Considerations on the efficiency of Portland cement concrete mixtures based on the particle packing concept

ABSTRACT Concrete is the most widely used building material and, recently, studies have been developed in pursuit of materials with superior mechanical performance and durability. In order to cover the reality of the civil works regarding the on-site production of conventional and high strength concrete, several mix design methods are proposed. Although these methods allow obtaining the ideal proportion between the constituent materials of the mixture, it is possible to optimize the composition by applying the concept of particle packing. Therefore, this paper aims to measure the efficiency of the particle packing of Portland cement concrete mixtures widely used in civil construction´s practice, obtained by traditional mix design methods. For this, three concrete mixtures were produced using the traditional IPT/EPUSP mix design method, being two of conventional strength and one of high strength. By knowing the proportion and particle size distribution of the constituent materials of these concretes, the distribution´s coefficient of each mixture was determined considering Alfred´s particle packing model. Thereafter, maintaining the same distribution coefficient, the concrete mixtures were optimized by applying the particle packing concept, determining the physical and mechanical properties of the concrete. During the optimization process, there were gaps between the particle size distributions of the component materials normally considered in the production of concretes, characterizing a lack in packaging. Regarding the properties of the hardened concrete, the optimized mix design generally presented superior physical and mechanical properties than the reference concrete.