Early-Age Autogenous Effects in Internally Cured Concrete and Mortar

ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • 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: Early-Age Autogenous Effects in Internally Cured Concrete and Mortar

Author(s): Benjamin E. Byard, Anton K. Schindler, and Robert W. Barnes

Publication: Special Publication

Volume: 290

Issue:

Appears on pages(s): 1-18

Keywords: Autogenous shrinkage, cracking, early-age stresses, internal curing, lightweight aggregate, internal relative humidity.

Date: 9/14/2012

Abstract:
One strategy for achieving excellent long-term performance of concrete bridge decks is to combine low permeability with minimal early-age cracking. Low permeability can be achieved through the use of concretes with low water-cement ratios; however, topical curing techniques are usually insufficient to maximize hydration and minimize autogenous shrinkage effects. This autogenous shrinkage causes stresses in restrained concrete, which can lead to deleterious early-age cracking. Curing effectiveness can be enhanced through the implementation of prewetted lightweight fine aggregates. Internal curing is provided as the aggregate water gradually desorbs into the surrounding paste. A study of the early-age behavior of internally cured concrete is described in this paper. Internal curing was provided by means of expanded shale, clay, and slate lightweight fine aggregates. Ten mixtures with water-cement ratios of 0.42, 0.36, and 0.30 were investigated. Compressive and tensile strengths of the internally cured concretes were similar to or slightly greater than the strengths of their non-internally cured counterparts, and concrete stiffness decreased as expected in the internally cured mixtures. Autogenous shrinkage strains and stresses were found to increase as the water-cement ratio decreases. However, the autogenous effects were reduced or eliminated in the internally cured concretes.