경량골재의 함수상태에 따른 가압 전·후 경량골재 콘크리트의 특성에 관한 연구

권대순,김세환,전현규,김상헌,서치호 大韓建築學會 2012 大韓建築學會論文集 Vol.28 No.8

<P> The application of lightweight aggregate can be a solution for improving concrete performance. Its adoption will derive improved functions such as decrease of dead load and the improvement of insulation and sound absorption. But, according to previous studies of lightweight aggregate concrete, the structure of lightweight aggregate is a porous body so that it shows a faster and higher absorption performance than normal aggregate, and thereby it causes hardship for workability, durability, quality control and pumpability. As this study is a fundamental study for activation of lightweight aggregate concrete, the concrete has been manufactured by varying the amount of contained water in lightweight aggregate. Moreover, through concrete pressurization tests, quality of concrete are measured before and after pressurization. And consequently the following conclusions are obtained. As increasing the amount of contained water in lightweight aggregate, values of slump flow and unit weight are increased, values of air content, strength and frost resistance are decreased. As pressurization on lightweight aggregate concrete, values of slump flow and air content are decreased, values of unit weight, strength and frost resistance are increased. </P>

3D 프린팅 격자구조 인공골재를 치환한 경량콘크리트의 압축강도 특성

박광민(Kwang-Min Park),민경성(Kyung-Sung Min),노영숙(Young-Sook Roh) 한국산학기술학회 2022 한국산학기술학회논문지 Vol.23 No.4

경량골재를 혼입한 경량골재 콘크리트는 건축구조물 경량화가 가능하다는 장점으로 지속적으로 수요가 증가하고 있다. 이를 위해 경량골재의 안정적인 공급과 품질 확보 방안이 필요하다. 본 연구는 3D 프린팅으로 경량 고강도의 격자 구조체를 출력하여 경량골재로서의 활용성을 검토하는 것을 목표로 했다. 골재 종류에 따른 콘크리트 밀도 및 압축강도를 평가하기 위하여 일반 부순골재, 바텀애시 및 준설토 기반 인공경량골재, 바텀애시 부산 경량골재 및 3D 프린팅 격자구조 경량골재를 사용하여 4가지의 배합설계를 진행했다. 실험 결과, 일반골재 콘크리트가 밀도 2.2 t/m³, 압축강도 45.9 MPa인 것과 비교하여, 3D 프린팅 격자구조 경량골재를 사용한 콘크리트는 밀도 1.7 t/m³, 압축강도 46.7 MPa이 발현됐다. 결과적으로 동급의 압축강도에서 밀도가 21.7 % 감소하는 효과를 확인했다. 따라서 3D 프린팅 격자구조 경량골재를 경량콘크리트에 사용할 수 있는 것을 시사한다. 향후 3D 프린팅 기반 굵은골재 대량 생산 및 경제성 검토를 실증적 차원에서 분석할 계획이다. The demand for lightweight aggregate concrete is continuously increasing due to its advantage of reducing the building"s weight. Therefore, stable supply and standard quality of lightweight aggregate are necessary. This study examined the applicability of a lightweight aggregate in concrete making by manufacturing a lightweight and high-strength lattice structure out of it by 3D printing. Later, the density and compressive strength of the concretes made of natural crushed, artificial lightweight, bottom ash lightweight, and 3D printed lattice structure lightweight aggregates were measured. This measurement showed that the 3D printed lattice structure lightweight aggregate concrete exhibited a density of 1.7 t/m³ and compressive strength of 46.7 MPa. On the other hand, the natural crushed aggregate concrete had a density of 2.2 t/m³ and compressive strength of 45.9 MPa. Likewise, the density of the concrete decreased by 21.7 % for the same compressive strength while using a 3D printed lattice structure lightweight aggregate instead of the natural crushed aggregate. Therefore, the 3D printed lattice structure lightweight aggregate can be used to make lightweight concrete. The mass production and economic feasibility of the 3D printed lattice structure lightweight aggregate will be studied in the future.

