Sulfate Attack on Concrete - Chapter 1 ppt

1 Introduction

Portland clinker-based concrete is the most important and versatile con￾struction material used. It is an extremely complex composite material and,

considering its chemical, physical, and microstructural intricacy, it is also a

very forgiving material: in spite of severe abuse by Man and Nature, most of

the immense amounts of Portland clinker-based concrete used World over

are performing its intended functions surprisingly well.

However, this generally good performance of concrete is not a satisfactory

excuse for improper or inadequate utilization by Man of the available know￾ledge generated during the past 100 or more years. To the contrary, the cost

of repair of deteriorated concrete and its possible replacement, not speaking

about the societal cost of expensive litigations and other unnecessary

expenses, more than justifies investment into better understanding of the

nature of concrete and its performance in the environment it is used. This

book is meant to be a humble contribution to dissemination of available

information about basic aspects of concrete material science and, more

specifically, about proper treatment of both fresh and hardened concrete

to assure long-lasting durability of concrete structures in sulfate-bearing

environment.

Man abuses concrete by:

• use of wrong or marginal concrete materials and improper mix pro￾portions;

• inappropriate use of concrete mix compositions in structures exposed

to harsh environment and structural design unsuitable for the given

environmental exposure;

• curing or heat treatment in conflict with chemistry and physics of concrete

microstructure development;

• wrong placement and finishing procedures; and

• lack of maintenance.

© 2002 Jan Skalny, Jacques Marchand and Ivan Odler