scholarly journals Bond strength between concrete substrate and metakaolin geopolymer repair mortars at ambient and elevated temperatures

2020 ◽  
Vol 9 (5) ◽  
pp. 10732-10745 ◽  
Author(s):  
Abdulrahman Albidah ◽  
Aref Abadel ◽  
Fahed Alrshoudi ◽  
Ali Altheeb ◽  
Husain Abbas ◽  
...  
Keyword(s):  
Bond Strength ◽  
Elevated Temperatures ◽  
Repair Mortars ◽  
Metakaolin Geopolymer

scholarly journals Evaluation of cementitious repair mortars modified with polymers

2017 ◽  
Vol 9 (1) ◽  
pp. 168781401668858 ◽  
Author(s):  
Tsai-Lung Weng
Keyword(s):  
Thermal Expansion ◽  
Bond Strength ◽  
Vinyl Acetate ◽  
Polyvinyl Acetate ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Ethylene Vinyl Acetate ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Repair Mortars

The aim of this study was to evaluate the effects of added polymers on the properties of repair mortars. Two types of polymers, ethylene vinyl acetate and polyvinyl acetate–vinyl carboxylate, were used as a replacement for 3%, 5%, and 8% of the cement (by weight). All tests were conducted using two water–cement ratios of 0.5 and 0.6. The effectiveness of the repair materials was evaluated according to setting time, drying shrinkage, thermal expansion, compressive strength, and bond strength. Specimens containing polyvinyl acetate–vinyl carboxylate at a water–cement ratio of 0.5 presented the highest compressive and bond strength. Specimens containing ethylene vinyl acetate presented strength characteristics exceeding those of the control at 28 days. The drying shrinkage of polyvinyl acetate–vinyl carboxylate specimens was similar to that of the control. At a water–cement ratio of 0.5, the thermal expansion of polyvinyl acetate–vinyl carboxylate specimens was lower than that of ethylene vinyl acetate specimens; however, at a water–cement ratio of 0.6, the thermal expansion was independent of the type of polymer.

scholarly journals Effect of Elevated Temperature on the Bond Strength of Prestressing Reinforcement in UHPC

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4990
Author(s):  
Petr Pokorný ◽  
Jiří Kolísko ◽  
David Čítek ◽  
Michaela Kostelecká
Keyword(s):  
Bond Strength ◽  
High Performance ◽  
Elevated Temperatures ◽  
High Performance Concrete ◽  
Future Research ◽  
Ultra High Performance Concrete ◽  
Negative Effect ◽  
Laboratory Investigations ◽  
Increasing Temperature ◽  
Positive Effect

The study explores the effect of elevated temperatures on the bond strength between prestressing reinforcement and ultra-high performance concrete (UHPC). Laboratory investigations reveal that the changes in bond strength correspond well with the changes in compressive strength of UHPC and their correlation can be mathematically described. Exposition of specimens to temperatures up to 200 °C does not reduce bond strength as a negative effect of increasing temperature is outweighed by the positive effect of thermal increase on the reactivity of silica fume in UHPC mixture. Above 200 °C, bond strength significantly reduces; for instance, a decrease by about 70% is observed at 800 °C. The decreases in compressive and bond strengths for temperatures above 400 °C are related to the changes of phase composition of UHPC matrix (as revealed by X-ray powder diffraction) and the changes in microstructure including the increase of porosity (verified by mercury intrusion porosimetry and observation of confocal microscopy) and development cracks detected by scanning electron microscopy. Future research should investigate the effect of relaxation of prestressing reinforcement with increasing temperature on bond strength reduction by numerical modelling.

Evaluating the bond strength between concrete substrate and repair mortars with full-factorial analysis

2013 ◽  
Vol 12 (5) ◽  
pp. 651-668
Author(s):  
Kamile Tosun Felekoglu ◽  
Burcu Felekoglu ◽  
A. Serdar Tasan ◽  
Burak Felekoglu
Keyword(s):  
Bond Strength ◽  
Factorial Analysis ◽  
Repair Mortars ◽  
Full Factorial

scholarly journals Experimental Investigation of the TRM-to-Masonry Bond after Exposure to Elevated Temperatures: Cementitious and Alkali-Activated Matrices of Various Densities

