• Title/Summary/Keyword: Aggregate temperature

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Effects of Temperature and Binder Viscosity on Consistency of Lightweight Polyester Mortars (온도와 결합재의 점도가 경량 폴리에스터 모르터의 컨시스턴시에 미치는 영향)

  • ;Ohama Yoshihiko;Demura Katsunori
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.04b
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    • pp.713-718
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    • 1998
  • This paper deals with the consistency of fresh lightweight polyester mortars as high-performance or multifunctional building materials. Fresh lightweight polyester mortars using an unsaturated polyester resin, lightweight fillers and aggregate are mixed with various mix proportions, and tested for slump-flow and slump as a measure of consistency. At 10, 20 and 3$0^{\circ}C$, the influences of mix proportioning factors on the slump-flow and slump of the lightweight polyester mortars are examined, and the empirical equations for the slump predictions are successfully proposed.

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Experiments on Thermal Conductivity of Concrete (콘크리트의 열전도율에 관한 실험적 연구)

  • 김진근;전상은;양은익;김국한;조명석;방기성
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10b
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    • pp.946-951
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    • 1998
  • In order to calculate the thermal stresses of massive concrete structures in non-steady state conditions the thermal properties of the materials have to be well known. Structural materials such as concrete, rock and soil are heterogeneous, damp and porous so that measurements of their thermal properties by conventional methods would result in large errors. In this study, thermal conductivity was measured by the device, QTM-D3 which is usually used in Japan. Variables are chosen as age, water content, temperature, aggregate content, S/A ratio and type of cementitious materials. Finally a model for thermal conductivity was proposed.

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Effect of EAF dust on the formation of ultra lightweight aggregates by using bottom ash and dredged soil from coal power plant (인공경량골재의 EAF dust 첨가에 따른 초경량화에 관한 연구)

  • Choi, Yun-Jae;Kim, Yoo-Taek
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.21 no.3
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    • pp.129-135
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    • 2011
  • EAF dust from steel industry used as primary materials for the production of lightweight aggregates. Fe compounds in EAF dust plays an important role in the bloating reaction. This study was conducted to evaluate the feasibility of using bottom ash and dredged soil from coal power plant and EAF dust. The effect of different raw material compositions and sintering temperatures on the lightweight aggregate properties were evaluated. The characteristic of thermal bloating of bottom ash and dredged soil were mainly influenced by ferrous materials. The specific gravity of aggregate was decreased with the addition of EAF dust and kerosene was reduced sintering temperature on the bloating formation. Lightweight aggregate containing 10% EAF dust having apparent density under 1.0 g/$cm^3$ were produced at $1150{\sim}1200^{\circ}C$.

Development of Concrete Method for Roof Planting (건물옥상 식재용 콘크리트공법의 개발)

  • 이상태;김진선;황정하;한천구
    • Journal of the Korean Institute of Landscape Architecture
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    • v.28 no.5
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    • pp.48-57
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    • 2000
  • This paper is dealing with the fundamental properties of planting concrete, replacing the existing cover concrete on the roof of a building. This study is to find out the physical characteristics of the planting concrete and rearing characteristics of the grass throughout the modeling experimental materials. As the results of the experiment, the physical properties of planting concrete show the following results; when the paste to aggregate ratio is 0.2~ 0.4, voids volume : 30~17%, unit weight: 1,710~2,010kg/m3, compressive strength : 45~145kgf/$\textrm{cm}^2$, its pH is more than 11, but is reduced to the proper degree for planting after being neutralized. Kentucky bluegrass covered with planting concrete is grown well. The planting concrete used with blast furnace slag cement shows a better properties at the height, the width and the covering rate by 1.1cm, 0.5mm and 7%, respectively, than those used with ordinary portland cement. Also, the less the paste to aggregate ratio is, the better the plant grows. The orders of the effects of temperature control are as follows; the system of planting concrete with grass>the system of planting concrete without grass>the system of mixed soil>the existed roof system. In case, the planting concrete is placed to the roofs of buildings instead of normal concrete slab, and a number of favorable effect can be expected such as the improvement os environmental factors, the reduction of construction cost, the saving of energy and the reduction of environment load. The future research on the change of a variety of the aggregate conditions and the application of the practical structures should be made, and also the research of the endurance also be performed.

