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This paper presents the results of theoretical and experimental studies concerning the durability of cement mortars and concretes.
The behavior of different cements in mortars and concretes which are exposed to attack by carbon dioxide in the atmosphere, sulfate ions or the alkali silica reacton (ASR) is described. The principal results which have been obtained during the past 10 to 15 years, part of which already have been published [1–11], also are summarized.
Carbonation of cement mortars and concretes follows a
The attack of sulfate solutions causes the initial cracking by topochemical ettringite formation which is followed by the formation of gypsum as a secondary reaction. The latter explains the often observed interim rehealing.
The alkali silica reaction (ASR) is considered as the result of dynamic osmosis equilibrium. The minimum relative humidity necessary for ASR is 80 ⪡ × < 85 percent. The delayed ASR leads to an increased deterioration of the structure. Water repellent agents are suitable to prevent the ASR. Pozzolans and blast furnace slags in cements reduce or prevent the ASR. The maximum expansion forces are observed to be 1.7 N/mm2. The damages on buildings can be determined on drill-core samples.
durability, sulfate resistance, carbonation, alkali aggregate reaction, building materials
Professor, Institute für Gesteinshüttenkunde der Rheinisch-Westfälischen Technischen Hochschule, Aachen,