What is self-leveling mortar?
Self-leveling mortar is a dry-mixed powder material composed of multiple active ingredients, which can be used by mixing water on site. After a slight spread of the scraper, you can get a high-level base surface.
Cement-based self-leveling floor compound components mainly include inorganic cementitious materials, polymer emulsions, mineral admixtures, sand, etc. The properties of the constituent materials and the material ratio affect the application effect of mortar. The performance of self-leveling concrete is manifested explicitly in two aspects, rheology, and technical specifications. The former plays a vital role in analyzing rheological properties, and the latter refers to the unified mortar technical standards. For this reason, many countries have conducted an experimental analysis. To explore the impact of mortar technical specifications on material quality and formulate mortar technical standards.
Analysis of factors affecting the preparation effect of cement-based self-leveling mortar
(1) Sand factor
The aggregate ratio has a direct impact on the flow effect of the mortar. Besides, it indirectly affects the shrinkage effect of the artillery. Among them, the amount of sand is positively correlated with the aggregate ratio, and the decrease in the amount of cement leads to the weakening of the flow effect. Appropriately increasing the amount of tap water used can meet the needs of fluidity, and the strength will be reduced accordingly. It can be seen from this that it is essential to control the collection ratio reasonably and that the reasonable control of the balance can achieve the primary goal of orderly flow and comprehensive display of mechanical properties. Summarizing the research data shows that the collection ratio is more significant than 0.9, and less than 1.0 is the most appropriate, which can significantly reduce the shrinkage cost.
(2) Dispersible latex powder
This material has an essential influence on the performance of self-leveling concrete. Too much or too little addition will reduce the working effect of the mortar. At the same time, it will also indirectly affect the degree of coagulation and adhesion. When the addition amount is greater than 3%, the viscosity is higher, and the construction speed will gradually decrease. The performance advantages of self-leveling mortar cannot be fully demonstrated. Only by reasonably controlling the content of latex powder can the battery compressive resistance and flow effect be improved. The test shows that the mixing amount is maintained at about 0.5%, and the mortar has a good flow effect. Once it exceeds the above-specified value, the viscosity of the battery will increase, which will affect the construction process. A comprehensive analysis of the mixing amount will control it at 2% ~ 2.5% Most suitable.
(3) Sulphoaluminate cement
Continue to add sulphoaluminate cement for half an hour, the fluidity of the mortar will be significantly reduced, and the strength of the self-leveling battery will also be affected to a certain extent. When self-leveling mortar does not add this substance, bleeding and sedimentation are very easy to occur, and the strength value does not meet the construction requirements; when the content of the additive reaches 10%, the strength will increase accordingly, and the flexural strength within one day will increase by 2.7MPa, The compressive strength is increased by 8.0MPa, the original bleeding settlement phenomenon can be improved, and the peeling problem will be solved accordingly; when the additive mass reaches 17%, the mortar has good fluidity, the surface is very smooth, and the strength can meet the construction needs; When the additive group is more significant than 20%, the fluidity of the self-leveling mortar will gradually weaken, and the power will also decrease accordingly. Therefore, it is most appropriate to control the addition of sulfoaluminate cement at 15% to 20%.
The defoaming agent has little effect on the fluidity of self-leveling mortar, but it affects the strength of self-leveling mortar to a certain extent. If the dosage is controlled at 0.5% to 1%, the power of the self-leveling mortar will increase correspondingly, and the flexural strength will increase by 0.9 MPa, the compressive strength is increased by 3.2MPa. If the amount of defoamer is less than the above value, the intensity change will increase, and there will be more pores on the surface of the mortar, which will affect the surface smoothness.
The thickener type is HPMC. Adding an appropriate amount of thickener can enhance the bonding strength and improve the surface smoothness. The thickener can be continuously increased for 20 minutes. The flow effect of the mortar changes from good to weak, and the strength of the mortar will also change, that is, first strengthen and then weaken. Analyze the suitable mixing amount of the thickener and control it to about 0.5%, which is beneficial to enhance the performance of the mortar, and the flow of the mortar can meet the needs of construction.
The performance of self-leveling mortar is greatly affected by the admixture. When the substitution amount of the admixture is less than 30%, the fluidity will be more and more optimized under the influence of the increase in the number of admixtures. Once the substitution amount exceeds the above percentage, the flow Sex will be significantly weakened. According to data analysis, the admixture amount is less than 10%, the mortar expansion degree is less than 125mm within half an hour, the flow effect is not apparent, and there is a big gap with the required standard value. The best control value of the admixture amount is about 25%. At the same time, the ratio between slag and fly ash is about 1.45. All influencing factors are prepared in accordance with the above requirements, which can significantly improve the performance of self-leveling mortar. At the same time, the configuration cost can be reasonably controlled, and the strength and fluidity of the mortar meet the construction requirements.
In summary, specific analysis of the configuration factors of cement-based self-leveling mortar can grasp the optimal configuration ratio of each factor, which will greatly improve the application effect of self-leveling mortar, and help improve the quality and aesthetics of buildings. Besides, relevant researchers can get theoretical support and continue to explore in the preparation of cement-based self-leveling mortar.
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