Deterioration of concrete structures by acid deposition — an assessment of the role of rainwater on deterioration by laboratory and field exposure experiments using mortar specimens

• Published in: Atmospheric Environment Vol. 34; no. 18; pp. 2937 - 2945
• Main Authors: Okochi, Hiroshi, Kameda, Hideki, Hasegawa, Shin-ichi, Saito, Nobuhiko, Kubota, Ken, Igawa, Manabu
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.01.2000; Elsevier BV; Elsevier Science
• Subjects: Acid deposition; Applied sciences; Building failures (cracks, physical changes, etc.); Building structure; Buildings. Public works; Calcium hydrate; Concrete; Concrete structure; Construction (buildings and works); Corrosion products; Durability. Pathology. Repairing. Maintenance; Exact sciences and technology; Neutralization; Calcium hydrate; Corrosion products; Concrete; Acid deposition; Neutralization; Calcium; Acid rain; Experimental device; Experimental study; Material weathering; Corrosion product; Field experiment; Experimental result; Simulation; Concrete construction; Laboratory test; Deposition; Hydrates
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/S1352-2310(99)00523-3

Deterioration of concrete structures caused by acid deposition was investigated by laboratory and field exposure of portland cement mortar specimens to acid deposition. Laboratory exposure experiment showed that the dissolved amount of calcium hydrates, which were the major components in mortar, increased with the increase in the acidity of simulated acid rain solution and the decrease in the flow rate. There was little difference in their amount among different temperature treatments after each exposure to the solution with the same acidity, namely left at room temperature, heated at 70°C, and cooled at −2°C. The neutralization progressed more deeply under the heated and cooled condition and was accelerated by even acid rain with pH 4.7 during a long period (90 exposure cycles, which correspond to the rainfall amount of 15 years in Japan). A field exposure experiment for two years indicated that the carbonation of calcium hydrates and the formation of other corrosion products such as chloride, nitrate, and sulfate were limited to the surface of mortar specimens. The neutralization progressed more deeply in mortar specimens sheltered from rainwater than in those washed by rainwater.