• Proceedings of the Korea Concrete Institute Conference
• /
• 1994.10a
• /
• pp.211-216
• /
• 1994

This study dealt with the properties for fly ash of conbined heat power plant and application for concrete industry. For this purpose, fly ash sampled Ulsan conbined heat power plant and analyzed for physical and chemical properties. As analyzed results of fly ash, contents of $SiO_ and Al_O_ $in the fly ash of Ulsan were less than those of Thermo-electric power plant(Boryuing), but contents of CaO were tem times as much as those of Boryung, because of these differences, it is expected that pozzolanic activity of concrete using fly ash of Ulsan will be different from another fly ash. Concrete specimens were tested to evaluate concrete preformance when 10 to 50 percent of the portland cement by weight in the concrete mix was replaced with fly ash of conbined heat power plant. As test results, workability and consideration in the fresh concrete were increased and concrete strength was showed more than 400kg/$\textrm{cm}^2$ for the required age. This study would be provided valuable data for the practical utilization of fly ash(conbined heat power plant). In the future, properties of fly ash concrete including long term strength, elapsed time, pozzolanic activity, modulus of elasticity, sulfate resistance, shrinkage, freeze-thaw durability and so on will be studied.

• Polymer(Korea)
• /
• v.27 no.6
• /
• pp.596-602
• /
• 2003

A Polymeric emulsifier was synthesized by solution polymerization with 2-ethylhexyl acrylate, n-butyl acrylate, and acrylic acid. A series of polymeric emulsifier have been used in the emulsion copolymerization of 2-ethylhexyl actryacrylate and n-butyl acrylate. The size of the synthesized latex particles was around 145 nm and its distribution was very narrow. Emulsion with polymeric emusifier showed no coagulum after 7 cycles of freeze-thaw test, while the emulsion with traditional emulsifier exhibited coagulum after 2 cycles. The adhesion tests showed that the initial tackiness and peel strength decreased as the molecular weight and acrylic acid content of polymeric emulsifier increased, whereas the holding power increased.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2008.11a
• /
• pp.13-16
• /
• 2008

This paper is to present the performance data for improved direct setting method using tile bond for application of porcelain tile under 1 percent absorptance. For this purpose, improved direct setting method type 1 & 2(tile bond curing time 0, 24H) were compared with the conventional setting methods(including direct setting method and improved pressure setting method) in the sight of the adhesive stability of porcelain tile. It tested for tiles after 14, 28days under standard condition and severe conditions. The severe conditions were water immersion, heat ageing(70℃) and freeze-thaw cycle. On the basis of test results, the adhesive strength of direct setting method was lowest for the conventional setting methods. But improved direct setting method using tile bonds(A, B) came close to the result of improved pressure setting method using tile bonds.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.14 no.11
• /
• pp.5915-5922
• /
• 2013

In this study, with the aim of improving the performance of shale to allow for its use as coarse aggregate for concrete, we coated shale aggregates with water repellents and polymers and evaluated their physical properties such as density, water absorption rate, wear rate, and stability depending on the coating method. In addition, the effects of the performance improvement were evaluated by assessing the properties of fresh concrete produced by varying the shale substitution ratio, as well as the compressive strength, flexural strength, and freeze-thaw resistance according to curing ages. The test results revealed that the absolute dry densities of all coated aggregates satisfied the standard density for coarse aggregates for concrete(>$2.50g/cm^3$),and the absorption rate of the shale aggregate coated with water repellent decreased by about 50% compared with that of uncoated shale. The wear rate of the polymer-coated shale decreased by up to 13.0% compared with that of uncoated shale. All coated aggregates satisfied the stability standard for coarse aggregates for concrete(${\leq}12$). The water repellent-induced performance improvement decreased the shale aggregates' slump by about 20~30mm compared with that of the uncoated shale aggregates, and the air content of the repellent-coated shale aggregate increased by up to 0.9% compared with that of the uncoated shale aggregate. The compressive strength of the polymer-coated shale aggregates at a curing age of 28 days was RS(F) 95.7% and BS(F) 90.0%, and the flexural strength was RS(F) 98.0 % and BS(F) 92.0% of the corresponding values of concretes produced using plain aggregates. Furthermore, the concrete using polymer-coated shale aggregates showed a dynamic modulus of elasticity of RS(F) 91% and BS(F) 88% after 300 freeze-thaw cycles, thus demonstrating improved freeze-thaw durability.

• International Journal of Highway Engineering
• /
• v.19 no.2
• /
• pp.7-15
• /
• 2017

PURPOSES : Infiltration of moisture, polluted material, and deicer into concrete, accompanied by freeze and thaw can cause significant deterioration of concrete pavement. In order to protect concrete from deterioration, it is necessary to prevent the infiltration of these concrete external materials. The moisture-repellent agent, which is a surface treatment and maintenance material added to concrete structures to render them water resistant, has advantages such as prevention of water infiltration and security against air permeation. Nano-coat, which is referred to as silicon hydride, is typically used as a moisture-repellent agent. Therefore, in this study, an attempt is made to use penetration-type Nano-coat as an alternative in order to evaluate its applicability through environmental resistance tests. METHODS : This study aimed to evaluate the applicability of penetration-type Nano-coat, which can provide water repellency to concrete, in concrete pavements, through various environmental resistance tests such as freezing and thawing resistance, chloride ion penetration resistance, and surface scaling resistance tests. The applicability of penetration-type Nano-coat was demonstrated based on the specification of KS F 2711, KS F 2456, and ASTM C 672. RESULTS :In the case of penetration-type Nano-coat applied on sound concrete, an increase in concrete durability was demonstrated by the negligible chloride ion penetrability and the absence of scaling, as revealed by visual observation of the surface, after 50 cycles of scaling resistance test. In addition, test result of the application of penetration-type Nano-coat on deteriorated concrete established that concrete surface pretreated by grinding provided improved durability than non-treated concrete. CONCLUSIONS :This study indicates that penetration-type Nano-coat is applicable as an effective alternative, to increase the durability of concrete structures. In addition, it was known that pretreatment of deteriorated concrete surface, such as grinding, is required to improve the long-term performance of concrete pavement.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.5
• /
• pp.1-8
• /
• 2023

