European Journal of Scientific Research ISSN 1450-216X Vol.31 No.1 (2009), pp. 132-141 © EuroJournals Publishing, Inc. 2009 http://www.eurojournals.com/ejsr.htm Equations for Mix Design of Structural Lightweight Concrete M. Abdullahi PhD Student, Civil Engineering Department Universiti Tenaga Nasional, Malaysia E-mail: abdulapai@yahoo.com Tel: +60173511985 H.M.A. Al-Mattarneh Dean, Faculty of Engineering Jerash Private University Jordan E-mail: hashem.almattarneh@yahoo.com Tel: +962779252569 B.S. Mohammed Senior Lecturer, Civil Engineering Department Universiti Tenaga Nasional, Malaysia E-mail: bashar@uniten.edu.my Tel: +60125756460 Abstract Equations for mix design of structural lightweight concrete are presented. Conventionally, mix design of concrete is conducted using the tabular data and charts in standards. This requires extra efforts of understanding the data in the code and interpolations are often required when intermediate values are needed. The process is also liable to human error as data may be erroneously taken by the mix designer. The tabular data and graphs in ACI 211.2-98 are converted to equations. Various models were tried and the best model that adequately represents the data was chosen based on the regression coefficient and its predictive capability. The equations were used to solve some mix design problems from reputable textural sources. The developed equations are capable of giving material constituents for the first trial batch of structural lightweight concrete. These equations can be used in place of the data in the code and would reduce the effort, time and energy expended in the manual process of mix design of structural lightweight concrete. The equations are also useful for mixture proportioning adjustment. Keywords: Concrete, Equations, Regression, Mix design 1. Introduction Concrete mix design is the process of choosing suitable ingredients of concrete and determining their relative quantities with the objective of producing the most economical concrete while retaining the specified minimum properties such as strength, durability, and consistency (Akhras and Foo, 1994; Neville, 1995). The selection of ingredient is normally done using data from tables and charts in the relevant mix design standard. While these data and numerical examples in the codes are sufficient to