International Journal of Emerging Technology and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, Volume 2, Issue 7, July 2012) 22 Optimization of concrete mix proportioning M. Shariq 1 , J. Prasad 2 , A. K. Ahuja 3 1 Assistant Professor, University Polytechnic, Faculty of Engineering & Technology, AMU Aligarh, India 2 Associate Professor (Retd.), 3 Professor, Department of Civil Engineering, IIT Roorkee, India Abstract— The aim of this paper is to carried out statistical analysis for optimization of various concrete mix proportions by using full factorial experimental technique. The variables such as 28 days cube compressive strength, water to cement ratio (w/c), coarse aggregate to total aggregate ratio (CA/TA) and total aggregate to cement ratio (TA/C) were the parameters to be used for optimization. Four w/c ratios 0.4, 0.45, 0.5 and 0.6, four CA/TA ratios 0.60, 0.63, 0.65 and 0.70 and four TA/C ratios 3.9, 4.6, 5.3 and 6.0 were selected for regression analysis. The influence of w/c ratio, CA/TA ratio and TA/C ratio on compressive strength was experimentally carried out and analyzed using polynomial regression analysis. Mathematical polynomial model has been developed for compressive strength of concrete as a function of mix proportions. Based on the statistical analysis, optimum concrete mix for different mix proportions is proposed. Keywords— Concrete mixes, compressive strength, optimization, full factorial technique. I. INTRODUCTION Design of concrete mixes is influenced by various factors, which depends upon the sources of materials and their properties, method of preparation, placement, compaction and curing of concrete, and the requirement of a construction job. For an aggregate from a particular source having a specific grading the optimum design of a concrete mix involve selection of proportions of ingredients that yield concrete of the desired strength, workability, and durability at minimum cost. The most important factors which influence are the water cement ratio (W/C), aggregate-cement ratio (TA/C) and the coarse aggregate to total aggregate ratio (CA/TA). Since these factors are interdependent hence study for various combinations is necessary. Different methods such as the ACI method, IS code method [1], grading curve method and IRC 44 method of mix proportioning adopted different procedure for determining proportions on the basis of required strength and workability. II. OBJECTIVES The current study consider the comprehensive effect of water-cement ratio (W/C), aggregate-cement ratio (TA/C) and coarse aggregate to total aggregate ratio (CA/TA) on concrete strength with the following objectives:  To study the influence of various factors in concrete mix proportioning.  To develop a statistical model from experimental data.  To optimize the mix proportioning for available material and conditions. III. MATERIAL PROPERTIES The properties of materials used in the concrete mixes such as cement, fine aggregate, coarse aggregate and water was confirmed to the specifications laid down in the Indian Standard codes [2, 3]. The following are the material properties used in the present study. Cement: Ordinary Portland cement 43 grade (OPC 43) was used throughout the investigation and stored in airtight silos to prevent from moisture. The physical properties of cement were carried out as per IS 4031-1988 [2]. The physical properties of cement are given in Table 1. Fine Aggregate, Coarse Aggregate and Water: The locally available river sand passed through IS: 480 sieve (aperture 4.75 mm square) and retained on IS: 15 sieve (150 micron size) was used as fine aggregate. The locally available crushed stone aggregate of maximum nominal size of 16mm was used as coarse aggregate. The physical properties of the fine and coarse aggregate are given in Table 2 as per IS: 383-1970 3 . The water to be used for both mixing and curing should be free from injurious amount of deleterious materials. In the present investigation potable water was used for mixing and curing As per IS: 456-2000 [4].