on the hydration process and microstructure of the mortar was explored.The XRD curve showed that the modified SCBA could effectively promote the secondary hydration reaction and generate more gelled products.MIP results showed that the modified SCBA could effectively optimize the pore size distribution and reduce the overall porosity,improve and optimize the micro pore structure,and make the structure densified,which effectively improved the strength and chloride corrosion resistance of mortar.SEM test results showed that when the modified SCBA was added into the cement composite,the micro pores in the internal structure could be effectively filled,and the structure was densified.At the same time,the pozzolanic effect of the modified bagasse ash consolidated some weak areas such as cracks and interface transition zone,and restrained the further damage of the structure.