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Separation of Radionuclide from Dismantled Concrete Waste (해체 콘크리트 폐기물로부터 방사성핵종 분리)

  • Min, Byung-Youn;Park, Jung-Woo;Choi, Wang-Kyu;Lee, Kune-Woo
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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    • v.7 no.2
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    • pp.79-86
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    • 2009
  • Concrete materials in nuclear facilities may become contaminated or activated by various radionuclides through different mechanism. Decommissioning and dismantling of these facilities produce considerable quantities such as concrete structure, rubble. In this paper, the characteristics distribution of the radionuclide have been investigated for the effects of the heating and grinding test for aggregate size such as gravel, sand and paste from decommissioning of the TRIGA MARK II research reactor and uranium conversion plant. The experimental results showed that most of the radionuclide could be removed from the gravel, sand aggregate and concentrated into a paste. Especially, we found that the heating temperature played an important role in separating the radionuclide from the concrete waste. Contamination of concrete is mainly concentrated in the porous paste and not in the dense aggregate such as the gravel and sand. The volume reduction rate could be achieved about 80% of activated concrete waste and about 75% of dismantled concrete waste generated from UCP.

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Effect of pumice powder and artificial lightweight fine aggregate on self-compacting mortar

  • Etli, Serkan;Cemalgil, Selim;Onat, Onur
    • Computers and Concrete
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    • v.27 no.3
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    • pp.241-252
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    • 2021
  • An experimental program was conducted to investigate the fresh properties, mechanical properties and durability characteristics of the self-compacting mortars (SCM) produced with pumice powder and Artificial Lightweight Fine Aggregate (aLWFA). aLWFA was produced by using fly ash. A total of 16 different mixtures were designed with a constant water-binder ratio of 0.37, in which natural sands were partially replaced with aLWFA and pumice powder at different volume fractions of 5%, 10% and 15%. The artificial lightweight aggregates used in this study were manufactured through cold bonding pelletisation of 90% of class-F fly ash and 10% of Portland cement in a tilted pan with an ambient temperature and moisture content. Flowability tests were conducted on the fresh mortar mixtures beforehand, to determine the self-compacting characteristics on the basis of EFNARC. To determine the conformity of the fresh mortar characteristics with the standards, mini-slump and mini-V-funnel tests were carried out. Hardened state tests were conducted after 7, 28 and 56 days to determine the flexural strength and axial compressive strength respectively. Durability, sorptivity, permeability and density tests were conducted at the end of 28 days of curing time. The test results showed that the pumice powder replacement improved both the fresh state and the hardened state characteristics of the mortar and the optimum mixture ratio was determined as 15%, considering other studies in the literature. In the aLWFA mixtures used, the mechanical and durability characteristics of the modified compositions were very close to the control mixture. It is concluded in this study that mixtures with pumice powder replacement eliminated the negative effects of the aLWFA in the mortars and made a positive contribution.

Effect of polypropylene and glass fiber on properties of lightweight concrete exposed to high temperature

  • Abdulnour Ali Jazem Ghanim;Mohamed Amin;Abdullah M. Zeyad;Bassam A. Tayeh;Ibrahim Saad Agwa;Yara Elsakhawy
    • Advances in concrete construction
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    • v.15 no.3
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    • pp.179-190
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    • 2023
  • The effect of glass fibres (GF) and polypropylene fibres (PPF) on the fresh properties and mechanical properties of lightweight concrete (LWC) exposed to high temperatures is investigated in this study. In this study, fifteen LWC mixtures were carried out in three different groups reinforced with PPF or GF fibers by 0%, 0.2%, and 0.4% by volume of concrete. The first group included aluminum powder (AP) as an air agent at 0.03% with the normal weight coarse aggregate (NWCA) by 100% of the weight of coarse aggregate. In the second group, 33% of the NWCA weight was replaced by lightweight coarse aggregate (LWCA). In the third group, 67% of the NWCA weight was replaced by LWCA. The slump, unit weight, Compressive strength (CS), tensile strength (TS), and flexural strength (FS) were examined. For two hours, the CS and FS were subjected to elevated temperatures of 200℃, 400℃, and 600℃, in addition to microstructure analysis of concrete. In comparison to the reference mixture, the fresh properties and bulk density of LWC decreased with the use of the air agent or the replacement of 67% of the NWCA with LWCA. As a result of the fiber addition, both the slump test and the bulk density decreased. The addition of fibers increased the CS; the highest CS was 38.5 MPa when 0.4% GF was added, compared to 28.9 MPa for the reference mixture at the test age of 28 days. In addition, flexural and TS increased by 53% and 38%, respectively, for 0.4% GF mixes. As well as, adding 0.4% GF to LWC maintained a higher CS than other mixtures.

