Title:
Superplasticizers: Their Effect on the Strength Properties of Concretes Made with ASTM Type I and V Cements
Author(s):
A. A. Ramezanianpour, V. Sivasundaram, and V. M. Malhotra
Publication:
Concrete International
Volume:
17
Issue:
4
Appears on pages(s):
30-35
Keywords:
cement additives (raw materials); compressive strength; flexural strength; microstructure; pore size distribution; superplasticizers; water-cement ratio; Structural Research
DOI:
Date:
4/1/1995
Abstract:
This investigation was undertaken to study the effect of superplasticizers on the engineering properties and microstructure of concretes made with ASTM Type V cement. The work was carried out in two phases. In Phase I, ASTM Types I and V cement concretes were made having three water-cement ratios, both with and without the addition of a superplasticizer, and the strength properties were determined at ages up to two years. In Phase II, concretes were made with only ASTM Type V cement at three water-cement ratios. At each water-cement ratio, a control concrete without superplasticizer and three concretes, each incorporating a different superplasticizer, were made. Compressive strengths at ages up to 90 days, and microstructure and porosity of the concretes at 28 days were determined. The results of the work in both phases show that the strength properties of the concrete made with ASTM Type V cement were adversely affected by the addition of the superplasticizer in the concrete. The setting times of the concrete were also retarded by the superplasticizer. The analysis of the microstructure of the concretes indicates that the excess superplasticizer is adsorbed on the alite and belite grains of Type V cement, thus inhibiting the hydration of these phases. This, in turn, leads to the lower strength development of the concretes made with ASTM Type V cement. This was found to be true for all three superplasticizers investigated. The strength development of the concretes made with ASTM Type I cement was not affected by the addition of the superplasticizer