Title:
Early Age Compressive Stress-Strain Properties of Low-,
Medium, and High-Strength Concretes
Author(s):
Arshad A. Khan, William D. Cook, and Denis Mitchell
Publication:
Materials Journal
Volume:
92
Issue:
6
Appears on pages(s):
617-624
Keywords:
Keywords:, age; compressive strength; curing; high-strength concretes;
modulus of elasticity; stress-strain relationships.
DOI:
10.14359/9781
Date:
11/1/1995
Abstract:
This paper presents a detailed study of early age compressive stress-strain responses of low-(30 MPa), medium (70 MPa) and high-strength (100 MPa) concretes. In particular; the stress-strain responses during the first 72 hr after casting are closely followed. Tests were carried out on 100 x 200-mm (4 x 8-in.) concrete cylinders. The influence of concrete strength on temperature rise due to temperature-matched curing is presented. The effect of three different curing conditions on the development of concrete compressive strength and elastic moduli is described: 1) temperature-matched; 2) sealed; and 3) air-dried curing. It was found that for earlyages, the compressive strength and elastic modulus gain of temperature-matched cured concrete cylinders are higher than those of the sealed cylinders, which, in turn, are higher than those of the air-dried cylinders. After an initial retardation period, the 70 and 100 MPa concretes showed a higher rate of elastic modulus gain than the 30 MPa concrete. It was observed that the current ACI Code expression for predicting the elastic modulus overestimates the stiffness for very early age concretes and for concrete strengths above 50 MPa.