A kind of steel slag sand-straw ash composite mortar and its preparation method

Abstract

Steel slag sand-straw ash co-doped mortar of the invention comprises the following raw materials (by weight): 5-30 parts of cement, 20-50 parts of river sand, 20-60 parts of steel slag sand, 1-20 parts of straw ash, 1-20 parts of fiber, and 0-5 parts of a mortar additive. By high value-added utilization of two industrial waste materials (steel slag and straw ash), the straw ash is used as an alkali-activator to activate early activity of steel slag and heat insulation function of straw fiber, high strength, low shrinkage, slight expansion, safety and stability, heat insulation and environmental protection of the steel slag sand-straw ash co-doped mortar have achieved good effects.

Description

technical field [0001] The invention belongs to the field of thermal insulation mortar, in particular to steel slag sand-straw ash composite mortar and a preparation method thereof. Background technique [0002] Mortar is a bonding substance used in building bricks, usually composed of a certain proportion of sand and cementing materials plus water. With the rapid development of cities, river sand, one of the commonly used materials in mortar, is increasingly in short supply. Due to the needs of environmental protection, mining of river sand has been banned in many areas, which makes it urgent to find alternatives to river sand. In the current process of preparing construction mortar, some industrial waste residues such as fly ash and slag have been widely used, which not only reduces the production cost of mortar to a certain extent, but also improves the working performance and durability of mortar. . Even so, the performance of mortar obtained by using fly ash, slag and...

AI Technical Summary

Problems solved by technology

Although the mortar has the function of heat preservation, it has the following defects: the requirement of the mortar for the steel slag raw material is "age the steel slag for one year, so that the free CaO is less than 3%", which not only takes too long, but also has low production efficiency and wastes the land resources, random uncertainty is strong; moreover, the gel activity of steel slag has basically disappeared after being placed for one year, and the strength of the obtained mortar can only reach 0.18MPa

Although the above-mentioned mortar has adopted industrial waste steel slag sand, which reduces the pollution of the steel slag to the environment, and the prepared mortar has the function of heat preservation, there are still the following problems: because the steel slag contains a certain amount of free calcium oxide and free magnesium oxide, so , capable of chemically reacting with water and carbon dioxide to produce volume expansion

Therefore, straw ash can accelerate the hydration of cement, and C-S-H gel has higher strength, which can improve the early strength of mortar; but the effective active content of straw ash is much less than that of cement, which will cause its later strength to decrease, and straw ash mixed with When the amount is too large, a large amount of potassium salt and magnesium salt will be dissolved in water and dispersed in the cementitious material, which will crystallize with age and cause "salting out" phenomenon, which seriously affects the durability of concrete

Therefore, in order to avoid the poor durability of concrete, the amount of straw ash needs to be strictly controlled, resulting in the amount of straw ash used in this technical solution is only 1.67%-1.75% of cement, which cannot achieve the effect of "recycling waste".

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