Minerals of expansive and non-shrinkage sulfomineral cements

Svetlana V Samchenko,Yuriy R Krivoborodov,Dmitriy A Zorin,V Murgul

doi:10.1051/matecconf/201710603006

Abstract

Usually to obtain expansive cements sulfoaluminate clinker or mix aluminate clinker with calcium sulfates (gypsum, hemihydrate, anhydrate) are used. For these cements ettringite is an important hydration product and kinetic reaction of this phase plays an important role in determinаting performance. The alternative aluminate phases may be ferrite containing ones. This article deals with the composition and properties of solid solution of calcium sulfoaluminate, sulfoferrite and sulfoaluminoferrite cements. It was studied an influence of calcium sulfate on structure and properties of calcium aluminate and ferrite phases, and their stability under high temperatures. Beside that the properties of cements containing these phases were studied. The investigation of hydration and properties of sulfomineral cements shows that ettringite and its analogies are formed in such way to provide expansion and compression of cement stone. Degree of expansion and self-stressing of cement stone depends not only on composition of sulfated minerals but on ratio and types of clinkers. The higher expansion is reached by the use of high alite containing Portland cement clinker together with sulfoaluminate or sulfoalumoferrite one, the lower expansion is reached by addition of sulfoalumoferrite and sulfoferrite clinkers. These cements are classified as self-stressing, expansive or shrinkage-compensating ones depend on the degree of their expansion after 28 days of curing.

Highlights

The chemistry of expansive cements was comprehensively discussed on the previous congresses and in many research publications [1,2]
Cement K is produced by intergrinding Portland cement clinker, gypsum and clinker consisting of C4A3 S
XR-analysis has revealed that the addition of Fe2O3 caused a shift in the major diffraction peaks of C4A3 S, this being the more manifest the more Fe2O3 added to the mineral (Table 1)

Summary

Introduction

The chemistry of expansive cements was comprehensively discussed on the previous congresses and in many research publications [1,2]. A majority of practical expansive cements have depended on the modification of a Portland cement in such a way as to increase the formation of ettringite. In a widely used terminology, expansive cements based on Portland cement and calcium sulfate are categorized as types K, M or S, according to the source of additional Al2O3 that is required. Type S cements are Portland cements high in C3A and with suitable contents of calcium sulfate.

Results

Conclusion