الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
ABSTRACT
Injection of cracks is one of the most important methods used in repairing cracked concrete elements. Injection can restore the element strength, stops liquid leakage and protects the reinforcing bars. Epoxy is the most common resin used in crack injection in order to restore the structural integrity. Since epoxy is very expensive, a preliminary study was conducted to develop a mixture of epoxy and cement with appropriate flowability and strength in order to reduce the cost of injection material. Epoxy was added to cement paste in order to obtain a mixture of higher strength to cost ratio and of adequate flowability in order to be easily injected into the cracks. Various formulations of different water/cement ratios and epoxy contents were used. Tests to determine the flexure and compressive strengths were carried out for these mixes. The mix with optimum characteristics comprising flowability, strength and cost was chosen for further study. The effectiveness of injection using epoxy as well as the developed mixture was tested in flexure and shear. The effect of size and depth of the crack as well as injection material type on the injection process was investigated using pre-cracked plain concrete beams and prisms. Flexural behaviour of repaired reinforced concrete beams by epoxy and developed mixture using the injection repair technique was assessed experimentally. Two methods of injection were studied: the traditional crack injection method and an enhanced injection method using a bar of injection material along a sufficient length in the tension side of the beam. Parameters of study included method of injection, type of injection material and level of damage.
Injection using epoxy and the developed mixture proved to be effective in restoring the entire flexural strength and a high percentage of shear strength for the plain concrete specimens. The developed mixture excelled the traditional epoxy injection material in repairing wide cracks. Also, the flexural strength of the reinforced concrete beams was restored by crack injection. The enhanced method of injection using a bar of injection material provided higher flexural strengths for the RC beam compared with the traditional method.