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Research progress on the flexural behaviour of externally bonded RC beams

Qeshta I. M. I., Shafigh P., Jumaat M. Z.

Archives of Civil and Mechanical Engineering

2016

Vol. 16, no. 4

982--1003

The flexural behaviour of strengthened reinforced concrete (RC) beams is more complicated compared to the normal beams due to the different bond conditions and properties of the externally bonded material. A significant number of research studies have been reported on the use of different types of material for flexural strengthening of RC beams using the external bonding (EB) technique. Although most research has focused on the conventional strengthening materials, namely, steel plates, FRP and ferrocement; unconventional materials, such as sprayed FRP and cement-based composites, have shown that they also have a significant effect on the behaviour of bonded beams. This paper presents a comprehensive state-of-the-art review of the different materials used for strengthening RC beams using the EB technique and their evaluation criteria. The behaviour of the strengthened beams is discussed in terms of load carrying capacity, stiffness under service loads, and ductility and failure modes. In addition, the effect of elevated temperatures on the externally bonded materials is also discussed. The critical review of the existing data can help for a better utilization and usage of the different materials for strengthening projects, which contributes significantly to the current efforts of developing optimum and feasible strengthening systems.

Effects of recycled concrete aggregate on the fresh properties of self-consolidating concrete

Safiuddin M. D., Salam M. A., Jumaat M. Z.

Archives of Civil and Mechanical Engineering

2011

Vol. 11, no 4

1023-1041

Concrete wastes are generally delivered to the landfill sites for disposal. Due to increasing charges of landfill and scarcity of natural coarse aggregate (NCA), recycled concrete aggregate (RCA) derived from concrete wastes is growing interest in construction industry. In the present study, RCA was used as partial and full re-placements of NCA to produce self-consolidating concrete (SCC). Different SCC mixes were produced with RCA substituting 0%, 30%, 50%, 70%, and 100% NCA by weight. The water to cement (W/C) ratio and high-range water reducer (HRWR) dosage were kept the same for all concretes. The effects of RCA on the key fresh properties such as filling ability, passing ability, and segregation resistance of SCC were investigated. The test results revealed that the filling ability and passing ability of SCC were improved for 30% and 50% RCA. The SCC mixes with 30% and 50% RCA also possessed adequate segregation resistance. In addition, strong correla-tions were observed for filling ability, passing ability, and segregation resistance. The overall test results suggest that RCA can be used to produce SCC substituting up to 50% NCA without affecting the key fresh properties of concrete.

Odpady betonowa są dostarczane zazwyczaj na składowiska odpadów w celu utylizacji. Ze względu na rosnące koszty składowania, a zarazem niedostatek naturalnego kruszywa grubego (NCA), kruszywowa uzyskane z recyklingu betonu (RCA) i pochodzące z odpadów betonowych zyskuje coraz większe zainteresowanie w branży budowlanej. W niniejszej pracy analizowane jest wykorzystanie RCA w postaci częściowego jaki i pełnego zastąpienie kruszywa NCA do produkcji betonu samozagęszczalnego (SCC). W pracy przeanalizowano wpływ RCA na kluczowe właściwości świeżego betonu SCC. Ogólne wyniki badań wskazują, że RCA może być użyty do produkcji SCC przy zastąpieniu przez niego do 50% NCA bez wpływu na kluczowe właściwości świeżego betonu.