Title:
Short-Term Impact of High-Aggregate Fines Content on Concrete Incorporating Water-Reducing Admixtures
Author(s):
Mohamed Nagib Abou-Zeid and Maged Maher Fakhry
Publication:
Materials Journal
Volume:
100
Issue:
4
Appears on pages(s):
280-285
Keywords:
concrete; fine aggregate; mixture proportion; water-reducing admixture.
DOI:
10.14359/12665
Date:
7/1/2003
Abstract:
Water-reducing and high-range water-reducing admixtures have been increasingly involved in concrete works. Aggregate fines passing sieve No. 200 (75 mm) are produced in large quantities; and, recently, some efforts have been exerted to investigate the feasibility of using such fines in concrete. The interaction between water-reducing admixtures and aggregate fines, however, has been questioned and is not fully understood yet. This paper represents a major part of a larger scale study addressing aggregate fines smaller than 75 mm used with a wide range of constituent materials and proportions. This paper covers 19 mixtures that were prepared with dolomite coarse aggregates, with and without fines, and with water-reducing and high-range water-reducing admixtures. Results indicate that the fines tested differed significantly from their parent rocks in physical and chemical properties. High fines also resulted in a remarkable increase in water demand, poor slump, and high slump loss. High admixture dosages fail in enhancing concrete workability/consistency in the presence of high fines content unless the water-cement ratio (w/c) is increased. At the same w/c, the fines contributed to some increase in compressive strength and improvement in flexural strength.