Research On The Application Of Manufactured Sand In The Pre-mixed Mortar

With the vigorous development of civil engineering and more attention paid on the project quality, more and more sand with higher quality is required, but the natural sand with regular quality is becoming less and less. Based on this fact, the natural sand is rise in price and the excessive exploration appears in some area. This will lead to the destroy of the environment and the nature energy crisis. Therefore, the way to introduce manufactured sand, which is produced by rock, to substitute natural sand can meet the strategic requirement of sustainable development and save natural resource. Pre-mixed mortar is a kind of architectural material with good performance. It is produced by the professional factory, can be used as mortar mixture. Now, it is becoming an important new type material in China. The effect and operation mechanism with the property of manufactured sand for pre-mixed mortar is analyzed in this paper, which provides the theoretical basis for the application of manufactured sand used in the pre-mixed mortar. The main content is as follows:First, the effect of the gradation and grain shape of the manufactured sand for pre-mixed mortar is analyzed. The results show that manufactured sand with good gradation can improve the workability, mechanical property, shrinkage property and frost resistance of the pre-mixed mortar. With the increased angularity index of the manufactured sand, the fluidity of the new mortar is becoming bad but the intensity and contractibility is improving after the hardening process.Second, the effect of the content of stone powders in the manufactured sand for pre-mixed mortar is analyzed. The results show that the workability of the pre-mixed mortar can be improved with the proper amount of the stone powders and the shrinkage rate of the pre-mixed mortar is reduced. What's more, some other properties, such as the compressive strength and frost resistance are also improved. More over, the bounds of the content of stone powders in the pre-mixed mortar are deduced in case of different cement dosage.In the end, according to the micro analysis, the promotion of the cement hydration brought by the stone powders in the manufactured sand is studied, and the mechanism of improvement in pore structure and interface structure is analyzed. On the one hand, the stone powders in the manufactured sand can participate in the hydration reaction with C3A, which will produce calcium carbonic aluminates hydrate to accelerate the hydration reaction of the cement. On the other hand, the stone powders in the manufactured sand has the property of filling effect, which can improve the pore structure of the hardened mortar and the compactness of the mortar, consequently the property of the pre-mixed mortar can be improved after hardening.