The Experts below are selected from a list of 2454 Experts worldwide ranked by ideXlab platform
Eric Garciadiaz - One of the best experts on this subject based on the ideXlab platform.
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use of raw rice husk as natural aggregate in a lightweight Insulating Concrete an innovative application
Construction and Building Materials, 2014Co-Authors: Morgan Chabannes, Laurent Clerc, Jean-charles Bénézet, Eric GarciadiazAbstract:Abstract As the building sector presents major impacts on the natural environment, the development of eco-friendly Concrete materials using plant aggregates has emerged as a high priority. This kind of Concrete allows moving towards a low carbon material with good thermo-physical properties. This is the case of hemp Concrete made out of hemp hurd mixed with a lime-based binder. Hemp Concrete is aimed at replacing usual systems based on Concrete blocks and mineral wool. In this way, it can qualify as a multifunctional material which takes a clear position regarding the energy efficiency and the optimization of building envelopes. This study deals with the development of an innovative Insulating Concrete having the same application than hemp Concrete one but using rice husks. Having examined physical and structural characteristics of plant aggregates, specimens made out of whole rice husks and a lime-based binder were manufactured by mixing and mechanical tamping. Both thermal and mechanical properties of the final Concrete materials were studied in comparison to hemp Concrete designed with the same process. The effects of an outdoor exposure of the specimens on the mechanical strength are discussed and the binding matrix mineral phases considered. It is established that for a same binder on aggregates mass ratio, the target dry density of rice husk Concrete is necessarily higher than those of hemp Concrete due to the different physical and morphological properties of rice husks. Thermal measurements show that rice husk Concrete can compete with hemp Concrete in terms of thermal insulation with a dry thermal conductivity ranging from about 0.10 W m−1 K−1 to 0.14 W m−1 K−1 depending on the mix proportioning. Compression test results on a defined mixture intended to be used as a filling material in a wall timber frame highlight lower mechanical performances for rice husk Concrete with an average compressive strength of 0.33 ± 0.03 MPa at 60 days compared to 0.48 ± 0.02 MPa for hemp Concrete.
Sang-yeop Chung - One of the best experts on this subject based on the ideXlab platform.
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The Effects of Anisotropic Insulations with Different Spatial Distributions on Material Properties of Mortar Specimens
International Journal of Concrete Structures and Materials, 2017Co-Authors: Sang-yeop Chung, Mohamed Abd Elrahman, Dietmar StephanAbstract:Insulating Concrete is a material designed to reduce heat conduction with pores/insulations, and these pores strongly affect the material characteristics. In general, the insulation effect is directly proportion to the pore volume, while the material strength decreases as the porosity increases. To overcome this contrary, anisotropic insulations with different spatial distributions are proposed and investigated in this study. A set of mortar specimens with different arrangements of coin-shaped insulations are produced to examine the anisotropic insulation effect on the material characteristics. In addition, different types of insulation materials and their effect on the materials are also investigated here. X-ray computed tomography images and probabilistic description methods are used to confirm the arrangement of the insulations. The thermal and mechanical responses for different directions are investigated using both experimental and numerical methods. From the results, it is demonstrated that the use of anisotropic insulations for a specific direction can enhance the insulation efficiently as well as minimizing the loss of compressive strength.
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Evaluation of effect of glass beads on thermal conductivity of Insulating Concrete using micro CT images and probability functions
Cement and Concrete Composites, 2016Co-Authors: Sang-yeop Chung, Tong-seok Han, Yun Kim, Jang Ho Jay Kim, Kwang Soo Youm, Jae Hong LimAbstract:Abstract Insulating Concrete is a type of Concrete that is designed to reduce thermal conductivity. Insulating Concrete contains numerous voids that play an important role in reducing heat conduction. Therefore, appropriate nondestructive methods are required to examine the spatial distribution of voids and constituents in a Concrete specimen. In this study, an Insulating Concrete specimen containing hollow glass beads to increase the Insulating effect is adopted. Then, micro computed tomography (CT) is used to investigate the spatial distribution of the voids in this specimen. By using a micro CT device, a series of cross-sectional images of the specimen at micrometer-order pixel size are generated by X-rays. To quantitatively describe the spatial distribution of voids in the specimen, probability functions such as two-point correlation, lineal-path, and two-point cluster functions are adopted. In addition, the thermal conductivity of the specimen is evaluated using finite element simulation. The results clarify the Insulating effect of glass beads on the Concrete specimen and reveal a strong relationship between the probabilistic characteristics of the void distribution and the material responses of Insulating Concrete.
