Title: Long-Term Mechanical Properties and Durability Characteristics of High-Strength/High-Performance Concrete Incorporating Supplementary Cementing Materials under Outdoor Exposure Conditions

Author(s): V. Mohan Malhotra, Min-Hong Zhang, Paul H. Read, and John Ryell

Publication: Materials Journal

Volume: 97

Issue: 5

Appears on pages(s): 518-525

Keywords: blast-furnace slag; carbonation; compressive strength; fly ash; high-strength concrete; modulus of elasticity; silica fume

DOI: 10.14359/9284

Date: 9/1/2000

Abstract:
This paper presents the results of tests performed on the compres-sive strength of high-strength/high-performance concrete at ages up to 10 years, the modulus of elasticity after 2, 4, and 10 years, and the carbonation depth and the resistance of concrete to chloride-ion penetration after 10 years. The tests were performed on drilled cores taken from the structural test elements simulatingconcrete columns. In addition, the compressive strength of cylin-ders cured in a moist room and in the field, as well as the compressive strength of drilled cores taken from the structural elements (walls) at ages up to 4 years was determined. After 10 years, the compressive strength of the cores drilled from the column elements of the control portland cement concrete and concrete incorporating various supplementary cementing materials ranged from 86.4 to 110.3 MPa. The highest strength was obtained for the high-volume fly ash concrete followed by the control portland cement concrete, slag concrete, silica fume concrete, and concrete incorporating a combination of slag and silica fume, in that order. Even though the high-volume fly ash concrete at ages up to 28 days had lower strength than the other concretes, it attained the highest strength gain of more than 120% between 28 days and 10 years. On the contrary, the concrete incorporating 12% silica fume had the highest compressive strength at ages up to 28 days, but it had a strength gain of only 18% beyond that age. In general, the moduli of elasticity of the moist- and field-cured cylinders and the cores taken from the column elements were simi-lar. For the cores drilled from the column elements, the fly ash concrete had the highest E-modulus at all three ages of 2, 4, and 10 years. The experimentally determined E-moduli ranged from 83 to 116% of the values calculated according to ACI Code 318. In tests performed in accordance with ASTM C 1202, the charge passed through all the concretes at 10 years was less than 1000 coulombs indicating very high resistance of the concretes to the chloride-ion penetration. After 10 years of outdoor exposure, the depth of carbonation in all the concretes was negligible.