• Title/Summary/Keyword: OPC mortar

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Physical and Waterproof Properties of Mortar Using Cement Sludge Treated with Hydrofluosilicic Acid (규불화수소산 처리 시멘트 슬러지를 사용한 모르타르의 물성 및 방수 특성)

  • 김승문;이병기;김도수;노재성
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10c
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    • pp.76-81
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    • 1998
  • The physical properties of cement sludge treated with hydrofluosilicic acid were investigated. The compressive strength of cement mortar substituted cement sludge was decreased than that of OPC(ordinary portland cement) mortar. Cement sludge, for improving its physical properties, was treated with hydrofluosilicic acid. And compressive strength of cement mortar substituted TCS was greatly improved than that of OPC mortar. Particularly, cement mortar substituted TCS had the higher value in water-proofness than of OPC.

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Classification of Alkali Activated GGBS Mortar According to the Most Suitable Usage at the Construction Site

  • Thamara, Tofeti Lima;Ann, Ki Yong
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.1
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    • pp.56-63
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    • 2020
  • The usage of OPC-free alkali activated ground granulated blast furnace slag(GGBS) mortar has been widely studied on the previous years, due to its advantages on sustainability, durability and workability. This paper brings a new view, aiming to classify the best application in situ for each mortar, according to the type and activator content. By this practical implication, more efficiency is achieved on the construction site and consequently less waste of materials. In order to compare the different activators, the following experiments were performed: analysis of compressive strength at 28 days, setting time measured by needles penetration resistance, analysis of total pore volume performed by MIP and permeability assessment by RCPT test. In general, activated GGBS had acceptable performance in all cases compared to OPC, and remarkable improved durability. Following the experimental results, it was confirmed that each activator and different concentrations impose distinct outcome performance to the mortar which allows the classification. It was observed that the activator Ca(OH)2 is the most versatile among the others, even though it has limited compressive strength, being suitable for laying mortar, coating/plaster, adhesive and grouting mortar. Samples activated with NaOH, in turn, presented in general the most similar results compared to OPC.

Fundamental Properties of MgO Base Ceramic Mortar for Concrete Repair Material (MgO계 세라믹 모르타르를 활용한 콘크리트 보수재료의 기초물성평가)

  • Park, Joon-Woo;Ann, Ki-Yong
    • Journal of the Korea Concrete Institute
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    • v.29 no.4
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    • pp.407-413
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    • 2017
  • The fundamental property of magnesia phosphate cement (MPC) for concrete repair material was investigated in this research. For mechanical properties, setting time, compressive strength and tensile/flexural bond strength were measured, and hydration products were detected by X-ray diffraction. The specimens were manufactured with dead burnt magnesia and potassium dihydrogen phosphate was admixed to activate the hydration of magnesia and a borax was used as a retarder. To observe the pore structure and ionic permeability of MPC mortar, mercury intrusion porosimetry was performed together with rapid chloride penetration test (RCPT). As a result, time to set of Fresh MPC mortar was in range of 16 to 21 min depend on the M/P ratio. Borax helped delaying setting time of MPC to 68 min. The compressive strength of MPC with M/P of 4 was sharply developed to 30 MPa within 12 hours. The compressive strength of MPC mortar was in range of 11.0 to 30.0 MPa depend on the M/P ratio at 12 hours of curing. Both tensile and flexural bond strength of MPC to old substrate (i.e. MPC; New substrate to OPC; Old substrate) were even higher than ordinary Portland cement mortar (i.e. [OPC; New substrate] to [OPC; Old substrate]) does, accounting 19 and 17 MPa, respectively. The total pore volume of MPC mortar was lower than that of OPC mortar. MPC mortar had the entrained air void rather than capillary pore. The RCPT showed that total charge passed of OPC mortar had more than that of MPC mortar, which can be explained by the pore volume and pore distribution.