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Investigation of the effects of anisotropic pores on material properties of Insulating Concrete using computed tomography and probabilistic methods
Energy and Buildings, 2016Co-Authors: Sang-yeop Chung, Mohamed Abd Elrahman, Dietmar StephanAbstract:Abstract Concrete is a random heterogeneous materials and its properties are affected by the spatial distribution of its constituents. In particular, Insulating Concrete, a material designed for reducing heat conduction, contains numerous voids within the material, and these voids strongly affect the physical properties of the material, such as thermal conductivity and strength. The thermal insulation property of the material is enhanced as the void ratio increases, while the strength of the material decreases as void ratio increases. In this study, the effect of anisotropic pores on the material properties of Insulating Concrete is investigated to overcome this contradiction. A Concrete specimen with anisotropic artificial pores is utilized in order to examine the effect of anisotropic pores on the material properties. The spatial distribution of pores within the specimen is visualized using X-ray tomography (CT) and quantitatively characterized using probabilistic description methods. The thermal and mechanical properties of the specimens are also examined by means of experiments and numerical simulations. The results show that an appropriate arrangement of anisotropic pores for a specific direction can be utilized for the reduction of thermal conductivity by minimizing the loss of material strength, and it can be a promising approach for developing more advanced Insulating material.
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Spatial Distribution of Voids in Insulating Concrete Analyzed by Micro-CT Images and Probability Functions
Advances in Materials Science and Engineering, 2015Co-Authors: Sang-yeop ChungAbstract:Insulating Concrete is a multiphase material designed for reduced thermal conductivity, and the void distribution in Concrete strongly affects its physical properties such as mechanical response and heat conduction. Therefore, it is essential to develop a method for identifying the spatial distribution of voids. To examine the voids of Insulating Concrete specimens, micro-CT (computed tomography) images can be effectively used. The micro-CT images are binarized to visualize the void distribution and stacked to generate 3D specimen images. From the obtained images, the spatial distribution of the voids and the microscopic constituents inside the Insulating Concrete specimens can be identified. The void distribution in the material can be characterized using low-order probability functions such as two-point correlation, lineal-path, and two-point cluster functions. It is confirmed that micro-CT images and low-order probability functions are effective in describing the relative degree of void clustering and void connectivity in Insulating Concrete.
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Analysis of Constituents of Insulating Concrete using Micro CT Images
Journal of Korean Society of Hazard Mitigation, 2013Co-Authors: Sang-yeop Chung, Tong-seok Han, Kwang Soo Yeom, Ji Su KimAbstract:Concrete is a multi-phase material whose material properties are affected by spatial distributions of phases. The void distribution in Concrete strongly affects physical properties of materials, such as mechanical response and heat conduction. To examine constituents of Insulating Concrete specimens, micro CT(micro computed tomography) image can be effectively used. Using micro CT images, the spatial distribution of constituents in Insulating Concrete, such as aggregates and glass beads to ensure the dispersed void distribution, can be detected. It is confirmed that micro CT images are effective in describing the spatial distribution of constituents of Insulating Concrete.
Prinya Chindaprasirt - One of the best experts on this subject based on the ideXlab platform.
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Mechanical and Thermal Properties of Recycling Lightweight Pervious Concrete
Arabian Journal for Science and Engineering, 2015Co-Authors: Prinya Chindaprasirt, Yuwadee Zaetang, Peem Nuaklong, Purimpat Sujumnongtokul, Vanchai SataAbstract:This paper presents an investigation of the use of recycled lightweight aggregate from waste autoclaved aerated Concrete block to make lightweight pervious Concrete (LWPC). The effects of fine sand (SA) and fly ash (FA) as additive materials on LWPC properties were also studied. The density, total void ratio, water permeability, compressive strength, splitting tensile strength, flexural strength, thermal conductivity, and surface abrasion of LWPC were tested. The results showed that all LWPCs had low density of 775–900 kg/m^3 and low thermal conductivity coefficient of 0.15–0.27 W/m K. The use of SA and FA improved the compressive strength, splitting tensile strength, flexural strength, and abrasion resistance of LWPC, while the total void ratio and water permeability seemed to reduce. The low thermal conductivity and low density of LWPC with reasonable 28-day compressive strength of 1.9–4.1 MPa suggested that it is suitable for use as thermal Insulating Concrete.
