Chinese
Steel slag is a by-product in the steelmaking process, mainly divided into three categories: converter slag, open hearth slag, and electric furnace slag, with converter slag having the highest emission. The annual emission of steel slag in China is about 100 million tons, and a large amount of steel slag accumulates for a long time, not only occupying a large amount of land resources, but also causing serious environmental pollution. It is particularly important to conduct research on the reduction, resource utilization, and high-value comprehensive utilization of steel slag.
Using converter slag as raw material and ceramic roller and silica fume as toughening agents, alkali activated steel slag based cementitious materials and concrete with ceramic roller and silica fume composite toughening were prepared. The mechanical properties, high temperature resistance, and freeze-thaw resistance of the cementitious materials and concrete were investigated; The properties of the prepared materials were characterized using XRD, SEM, Lotte method, and thermochemical characterization methods. The hydration product soil of alkali activated and steel slag based cementitious materials should be mineral phases such as hydrated silica, calcium carbonate, calcium carbonate, and quasi peak zeolite. The daily production of calcium oxide increases with the extension of the aging distance. The compressive strength of alkali activated steel slag based cementitious materials shows a certain variation law with the dosage of the activator. When the dosage of the activator is 11wt9, the compressive strength of each age reaches its maximum value. When the dosage of the activator is too large, the strength tends to decrease. The larger specific surface area of the steel cleaning raw material helps to improve the alkali activated steel. Clear the early strength of its cementitious material.
The percentage of small pore volume in alkali activated steel slag based cementitious materials increases with age, while the volume of large pores decreases significantly with age. Thermochemical results indicate that alkali activated steel slag based cementitious materials undergo processes of free water removal, bound water removal, and calcium hydroxide decomposition. Preliminary attempts have been made to use this cementitious material for photocatalytic reactions. Ceramic rod silica fume composite toughened alkali activated steel slag based cementitious materials can effectively inhibit the formation of calcium oxide in the steel slag based cementitious materials during the hydration process. The main hydration products are hydrated calcium silicate and calcium hydrogen silicate, and the microstructure of the matrix is dense; After adding 10wt% 6 silica fume and 0.2wt% 9% 6 ceramic roller, the volume percentage of small pores in the alkali activated steel slag based composite cementitious material increased, and the compressive and flexural strength were significantly improved. At the same time, the specific surface area of the steel slag powder increased, which can significantly improve the mechanical properties of the ceramic Kun rod silica fume toughened alkali activated steel slag based cementitious material. During the hydration process, silica fume participates in chemical reactions as an active ingredient, thereby accelerating the formation of hydrated calcium silicate, and ceramic rollers can react with it.
CSH gel is closely bound to play a role in strengthening and reinforcing. The high temperature resistance test results of alkali activated steel slag based cementitious materials, silica fume reinforced alkali activated steel slag based cementitious materials and ceramic roller silica fume composite toughened alkali activated steel slag based cementitious materials show that when the temperature is in the range of room temperature to 450 ℃, the hydration process of steel slag based cementitious materials is accelerated, and the compressive strength of various test blocks gradually increases; When the temperature exceeds 450 ℃, new chemical reactions occur in the test block, generating mineral phases such as calcium ferrite and magnesium iron spinel. New interfaces are formed between the newly generated mineral phases, resulting in uneven matrix and a sharp decrease in the flexural strength of the test block. The compressive strength of alkali activated steel slag concrete reinforced with ceramic roller and silica fume prepared with a water slag ratio of 04 is 52.2MPa, which meets the C40 design standard. The frost resistance of alkali activated steel slag concrete is f50, while the addition of ceramic roller and ash improves the frost resistance of alkali activated steel slag concrete to F150.