Papers by Keyword: Repair Material

Abstract: Geopolymer mortars which produced by the reaction of fly ash with an alkaline activator and added with sand is going to be developed for use as concrete repair material. Thus, the typical and standard requirement as repair material is reviewed. This paper also discusses the efficiency of geopolymer mortar which is mainly dependent on the excellent bond between the sand and geopolymer binder. Based on the determined formulation of geopolymer mortar, the standard for testing is determined making it potentially becoming as an excellent repair materials.

Abstract: In recent years, concrete repair has become an integral part of the construction industry. With the vast quantity of concrete used in the South African construction industry over the past 100 years, one can expect an increase in repair and rehabilitation requirements during the extended lifecycle of exposed concrete structures. Crack repair, re-profiling of spalled areas and surface sealing with polymer related materials forms the bulk of such repair and rehabilitation operations. Due to the complexity of these projects and the variety of professionals and other stakeholders involved from the diagnostics to the implementation phase (specialists consultants, contractors, suppliers and owners of the structures), considerable problems seem to have surfaced to ensure cost-effective but sustainable and durable outcomes. It has been found that in many concrete repair projects, the responsibility for the repair work, adequate quality control and the assessment of successful patch repairs are not fully embraced by the various stakeholders.This concern has led to the research as reported in this paper. The research entailed a series of questionnaires drawn up specifically for the four different stakeholder sectors of the concrete repair industry. The results indicate that, although there is agreement that concrete repair is a highly specialized field, there is not enough training in the correct use of the repair materials, nor enough knowledge regarding the diagnostics or material specification and selection processes. Knowledge on polymer modified mortar are also minimal. These problems are compounded by inadequate quality control and lack of ongoing monitoring of patch repair failure. The paper concludes with suggestions on the way forward.

Abstract: Corrosion of reinforcement is one of the causes of concrete deterioration by the water contained chloride ions and gas, for example hydrogen sulfide that penetrate into the concrete structures. By performing the related transport properties testing, it will fulfill the main objective of this research that is to investigate the fluid transport and bonding properties between normal concrete substrate (NC) and green USM reinforcement concrete (GUSMRC) containing ultra-fine palm oil fuel ash (UPOFA) as repair material. GUSMRC is the type of concrete that has been upgraded from the ultra-high performance fiber reinforces concrete (UHPFRC) with 50 % of UPOFA replacing the cement. Recently many researchers have found that the POFA can be used as partial cement replacement in the concrete which can improve the durability and also the fluid transportation properties. For the bonding properties, two types of surface treatment / roughness will be perform to investigate the greatest bonding and also the durability between NC substrate that act as an old structures with GUSMRC as new repair material. It’s important to perform the other related testing so that the future results obtained can be conclude either this new green ultra-high concrete can resist the harmful environmental aggression and also if it has an excellent bonding with the old concrete as a repair material.

Abstract: Ultra high performance fiber concrete (UHPFC) is an advanced formula concrete that is proven to be more superior than conventional concrete because it embrace the qualities of steel and concrete. Therefore UHPFC properties which include high durability and strength are fully exploited in the research of rehabilitation and strengthening in concrete and even non-concrete structures. This article presents the findings of an experimental study carried out to examine the bonding strength behaviour between normal concrete (NC) substrate and UHPFC as a repair material, under flexural strength test by using third-point loading beam test method. Three types of NC substrate surface preparation were used: as-cast (without surface preparation) as a reference, wire-brushed, and sand-blasted. The flexural test results clearly indicated that all failures occurred through the NC substrate and no de-bonding was observed in the interface between NC substrate and UHPFC. The results of the flexural strength confirmed that adhesion bond strength between NC substrate and UHPFC was stronger than the substrate regardless, the substrate roughness. This proves that UHPFC is able to link and bond strongly with the substrate.

Abstract: The most common form of rehabilitation for a deteriorated structure is to remove the deteriorated concrete and replace it with a new material, thus increasing the design life of the structure. Good adhesion of a repair material to concrete is of vital importance in the application and performance of concrete repairs. A major factor that influences the durability of the repair is the bond strength between the new material and the substrate. In this investigation, the most common repair materials, produced by international reputed manufactures, available in the local market were selected from cementitious repair mortars and cementitious polymer modified mortars. The performance of these materials were evaluated in terms of compressive strength, tensile strength, bond strength in tension and bond strength in modulus of rupture.

Abstract: The surfaces of concrete airfield aprons and runways deteriorate for a number of reasons, such as surface scaling due to freeze/thaw, impact loading, hot weather, de-icing fluids, deterioration of joints, jet fuel chemicals and so on. A limited field and laboratory study was performed to investigate the constructability and performance of prospective materials for repair of airfield concrete damaged by exposure to heat and oil. Two prospective coating materials and six prospective inlay materials were field-testes at the Base in USA Kansas, and were evaluated in the laboratory at the University of Florida before and after the field installation. The results of the study indicate that it is feasible to repair these damaged concrete surfaces by placing a suitable inlay material with a minimum depth of 2 inches. Among the prospective inlay materials investigated, two promising materials for this application are a magnesium phosphate concrete (Set-45) and a calcium aluminate concrete (Fondag). Both two concretes set very quickly, and make high early-strength, impermeable patches that bond to clean and dry surfaces. Guidelines for the placement of inlay materials for this purpose are proposed based on the experience from this study.