• Journal of the Architectural Institute of Korea Structure & Construction
• /
• v.35 no.9
• /
• pp.199-206
• /
• 2019

Experimental study on the durability characteristics to examine the feasibility of concrete with high water-tightness and self-healing performance to minimize maintenance of concrete for artificial ground is as follows. 1) When blending agent, swelling agents, and curing accelerator were added on the ternary system cement with blast-furnace slag fine particles and fly ash to give a self-healing property, higher blending strengths by 82% at design standard strength of 24MPa and by 74% at design strength of 30MPa, respectively could be obtained. 2) The permeability test for the specimens having high water-tightness and no shrinkage showed that the permeability was reduced at maximum of 98%. However, the permeability was decreased as the design strength was increased, showing the reduction rate of 87% at the design strength of 50MPa. 3) The depth of carbonation of blast-furnace slag and fly ash was increased in all the specimens compared with those of OPC only. However, as the material age was increased, carbonation penetration depth was decreased compared with the reference blend. 4) Compared with the reference blending using only OPC, the freeze-thaw resistance was higher in the case of blending with 40% of blast-furnace slag and 10% of fly ash at the design standard strength of 50MPa. In addition, the freeze-thaw resistance in general was superior in the design standard strength of 50MPa with the lower water-binder ratio (W/B) as compared with the design standard strength of 24MPa and 30MPa with the high water-binder ratios.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2013.11a
• /
• pp.126-127
• /
• 2013

For the decades, various of materials were used to instead of cement as the high volume CO₂ occurred during the process of cement manufacture. In this paper, incineration plant ash was used in the mortar which incorporating high volume of blast furnace slag. Water to binder ratio(W/B) is fixed as 50%,BS+RP's replacement ratio is fixed as 80%,and the replacement ratio of WA1 is range as 0,0.5,1,2,3,4,5%.For the fresh mortar, flow and chloride contents has been tested. For the hardened mortar, compressive strength at 3,7,28 days has been tested. the result shows that when the replacement ratio of WA1 is 0.5%,the chloride contents is less than 0,3 kg/m3,the flowability and strength also performed better than other replacement types of mortar.

• Computers and Concrete
• /
• v.10 no.6
• /
• pp.587-607
• /
• 2012

The purpose of this research is to propose a design technique of concrete mix proportions satisfying service life through genetic algorithm (GA) and neural network (NN). For this, thirty mix proportions and the related diffusion coefficients in high performance concrete are analyzed and fitness function for diffusion coefficient is obtained considering mix components like w/b (water to binder ratio), cement content, mineral admixture (slag, flay ash and silica fume) content, sand and coarse aggregate content. Through averaging the results of 10 times GA simulations, relative errors to the previous data decrease lower than 5.0% and the simulated mix proportions are verified with the experimental results. Assuming the durability design parameters, intended diffusion coefficient for intended service life is derived and mix proportions satisfying the service life are obtained. Among the mix proportions, the most optimized case which satisfies required concrete strength and the lowest cost is selected through GA algorithm. The proposed technique would be improved with the enhancement of comprehensive data set including wider the range of diffusion coefficients.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2009.05a
• /
• pp.307-308
• /
• 2009

The ultra high strength concrete classed 80 MPa for Lotte Town at pusan has many hydrated materials due to low water to binder ratio and high admixture contents and improved void structure caused by C-S-H gel corresponding to pozzolan and latent hydraulicity of FA and BS. Moreover, durability of the concrete is superior because there was no penetration of carbon dioxide, chloride and chloric ion caused by its fine internal constitution.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.469-470
• /
• 2010

The high-strength concrete(HSC) compared to normal concrete represents higher autogenous shrinkage due to lower water-to-binder ratio(W/B) and supplementaries, fly ash(FA) and granulated blast-furnace slag(BFS), etc. The potential of early age cracking which reduces durability of concrete structures is normally influenced by autogenous shrinkage and degree of restraint. Therefore, this paper studies on the evaluation of the characteristics of autogenous shrinkage for HSC, ultra-high-strength concrete(UHSC) containing admixtures by experimental test and the test results are compared with existed prediction models.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.05a
• /
• pp.681-686
• /
• 2003

