| Soda residue is the waste discharged by the soda ash industry,which is characterized by an extensive amounts,complex chemical composition,and difficult recycling.Cement has the characteristics of high strength,excellent plasticity,and durability,etc.and is widely used in construction projects.The amount of consumption is considerable.At present,the research and comprehensive application of soda residue in the cement substrate are few.In this paper,the waste residue discharged from the production of soda ash by the ammonia-soda method of Guangdong nan fang soda co.,ltd.Was taken as the research object to modify soda residue and its application in wet mixed mortar.The main research contents and results are as follows:The main research contents and results are as follows:1.Research on modification of soda residue:The results show that the sodium carbonate modification can effectively reduce the content of sulfate ions in the original slag.In the range of 60%,70% of the ideal dosage of sodium carbonate,the content of sulfate ions decreased the most,with a decrease rate of86.8%.The optimal stirring time of modified soda residue is 60 min,and the content of the sulfate ion of modified soda residue is less than 3.5%,which can meet the requirements of building application.2.Influence of modified soda residue on the fracture resistance,compressive strength,and rheological properties of cement paste:(1)When soda residue replaces cement,the colour of the cement paste sample changes from grey-black to grey-white,and there are white particles in the section of the example.The larger the soda residue content is,the more the white particles are distributed,and the poor dispersion of soda residue is.An appropriate amount of modified soda residue mixed into the cement paste can slightly improve the compressive and folding strength.The results show that only the modified soda residue with the conversion rate of 60% or 70% can improve the folding and compressive strength of the cement paste when the content is 5%,and the other modified soda residue groups can reduce the folding and compressive strength of the cement paste.(2)The rheological property of cement paste can be improved by adding an appropriate amount of modified soda residue into the net cement paste.In contrast,the rheological property of cement paste can be reduced by excessive incorporation.The cement paste shows the rheological characteristics of Bingham fluid.The addition of soda residue does not change the fluid model of cement paste,but it will affect the rheological properties of the new mud.In this study,the optimal dosage of unmodified soda residue to yield stress of mud was 5%,and that of modified soda residue was 20%,The optimal dosage of plastic viscosity in both groups was 5%.With the increase of shear rate,the cement paste mixed with soda residue will show the phenomenon of shear thinning.3.Influence of modified soda residue on wet mixed mortar performance:(1)Impact of modified soda residue on consistency,setting time,bulk density,air content,and water retention of wet mixed mortar.The results show that the texture of damp mortar can be improved by using modified soda residue as an admixture.When the content is less than 10%,the setting time of wet mixed mortar will be prolonged.However,when the dosage is more than 10%,the setting time of wet mixed mortar will be significantly shortened.With a 100% dosage,the setting time can be reduced by 396 min.The bulk density of wet mixed mortar decreases gradually with the increase of the content of modified soda residue,and the maximum decrease is 8%.The air content of wet mixed mortar increases with the content of modified soda residue,and the increased range is 55%.The modified soda residue has a strong ability to absorb free water,which is beneficial to improve the water retention rate of wet mixed mortar.(2)Influence of modified soda residue on unit volume water loss and drying shrinkage of wet mixed mortar.The results show that the modified soda residue can reduce the water loss per unit volume of damp mortar,and the modified soda residue can lower the water loss per unit volume by 76.4%?85.2% in the range of 10%?20% under the standard curing condition.Modified soda residue can effectively reduce the drying shrinkage of wet mixed mortar.Still,optimal mixing amount of modified soda residue under different working conditions is not the same,under the terms of winning the bid,the revised soda residue mixing amount is 20%,can reduce the maximum drying shrinkage,the reduction range of up to 84.8%;Under the same dosage,the standard curing condition had the best effect on lowering the drying shrinkage of wet mixed mortar,followed by the high temperature and high humidity condition,and then the room temperature condition.(3)Influence of modified soda residue on the flexural and compressive strength of wet mixed mortar.The research shows that: when the content of modified soda residue is less than 20%,the mixture of modified soda residue in wet mixed mortar can improve the flexural and compressive strength,but when the content is more than 20%,the flexural and compressive strength of wet mixed mortar will decrease.The effect of modified soda residue on the compressive strength of damp mortar is better than that of unmodified soda residue.When the amount of modified soda residue is the same,the flexural and compressive strength of wet mixed mortar is the best under the condition of high temperature and high humidity,followed by the standard curing condition,and then the room temperature condition.(4)Influence of modified soda residue on the impermeability and tensile bond strength of wet mixed mortar.The results show that the content of modified soda residue can increase the impervious property of wet mixed mortar in the range of 10%?20%,and the maximum increase is 11.6%.When the content of modified soda residue is more than 20%,the anti-permeability will be decreased.The tensile bond strength of wet mixed mortar will decrease with the addition of modified soda residue,and the curve of tensile bond strength will show a steep decline and then a gentle trend with the increase of the content of modified soda residue.The maximum reduction range of tensile bond strength of wet mixed mortar is 30%.(5)Influence of modified soda slag on pore structure parameters in submicroscopic state of wet mixed mortar.The research shows that the modified soda residue can increase the average chord length and pore spacing coefficient of wet mixed mortar pore structure,and the average chord length and pore spacing coefficient of the pore structure increase with the increase of the modified soda residue content.The average chord length of the pore structure can be increased by 71%,and the pore spacing coefficient can be increased by 44%.The pore specific surface area decreased by 48% with the increase of the content of modified soda residue.When the content of modified soda residue is less than 10%,the pore ratio and bubble density of wet mixed mortar will decrease,and the maximum decrease is 52% and 48%,respectively.When the content of the modified soda slag is more than 10%,the pore ratio and bubble density of wet mixed mortar will increase. |
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