CONCRETE IN HOT ENVIRONMENTS - CHAPTER 2 pot

Chapter 2

Setting and Hardening

2.1. INTRODUCTION

Setting and hardening of cement can be described and discussed from three

different points of view—phenomenological, chemical and structural. The

phenomenological point of view, by definition, is concerned with the changes

in the cement-water system (or the concrete) which are only perceptible to or

evidenced by the senses. The chemical point of view is concerned with the

chemical reactions involved and the nature and composition of the reactions

products. Finally, the structural point of view is concerned with the structure

of the set cement, and with the possible changes in this structure with time.

Hence, the following discussion is presented accordingly. This discussion

mainly considers the cement paste, i.e. a paste which is produced as a result

of mixing cement with water only. Nevertheless, it is valid and applicable to

mortar and concrete as well because, under normal conditions, the aggregate

is inert in the cement-water system and its presence, therefore, does not affect

the processes involved.

2.2. THE PHENOMENA

Mixing cement with water produces a plastic and workable mix, commonly

referred to as a ‘cement paste’. These properties of the mix remain unchanged

Copyright 1993 E & FN Spon