One of the major degradation processes of reinforced concrete (RC) structure is corrosion of reinforced steel due to chloride attack. Severe environments, such as marine environment and exposure to de-icing salts, could accelerate the steel corrosion of RC structures through the chloride ion intrusion into concrete. In order to delay this degradation process, several kinds of admixtures have been used in concrete mix. In this study, effective diffusion coefficient of chloride ion ($D_{eff}$) and total passed charge of concrete with and without fly ash were measured using electrical method. It is found that fly ash concrete has much less chloride ion coefficient than ordinary concrete at later age. By analyzing the test results, $D_{eff}$ at 28 and 90 days was obtained as a function of water-binder ratio (W/B) and an equation for predicting $D_{eff}$ with age was proposed considering the decreasing rate of $D_{eff}$.

• Proceedings of the Korea Concrete Institute Conference
• /
• 1996.10a
• /
• pp.276-282
• /
• 1996

This study dealt with the properties for fly ash of combined heat power plant and application for concrete industry. For this purpose, fly ash of ulsan combined heat power plant was analyzed for physical and chemical properties and tested the properties of the super flowing concrete. As results of fly ash, contents of SiO2 and Al2O3 in the fly ash of Ulsan were less than those of thermal power plant(Boryung), but contents of CaO were ten times as much as those of Boryung. In order to satisfy the properties of the Super Flowing Concrete using class C fly ash, mixing conditions were determined the optimum water-binder(w/b), volume ratio of fine aggregates(Sr) and coarse aggregates(Gv).

• Journal of Environmental Science International
• /
• v.19 no.1
• /
• pp.105-114
• /
• 2010

The objective of the paper is to experimentally investigate the compressive strength of the concrete incorporating fly ash. Ordinary Portland cement(OPC). Water to binder ratio(W/B) ranging from 30% to 60% and curing temperature ranging from $-10^{\circ}{\sim}65^{\circ}C$ were also adopted for experimental parameters. Fly ash was replaced by 30% of cement contents. According to the results, strength development of concrete contained with fly ash is lower than that of plain concrete in low temperature at early age and maturity. In high curing temperature, the concrete with fly ash has higher strength development than that of low temperature regardless of the elapse of age and maturity. Fly ash can have much effect on the strength development of concrete at the condition of mass concrete, hot weather concreting and the concrete products for the steam curing.

• Structural Engineering and Mechanics
• /
• v.46 no.4
• /
• pp.447-458
• /
• 2013

Splitting tensile strength (STS) is a respectable mechanical property reflecting ability of the concrete. The STS of concrete is mainly related to compressive strength (CS), water/binder (W/B) ratio and concrete age. In this study, the assessment of STS is made by a novel uncertainty-oriented method which uses least square optimization and then predicts STS of concrete by uncertain (fuzzy) numbers. The approximation method addresses a novel integration of fuzzy set theory and multivariate statistics. The numerical examples showed that the method is applicable with relatively limited data. In addition, the prediction of uncertainty at various levels of possibility can be described. In conclusion, the uncertainty-oriented interval analysis can be suggested an effective tool for appraising the uncertainties in concrete technology.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.20 no.4
• /
• pp.128-135
• /
• 2016

In the current concrete structure of the highway is still the major problem most of concrete deterioration caused by the freeze-thaw and deicing salt, which is of issues that are not completely resolved. In particular, a single freezing event does not cause much harm, durability of concrete under multi-deterioration environment by repeated freeze-thaw and deicing salt is rapidly degraded and reduce its service life. In this study, the exposure environmental condition according the regional highway points were established. The damage condition and chloride content of the concrete at general and severe environmental exposure condition were also investigated. In addition, the experimental test of chloride ion permeability, scaling resistant and freeze-thaw resistance were carried out to improve the durability of the mechanical placing concrete of subsidiary structure. According to the results of this study, in observation of concrete surface condition, the concrete exposed by severe environmental condition showed broad ranges of damage with high chloride contents. Meanwhile, the water-binder(W/B) ratio and the less water content, and fly ash concrete than the specified existing mix proportion is significantly improved the durability. Also, the optimal mix proportion derived for test is satisfied the strength and air contents, water-binder ratio, and durability criteria of concrete specifications, as well as service life seems greatly improved.