Preparation Of Cement-based Permeable Crystalline Waterproof Coating And Performance Research

With the development of science and technology,people have higher requirements for the performance of cement-based materials.It is hoped that the current buildings will have better durability and be less prone to leakage,which can greatly reduce the maintenance cost in the later period.How to improve the waterproof performance of concrete buildings is the focus that needs to be solved urgently.This topic uses calcium material A,soluble silica material B,phosphonic carboxylic acid complexing agent C and other active masterbatch,which can be mixed with cement and quartz sand to prepare cement-based permeable crystalline waterproof coating,and explore its effect on cement-based The material’s protective performance,penetration depth and microscopic mechanism of action provide a technical and theoretical basis for deeper research on this type of material.Research indicates:Using a three-factor,three-level orthogonal design experiment,the active masterbatch formulation and dosage were determined by using the bond strength and water penetration height as indicators.Determine the optimal ratio of masterbatch:A content is 0.5%,B content is 1.0%,and C content is 0.45%.The application performance test shows that when the water-cement ratio of the coating is 0.300,the maximum bond strength is 2.48 MPa,and it has excellent crack resistance.The 2 mm mortar plaster surface has no cracking for 28 days,and the 28 d compressive strength of the coating is 36.81 MPa,the flexural strength is12.36MPa,each index is better than the national standard.The formulated penetrating crystalline waterproof coating significantly improves the protective performance of cement-based materials.When the amount of paint reaches1.5kg/m²,the transmission performance of water in concrete and mortar is the lowest,which is about half of that of the blank group.In addition,the resistance to acid,alkali and salt corrosion of the test block is improved.After 28 days of soaking,the mass loss rate is 0.09%,and the maximum compressive strength ratio is about 116%.In addition,the paint is used to repair the hollow bricks,and the 1.5mm thick coating drops only 0.4 mm within 1 d of water level.After the coating is removed,it still has a good repair performance.The compatibility of the coating and the substrate is related to the curing conditions,the curing cycle and the thickness of the coating,and has nothing to do with the strength of the substrate.The penetration depth of the coating is affected by many factors.Among them,the penetration depth in C30 concrete is shallower than that in C20 concrete,and the water absorption coefficient at 0-20mm in the vertical direction is about 60.5%of the blank group.At this time,the coating effect is the best.When the substrate age is 3d,the penetration depth of the coating can reach 53mm and 38mm,and the penetration depth of 28d is 44mm and23mm,respectively.In addition,in C30 concrete,the penetration depth of 30d～45d paint begins to reach saturation.Combined with the analysis of the pore structure,the introduction of the coating can significantly reduce the capillary pore volume,reducing the capillary pore volume by about 50.9%,but the porosity occupied by the gel pore volume is increased.Analysis of SEM and XRD results showed that the microscopic morphology and hydration products of the blank group at a distance of 60mm from the coating were similar to that of the blank group.There were a lot of hydrated calcium silicate gel and Ca（OH）₂.There were a lot of needles at 0mm and 20mm.Rod-shaped crystals are produced,and EDS analysis is for calcium silicate crystals and calcium carbonate cry-stals.TG analysis showed that the introduction of the coating increased the content of hydrated calcium silicate and calcium carbonate.Through the analysis of the mechanism of the permeable crystalline waterproof coating,it can be summarized into fourprocess es:permeation-crystallization-complexation-precipitation.Various components interactto fo-rm a reciprocating cycle,which improves the waterproof and anticorrosive performan-ce of the cement stone.