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use of lightweight aggregates in pervious Concrete
Construction and Building Materials, 2013Co-Authors: Yuwadee Zaetang, Ampol Wongsa, Vanchai Sata, Prinya ChindaprasirtAbstract:Abstract In this study, the use of lightweight aggregate (LWA) for making lightweight pervious Concrete (LWPC) was presented. Diatomite (DA) and pumice (PA) were used as natural LWAs in pervious Concretes. Three cement paste contents of 15%, 20%, and 25% by volume were used. The results were compared to those of LWPC containing recycled LWA from autoclaved aerated Concrete (RA). The results indicated that the use of DA, PA, and RA as coarse aggregates in pervious Concrete could reduce the density and thermal conductivity about 3–4 times compared with pervious Concrete containing natural aggregate. The densities were 558–775 kg/m3 which were lower than 800 kg/m3 and suited for use as Insulating Concrete. The 28-day compressive strengths of LWPCs ranged from 2.47 to 5.99 MPa. The increase in cement paste content improved the mechanical properties of LWPCs. LWPC containing DA showed higher mechanical properties and a lower thermal conductivity than those of RA and PA. However PA exhibited higher water permeability.
Johnson U Alengaram - One of the best experts on this subject based on the ideXlab platform.
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evaluation of thermal conductivity mechanical and transport properties of lightweight aggregate foamed geopolymer Concrete
Energy and Buildings, 2014Co-Authors: Johnson U Alengaram, Mohd Zamin Jumaat, Kim Hung MoAbstract:Abstract Energy efficiency is the predominant criterion in green building indices, which, in turn, contributes to sustainable development. One of the materials commonly used in the insulation of buildings is foamed Concrete. This investigation presents the main objective of the experimental results concerning the thermal conductivity of oil palm shell foamed geopolymer Concrete (OPSFGC), utilizing waste materials such as low-calcium fly ash (FA) and palm oil fuel ash (POFA) as cementitious materials, and oil palm shell (OPS) as lightweight coarse aggregate (LWA). Three OPSFGC mixtures with densities of 1300, 1500 and 1700 kg/m3 were prepared using an artificial foaming agent; a control mix without foam and conventional materials – block and brick – were used for comparison. The test results on the mechanical and transport properties are also discussed. The thermal conductivity of OPSFGC13 of about 0.47 W/mK was 22% and 48% lower than the conventional wall materials, block and brick, respectively. OPSFGC, with a density of 1300 and 1500 kg/m3, could be categorized as structural and Insulating Concrete, Class-II, whereas OPSFGC with a density of 1700 kg/m3 is classified as Class-I structural grade Concrete with a compressive strength and thermal conductivity of about 30 MPa and 0.58 W/mK, respectively.
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a comparison of the thermal conductivity of oil palm shell foamed Concrete with conventional materials
Materials & Design, 2013Co-Authors: Johnson U Alengaram, Baig Abdullah Al Muhit, Mohd Zamin Jumaat, Michael Liu Yong JingAbstract:Abstract Foamed Concrete (FC) is characterized by its low self-weight and insulation properties. This paper reports on the thermal conductivity of structural and non-structural grade foamed Concretes developed using locally available waste materials – oil palm shell (OPS) – as lightweight coarse aggregate. Six mixes of oil palm shell foamed Concrete (OPSFC) of oven-dry density ranging from 1100 to 1600 kg/m 3 were prepared and tested for thermal insulation and compared with the non-foamed oil palm shell Concrete (OPSC) as the control Concrete and conventional materials, such as brick and block. Non-structural grade OPSFC with a density of 1100 kg/m 3 showed the lowest thermal conductivity of 0.40 W/m K, which is 33% and 56% lower than the conventional materials – block and brick – respectively. OPSFC with 1500 and 1600 kg/m 3 can be considered as structural and Insulating Concrete as per the RILEM classification. The tiny air pores created in the Concrete act as an insulator and it was found that the thermal conductivity of OPSFC with densities of 1100 and 1300 kg/m 3 are similar to those of pumice Concrete and expanded perlite aggregate Concrete (EPAC), respectively.
