The Effect Of Foreign Oxides On The Cement With High Calcium

The traditional 50-60% C3S content limit of clinker was surpassed by the named high C3S clinker with about 70% C3S. The high C3S clinker is not only endowed with better cementitious property, but also with greatly helping various supplementary materials like fly ash, slag, which are added into cement as performance adjustment materials, exerting their reactivity as completely as possible. In addition, on the condition of the same amount of clinker in cement, the strength grade of cement can be obviously improved by using high C3S clinker, and on the condition of the same cement strength grade, the content of clinker in cement can be decreased. Finally, the energy spent in producing cement is reduced, and the burden on the environment is alleviated.Increasing the content of C3S in clinker is considered to be one of the effective ways to gain high strength cement, but the burning temperature is doomed to be climbed up. So, Increasing the content of C3S in clinker without rising the burning temperature, or even lower the burning temperature seems to be one of the key questions in producing high C3S clinker.This paper studies the influences of three different and representative oxides TiO₂ CuO BaO on bumability and C3S crystal morphology in order to provide evidences to choose the effective burning-temperature-reducing oxides. (1) Burning temperatures are lowered down as much as about 50℃,100℃ respectively by adding TiO2,CuO in raw materials, which is justified by analyses the amount of f-CaO and XRD of samples, and the excellent content is about 1%. On the contrary, BaO has a negative effect on the bumability. (2) It is proved by the SEM that small contents of oxides do little influences on transformation of C3S crystal system, but do influence the size of C3S crystal grain violently. The grain size is bigger at the oxides content over 1% than the one at the oxides content-1% .At the same time, this paper studies the influences of TiO2 CuO BaO on the kinetic model of the reaction by analysis the amount of f-CaO preliminarily in order to gain the kinetic data of reaction. The first 0-40min is called the first stage of the reaction, and the rate of the reaction is fast. Obviously oxides content does have an effect on the kinetic index. Then the growth of crystal is in the charge of the whole reaction, therefore the speed is slowed down.At last this paper studies the compressive strength of samples. It is found that the 28 day's compressive strengths are very close to each other because of the same amount of C3S in clinkers. But the strengths before 7 day are quite differently, the samples with oxides do better than those without ones. This can be explained by different C3S crystal grain sizes between clinkers with and without oxides. The smaller the grain size is, the more completely the reaction goes.