An Experimental Study on the Resistance of Low-Heat Cement Mortar in Chemical Attack (저발열시멘트 모르터의 호학저항성에 대한 실험적 연구)

  • 문한영;신화철;김성수;강석화
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04a
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    • pp.183-186
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    • 1998
  • This paper deals with 28, 56, 91 days age compressive strength and ratio of weight when OPC and Low-Heat cement mortar immersed in chemical solution. As a result of experiment, the resistance of Low-Heat Cement motar in chemical attack is more effective than that of OPC, because of lower $C_3$A content and Pozzolanic reactions. Especially in long term age compressive strength, Low-Heat cement mortar shows higher strength in all kind of chemical solution compared with compressive strength of OPC motar.

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Improving Quality of Eco-Mortar Incorporating Blast Furnace Slag and Recycled Aggregate Depending on Replacement Gypsum and Cement (고로슬래그 미분말과 순환잔골재를 사용하는 친환경 모르타르에 탈황석고 및 시멘트에 의한 품질향상)

  • Baek, Byung Hoon;Han, Cheon-Goo
    • Journal of the Korea Institute of Building Construction
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    • v.15 no.2
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    • pp.193-199
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    • 2015
  • As a solution of both environmental issue of reducing carbon dioxide emission and sustainable issue of exhausting natural resources, in concrete industry, many research on recycling various by-products or industrial wastes as the concrete materials has been conducted. The aim of this research is feasibility analysis of additional reaction with ordinary Portland cement and flue gas desulfurization gypsum based on the blast furnace slag and recycled fine aggregate based mortar to achieve the normal strength range. Consequently, in the case of mortar replaced 10% FGD and 30% OPC for BS, 80% of plain OPC mortar's compressive strength was achieved. Furthermore, when the water-to-binder ratio is decreased to keep the practically similar level of flow, it is expected to be achieve the equivalent compressive strength to plain OPC mortar.

A Study on the Dry-Shrinkage Properties For Floor Mortar With Crack-Reducing (균열저감형 바닥마감전용 모르터의 건조수축특성 연구)

  • 이종렬;이웅종;채재홍;박경상;김기수
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.175-180
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    • 1999
  • The heating system of korea apartment house is called Ondol. The surface finishing mortar of this floor system typically used the cement based mortar, where the surface finishing mortar easily appears the crack. To order to crack control, the cement that added expansive additive used to reducing dry-shrinkage. For the surface finishing mortar, the types of shrinkage is known as plastic shrinkage, dry-shrinkage and autogenous This experimental study is to investigate the difference on dry-shrinkage of the cement that added expansive additives and OPC. The test method is varied the ration of water/cement (W/C) and the ratio of sand/cement(S/C). For OPC, The increase of the ratio of S/C is reduced dry-shirnkage but for the cement that added expansive additives, the increase of the ratio of S/C is augmented dry-shrinkage For OPC, The increase of the ratio of W/C is augmented dry-shrinkage but for the cement that added expensive, the increased of the ratio of W/C is reduced dry-shrinkage.

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Mechanical Properties of Early Strength Mortar with Ground Granulated Blast Furnace Slag and Expansive Additive (고로슬래그미분말 및 팽창재를 혼입한 조강형 모르타르의 역학적 특성)

  • Koo, Kyung-Mo;Choi, Jae-Won;You, Byeong-Know;Cha, Wan-Ho;Kang, Bong-Hee
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.9 no.2
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    • pp.177-184
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    • 2021
  • In this study, the effects of ground granulated blast furnace slag(GGBFS) and expansive additive(EA) on early strength mortar were examined for the purpose of reducing carbon and improving cement performance. As a result, ealry strength Portland cement(EPC) tended to decrease in flow compared to ordinary Portland cement(OPC), but binder with EPC and GGBFS was possible to obtain higher liquidity than OPC. EPC showed higher compressive strength and shrinkage than OPC. The compressive strength of specimen with EPC and GGBFS was reduced proportionally to the replacement ratio of GGBFS. The replacement ratio of GGBFS above the compressive strength equivalent to OPC was higher under low temperature conditions. The use of GGBFS resulted in high shrinkage compared to OPC, and this characteristic was even greater under low temperature conditions. The shrinkage of specimen with EA was decreased in early ages, but was higher than the OPC in long-term ages.

