Pore Structure and Carbonation of Lightweight Concrete After 10 Years' Exposure


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Title: Pore Structure and Carbonation of Lightweight Concrete After 10 Years' Exposure

Author(s): R. N. Swamy and E. D. Jiang

Publication: Special Publication

Volume: 136


Appears on pages(s): 377-396

Keywords: carbonation; concretes; density (mass/volume); durability; exposure; lightweight aggregates; lightweight concretes; pore structure; porosity; Materials Research

Date: 1/1/1993

The problem of concrete deterioration and its durability has become a matter of great concern to everyone involved in the construction industry. Carbonation and chloride ingress are the two major sources of deterioration, and the penetration of both is influenced by the pore structure of the concrete. Paper presents data on pore structure, carbonation depths, and the interrelationship between the two in structural lightweight concrete after 10 years' outdoor exposure in an industrially polluted area. The concrete was made with expanded slate aggregate using either all lightweight aggregates or with part of the lightweight fines replaced by sand. Both cement content and water-cement ratios were varied. The results showed that the total pore volume was influenced by both the water-cement ratio and fine aggregate content of the concrete. The total pore volume was higher for concretes containing all lightweight fines than for concrete with part replacement of fines by sand. However, for a given pore volume, carbonation was higher for the concretes containing sand than for concrete containing all lightweight aggregates. This phenomenon is explained in terms of the pore structure of the concrete, and a pore structure characteristics parameter is introduced to correlate carbonation with pore volume.