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 140
Author(s):  
Paraskevi D. Askouni ◽  
Catherine (Corina) G. Papanicolaou ◽  
Lazar Azdejkovic
Keyword(s):  
Experimental Investigation ◽  
Fly Ash ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Elevated Temperatures ◽  
Normal Weight ◽  
Heat Protection ◽  
Exposure Temperature ◽  
Alkali Activated ◽  
Textile Reinforced Mortar

Limited research has focused on the effect of high temperatures on the textile-reinforced mortar (TRM)-to-masonry bond. In this study, masonry prisms that were furnished with double-layered TRM strips were tested under shear bond conditions after their exposure to 200 °C and 400 °C for 1 h using the single-lap/single-prism setup. A total of four TRM systems were applied sharing the same type of textile –a dry AR glass fiber one– and different matrices: two cementitious matrices, namely a normal-weight (TRCNM) and a lightweight (TRCLM) one, and two counterpart alkali-activated matrices (TRAANM and TRAALM) based on metakaolin and fly ash. Specimens’ exposure to elevated temperatures did not alter their failure mode which was due to the sleeve fibers’ rupture along with core fibers’ slippage from the mortar. The residual bond capacity of the TRM systems decreases almost linearly with increasing exposure temperature. The alkali-activated textile reinforced mortars outperformed their cement-based counterparts in terms of bond strength at every temperature. All systems retained close to 50% of their original shear bond strength after heating at 400 °C. Per the type of binder, lightweight matrices resulted in either comparable (cement-based systems) or better (alkali-activated systems) heat protection at the TRM/masonry interface.

Properties Evaluation of Repair Mortars Containing EVA and VA/VeoVa Polymer Powders

2017 ◽  
Vol 25 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Tsai-Lung Weng ◽  
Wei-Ting Lin ◽  
Cheng-Hao Li
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Thermal Expansion ◽  
Flexural Strength ◽  
Bond Strength ◽  
Drying Shrinkage ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Repair Materials ◽  
Repair Mortars

The repair of damaged structures is a complicated problem in the construction industry and it is no uniform standard for evaluating the effectiveness of repair materials. Two different redispersible polymer powders, ethylene vinyl acetate (EVA) and polyvinyl acetate-vinyl carboxylate (VA/VeoVa), were added in the repair mortars with two water-cement ratios and three polymer-cement ratios. The effectiveness of repair materials was evaluated according to the physical, mechanical properties and micrographs. Testing program includes setting time, drying shrinkage, thermal expansion, compressive strength, tensile strength, flexural strength, bond strength, X-ray diffraction analysis, scanning electron microscopy observation. Test results show that the specimens with VA/VeoVa and w/c of 0.5 have highest compressive strength, tensile strength, flexural strength and bond strength. The specimen with EVA also has higher strength than control one at the age of 28 days. The drying shrinkage deformation of VA/VeoVa specimen is close to the control one. The specimens with VA/VeoVa have lower thermal expansion than EVA specimen when the water-cement ratio is 0.5 and there is no difference between EVA and VA/VeoVa specimens for the water-cement ratio of 0.6. The micrographs show that adding polymer powder can reduce the pore and improve the durability.

The Effect of Using Sugar-Cane Bagasse Ash as a Cement Replacement on the Mechanical Characteristics of Concrete

2020 ◽  
Vol 1002 ◽  
pp. 565-577
Author(s):  
Aamer Najim Abbas ◽  
Halah Al-Nealy ◽  
Abdulhadi Al-Saadi ◽  
Merza Imran
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Bond Strength ◽  
Mechanical Characteristics ◽  
Elevated Temperatures ◽  
Waste Product ◽  
Strength Test ◽  
Sugar Cane Bagasse ◽  
Concrete Mechanical Properties ◽  
Sugar Cane Bagasse Ash

This paper deals with the use of bagasse debris for sugarcane in concrete cement. The bagasse ash for sugarcane waste product. The bagasse ash is the waste material of the combustion of bagasse for energy in sugar plants. The bagasse debris is normally arranged in landfills and is presently effecting on a natural environment. Experimental work included pouring a concrete of C30 grade were and testing to investigate the concrete mechanical properties, slump test, elevated temperatures test and bond strength test. The bagasse ash was partially replaced with cement in percentages of (0, 3, 5, 7 and 10) % by of cement weight. The results of tests indicated that the best quantity was 7% by weight of cement gives the best compressive and tensile strength.

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