Gypsum under control

Gypsum constituents in recycled concrete – origin, effects and removal by jigging, part 1 

Summary: Gypsum is being used increasingly as a building material because of its ­favourable properties. If this building materials is not selected during demolition or not removed during processing then the recycled building materials produced cannot be used because, for one thing, they do not fulfil environmental requirements. Apart for this there are also construction engineering problems that lead to the formation of secondary ettringite, which initiates expansion phenomena both in concretes and in unbound base courses. Possible countermeasures by using additional processing steps are described below.

1 Introduction

Gypsum is a building material that is used in interior finishing work as plaster, floor screed and in the form of panels. Gypsum building materials are characterized by their simple workability and favourable structural engineering properties. At the same time comparatively little energy is required for their production, which has ecological and economic advantages. All this means that, apart from cyclical economic effects, the gypsum industry is in a growth phase worldwide [1]. As a consequence there is a disproportionately large increase in the amount of gypsum materials in...

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