• Title/Summary/Keyword: 규석

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Improvement of Strength Characteristics in ALC added Silica Powder and Gypsum (규석 분말 및 석고 혼입에 따른 경량기포콘크리트의 강도특성 개선)

  • Song, Hun;Chu, Yong-Sik;Lee, Jong-Kyu
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.7 no.4
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    • pp.128-135
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    • 2012

  • Autoclaved lightweight concrete, also known as autoclaved aerated concrete(AAC) or autoclaved cellular concrete (ACC), is made with fine silica powder, quik lime, cement, and an Al powder. ALC contains 70~80% air. The lightweight material offers excellent sound and thermal insulation, and like all cement-based materials, is strong and fire resistant. However, ALC have high water absorption, low compressive strength and popout the origin of the low surface strength in its properties. These properties make troubles under construction such as cracking and popout. Thus, this study is to improve the fundamental strength by controls of increasing of admixtures, gypsum and silica powder size. Admixtures make use of metakaolin and silica fume. From the test result, the ALC using admixture have a good fundamental properties compared with plain ALC. Compressive strength, specific strength and abrasion's ratio were improved depending on increasing admixtures ratio's, gypsum and silica powder size.

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A Study on the Variation of Physical Properties on the Secondary Product of Cement by Using Crushed Stone Powder (폐석분을 사용한 시멘트 2차 제품의 물리적 특성에 관한 연구)

  • Park, Ji-Sun;Lee, Sea-Hyun;Song, Hun
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.6 no.4
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    • pp.103-111
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    • 2012

  • One of the basic physical properties of the hardened cement paste, the rigidity, is deteriorated during concrete matrix forming, depending on the replacement rate of the crushed stone powder, and due to drying shrinkage. Therefore, the concrete containing crushed stone powder has been limitedly used as non-structural construction material. To improve these disadvantages, a hydrothermal reaction employing method can be considered. High-temperature and high-pressure water is involved in the hydrothermal reaction in the mixing with specific materials. The rigidity improving mechanism is related to the synthesis of calcium silicate. The calcium silicate is produced through reaction between calcium compounds and the silicic acid. Various kinds of calcium silicate can be produced depending on the CaO/$SiO_2$ mole ratio, the temperature of the hydrothermal synthesis, the pressure, and the reaction time. The product of the synthesis mechanism, tobermorite crystal, plays a pivotal role for the rigidity reinforcement. The crushed stone powder, analyzed in this study, contains 50 to 60% of $SiO_2$ and 10 to 20% $Al_2O_3$. The composite rate is appropriate to create the tobermorite crystal through formation of hardened cement matrix under the hydrothermal synthetic conditions and with the CaO in the cement. Moreover, further reinforcement was promoted using the property of material under the identical density through promoting the formation of tobermorite crystal.

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