• 한국농공학회논문집
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• 제55권3호
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• pp.113-121
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• 2013

Recently, it has been studied for the application of nano-materials in the concrete. Applied a small amount of nano-materials can achieve the goal of high strength, high performance and high durability. The small addition of nano clay improves strength, thermal stability, and durability of concrete because of the excellent dispersion. The present study has investigated the effectiveness, when varying with the contents of nano clay, influencing the pull-out behavior of macro synthetic fibers in nano materials cement mortar. Pullout tests conducted in accordance with the Japan Concrete Institute (JCI) SF-8 standard for fiber-reinforced concrete test methods were used to evaluate the pullout performance of the different nano clay. Nano clay was added to the 0, 1, 2, 3, 4 and 5 % of cement weight. The experimental results demonstrated that the addition of nano clay led to improve the pull-out properties as of the load-displacement curve in the precracked and debonded zone. Also, the compressive strength, flexural strength and pullout performance and of Mix No. 1 and No. 2 increased up to the point when nano clay used increased by 2 and 3 % contents, respectively, but decreased when the exceeded 3 and 4 %, respectively. It was proved by verifying increase of the scratching phenomenon in macro synthetic fiber surface through the microstructure analysis on the surface of macro synthetic fiber.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2023년도 봄 학술논문 발표대회
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• pp.151-152
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• 2023

This study investigates the effect of nano-silica and nano-calcite on the hydration properties and mechanical performance of limestone calcined clay cement (LC³) paste. The pastes were synthesized by replacing limestone with nano-silica and nano-calcite in order to enhance the mechanical properties in both early and late stages of hydration. The nano-calcite enhanced the strength of LC³ pastes at 1 day of hydration, however, the strength decreased compared to the ordinary LC³ pastes afterwards due to excessive amount of carboaluminate produced in the pastes. On the other hand, nano-silica improved the mechanical properties of LC³ pastes at all ages of hydration. This is mainly due to the nucleation effect and pozzolanic reaction of nano-silica, affecting the early age and late ages of hydration, respectively. The nucleation effect of both nanomaterials were confirmed by the analysis of hydration heat, supporting the enhanced early age strength of nanomaterial incorporated LC³ pastes. Furthermore, the dense matrix was shown in the pore size distribution, and the increased C-S-H due to the pozzolanic reaction evidence the improved compressive and splitting tensile strength of nano-silica incorporated LC³ pastes.

• 한국세라믹학회지
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• 제48권6호
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• pp.510-515
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• 2011

In this study, as a material used to replace silica fumes for high strength concrete, nano-silica compound with organic functional group for dispersion and with inorganic silica group that can cause a pozzolan reaction is synthesized, These nano silica compound is divided into IC, which is nano size $SiO_2$ with irregularly combined hydroxyl group and carboxyl group, and RC, which is nano size $SiO_2$ with regularly combined hydroxyl group and carboxyl group. The effects of these nano silica compound on the hydration of cement are reviewed. As a result, all of synthesized nano-silica compounds have excellent dispersion on the cement flow, we think that dispersion property is the effect of air entraining by synthesized nano-silica compounds. The result of the microstructure observation showed that the particle size of the synthesized nano-silica is smaller than silica fume and spread evenly among the cement particles. In initial The phenomenon of strength decreasing occurred due to delayed hydration reaction by the synthesized nano-silica with carboxyl(-COOH) and hydroxyl(-OH) functional group.

• Structural Monitoring and Maintenance
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• 제11권2호
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• pp.71-86
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• 2024

In this study, to reduce the amount of cement consumed in the production of cementitious composites, the effects of partial replacement of cement weight with nano-silica, silica fume, and copper slag on the mechanical properties of polypropylene fiber-reinforced cementitious composites are investigated. For this purpose, the effect of replacing cement weight by each of the aforementioned materials individually and in combination is studied. A total of 34 mix designs were prepared, and their compressive, tensile, and flexural strengths were obtained for each mix. Among the mix designs with one cement replacement material, the highest strength is related to the sample containing 2.5% nano-silica. In this mix design, the compressive, tensile, and flexural strengths improve by about 33%, 13%, and 15%, respectively, compared to the control sample. In the ones with two cement replacement materials, the highest strengths are related to the mix made with 10% silica fume along with 2% nano-silica. In this mix design, compressive, tensile, and flexural strengths increase by about 42%, 18%, and 20% compared to the control sample, respectively. Furthermore, in the mixtures containing three cement substitutes, the final optimal mix design for all three strengths has 15% silica fume, 10% copper slag, and 2% nano-silica. This mix design improves the compressive, tensile, and flexural strengths by about 57%, 23%, and 26%, respectively, compared to the control sample. Finally, two relationships have been presented that can be used to predict the values of tensile and flexural strengths of cementitious composites with very good accuracy only by determining the compressive strength of the composites.

