Study On The Utilization Of SiMn Slag In Construction Materials

In the past decade, the production of silicon-manganese alloy is continuouslyincreasing, about300million tons of SiMn slag generated every year. Large number ofSiMn slag not only taken up land, but also polluted the environment. So, studying theutilization of SiMn slag in construction materials has important practical significance.In this paper, the physical-chemical properties of SiMn slag were studied, and threeways of utilization of SiMn slag in construction materials were developed whichinclude the using as cement and concrete mineral admixture, alkali activatedcementitious material and pavement concrete aggregates. Meanwhile, In order toenhance the activity of blocky SiMn slag, the thermal activation andchemically-adjusted thermal activation have been explored. Afterwards, he followingconclusions can be drawn:①SiMn slag mainly contains CaO （25%~27%）and SiO2（35%~37%）, the quality index and coefficient of basicity of SiMn slag are about1.0and0.8respectively.Blocky SiMn slag mainly contains CaSiO3、CaAl2O4、Ca2Al2SiO7、Ca2MgSi2O7、MgSiO3and other crystalline phases. Granular SiMn slag composes of non-crystallineand a little amount of aluminum silicate, quartz etc. The28d compressive strength ratioof standard mortar with blocky SiMn slag and granular SiMn slag to that without slagare82.6%and93.3%respectively. SiMn slag can be used as cement and concretemineral admixtures, alkali activated cementitious materials etc.②SiMn slag mineral admixture reduces the early strength of cement paste, mortarand concrete. But the late strength of the three cement-based materials and thedurability of concrete were improved when the dosage of SiMn slag mineral admixtureis about10%to20%, the effect of enhancement is increased with the fineness of SiMnslag powder. Meanwhile, the effect of granular SiMn mineral admixture is better thanthat of the blocky SiMn slag.③The thermal activation and chemically-adjusted thermal activation can improvethe early activity of blocky SiMn slag about50%, the late activity of thermal activationblocky SiMn slag is decreases, while that of the chemically-adjusted thermal activationis similar with the untreated blocky SiMn slag. The highest activity of blocky SiMn slagwas abtained when the slag was calcined at1050℃followed by fast cooling. Whenthe lime is used as adjusting agent, the quality coefficient is adjusted up to1.48, and calcined at1050℃followed by fast cooling, the activity of this chemically-adjustedthermal activated blocky SiMn slag is the highest.④When the Na2SO4, NaOH and water glass were used as activator of granularSiMn slag cementitious material, the optimal dosage of the three activators is3%,4%and5%respectively. Water glass is the best activator, when the dosage is5%, the28dcompressive strength and flexural strength of alkali activated granular SiMn slagcementitious material are64.1MPa and9.5MPa.⑤Blocky SiMn slag coarse is aggregate applicable to ordinary types of pavementconcrete when it is used with appropriate proportion. The replacement rate of blockySiMn slag coarse aggregate to natural coarse aggregate is over50%, the mechanicalproperties and abrasion resistance of pavement concrete are were increased about10%and30%respectively, drying shrinkage reduced15%. When the blocky SiMn slag isused as coarse aggregate in pavement concrete, it can fully replace the natural coarseaggregate and the utilization rate of blocky SiMn slag can reach100%.It is showed from the above that the utilization of SiMn slag in constructionmaterial such as cement and concrete, pavement concrete and alkali activatedcementitious materials not only reduced the environmental pollution of SiMn slag, butalso produced excellent construction materials, and it can be extensively applied.