Research On The Hydration Mechanism And Properties Of A New Kind Of Limestone Slag Cement

With implement of sustainable development strategy, resourees,energy and Environmental problems become the main factor to restraint the cement industry.Low-clinker or non-clinker cement cement,which is produced from little Portland cement clinker and more industriai waste residue and Low-cost admixtures, is a task of environmental and economic assignment.In this paper, on the basis of limestone, slag as raw materials, Low-clinker or non-clinker cement adding some gypsum, clinker, or slag which is in line with the national GB/T 3183-2003 "masonry cement" standards can be prepared。The study results can significantly reduce the energy consumption of cement production, greenhouse gas emissions and other exhaust gas and dust emissions,it is of great significance. This paper focuses on a new type of limestone slag cement hydration mechanism and durability.The main research contents and the result of the study in this paper are generalized as the following:First, the main effect of the clinker, limestone and gypsum had been studied in the limestone slag-based low-clinker, The few clinker played a role in adjusting the alkalinity. The optimum increased content of clinker was favorable to the strength development of the cement. The strength of the cement reduced with the increased content of limestone and. The effect of specific surface was not obvious on the 28-day compressive strength of cement, but the 7-day compressive strength of cement increased with the increased specific surface. A small amount of gypsum dosage had little impact on cement strength, when the volume of gypsum is over 7%, the cement strength began to show significant downward trend.Second,the effect of the steel slag, limestone and gypsum had been studied in the limestone slag-based non-clinker cement, steel slag had an important role in the strength of limestone slag cement without clinker, appropriate dosage can provide appropriate basicity conditions, excitated the blastfurnace slag hydration activity effectively, and conduced to the cement strength, but an excessive amount of slag dosage made high alkalinity of cement paste, resulting in expansion of ettringite crystals destruction, which adverse the development of the cement strength.Last, the durability of the limestone slag-based non-clinker cement has been studied, results showed that the limestone slag-based non-clinker cement late sustained generate CSH, which continue to fill gaps in the cement, the cement structure to keep dense, the intensity continued to increase. The limestone slag-based non-clinker cement had a very strong anti-sulphate erosion capability, and shrinkage rate were much lower than ordinary portland cement, but the anti-carbonization capability and anti-high temperature capability were lower than ordinary portland cement, needing further improvement。Conservation of limestone slag-based non-clinker cement in limewater can improve the early strength, but also improve the ability of anti-carbonation.