DefinePK

Abstract

Concrete mixes are designed to achieve a defined workability, strength and durability. The design is geared towards the selection and proportioning of constituents to produce a concrete with pre-defined characteristics both in fresh and hardened states. This study investigates the variation of concrete compressive strength with mix designed methods. Four common mix design methods were used namely: American Concrete Institute (ACI), Department of Environment (DOR), Road Note 4 (RN4) and CPIIO. The Ibeto brand of Portland cement was used in the research and a characteristic strength of 20N/mm2 was designed for using the first four mix design methods. The concrete components used were tested for specific gravity; moisture content and grading were found suitable. Four sets of concrete cubes (150x150x150 mm) each were casted using four mix designs. Compressive strengths were evaluated at 7, 14, 21, and 28 days of curing. The 28th day strengths of the four sets of concrete were found to be 30.7 N/mm2, 33.7 N/mm2, 33.0 N/mm2, and 35.1 N/mm2 for ACI, DOE, RN4, and CP110 mix design methods respectively.