Research on the formation of M1-type alite doped with MgO and SO_3-A route to improve the quality of cement clinker with a high content of MgO

摘要

This paper discusses the effect of SO3 dopants on the M-1 polymorph formation and mechanical properties of alite containing a high content of MgO. The structure of the M-1 alite is identified by XRD, high-temperature XRD and TEM analysis. A characteristic XRD pattern of M-1 alite doped with MgO and SO3 is determined, and TEM results show that M-1 alite has an incommensurate modulated structure feature with 2.4 times the subcell dimension along [(2) over bar1 0 ](H)* and could be expressed as ha* + kb* + lc* + m/[2.4 (-2a* + b*)], where m = +/- 1. The First-Principles method is used to simulate the structure of M-1 alite, and the calculated Delta Cohesive Energy is approximately 11-12 eV between the M-1 and M-3 alite. Quantitative analysis is performed by the Rietveld method. The SO3/MgO (mass ratio from SO3 to MgO) and M-1% in alite (M1-C3S%/M1-C3S%+M3-C3S% x 100%) are shown to have a strong linear relationship, which can be defined as M1-C3S%/M1-C3S%+M3-C3S% x 100% = 24.73 + 108.11 * SO3/MgO (%). Mechanical properties results show that appropriate SO3 dopant can improve the compressive strength of alite containing high MgO while over dosed SO3 will lead to a contrary effect because of the decomposition of alite. The relationship between M-1% in the alite and the compressive strengths at different ages is also given. The optimal M-1% in alite is approximately 68% and the best SO3/MgO ratio is approximately 0.43 because the compressive strength could be maximized at each age. (C) 2018 Elsevier Ltd. All rights reserved.