Study On Compound Cementitious Capillary Crystalline Waterproof Coating

Cementitious capillary crystalline waterproof（CCCW）coating is a kind of environmental-friendly material which can realize both crack repair and external waterproof,and is widely used in the field of cement-based waterproof engineering.However,there are still some problems,such as supplementary materials like cellulose ether and redipersible powder to improve the application effect of CCCW coating by has not provoked much attention.When CCCW is applied to the surface of cement matrix,the synergistic mechanism between the active chemicals in CCCW and mineral admixtures in cement matrix remains unclear.It is of practical significance to apply supplementary materials in the design of CCCW to give full play to the capillary crystallization of active chemicals and to explore the improvement on cement matrix properties,together with the mechanism of CCCW.Based on this,this paper studies the optimization of CCCW coating formulation by adding supplementary materials,and explores the improvement and mechanism of the performance of optimized compound waterproof coating（JC）on different composition of cement mortar,which provides a basis for the improvement of CCCW formulation.The main research results are as follows:（1）A compound CCCW coating with better performance and easy application was obtained through orthogonal experimental design and statistic analysis.Based on the research results of the relationship between the composition of supplementary materials and properties under single factor analysis,the further optimized CCCW coating is composed of cement,quartz sand,active chemicals,redispersible powder and polycarboxylic acid water-reducing agent,with a mass of 554.1,369.4,70.0,5.0,1.5g per kilogram respectively.The relationship between the composition and content of supplementary materials and the properties of applied mortar was clarified.The fluidity of coating,impermeability pressure of mortar and bonding strength of mortar surface were greatly enhanced by the redispersible powder.The compressive strength and flexural strength of coating were most affected by adjusting the cement-sand ratio of coating.The properties were least affected by water reducer.（2）The JC coating prepared in this study can effectively improve the water absorption capability of applied mortar.The maximum improvement degree of composition factors such as blast furnace slag,water-cement ratio of mortar and fly ash on improving water absorption of mortar with JC coating after curing for 3 days was 43.1%,56.8%and 84.0%,respectively.When using JC coating at 28d curing age of mortar,the maximum improvement degree was 29.2%,20.7%and 9.4%,respectively.Applying JC coating can reduce the initial and secondary water absorption rate of mortar,and the reduction of the initial water absorption rate was larger than the secondary water absorption rate.（3）The prepared JC coating can improve the waterproof performance of applied mortar.When applying JC coating at 3d curing age of mortar,the comprehensive effect of exterior waterproofing and capillary crystallization of active chemicals was improved gradually with increasing water-cement ratio of mortar and decreasing fly ash or blast furnace slag content.The improvement of mortar waterproof performance by JC coating with 28d curing age was less than that with 3d curing age.JC coating had little effect on improving waterproof performance of mortar when fly ash content was 0～10%and blast furnace slag content was 10～20%and 30～40%.（4）There are synergistic and competitive effects between active chemicals and volcanic ash mineral admixtures such as fly ash and blast furnace slag on calcium hydroxide in the system.The addition of mineral admixtures such as fly ash and blast furnace slag changed the content of calcium hydroxide in mortar and affected the crystallization of active chemicals in the coating in mortar.Applying JC coating on the surface of mortar can further reduce the content of Ca（OH）₂ in the composite system.When the total amount of cement replaced by fly ash and blast furnace slag is less than 10%,the combining ability of calcium hydroxide with active chemicals was stronger than fly ash and blast furnace slag.There are 40 pictures,38 tables and 110 references in this thesis.