The Study Of Magnesium Slag On The Drying Shrinkage Of Concrete

In recent years the rapid development of magnesium industry, magnesium slag emissions increased dramatically, led to increasing pollution, at the same time restricts the further development of magnesium industry; Concrete commercial concrete has higher strength and liquidity, therefore the use amount of admixture and the admixture is bigger, cause the dimensional stability of concrete affected; The chemical composition of magnesium slag and cement, hydration activity to a certain extent, MgO style has contained the dilatability, magnesium slag as concrete admixture, can improve the strength of concrete, has potential compensation on the drying shrinkage of concrete, and can reduce the engineering cost, reduce environmental pollution, so this topic has high research significance, and received the national natural science fund project support.This topic is mainly taking typical C30 concrete as the research object, Through single factor experiment design plan, the orthogonal experiment, useing the chart analysis, such as poor analysis, analysis of variance analysis method, with magnesium slag content, digestion time, replacement ratio of fly ash and slag as the main factors such as replacement ratio and ages, will be part of the fine aggregate concrete by magnesium slag to replace, the magnesium slag drying shrinkage deformation of concrete were studied, to reveal the mechanism of magnesium slag on the drying shrinkage deformation of concrete, the establishment of a significant relationship model, for the application of magnesium slag in concrete laid a theoretical foundation, studies the following conclusions:(1)With the increase of the dosage of magnesium slag drying shrinkage of concrete and gradually reduce, the compressive strength hump-like curve, are most strong in magnesium slag dosage was 20%.(2) The drying shrinkage of concrete is gradually increasing with the increase of magnesium slag digestion time, reasonable digestion time is 3d.(3) Magnesium slag and fly ash composite, the drying shrinkage of concrete decreases with the increase of dosage of magnesium slag, and decreases with the increase of fly ash, the strength of concrete increases with the increase of dosage of magnesium slag, decrease with the increase of fly ash replacement ratio.(4) Magnesium slag and mineral composition, drying shrinkage of concrete decreases with the increase of dosage of magnesium slag, before 7 d decreases with the increase of mineral powder, after 7 d increases with the increase of mineral powder.(5) Magnesium slag and fly ash, mineral composition, drying shrinkage of concrete decreases with the increase of dosage of magnesium slag, along with the increase of active admixture is reduced, with the increase of the mineral powder composite rate before the 7 d is reduced, increased after 7d.