Fly Ash Effects on Mortar Permeability


  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal


Title: Fly Ash Effects on Mortar Permeability

Author(s): Parviz Soroushian and Abdulrahman Alhozaimy

Publication: Special Publication

Volume: 158


Appears on pages(s): 111-126

Keywords: capillarity; concretes; deterioration; fly ash; hydration; microcracking; permeability; shrinkage; Materials Research

Date: 1/1/1996

Water is generally involved in every form of concrete deterioration; the permeability of concrete usually determines the rate of deterioration. Since the permeation of water into concrete takes place through the capillary pores, a reduction in the volume of large (greater than about 0.01 micron) capillary voids in the paste matrix will reduce permeability. This can be assisted by the partial substitution of cement with fly ash in the paste. As a pozzolanic material, fly ash reacts chemically with the calcium hydroxide resulting from cement hydration to form compounds (mainly calcium silicate hydrate) with cementitious properties. The effects of fly ash type and content on the permeability characteristics of concrete materials subjected to two different curing conditions were investigated. Four different fly ash contents and three different fly ash types were considered to provide sufficient data for powerful statistical analysis of results. Fly ash was observed to be capable of reducing the permeability of concrete, even at early ages. Selection of fly ash type (Class F vs. Class C), the level of cement substitution with fly ash, and curing conditions had important effects on the permeability characteristics of fly ash concrete. The interactions between these factors were also generally important.