Study on the Influence of Water-Reducing Additives in Concretes for Civil Construction

Abstract

Water-reducing additives for concretes are high efficiency dispersants that promote reduction of viscosity in suspensions, minimizing the amount of water used to hydrate the cement, thus enabling the fabrication of concrete with excellent properties. However, different forms of interaction between cement and additives are observed. In this work the properties of concrete formulated with three dosages of a polycarboxylate-based water-reducing additive and cement type CPII E-32 from two distinct manufacturers were investigated. In the experimental part, we verified the importance to use this technology justified by excellent results obtained for mechanical resistance and plasticity properties of the concretes. Through statistical analysis it was possible to point a discrete superiority in compositions using Holcim cement in function of its physical and chemical characteristics, in which the interaction process showed to be more efficient.

New mathematical modelling for grain size distribution adjustment in concrete

“…The reference formulation of the concrete, denominated C1, was calculated using the equation of Andreasen. The amount of cement used was calculated in order to obtain mechanical strength of 35 MPa after 28 days [10]. It was calculated four formulations with the substitution of fine gravel by syenite, in the proportions of 25% (C1-25), 50% (C1-50), 75% (C1-75) e 100% (C1-100).…”

“…The formulations obtained are listed in Table I. The content of additive was fixed at 0.4 wt% of cement, due to good results presented in [10], and the water content was determined at the moment of mixing, in order to obtain a self-compacting concrete. For each formulation, it was analyzed the properties in the fresh and hardened state.…”