Strength Properties of Mortar Containg Metakaolin (메타카올린을 혼합한 모르타르의 강도특성)

  • Moon, Dae-Joong;Ju, Jae-Eok;Jo, Jeong-Hyun;Kang, Hyun-Jin;Choi, Yun-Wang
    • Proceedings of the Korea Concrete Institute Conference
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    • 2005.11a
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    • pp.639-642
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    • 2005
  • Main components of metakaolin(MK) were $SiO_2\;and\;Al_2O_3$. and specific surface was 2.2 times larger than that of ordinary portland cement(OPC). MK indicated the fine particle and fiber texture. Flow value of mortar with MK was decreased linearly each $13\%$ as the replacement ratio of MK was increased each $5\%$. Compressive strength of mortar with MK was increased more than that of mortar with OPC by 3days. Compressive strength of mortar with $10\%$ MK was about 83MPa at 28 days. When MK was replaced with $10\%$ of cement volume, flexural strength and modulus of elasticity of mortar was indicated the maximum value at 28 days.

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The Evaluation of Durability Performance in Mortar Curbs Containing Activated Hwangtoh (활성 황토를 혼입한 모르타르 기반 경계석의 내구성능 평가)

  • Kwon, Seung-Jun;Kim, Hyeok-Jung;Yoon, Yong-Sik
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.8 no.4
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    • pp.520-527
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    • 2020
  • Hwangtoh is the rich resource that accounts for about 15.0% of the domestic soil, and can be used as the admixture of concrete with Pozzolan characteristics if activated by rapidly freezing after burning with high temperature. In this study, the mortar curbs containing active hwangtoh were produced, based on the mixture for the mortar curbs sold on the market. The substitution rate of active hwangtoh were considered 10.0% and 25.0%, and the test items were selected to compressive and flexural strength tests, freezing/thawing resistance tests, accelerated carbonation tests, and accelerated chloride diffusion tests. In the results of the mechanical performance, it was showed that the highest strength was evaluated in OPC mixture, and the increase in strength was small by the increase of age, which was believed to be due to the fact that most of the strength in each mixture was created in three days of steam curing. The results of the freezing/thawing tests for 28 aged days showed the reduction rate of compressive strength was 85.0% or higher for all specimen, meeting the criteria presented. The accelerated carbonation tests were carried out on the specimen at 28 days of age, and the results showed that the mortar with active hwangtoh had lower carbonation resistance performance than mortar with OPC. The passed charge of each mixture was assessed in accordance with ASTM C 1202 on 28 and 91 aged days. The OPC mixture had "Low" rate and the mortar with active hwangtoh had "Moderate" rate. So it was thought that the mortar with active hwangtoh had appropriate resistance performance for chloride attack.

Durability Properties of Ultra Rapid Hardening Mortar Produced with Alumina-based Binder for Repairing Sewage Treatment Pipes (하수관거 보수용 알루미나계 결합재 초속경 모르타르의 내구 특성)

  • Eun-Ho, Kim;Byung-Jae, Lee;Sun-Mok, Lee;Yun-Yong, Kim
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.10 no.4
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    • pp.482-488
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    • 2022
  • In this study, the durability of ultra rapid hardening mortar for sewage pipe was evaluated by type of mortar binder. As a result of analyzing the internal structure for each type of mortar, it was confirmed that Al2(OH)3 was generated in the internal structure of the CAC-based mortar, and its corrosion resistance was superior to that of other types of mortar. As a result of the compressive strength test, OPC had the tsmallest strength, followed by CAC100 > CAC100P > CAC80. This trend was similar to the previous study results. Chloride ion penetration resistance and freeze-thaw test showed similar trends. That is, CAC and C12A7 were better than OPC, and CSA was worse than OPC. This is mostly beacuse of cracks caused by expansion of CSA-based mortar. CAC100P mix showed the best chemical resistance. It is thought that this is because the alumina gel formed inside the mortar and the polymer combine to make the internal structure more dense.