• Computers and Concrete
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• v.12 no.5
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• pp.651-668
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• 2013

Concrete structures need repairing due to various reasons such as deteriorative effects, overloading, poor quality of workmanship and design failures. Cement based repair mortars are the most widely used solutions for concrete repair applications. Various factors may affect the bond strength between concrete substrate and repair mortars. In this paper, the effects of polymer additives, strength of the concrete substrate, surface roughness, surface wetness and aging on the bond between concrete substrate and repair mortar has been investigated. Full factorial experimental design is employed to investigate the main and interaction effects of these factors on the bond strength. Analysis of variance (ANOVA) under design of experiments (DOE) in Minitab 14 Statistical Software is used for the analysis. Results showed that the interaction bond strength is higher when the application surface is wet and strength of the concrete substrate is comparatively high. According to the results obtained from the analysis, the most effective repair mortar additive in terms of bonding efficiency was styrene butadiene rubber (SBR) within the investigated polymers and test conditions. This bonding ability improvement can be attributed to the self-flowing ability, high flexural strength and comparatively low air content of SBR modified repair mortars. On the other hand, styrene acrylate rubber (SAR) modified mortars was found incompatible with the concrete substrate.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.319-322
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• 1999

The adhesion properties of polymer cement mortars for cement concrete repair were evaluated with respect to polymer-cement ratios and the surface conditions of cement concrete substrate. Styrene-butadiene rubber (SBR) was used as an additive for polymer cement mortars. The adhesion strength of cement mortar was smaller than that of polymer cement mortar. The adhesion strengths to the dry surfaces of substrate were larger than those to the wet surfaces, indicating that the dryness of substrate increased the adhesion strength in repairing concrete structures.

• Advances in concrete construction
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• v.15 no.6
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• pp.431-444
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• 2023

This study investigated the use of latex-modified sand concrete reinforced with sisal fibers (LMSC) as a repair material. Notably, no prior research has explored the application of LMSC for this purpose. This paper examines the interface bond strength and the type of failure between LMSC as a repair material and the normal concrete (NC) substrate utilising four different surfaces: without surface preparation as a reference (SR), hand hammer (HA), sandblasted (SB), and grooved (GR). The bond strength was measured by bi-surface shear, splitting tensile, and pull-off strength tests at 7, 28, and 90 days. Scanning electron microscopy analysis was also performed to study the microstructure of the interface between the normal concrete substrate and the latex-modified sand concrete reinforced with sisal fibers. The results of this study indicate that LMSC has bonding strength with NC, especially for HR and SB surfaces with high roughness. Therefore, substrate NC surface roughness is essential in increasing the bonding strength and adhesion. Eventually, The LMSC has the potential to repair and rehabilitate concrete structures.

• Journal of the Korea Institute of Building Construction
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• v.3 no.4
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• pp.73-78
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• 2003

In this Study, we examined the influence of characteristics of rolling loads by casters on separation resistance of substrate concrete and synthetic resin floor coating. In the experiment, we first prepared floor samples having substrate concrete of various compressive strength, surface hardness and surface configurations, then put the coated samples to the test of separation resistance with Rolling Caster Loading Machine. Three loading conditions consisted of different kinds of casters, rolling conditions, and coating materials. Consequently, we clarified that the grade of separation resistance varied widely according to the characteristics of substrate concrete and rolling loads.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1225-1228
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• 2001

The purpose of this study is to develop for finishing method of concrete structures applying metal spraying system. In the experiments, the pull out tests were conducted using the specimen which was applied by various surface treatment of concrete substrate. As a result, it was confirmed that the adhesion strength of metal spray was effected by surface condition of concrete and the construction of primer or the coarse surface agent to the concrete substrate is very effective to the new finishing method of concrete for the metal spraying system.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10c
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• pp.145-150
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• 1998

This study deals with the effect on performance of epoxy resign mortar mixed special cement for surface control and maintenance of aging concrete construction. The test of main property of epoxy resign in this study are the evaluation on the adhesive strength between substrate and epoxy resign mortar under the environment of wet or concrete substrate surface. We gained the test results of good adhesive strength over 15 kgf/$\textrm{cm}^2$ under the wet and dry condition of concrete surface.

• Journal of the Korea Concrete Institute
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• v.13 no.5
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• pp.507-515
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• 2001

Significant improvements in bond strength between new and existing concrete can be achieved through the modification of the new concrete by latex. This study focuses on the investigation of bond strength of latex modified concrete. Pull-out bond test and uniaxial direct tensile bond test are adopted for evaluating the adhesion characteristics of latex modified concrete to conventional concrete substrate. The main experimental variables are test methods, latex-cement ratio, surface preparations and moisture levels. The results are as follows; The increase of latex-cement ratio substantially improves the adhesion between latex modified concrete and substrate. The effects of surface preparation at substrate into the bonding of latex modified concrete are quite different according to the conditions of surfaces. Thus, an adequate surface preparations are essential for good bond strength. Because the moisture level of the substrate may be critical to achieving bond, optimum moisture condition for a conventional concrete has evaluated in this study. The saturated condition of surface is the most appropriate moisture level among the considered, followed by dry condition and wet condition.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.10a
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• pp.330-335
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• 1998

This research was conducted to evaluate the adhesion in tension of the polymer mortars for cement concrete repair. Various polymer types, binder ratios, and wet/dry conditions of the surface were considered in this study. Styrene-butadiene rubber (SBR) and ethylen vinyl acetate (EVA) used for polymer cement mortars. Epoxy resin (EP), and unsaturated polyester resin (UP) were used for polymer mertars. Adhesion in tension for the dry condition of the substrate surface was higher than that for the wet condition of the substrate surface under the same binder ratio. Therefore, in repairing concrete, the dry surface condition was effective on adhesion.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.979-984
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• 2001

Poor water-proofing integrity is related to many factors : site procedure, workmanship, weather. substrate conditions, installation(including asphalt application) conditions. The evaluation of adhesive properties tested by concrete surface moisture and asphalt application was based on laboratory test and observations. This report describes the pull-off test results of waterproofing systems currently used for installing and reparing for concrete bridge decks. The test results showed that the moisture condition fully affected the adhesive properties of sheet membranes and sealer but partially for liquid membranes.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.9
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• pp.19-26
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• 2018

The focus of this study was centered around 15 common injection type water leakage repair materials (3 different types for each; synthetic polymer, cementitious, acrylic, epoxy, urethane) used in concrete structures of Korea and analyzing their wet surface adhesion performance in accordance to the ISO TS 16774 Test Method for Repair Materials for Water-leakage Cracks in Underground Concrete Structures, Part 4: Test Method for Adhesion on Wet Concrete Surface, and the results of this study was taken to be place under a comparative analysis with the results of the preceeding study on response to substrate movement performance study. The results of this comparative study showed that other than 1 specimen of 1 type of the acrylic and 3 specimens of 1 type of the synthetic polymer type materials, all of the 93% of the specimens used in this study showed stable adhesion on wet substrate surface, and we were able to determine that materials that have proper response properties against substrate movement are highly flexible and have high adhesion properties, but their adhesion properties on wet substrate would change based on their viscosity.