AS 3735 SUPP 1-1991

Gives background material and explanations to corresponding clauses in AS 3735.

A lower concrete strength limit of 20 MPa has been imposed, as strength grades less than this are not considered suitable for structures.An upper concrete strength limit of 50 MPa has been adopted, because much of the research on which the Standard is based involved concrete strengths at or below this value. Nevertheless, higher strength concretes are being used in Australia and overseas (Refs. C1.7.1 and C1.7.2). The Standard may be applied to such concretes, provided that the physical properties appropriate to them are used in design.The Standard also limits the use of lightweight aggregate in structural concrete. Most Australian structural concretes employ only lightweight coarse aggregate, resulting in a concrete with a surface- dry density that is seldom less than 1800 kg/m 3.In the preparation of a Standard such as this, a certain level of knowledge and competence of the majority of users has been assumed. As indicated by the Note to Clause 1.1, it was assumed that the predominant users of this Standard would be professionally qualified civil engineers experienced in the design of concrete structures for retaining liquids, or equally qualified but less experienced persons working under their guidance. It is therefore intended that the Standard be applied and interpreted primarily by such persons.

First published as AS 3735 Supplement 1-1991.