Morgan Chabannes - One of the best experts on this subject based on the ideXlab platform.
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Design and multi-physical properties of a new Insulating Concrete using sunflower stem aggregates and eco-friendly binders
Materials and Structures, 2015Co-Authors: Morgan Chabannes, Vincent Nozahic, Sofiane AmzianeAbstract:In the interests of sustainable development, building materials using lignocellulosic aggregates like hemp Concretes are more and more used in green construction. This type of Concrete made of plant aggregates has particularly attractive thermal and hygroscopic properties. The hemp produced by agricultural holdings represents 10,000 ha in France whereas sunflower production is about 700,000 ha. The purpose of the article is to bring scientific elements which demonstrate that aggregates from the sunflower stem can be valorised in the same way as hemp hurd for the manufacturing of building materials. This study could encourage the development of new outlets for agricultural crops. Moreover, the sunflower aggregates could be available at low costs and promote a local economy as compared to hemp hurd. The experimental program includes the physical and thermal characterisation of the raw materials and the design of Concrete where aggregates, obtained from an industrial grinding process, are associated with a binder. The characterisation of the aggregates mainly consists of the granulometric study by image analysis, the water absorption and the determination of thermal properties using especially the hot wire method. Two binders are used to prepare cylindrical specimens of sunflower Concrete. Two kinds of mixture are tested in compression after 60 days, in thermal conductivity and capillary water absorption. The first one, called wall mixture, has a binder on aggregates mass ratio of 2 ( B / A = 2) and the second mixture, called roof mixture, has a B / A mass ratio of 1. Hot wire test results demonstrate for the wall mixtures an average dry thermal conductivity of 0.096 ± 0.003 W m^−1 K^−1 for the two binders. Compression results show an average compressive strength value at 60 days of 0.50 ± 0.1 MPa for the wall mixtures and 0.10 ± 0.01 MPa for the roof mixtures after an average 17 % strain. The results obviously show that the sunflower Concrete reaches thermal and mechanical properties very close from those of hemp Concrete. The capillary absorption test confirms the high absorbent potential of the sunflower aggregates but also the role of the binder towards the water uptake behaviour of lignocellulosic Concretes.
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use of raw rice husk as natural aggregate in a lightweight Insulating Concrete an innovative application
Construction and Building Materials, 2014Co-Authors: Morgan Chabannes, Laurent Clerc, Jean-charles Bénézet, Eric GarciadiazAbstract:Abstract As the building sector presents major impacts on the natural environment, the development of eco-friendly Concrete materials using plant aggregates has emerged as a high priority. This kind of Concrete allows moving towards a low carbon material with good thermo-physical properties. This is the case of hemp Concrete made out of hemp hurd mixed with a lime-based binder. Hemp Concrete is aimed at replacing usual systems based on Concrete blocks and mineral wool. In this way, it can qualify as a multifunctional material which takes a clear position regarding the energy efficiency and the optimization of building envelopes. This study deals with the development of an innovative Insulating Concrete having the same application than hemp Concrete one but using rice husks. Having examined physical and structural characteristics of plant aggregates, specimens made out of whole rice husks and a lime-based binder were manufactured by mixing and mechanical tamping. Both thermal and mechanical properties of the final Concrete materials were studied in comparison to hemp Concrete designed with the same process. The effects of an outdoor exposure of the specimens on the mechanical strength are discussed and the binding matrix mineral phases considered. It is established that for a same binder on aggregates mass ratio, the target dry density of rice husk Concrete is necessarily higher than those of hemp Concrete due to the different physical and morphological properties of rice husks. Thermal measurements show that rice husk Concrete can compete with hemp Concrete in terms of thermal insulation with a dry thermal conductivity ranging from about 0.10 W m−1 K−1 to 0.14 W m−1 K−1 depending on the mix proportioning. Compression test results on a defined mixture intended to be used as a filling material in a wall timber frame highlight lower mechanical performances for rice husk Concrete with an average compressive strength of 0.33 ± 0.03 MPa at 60 days compared to 0.48 ± 0.02 MPa for hemp Concrete.