Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Bleeding: Evaluation of its effects on concrete behaviour
Abstract In many existing structures strength variations of about 20–30% between upper and lower levels have been registered. These differences are attributed to bleeding and segregation of concrete. In the present work standard specimens and structural elements (2.00 m high) were molded with concretes of different bleeding capacity and velocity. The influence of bleeding on hardened concrete characteristics was studied: visual appreciation of localized defects, determination of absorption, specific gravity, compressive and tensile strength, and strain measurements. With a high bleeding velocity the formation of vertically-oriented channels was observed. With a high bleeding capacity water accumulated under coarse aggregates causing on drying approximately horizontally-oriented fissures. These localized defects are responsible for concrete anisotropic behaviour. The presence of defects was not detected in standard specimens owing to their small volume and height. According to the measured bleeding parameters a decrease of strength of up to 30% in the upper levels and a difference of about 25% according to the loading direction were registered. From the evaluations realized it comes out that when the bleeding of concrete is high the results of tests made on molded specimens are not representative of the real state of the structure.
Bleeding: Evaluation of its effects on concrete behaviour
Abstract In many existing structures strength variations of about 20–30% between upper and lower levels have been registered. These differences are attributed to bleeding and segregation of concrete. In the present work standard specimens and structural elements (2.00 m high) were molded with concretes of different bleeding capacity and velocity. The influence of bleeding on hardened concrete characteristics was studied: visual appreciation of localized defects, determination of absorption, specific gravity, compressive and tensile strength, and strain measurements. With a high bleeding velocity the formation of vertically-oriented channels was observed. With a high bleeding capacity water accumulated under coarse aggregates causing on drying approximately horizontally-oriented fissures. These localized defects are responsible for concrete anisotropic behaviour. The presence of defects was not detected in standard specimens owing to their small volume and height. According to the measured bleeding parameters a decrease of strength of up to 30% in the upper levels and a difference of about 25% according to the loading direction were registered. From the evaluations realized it comes out that when the bleeding of concrete is high the results of tests made on molded specimens are not representative of the real state of the structure.
Bleeding: Evaluation of its effects on concrete behaviour
Giaccio, Graciela (Autor:in) / Giovambattista, Alberto (Autor:in)
1986
Aufsatz (Zeitschrift)
Englisch
Bleeding: Evaluation of its effects on concrete behaviour
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