Joint Stiffness Evaluation in Jointed Plain Concrete Pavement (줄눈 콘크리트 포장의 줄눈강성 산정 연구)

  • Chon, Beom Jun;Lee, Seung Woo;Kwon, Soon-Min;Kim, Seong-Min
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.29 no.1D
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    • pp.49-54
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    • 2009
  • The excellent load transfer at transverse joints ensures the high performance of jointed plane concrete pavements(JPCP). Load transfer efficiency(LTE) is affected by dowel-bars, aggregate interlock and types of underlying layers, and these factors have to be modelled adequately for a reasonable analysis of JPCP. Generally, the joint stiffness has been represented by a spring model for the shear transfer by aggregate interlock or dowels. However dowel-bars, aggregate interlock and types of underlying layers have not been considered together in the design of joints. In this study, the joint stiffness that considered those factors was presented by comparing LTE obtained using FWD(Falling Weight Deflectometer) with theoretical results obtained using the finite element analysis. In addition, the effects of temperature and concrete age, on the joint stiffness were investigated.

Consideration on the Application of Low-Heat Concrete with Ferronickel Slag Aggregate to LNG Storage Tank (페로니켈슬래그 골재를 활용한 저발열 콘크리트의 LNG 저장탱크 적용성 검토)

  • Sang Hyeon Cheong;Sukhoon Pyo;Hyeong-Ki Kim
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.12 no.1
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    • pp.17-24
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    • 2024
  • The characteristics of low-heat concrete, mixed with ground blast furnace slag and ferronickel slag aggregate, were analyzed. Moreover, the applicability of this concrete for mass concrete in LNG storage tanks was examined. Initially, the study investigated the characteristics of fresh and hardened concrete. Subsequently, the temperature rising curve was obtained. Utilizing the obtained parameters from the curves, a series of thermal stress analyses for the LNG storage tank were conducted to assess the risk of cracking. The results confirmed that concrete mixtures incorporating ground blast furnace slag and ferronickel slag aggregate not only exhibited sufficient workability but also achieved a compressive strength of approximately 40 MPa within 28 days. Furthermore, the concrete demonstrated a lower terminal heat rise and a faster heat generation rate compared to low-heat Portland cement concrete. An analysis of thermal stress in various sections of the LNG tank validated a low risk of cracking.

Volume Change Caused from the Moisture Change in the Limestone Material Pressured under High Temperature (고온을 받은 석회암 골재의 습도경시변화에 따른 체적거동)

  • Feng, Hai-Dong;Son, Ho-Jung;Heo, Young-Sun;Han, Min-Cheol;Yang, Seong-Hwan;Han, Cheon-Goo
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.11a
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    • pp.111-113
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    • 2011
  • This study investigated about how much the limestone's volume was changed as time passed while maintaining a certain level of moisture condition in the limestone material for concrete under high temperature. The result is summarized as follows: It was appeared that the limestone material under high temperature emitted some CO2 resulting from the decarboxylation, so that as the heating temperature was increased, the limestone's length change rate was decreased. In the leave time change after heating the stone, the both conditions of 50% and 100% made the limestone create Ca(OH)2 using some H2O. So it was appeared that as time passed, the limestone's length change rate first increased because of its volume expansion, but the rate was reduced after the limestone material was crumbled.

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