• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.650-657
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• 2021

Alkali activators that stimulate mineral compounds are expensive materials, but in order to replace industrial products of high alkali in gredien ts, both product an d econ omic feasibility must be satisfied. In this study, alkali in dustrial waste(LW) from the LCD man ufacturin g process were used for the purpose of alkali active reaction of GGBFS for high stren gth concrete over 50MPa. Concrete mixed with LW had reduced workability, but it had the characteristic of increasing compressive strength. Analysis using ACI 209 Compressive Strength Model Equation was made to compare the changes in strength coefficients according to LW mixing. The durability test of concrete, such as Chloride Penetration Resistance and carbonation resistance, also showed excellent performance. In the Adiabatic temperature rise test results, the concrete mixed with LW had the effect of accelerating the initial hydration heat. However, the final Adiabatic temperature rise was not significantly affected by the mixing of LW.

• Journal of the Korea Concrete Institute
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• v.21 no.2
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• pp.147-152
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• 2009

The compressive strength test, bulk density and mortar absorption ratio were carried out to utilize the data as the basic sources for the lightweight mortar and the lightweight concrete, through the study on the physical characteristics of the artificial lightweight aggregate (ALA) made of waste glasses, which was developed for the first time in the country. On the basis of these experiments, the density and the unit volume weight of the ALA showed the value less than 50% of the common aggregate due to the independent pore structure, and the mortar that contains ALA had no big difference from the Control mortar in the test of the absorption ratio. It is judged that this happens based on the internal independent pore structure of the ALA. In case of the mortar containing ALA, there was a tendency of declination in the compressive strength and the bending strength as the mixing rate is increasing, but all mortar showed more than 70% of the Control mortar compressive strength except for the La50 mortar. Hereafter, it is judged that according to the control of the mixing ratio of mineral admixing agent, water and cement, it will realize the equal strength to the control mortar, and the long term edurance is needed to be considered together.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.3
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• pp.125-133
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• 2011

The requirement for durability of concrete bridge deck is increasing as the deterioration for the concrete bridge deck exposed to severe environment has been increased. For this reason, the concern about high-durable concrete is being high. Recently, a metakaolin is highly spotlighted as new admixture because its strength and durability are equivalent to silica fume. On the other hands, there are few researches for the metakaolin concrete bridge deck in domestic. So many various long-term data on the mechanical property and durability is needed to apply metakaolin concrete at the concrete bridge deck construction field. This study is aim to evaluate the long-term mechanical properties and durability of metakaolin concrete bridge deck with curing age. Mechanical properties are estimated by the compressive and flexural strength, and the drying shrinkage, the chloride resistance, the scaling, and freezing and thawing characteristics are compared with curing age. According to the results, when the metakaolin concrete is used, the development of compressive and flexural strength proceed in both the early and old ages. It is also improved the resistance of chloride penetration, freezing and thawing in concrete. It was showed that replacement of metakaolin was efficient for the reduction of the drying shrinkage.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.109-116
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• 2017

This paper describes the investigation into the durability alkali-activated materials(AAM) mortar and paste samples manufactured using fly-ash(FA) and ground granulated blast furnace slag(GGBFS) exposed to a sulfate environment with different GGBFS replace ratios(30, 50 and 100%), sodium silicate modules($Ms[SiO_2/Na_2O]$ 1.0, 1.5 and 2.0). The tests involved immersions into 10% sodium sulfate solution($Na_2SO_4$), 10% magnesium sulfate solution($MgSO_4$), 10% magnesium nitrate solution($Mg(NO_3)_2$) and 5% magnesium nitrate($Mg(NO_3)_2$+5% sodium sulfate solution+$Na_2SO_4$). The evolution of compressive strength, weight, length expansion and microstructural observation such as x-ray diffraction were studied. As a results, in case of immersed in $Na_2SO_4$, $Mg(NO_3)_2$ and $Mg(NO_3)_2+Na_2SO_4$ shows increase in long-term strength. However, for samples immersed in $MgSO_4$, the general observation was that the compressive strength decreased after immersion. The most drastic reduction of compressive strength and expansion of weight and length occurred when GGBFS or Ms ratios were higher. Also, the XRD analysis of samples immersed in magnesium sulfate indicated that expansion of AAM caused by gypsum($CaSO_4{\cdot}2H_2O$) and brucite(MgOH). The results showed that, an additional condition $Mg^{2+}$ in which ${SO_4}^{2-}$ is the presence of a certain concentration, sulfate erosion has to be accelerated.