경량골재의 공극구조와 흡수특성에 따른 경량골재콘크리트 특성 평가 연구

박대오(Park Dae-Oh),사순헌(Sa Soon-Heon),김상헌(Kim Sang-Heon),지석원(Ji Suk-Won),최수경(Choi Su-Kyeong),서치호(Seo Chee-Ho) 대한건축학회 2009 大韓建築學會論文集 : 構造系 Vol.25 No.3

Lightweight aggregate mainly consist of multi-crystalline structure and has many internal pores. It may be abnormal water moving in lightweight aggregate on account of the change of external circumstance. The abnormal water moving is influenced by distribution, shape, size and prewetting and each factors considerably control it. Recently, in domestic and foreign construction industry, lightweight aggregate is delivered from factory with controlling lightweight aggregate's water absorption to improve workability. But, unfortunately, there are few studies about workability and mechanical property which is influenced by controlling the percentage of water absorption. In this study, we analyzed the pore system and water absorption characteristic of domestic and foreign lightweight aggregate. And that acquired the experimental data about mechanical properties and frost resistance of lightweight aggregate concrete according to the pore system and water absorption characteristic, makes a good use of lightweight aggregate concrete.

경량골재의 종류에 따른 시멘트 경화체의 강도 특성 평가

편명장 ( Pyeon Myeong-jang ),정수미 ( Jeong Su-mi ),김주성 ( Kim Ju-sung ),김호진 ( Kim Ho-jin ),박선규 ( Park Sun-gyu ) 한국건축시공학회 2022 한국건축시공학회 학술발표대회 논문집 Vol.22 No.1

Lightweight aggregate is a porous material that has a lower density than natural aggregate and is a lightweight construction material. Lightweight Aggregate has a suitable purpose because it is effective in reducing the heavy unit mass in high-rise buildings. However, since lightweight aggregate has weak strength and high water absorption compared to natural aggregate, it is difficult to control the quality of concrete. Although lightweight aggregate has disadvantages such as high water absorption, it is expected that the demand for lightweight aggregate concrete will continue to use in the future because the advantage of being able to reduce the weight of concrete is greater. In this study, we conducted an experimantal study on the compressive strength property of cement matrix according to the type of lightweight aggregate.

Experimental & computational study on fly ash and kaolin based synthetic lightweight aggregate

Süleyman İpek,Kasım Mermerdaş 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.4

The objective of this study is to manufacture environmentally-friendly synthetic lightweight aggregates that may be used in the structural lightweight concrete production. The cold-bonding pelletization process has been used in the agglomeration of the pozzolanic materials to achieve these synthetic lightweight aggregates. In this context, it was aimed to recycle the waste fly ash by employing it in the manufacturing process as the major cementitious component. According to the well-known facts reported in the literature, it is stated that the main disadvantage of the synthetic lightweight aggregate produced by applying the cold-bonding pelletization technique to the pozzolanic materials is that it has a lower strength in comparison with the natural aggregate. Therefore, in this study, the metakaolin made of high purity kaolin and calcined kaolin obtained from impure kaolin have been employed at particular contents in the synthetic lightweight aggregate manufacturing as a cementitious material to enhance the particle crushing strength. Additionally, to propose a curing condition for practical attempts, different curing conditions were designated and their influences on the characteristics of the synthetic lightweight aggregates were investigated. Three substantial features of the aggregates, specific gravity, water absorption capacity, and particle crushing strength, were measured at the end of 28-day adopted curing conditions. Observed that the incorporation of thermally treated kaolin significantly influenced the crushing strength and water absorption of the aggregates. The statistical evaluation indicated that the investigated properties of the synthetic lightweight aggregate were affected by the thermally treated kaolin content more than the kaoline type and curing regime. Utilizing the thermally treated kaolin in the synthetic aggregate manufacturing lead to a more than 40% increase in the crushing strength of the pellets in all curing regimes. Moreover, two numerical formulations having high estimation capacity have been developed to predict the crushing strength of such types of aggregates by using softcomputing techniques: gene expression programming and artificial neural networks. The R-squared values, indicating the estimation performance of the models, of approximately 0.97 and 0.98 were achieved for the numerical formulations generated by using gene expression programming and artificial neural networks techniques, respectively.

