• Proceedings of the Korea Concrete Institute Conference
• /
• 2008.04a
• /
• pp.725-728
• /
• 2008

This study was to establish 3 levels of high fineness fly ash like 4000, 6000, and 8000 class and 30% replacement ratio in order to analyze mechanics and shrinkage properties of concrete by using high fineness fly ash. Furthermore, this study was to make a plan in two levels of water-binder ratio like 40% and 50%. In addition, as a result of measurement by the establishment of combined condition of ternary system as 20% replacement ratio level of three sorts of ground granulated blast furnace slag, there was a tendency to be equal or higher to the plain concrete as the fineness of fly ash increased in strength property. Simultaneously, this study had a tendency in the relationship between the compressive strength and elastic modulus that the more the fineness of fly ash, the more the elastic modulus increased a little. In addition, this study had a tendency that the more elastic modulus moved to the long-term aged one, the more it increased definitely. The effect on the fineness of fly ash remained at a low level in the drying shrinkage. This study has shown that the more the fineness increased, the more the elastic modulus decreased.

• Proceedings of the Korean Society of Agricultural Engineers Conference
• /
• 2005.10a
• /
• pp.97-101
• /
• 2005

High strength concretes utilizing EVA with micro particles were prepared by varying polymer/binder mass ratio and curing conditions with a constant water/binder mass ratio of 0.3. The EVA modified concretes on the compressive and flexural strength, microstructure, ultrapulse modulus in curing condition(dry and water curing) were studied. Also, scanning electron microscope analysis(SEM) was performed to reveal the presence of polymer film and cement hydrates in the concrete. The compressive strength of the EVA modified concretes cured at water conditions ere higher than that of the EVA modified concretes cured at dry conditions. But, the flexural strength of the specimens cured at dry conditions were higher than that of the specimens cured at water conditions. Due to the interaction of the cement hydrates and polymer film, an interpenetrating network originated in which the aggregates were embedded. The curing of the polymer modified concrete involves two step of cement hydrates and polymer modification, and cement hydrates was promoted in water conditions and polymer film formation take place when water evaporates and was thereby was favored in dry conditions. By SEM analysis, influences of polymer modification was strengthening of the transition zone between the aggregate and the paste, and the porosity of transition zone decreases. By spring analysis, it could known that polymer film affects in porosity decrease and strengthening of transition zone.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.89-92
• /
• 2006

To investigate the properties of high flowing and high strength concrete with crushed sand and fly ash for CFT structure, many batches were performed by a trial-error method. In the experiment W/B was set up three levels as 0.25, 0.30 and 0.35. Also the variables of the experiment were a substitution ratio of fly ash, a blend ratio of crushed sand and the ages of specimens(3, 7, 28 days). The results of this study are summarized as the follows; 1) The effect a substitution ratio of fly ash on the compressive strength was not consistent with age. For twenty-eight day compressive strength, the best result was come out when cement was substituted by 10% of fly ash. 2) The decrease of the water binder ratio, the increase of compressive strength and elastic modulus. Also the relationship is very similar to the case of a normal concrete

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.2 no.3
• /
• pp.180-187
• /
• 2014

The purpose of this study is to evaluate on the mechanical properties of High Volume Mineral Admixture(HVMA) high strength concrete to reduce the amount use of Ordinary Potland Cement, to discover the optimized HVMA binder and to test HVMA concrete based on the change of W/B and curing temperature. The results were shown as follows: The HVMA binder using the mixture of combined heat power plant fly ash and anhydrous gypsum known as inorganic activators with the mixture of blast furnace slag and fly ash was optimized. The mixture of HVMA high strength concrete at 26% of W/B ratio had a good result on flow characteristic and mechanical properties. High strength HVMA concrete over 50MPa is possibly manufactured over curing temperature $20^{\circ}C$.

• Journal of the Korea Institute of Building Construction
• /
• v.7 no.4
• /
• pp.117-124
• /
• 2007

Focused on the material-related aspect for enhancing the durability of concrete, the present study analyzed the effect of glycol ether admixture, which is a chemical admixture that can compact the structure of concrete by entraining air inside the concrete, on the basic physical properties and durability characteristic of the concrete. In analyzing the results of experiment, we examined the basic physical properties and durability characteristic of concrete according to addition rate based on OPC and selected the optimal addition rate. In addition, with the optimal addition rate, we added glycol ether admixture to concrete, which contained fly ash used as binder and high-performance water reducing agent for reducing the unit quantity, and examined changes in the characteristics of the concrete. According to the result, the optimal addition rate of glycol ether admixture was 3% of the unit quantity of cement, and the addition of binder and chemical admixture did not have a significant effect on unhardened concrete but reduced the air content. In addition, concrete showed resistance performance of around 30% to carbonation and around 40% to drying shrinkage. In addition, as for resistance to freezing and thawing, the relative dynamic modulus of elasticity was over around 85% through atmospheric curing. These performances prove the effect.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.5
• /
• pp.5-12
• /
• 2014

