Investigation on Redefining the Silt Content of Sand in Concrete Production

Abstract

This study investigates redefining the silt content of sand in concrete production. Fine aggregate has properties that differ from natural sands; for this reason, the plastic and hardened properties of concrete produced using manufactured fine aggregate differ from the properties of concrete made with natural sands. In most current standards used for construction purposes, the fines or material passing the N200 sieve content limitations have been intended for natural sands. Even though there are standards that have tried to stipulate for manufactured fine aggregate, the limits allow small amounts. The manufactured fine aggregate producers have faced difficulty meeting the standards specification and washing aggregate to lower silt content. This results in incrementing costs and develops environmental issues. The high proportion of silt fines found in the manufactured sand has been investigated in this research and the impact of the material on the properties of concrete both in fresh and hardened state. Thus concrete specimens with a w/c ratio of 0.58, 0.54, and 0.45 with different silt content of fine aggregate, ranging from 0% to 15%, were cast and tested on the Normal Strength Concrete, Intermediate Strength Concrete, and High Strength Concrete. Finally, the results of the tests have shown that better workability and better strength can be achieved with a concrete mix of up to 15 % silt content. The first trial faces workability and finishable difficulties. This was adjusted with a fairly increased water-cement ratio instead of using chemical solutions.

Keywords: Concrete production, Manufactured fine aggregate, Redefining silt content

DOI: 10.7176/CER/17-2-03

Publication date: May 31st 2025