Quantification of structure formation in setting stuccoes influenced by additives

Summary: The additives used to control the hydration of calcium sulfate hemihydrate generally influence the morphology of the developing dihydrate crystals. These morphological modifications have a direct effect on the microstructure of the solidified product, resulting in definitive determination of its macroscopic properties. The following presents an analytical method which permits simultaneous and thus prompt quantification of the developing microstructure. The results obtained using this procedure have been confirmed by comparison with conventional test methods.

1 Introduction

The setting of stucco is controlled by means of the addition of additives. These generally cause acceleration or retardation of the rehydration of the hemihydrate to dihydrate. In many cases, such intervention in the setting process results in morphological modification of the nascent dihydrate crystals [1]. Crystal morphology, for its part, influences the macroscopic properties of the finished product. Up to now, the integral effects of the structural changes associated with the crystal morphology of stucco have been determined solely via determination of the mechanical...

Related articles:

Issue 6/2016 UNIVERSITY OF SIEGEN

Investigation of the influence of ­crystal ­morphology on the strength development of ­various a-hemihydrates by use of an in-situ ­ultrasonic technique and complementary methods

The hydration of calcium sulphate hemihydrate is a dynamic process composed of various chemical reaction steps that take place in parallel. These reaction steps influence the utility properties of the...

more
Issue 10/2020 UNIVERSITY OF SIEGEN

Investigation of hydration mechanisms of alpha and beta hemihydrate

1 Introduction Calcium sulfate hemihydrate [CaCO4???0.5H2O(s)] can be found naturally in very dry climate regions in Egypt, Australia, Death valley and Kuwait as bassanite, but in the presence of...

more
Issue 11/2010

Progress of hydration and the structural development of hemihydrate plaster

1 Hydration and hardening of gypsum-based plasters The hardening of gypsum building materials is based on the crystallization of calcium sulfate dihydrate from a solution that is supersaturated with...

more
Issue 03/2009 Materials Science

Acceleration of the setting of hemihydrate plaster with calcium sulfate dihydrate

1 Introduction Calcium sulfate binders are required to have widely varying properties to meet technical and economic requirements. In particular, it has to be possible to vary the workability time and...

more
Issue 4/2015 WUHAN UNIVERSITY OF TECHNOLOGY

Application of new types of retarders in improving the properties of FGD gypsum

1 Introduction China is a developing country with coal as its main energy resource. The energy infrastructure is dominated by the coal fired power industry. Taking 2012 as an example, the yield of...

more