| The rapid development of urban and rural construction process in the new era,the increasing demand for commercial concrete,has greatly promoted the development of ready-mixed concrete industry,but also exposed the related problems;The waste concrete pulp produced by commercial mixing station not only causes a waste of resources,but also has a great impact on the environment.How to deal with the waste concrete pulp reasonably is the key to solve the problem.In view of this,this paper systematically studies the influence of the dried concrete waste slurry on cement mortar after pressure filtration.In this paper,the waste concrete pulp after being filtered by drying ball milling is studied by cement chemical analysis,particle size analysis,XRD and SEM.The effects of different dosage on the properties of cement slurry and cement mortar were studied.The influence of the mixture amount of the pressed filtered dry concrete slurry powder on the properties of M15 masonry mortar under the two mixing modes of internal and external mixing was studied,and the influence on hydration products and microscopic morphology of mortar was analyzed by XRD and SEM.The results are as follows:(1)The quality of compressed and filtered concrete waste pulp and dry powder is used to replace the cementing material in the cement mortar.With the increase of the mixing amount,the cement setting time is shortened,the water consumption of standard consistency and the foldcompression ratio of the cement mortar are increased,and the fluidity and flexural and compressive strength of the cement mortar are reduced.(2)The pressed and filtered dry concrete slurry powder is used as cementing material instead of cement.With the increase of the mixing amount,the mortar consistency decreases,the water retention rate and water absorption rate increase,the apparent density decreases,and the working performance can meet the requirements of normal construction;When used as cementing material,the dry waste pulp powder has adverse effect on the mechanical properties of mortar,and the influence degree increases with the increase of mixing amount.When used as cementing material,the utilization rate of dry waste pulp powder is low.(3)The results show that the mortar consistency is negatively correlated with the mixing amount,while the water retention and water absorption are positively correlated with the mixing amount.The addition of waste pulp dry powder can improve the 7d compressive strength of mortar,and the 28 d compressive strength of mortar at 5% is also significantly higher than that of the reference group.The 3d compressive strength decreases with the increase of the mixing amount,and the influence trend on the bending strength of each age is first increased and then decreased.The peak bending properties of 3d,7d and 28 d are 5%,10% and 10%,respectively.The addition rate of 15% can improve the flexural property of each age,so the dry waste slurry powder as an admixture can improve the mechanical property of mortar in a certain dosage.(4)The internal or external mixing of the pressed concrete waste pulp dry powder has no effect on the type of hydration products,and the diffraction intensity of each product will change with the mixing method or age.When the waste pulp dry powder is mixed,the pore cracks of the mortar increase,and the distribution of C-S-H gel is scattered,and the degree deepens with the increase of mixing amount.When the waste slurry dry powder is mixed,it can be seen that the pore cracks are reduced compared with the reference group when the mixing amount is 10%,but the pore cracks increase and are significantly more than that of the reference group when the mixing amount is 30%,which indicates that the waste slurry dry powder can reduce the pore cracks of the mortar within a certain mixing amount. |
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