인공 경량골재로 치환된 플라스틱 골재 종류에 따른 시멘트 복합체의 역학적 성질에 관한 연구

천현욱 ( Cheon Hyeon-uk ),( Ruziev Jamshid ),이헌석 ( Lee Heon-seok ),강용학 ( Kang Yong-hak ),김우석 ( Kim Woo-suk ) 한국복합신소재구조학회 2020 복합신소재구조학회논문집 Vol.11 No.6

최근에는 대규모 건축 및 토목 구조물로 인해 건설 부재의 고강도 및 경량화에 대한 요구가 높아지고 있다. 기존의 경량 시멘트 복합체의 경우 단위 체적 중량이 낮아질 수 있으나 강도 저하 문제가 발생한다. 일반적으로 경량화를 위해서는 시멘트 복합체를 배합할 때 일반 경량골재와 고무경량골재, 플라스틱 펠릿 등 다양한 인공 경량골재를 이용한 시멘트 복합체를 혼합하여 경량화를 확보할 수 있다. 이 중 시멘트 복합체의 인공 경량골재로 플라스틱을 사용하면 상대적으로 골재 자체의 강도를 확보할 수 있지만 재료의 표면 특성으로 인해 시멘트 페이스트에 부착하는 데 불리하고 골재로서의 사용이 불리하다. 이에 본 연구에서는 골재로 가장 적합한 플라스틱의 유형을 선택하기 위해 다양한 유형의 플라스틱 시멘트 화합물을 변수로 하여 실험을 진행하였고 실험 결과 플라스틱의 비중이나 표면 재질에 의해서 시멘트 복합체의 물리적 성질이 변화하는 것을 확인할 수 있었다. Recently, as the construction of civil structures has increased, so has the demand for lightweight, high-strength structures. In the case of conventional lightweight cement composites, the unit volume weight can be lowered, but this leads to reduced strength. Generally, a lightweight composite can be created by mixing in a lightweight aggregate when combining cement composites. Various cement complexes use artificial lightweight aggregates, such as rubber aggregates and plastic pellets; of these, plastic sticks can secure the strength of the relatively high-strength aggregate, but the surface properties of the material make it disadvantageous to attach to the cement paste. In this study, cement composites using various types of plastic were produced and tested to determine the types of plastic most suitable as aggregates. The results confirm that the physical performance of the cement composites changes according to the specific gravity and/or surface of each plastic aggregate.

Effects of fiber types and volume fraction on strength of lightweight concrete containing expanded clay

Rustamov, Sardorbek,Kim, Sangwoo,Kwon, Minho,Kim, Jinsup Techno-Press 2021 Advances in concrete construction Vol.12 No.1

The main goal of this research is to investigate the effect of polyvinyl alcohol (PVA) fiber and steel fiber on lightweight concrete, in which lightweight aggregate was used as the coarse aggregate. The lightweight aggregate was a kind of expanded clay aggregate made using bottom ash from a thermal power plant located in South Korea. Three types of specimens, lightweight concrete without fibers (LC), lightweight concrete containing polyvinyl alcohol fiber (LCPVA), and lightweight concrete with steel fiber (LCSF) were cast with two different fiber-volume fractions (0.5 and 1.0%). Tests of their compressive strength and splitting tensile strength were performed to evaluate the effectiveness of fiber type and fiber-volume fraction in lightweight concrete at 28 days and after 90 days. The results indicated that using fibers in lightweight concrete improved both the compressive strength and splitting tensile strength. The addition of fibers in lightweight concrete showed a positive effect, and the effectiveness of PVA fiber at 28 and 90 days (regarding compressive strength and splitting tensile strength) was more pronounced than steel fiber. Overall, it can be concluded that the 1.0% PVA fiber-volume fraction showed good performance in the lightweight concrete.