• 한국세라믹학회지
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• 제50권4호
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• pp.275-279
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• 2013

The purpose of this study was to prepare calcium phosphate cement [CPC] for use in artificial bone. Nano-crystalline calcium phosphate [CaP] was precipitated at $37^{\circ}C$ using highly active $Ca(OH)_2$ in DI water and an aqueous solution of $H_3PO_4$. From the XRD measurements, the nano-CaP powder was close to apatitic TCP phase and the powders fired at $800^{\circ}C$ showed a critical ${\beta}$-TCP phase. A mixture of one mole $CaCO_3$ and two moles di-calcium phosphate was calcined at $1100^{\circ}C$ to make a reference ${\beta}$-TCP material. The nano-CaP powders were added to the normal ${\beta}$-TCP matrix and fired at $900^{\circ}C$ to make a ${\beta}$-TCP block. The sintered block showed improved mechanical strength, which was caused by the solid state interaction between nano-CaP and normal ${\beta}$-TCP.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2005년도 봄학술 발표회 논문집(II)
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• pp.13-16
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• 2005

Nanoscale materials are of great interest due to their unique optical, electrical and magnetic properties. Due to the recent amazing achievements in nano technology, new materials were developed. But these nano technology is not apply to the construction part in spite of exellent properties of nano size material. The purpose of this study is to apply to nano technology into building materials. To develop the high performance concrete, nano cement particles is prepared by mechanical method. In the results of this study, the nano silica powder increase effect according to increase of the mixing amount, appeared that compressive strength increased but is limit in increment. For the production of high-strength concrete, nano silica powder was suitable the binder ratio from 20$\%$. And, the compressive strength of concrete are especially dependent on the curing temperature.

• Advances in concrete construction
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• 제17권3호
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• pp.135-150
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• 2024

Nano-silica's growing use in construction, known for enhancing strength and durability by reducing porosity, drives this research's significance, especially considering Ecuador's reliance on cement in construction. A comprehensive comparative study on mortars made with General Use cement and aggregates from Pifo and San Antonio quarries has been studied. It explores the impact of incorporating nano-silica in varying proportions (0.75%, 1.00%, 1.25%) on mortar properties, contrasting them with conventional and prefabricated mortars. laboratory Testing is conducted according to standards to assess both fresh and hardened state properties, and microscopic analysis reveals the optimal nano-silica proportion's effects on mortar characteristics. Results shows that Incorporating 0.75% nano-silica resulted in a 61% increase in compressive strength at 7 days and. For a nanosilica content of 1.25%, a 14% increase in compressive strength was observed at 28 days in relation to the conventional mortar and the permeability of the mortar decreased by 30% when adding 0.75% nanosilica. It discusses economic viability and provides insights through SEM and EDS analyses. Overall, it underscores nano-silica's potential to enhance mortar properties and its relevance in creating more efficient and durable construction materials.

• 한국건설순환자원학회논문집
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• 제2권4호
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• pp.297-306
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• 2014

Recently nano-materials are gaining more importance in the construction industry due to its enhanced energy efficiency, durability, economy, and sustainability. Nano-silica addition to cement based materials can control the degradation of the fundamental calcium-silicate-hydrate reaction of concrete caused by calcium leaching in water as well as block water penetration and therefore lead to improvements in durability. In this paper, the influence of synthesized nano silica from locally available rice husk on the mechanical properties and corrosion resistant properties of OPC (Ordinary Portland Cement) has been studied by conducting various experimental investigations. Micro structural properties have been assessed by conducting Scanning Electron Microscopy, Thermo gravimetry and Differential Thermal Analysis, X-Ray Diffraction analysis, and FTIR studies. The experimental results revealed that NS reacted with calcium hydroxide crystals in the cement paste and produces Calcium Silicate Hydrate gel which enhanced the strength and acts as a filler which filled the nano pores present in concrete. Hence the strength and corrosion resistant properties were enhanced than the control.

• 한국산학기술학회논문지
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• 제12권3호
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• pp.1452-1457
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• 2011

실리카흄과 이산화티타늄을 건식 및 습식방식에 의해 나노화하여 시멘트 모르타르의 강도특성실험을 수행하였다. 실험변수는 건식 및 습식 방식으로 제조된 혼화재를 각각 5,10,15,20%의 첨가율로 하였다. 그 결과 실리카흄과 이산화티타늄을 사용했을 때의 시멘트 모르타르 강도 특성이 유사하게 나타났으며 건식과 습식 혼화재의 비교에서는 습식 혼화재를 사용했을 때가 더 큰 강도 특성을 보였다.

• 한국건축시공학회지
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• 제10권6호
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• pp.61-66
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• 2010

현재 지구촌 온난화에 의하여 환경이 열악해지고 있으며 그에 따라 건설분야에도 시멘트 제조에 따른 $CO_2$ 발생 저감하기 위한 노력을 하고 있다. 이에 시멘트 대체할 재료가 필요하다. 본 연구에서는 기존 비소성 시멘트의 문제점으로 지적 되는 경제성 및 초기강도 확보를 위해 산업부산물인 고로슬래그를 대상으로 연구를 진행하였으며 고가의 알칼리 자극제량을 최소화함으로서 실용화 가능한 비소성 시멘트 기술을 진행하고자 한다. 그리고 NT를 사용하여 분말도를 최대화 하여 고로슬래그의 초기강도를 개선시켰다. 본 연구는 알칼리 자극제를 사용한 나로슬래그를 치환한 비소성시멘트를 기초로 하고 있으며, 현장에서 사용가능한 비소성시멘트의 기초적 물성 및 품질을 조사하였다. 여러 자극제가 슬래그 중량의 10%로 사용되었으며 휨강도, 압축강도, 응결시간, 단열온도, 상승열등을 비교 분석하였으며 그 기초적 자료를 제시하는데 목적이 있다.