Title: Influence of Materials on the Action of Admixtures in Antiwashout Underwater Concrete

Author(s): Takeshi Ohtomo, Yasundri Matsuoka, Yoshitaka Nakagawa, and Jun Nakahira

Publication: Materials Journal

Volume: 92

Issue: 3

Appears on pages(s): 315-320

Keywords: admixtures; adsorption; air-entraining agents; concretes; fine aggregates; fly ash; setting (hardening); water-reducing agents; Materials Research

DOI: 10.14359/1124

Date: 5/1/1995

Abstract:
The actions of chemical admixtures in antiwashout underwater concrete and the mechanism of flowability retention of the concrete were clarified by investigating the influences of different types of mineral admixtures and fine aggregates on the setting characteristics and flowability retention of concrete and mortar. Based on this investigation, it was shown that flowability retention and the substantial delay of setting time of antiwashout, underwater concrete resulted from increasing the concentration of air-entraining (AE) water-reducing agent in the liquid phase so that the adsorption of the antiwashout admixture by cement particles holds back the adsorption of AE water-reducing agent. Difference in adsorption of antiwashout admixtures and AE water-reducing agent by materials such as fly ash and fine aggregate are considered to the cause of the difference in flowability and setting characteristics with different materials.