Zuhair Al-Jaberi; John J. Myers; K. Chandrashekhara
Abstract
The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability ...
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The interest in advanced composites in repairing and strengthening infrastructure systems has considerably increased, especially as the application externally bonded (EB) fiber reinforced polymer (FRP) has become more well established. Previous research on bond behavior has focused on impact of durability by considering exposure to harsh environmental conditions and testing the specimens after exposure, rather than testing bond performance during exposure. The influence of directly applying temperature on bond behavior represents an open topic that needs to be investigated in more detail. This study is one of the first studies to investigate the bond behavior when the composite is subjected to tension force simultaneously with applying temperature. The temperatures considered in this study were at freezing, ambient, and high temperature, which are more representative of structural elements under field conditions. A total of 16 specimens were strengthened and tested under single-lap direct shear. The key parameters investigated include (a) the type of fiber [laminate carbon vs. wet layup glass] (b) the level of temperature applied on specimen, including ambient condition 21°C (70 °F), freeze condition -18 °C (0 °F) and hot weather 49 °C (120 °F), and (c) the exposure regime (direct exposure during loading process vs. loading after exposure). Most of the specimens were subjected to tension force simultaneously with applying temperature, and the other specimens were later tested after exposure to the heating and cooling cycles. These cycles are proposed to simulate 20 years of the typical in-situ weather conditions in the Central United States. The results showed that overall the EB strengthening systems exhibited good performance when subjected to cycles of heating and cooling prior to testing. High reduction of FRP-epoxy bond properties was up to 59% when exposed to high service temperatures. Different modes of failure were observed such as debonding at fiber-matrix interface and debonding due to shearing in laminate.
Rajiv Gupta; Ayub Ahmed; Sasidhar Kumar Reddy Ithepalli
Abstract
Large quantities of ash are generated every year by the various manufacturing industries as a waste by-product. This study aims to utilize waste by-product in concrete and to reduce its cost by replacing cement in parts with bottom ash. This research presents the results of the experimental investigations ...
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Large quantities of ash are generated every year by the various manufacturing industries as a waste by-product. This study aims to utilize waste by-product in concrete and to reduce its cost by replacing cement in parts with bottom ash. This research presents the results of the experimental investigations to study the use of bottom ash as partial replacement for cement in concrete and masonry units. Bottom ash is the coarser material, which falls into furnace bottom and constitutes about 20% of total ash content. The strength development for various percentage replacements (5-15%) of cement with bottom ash has been compared to control specimens of concrete and masonry.
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