Weatherstrip coatings of urethane and silicon type which are fit to EPDM and thermoplastic materials are used in sealing systems for automotive applications for noise reduction and high slip characteristics for external applications, respectively. Polyurethane binder was successfully synthesized from poly(butyladiphate)diol (PBAD), poly(tetramethylene)glycol (PTMG) and isocyanate as starting materials. Then, polyurethane coating agents were prepared by using various additives. To investigate effects of segment types on the abrasion resistance of polyurethane coating agents, thin films based on polyurethane coating materials were fabricated. With increasing the amount of hard segment in the coating agent, abrasion resistance, modulus and tensile strength of the coating films were improved, but the elongation of the coating films was decreased.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.34 no.3
• /
• pp.763-771
• /
• 2014

Recently, a huge amount of sulfur has been produced as a byproduct of petroleum refining processes in Korea. Sulfur concrete is made of modified sulfur binder instead of cement paste, which has advantages of reducing $CO_2$ emission from cement industry as well as utilizing surplus sulfur. Also, sulfur concrete is a sustainable material that can be repetitively recycled. In this study, the physical properties of sulfur concrete are experimentally investigated. From the test results, sulfur concrete showed compressive strengths higher than at least 50MPa. Also, the unit weight, modulus of elasticity and splitting tensile strength of sulfur concrete was similar to that of Portland cement concrete (PCC). The coefficient of thermal expansion of sulfur concrete was a little larger than that of Portland cement concrete and sulfur concrete with mineral filler is helpful to lower the coefficient of thermal expansion. recycled aggregate sulfur concrete resulted in a slight reduction in the compressive strength, but sulfur concrete with recycled aggregate can achieve the high strength characteristics.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1999.10a
• /
• pp.139-142
• /
• 1999

The purpose of this experimental research is to investigate the mechanical properties of ordinary strength and high strength concrete containing waste glass powder. For this purpose, after production of concrete containing waste glass powder for different unit weight of binder and placement ratio of waste glass powder, optimum mixing proportions of them was determined, and then mechanical properties such as static modulus of elasticity as well as compressive, tensile and flexural strength were tested and analyzed for concrete produced according to optimum mixing proportions. As a result, the concrete containing waste glass powder has as excellent workability and strength, it's strengths are analogus to those of silica fume, it's workability is somewhat better than that of silica fume.

• International Journal of Highway Engineering
• /
• v.14 no.5
• /
• pp.75-83
• /
• 2012

PURPOSES: Suggestion of asphalt binder constitutive model based on time-temperature superposition principle and overstress concept in order to describe behavior of asphalt binders. METHODS: A series of temperature sweep tests and multiple stress creep and recovery(MSCR) tests are performed to verify the applicability of time-temperature superposition principle(t-Ts) and to develop viscoelastoplastic constitutive equation based on overstress concept. For the tests, temperature sweep tests at various high temperature and various frequency and MSCR test at $58^{\circ}C$, $64^{\circ}C$ $70^{\circ}C$, $76^{\circ}C$, and $82^{\circ}C$ are performed. From the temperature sweep tests, dynamic shear modulus mastercurve and time-temperature shift function are built and the shift function and MSCR at $58^{\circ}C$ are utilized to determine model coefficients of VBO model. RESULTS: It is observed that the time-temperature shift function built at low strain level of 0.1% is applicable not only to 1.0% strain level temperature sweep test but also maximum 500,00% strain level of MSCR test. As well, the modified VBO model shows perfect prediction on MSCR measured strain at the other temperatures. CONCLUSIONS: The Time-temperature superposition principle stands hold from very low strain level to very high strain level and that the modified VBO model can be applicable for various range of strain and temperature region to predict elastic, viscoelastic, and viscoplastic strain of asphalt binders.

• International Journal of Highway Engineering
• /
• v.11 no.1
• /
• pp.1-12
• /
• 2009

A new mix design procedure for cold in-place recycling using foamed asphalt (CIR-foam) has been developed for Iowa Department of Transportation. Some strengths and weaknesses of the new mix design parameters were considered and modified to improve the laboratory test procedure. Based on the critical mixture parameters identified, a new mix design procedure was developed and validated to establish the properties of the CIR-foam mixtures. As part of the validation effort to evaluate a new CIR-foam mix design procedure, dynamic moduli of CIR-foam mixtures made of seven different reclaimed asphalt pavement (RAP) materials collected throughout the state of Iowa were measured and their master curves were constructed. The main objectives of this study are to provide: 1) standardized testing procedure for measuring the dynamic modulus of CIR-foam mixtures using new simple performance testing (SPT) equipment; 2) analysis procedure for constructing the master curves for a wide range of RAP materials; and 3) impacts of RAP material characteristics on the dynamic modulus. Dynamic moduli were measured at three different temperatures and six different loading frequencies and they were consistent among different RAP sources. Master curves were then constructed for the CIR-foam mixtures using seven different RAP materials. Based upon the observation of the constructed master curves, dynamic moduli of CIR-foam mixtures were less sensitive to the loading frequencies than HMA mixtures. It can be concluded that at the low temperature, the dynamic modulus is affected by the amount of fines in the RAP materials whereas, at the high temperature, the dynamic modulus is influenced by the residual binder characteristics.