경량골재의 함수상태에 따른 가압 전․후 경량골재 콘크리트의 특성에 관한 연구

권대순(Kwon Dae-Soon),김세환(Kim Se-Hwan),전현규(Jeon Hyun-Kyu),김상헌(Kim Sang-Heon),서치호(Seo Chee-Ho) 대한건축학회 2012 大韓建築學會論文集 : 構造系 Vol.28 No.8

The application of lightweight aggregate can be a solution for improving concrete performance. Its adoption will derive improved functions such as decrease of dead load and the improvement of insulation and sound absorption. But, according to previous studies of lightweight aggregate concrete, the structure of lightweight aggregate is a porous body so that it shows a faster and higher absorption performance than normal aggregate, and thereby it causes hardship for workability, durability, quality control and pumpability. As this study is a fundamental study for activation of lightweight aggregate concrete, the concrete has been manufactured by varying the amount of contained water in lightweight aggregate. Moreover, through concrete pressurization tests, quality of concrete are measured before and after pressurization. And consequently the following conclusions are obtained. As increasing the amount of contained water in lightweight aggregate, values of slump flow and unit weight are increased, values of air content, strength and frost resistance are decreased. As pressurization on lightweight aggregate concrete, values of slump flow and air content are decreased, values of unit weight, strength and frost resistance are increased.

폐유리분말 코팅에 따른 저흡수 경량골재의 흡수특성 및 미세구조

이한백(Lee Han-Baek),서치호(Seo Chee-Ho),김상헌(Kim Sang-Heon) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.9

As quantity of waste glass powder on the surface of lightweight aggregates increased, absolute dry density increased and water absorption reduced. This reasons are because the amount of coating increases, open pores on the surface of lightweight aggregates become more likely to be closed pores as well as increase to waste glass coating layer relatively reduced pore volume within lightweight aggregates. As sintering temperature of lightweight aggregates increased, absolute dry density reduced and water absorption increased. This reason such as above is because increase of sintering temperature invigorated CaCO₃ foaming agent included inner layer. In case of sintering less than 800℃ most lightweight aggregates, water absorption had been shown below 4% at 30wt% of waste glass powder and below 3% at 50wt% of waste glass powder. Thus coating of waste glass powder on the surface of lightweight aggregates proved effective in controlling water absorption. In conclusion, we manufactured lightweight aggregate for energy saving, main ingredient is used waste glass of a low softening point(about 700℃) and bottom ash containing unburned fixed carbon and volatile matter about 20~25%, which was possible to sinter by decreasing the sintering temperature about 20~30% than existing products. Manufacturing technology of lightweight aggregate has been secured similar water absorption level of natural aggregate, less than 3%, as sintering after coating the external surface with waste glass powder.

Composition design of the optimum bloating activation condition for artificial lightweight aggregate using coal ash

Young Min Wie,Ki Gang Lee 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.2

This study analyzed the characteristics of reject ash and bottom ash as raw materials for lightweight aggregate and suggested an optimum mixing ratio for recycling coal ash. The physical and chemical properties of reject ash and bottom ash for the manufacture of lightweight aggregate were examined. Rapid sintering tests were conducted to find an optimum mixing ratio to produce lightweight aggregates, density was measured, and cross-sections were observed. XRD-CT analysis was performed to observe the crystal phase distribution of the lightweight aggregate. Aggregate was sintered in a pilot rotary kiln using the optimum mixing ratio obtained through the experiment and its properties were measured. Coal ash has been found to be an unsuitable raw material for producing lightweight aggregate. By adding 3 wt% of carbon and 5 wt% of Fe2O3 to the bottom ash-dredged soil mixture, it was possible to prevent the adhesion of aggregate at the bloating activation temperature by lowering the firing temperature. Aggregates manufactured in the pilot rotary kiln meet the relevant standards and exhibit properties similar to those of commercial aggregates.