Marine and hydraulic structures are subject to durability damage not only due to the penetration of sea water but also due to the attachment of marine organisms. Therefore, in this study, we tried to develop an antifouling coating agent with self-cleaning function for marine concrete. It was confirmed that the antifouling coating agent mixed with AKD, cellulose nanofibers and BADGE had sufficient antifouling performance at a well hydrophobicity of around 140° in contact angle and an inclination angle of 15°. In the abrasion resistance test of the surface, only a maximum loss of 0.015 g occurred. In the durability test, as a result of the chloride ion permeation test, almost no chloride ion permeation occurred in the variable where the coating agent was applied, and carbonation and freeze-thaw damage also rarely occurred, so it was analyzed that it was effective in securing durability of concrete.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.13 no.3
• /
• pp.13-24
• /
• 1993

The influence of the bubble structure and strength characteristics on the freeze-thaw resistance of high strength concrete is investigated by the laboratory experiment. The test conditions are formed in the manner that water is continueusly supplied externally and the specimens were received severe weather actions from ordinary to significantly low temperatures. The experiments are performed in two stages. In the first stage, the relation between the durability to frost action and the bubble structure is analyzed especially with respect to the water-cement ratio and the amount of air. The AE and non-AE concrete specimens made of ordinary portland cement are used in the test. In the second stage, the non-AE concrete specimens using vibratory compaction to improve the durability to frost action, and the high watertight specimens of rapid hardening portland cement to increase their initial strength are produced and tested. The degree of watertightness of the specimens is determined by measuring the permeability of the specimens and the bubble structure of the high watertight concrete is also estimated.

• Advanced Composite Materials
• /
• v.17 no.3
• /
• pp.277-299
• /
• 2008

High quality and expedient processing repair methods are necessary to enhance the service life of bridge structures. Deterioration of concrete can occur as a result of structural cracks, corrosion of reinforcement, and freeze.thaw cycles. Cost effective methods with potential for field implementation are necessary to address the issue of the vulnerability of bridge structures and how to repair them. Most infrastructure related applications of fiber-reinforced plastics (FRPs) use traditional hand lay-up technology. The hand lay-up is tedious, labor-intensive and relies upon personnel skill level. An alternative to traditional hand lay-up of FRP for infrastructure applications is Vacuum Assisted Resin Transfer Molding (VARTM). VARTM uses single sided molding technology to infuse resin over fabrics wrapping large structures, such as bridge girders and columns. There is no work currently available in understanding the interface developed, when VARTM processing is adopted to wrap fibers such as carbon and/or glass over concrete structures. This paper investigates the interface formed by carbon fiber processed on to a concrete surface using the VARTM technique. Various surface treatments, including sandblasting, were performed to study the pull-off tensile test to find a potential prepared surface. A single-lap shear test was used to study the bond strength of CFRP fabric/epoxy composite adhered to concrete. Carbon fiber wraps incorporating Sikadur HEX 103C and low viscosity epoxy resin Sikadur 300 were considered in VARTM processing of concrete specimens.

• Tunnel and Underground Space
• /
• v.11 no.4
• /
• pp.352-361
• /
• 2001

Mode I fracture toughness ( $K_{IC}$) of the frozen rocks and that of the frozen-thawed rocks were obtained by using BDT and CCNBD specimens. The test temperatures ranged from +$25^{\circ}C$ to -16$0^{\circ}C$. Wet and air-dry specimens of granite and sandstone were used in order to investigate the effect of water and porosity on fracture toughness. The SEM images of the frozen-thawed rocks were also analysed to check the density of thermal cracks. The $K_{IC}$ of the frozen rocks increased as the test temperature went down. The rate of increase was higher in wet condition than in dry condition and the rate of increase for wet granite was higher than that for wet sandstone. The $K_{IC}$ of the frozen-thawed rocks varied within 15% from the $K_{IC}$ of the rocks at room temperature. After one freeze-thaw process, thermal crack occurred in granite but no thermal cracks occurred in sandstone. And the crack density was increased as the temperature went down.n.

• International Journal of Highway Engineering
• /
• v.12 no.3
• /
• pp.103-111
• /
• 2010

Recently, usage bicycle has been encouraged to reduce energy consumption and $CO_2$. For this purpose, lots of bike road construction are planned. Typical type of pavement used in bikeroad such as asphalt concrete pavement, portland cement concrete pavement, colored pavement, soil pavement. However, these pavement types may need high construction cost comparing the required capacity of bike road. In this study, roller compacted concrete pavement which are economical and durable, are investigated to use as bike road pavement. The optimum compaction level and mix design of roller compacted concrete pavement are suggested by exploring strength test with various mixture ratio and compaction level, Also durability was examined based on freeze-thaw and scaling test. In addition, the cost and amount of carbon emission during in the construction of roller compacted concrete were evaluated and compare with the cost and carbon emission of typical portland cement concrete.