scholarly journals Study on Water Absorption and Thermal Conductivity of Tunnel Insulation Materials in a Cold Region under Freeze-Thaw Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Youyun Li ◽  
Huan Wang ◽  
Li Yang ◽  
Shiqiang Su
Keyword(s):  
Thermal Conductivity ◽  
Water Absorption ◽  
Thermal Insulation ◽  
Insulation Material ◽  
Cold Region ◽  
Thermal Insulation Material ◽  
Freeze Thaw ◽  
Insulation Materials ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

A thermal insulation layer is often deposited on the lining structure of tunnels in cold regions to solve the problem of frost damage. When the air humidity in the tunnel becomes excessively high, the thermal insulation material tends to absorb water, leading to significant changes in thermal conductivity. Moreover, the temperature differences between the day and night cycles have been observed to be significant in portal sections of cold region tunnels, which facilitate the freeze-thaw cycle and, consequently, deteriorate the performance of the thermal insulation material. Therefore, the purpose of this study is to determine the changes in the water absorption, thermal conductivity, and microstructure of polyurethane and polyphenolic insulation boards under freeze-thaw conditions. To this end, an indoor water absorption test was conducted for both the insulation boards till they were saturated, which then underwent a freeze-thaw cycle test. It was determined that the water absorption and thermal conductivities of these boards increased linearly with the number of freeze-thaw cycles. In order to explore the change of thermal conductivity of thermal insulation materials after moisture absorption, this study provides insights into the relationship between the thermal conductivities and water contents of tunnel insulation materials under normal and freezing temperatures.

Effect of Operating Temperatures on Thermal Conductivity of Polystyrene Insulation Material: Impact on Envelope-Induced Cooling Load

2014 ◽  
Vol 564 ◽  
pp. 315-320 ◽  
Author(s):  
Maatouk Khoukhi ◽  
Mahmoud Tahat
Keyword(s):  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Energy Performance ◽  
Building Envelope ◽  
Insulation Material ◽  
Cooling Load ◽  
Thermal Insulation Material ◽  
Insulation Materials ◽  
Energy Performance Of Buildings ◽  
The Impact

The impact of the thermal conductivity (k-value) change of polystyrene insulation material in building envelope due to changes in temperature on the thermal and energy performance of a typical residential building under hot climate is investigated. Indeed, the thermal and energy performance of buildings depends on the thermal characteristics of the building envelope, and particularly on the thermal resistance of the insulation material used. The thermal insulation material which is determined by its thermal conductivity, which describes the ability of heat to flow cross the material in presence of a gradient of temperature, is the main key to assess the performance of the thermal insulation material. When performing the energy analysis or calculating the cooling load for buildings, we use published values of thermal conductivity of insulation materials, which are normally evaluated at 24°C according to the ASTM standards. In reality, thermal insulation in building is exposed to significant and continuous temperature variations, due essentially to the change of outdoor air temperature and solar radiation. Many types of insulation materials are produced and used in Oman, but not enough information is available to evaluate their performance under the prevailing climatic condition. The main objective of this study is to investigate the relationship between the temperature and thermal conductivity of various densities of polystyrene, which is widely used as building insulation material in Oman. Moreover, the impact of thermal conductivity variation with temperature on the envelope-induced cooling load for a simple building model is discussed. This work will serve as a platform to investigate the effect of the operating temperature on thermal conductivity of other building material insulations, and leads to more accurate assessment of the thermal and energy performance of buildings in Oman.

scholarly journals Preparation and properties of silicate inorganic exterior wall insulation based on thermal energy storage

2020 ◽  
Vol 24 (5 Part B) ◽  
pp. 3109-3118
Author(s):  
Zifan Zhou ◽  
Guofu Tu ◽  
Feng Xu ◽  
Zhaofeng Song ◽  
Na Li
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Thermal Insulation ◽  
Thermal Energy ◽  
Testing Machine ◽  
Insulation Material ◽  
Exterior Wall ◽  
Thermal Insulation Material ◽  
Insulation Materials ◽  
Insulation Performance

The key to building energy conservation is how to make the exterior wall have good thermal insulation performance, reduce the heat loss of the building?s peripheral structure, develop new exterior wall insulation materials, and effectively achieve energy saving. In this paper, a new type of composite silicate insulation material was prepared by using fly ash, sepiolite fiber, basalt fiber, and cement as raw materials. According to the analysis of the action of each component of the composite silicate thermal insulation material, the composite silicate thermal insulation material is prepared by selecting different raw material ratios, and the fly ash and sepiolite fibers are analyzed by a thermal conductivity measuring instrument and a hydraulic universal testing machine. The influence of water-cement ratio on the thermal conductivity, tensile strength, and compressive strength of composite silicate insulation materials. Through research, it is found that this composite silicate exterior wall insulation material utilizes some abandoned resources to help the building exterior wall to store thermal energy. The preparation process is simple, the insulation performance is good, the mechanical strength is high, and there is great promotion value and application prospect.

A Novel Building Thermal Insulation Material: Expanded Perlite Modified by Aerogel

2011 ◽  
Vol 250-253 ◽  
pp. 507-512
Author(s):  
Zi Sheng Wang ◽  
Hao Chi Tu ◽  
Jin Xiu Gao ◽  
Guo Dong Qian ◽  
Xian Ping Fan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Property ◽  
Thermal Insulation ◽  
Production Cost ◽  
Building Materials ◽  
Low Cost ◽  
Insulation Material ◽  
Expanded Perlite ◽  
Thermal Insulation Material ◽  
Supercritical Fluid Drying

Aerogel is regarded as one kind of super thermal insulation materials which could be large-scalely used as building materials. However, the aerogel’s production cost and poor mechanical property limit the its applications. In this paper, we put forward a new low cost way to produce a novel building thermal insulation material: synthesized the aerogel within the expanded perlite’s pores, and using sodium silicate as precursor without adopting supercritical fluid drying and surface modification. The thermal conductivity of expanded perlite was successfully decreased after modified by aerogel.

scholarly journals Thermal Insulation and Mechanical Properties of Polylactic Acid (PLA) at Different Processing Conditions

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2091
Author(s):  
Mohamed Saeed Barkhad ◽  
Basim Abu-Jdayil ◽  
Abdel Hamid I. Mourad ◽  
Muhammad Z. Iqbal
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polylactic Acid ◽  
Thermal Insulation ◽  
Annealing Time ◽  
Insulation Material ◽  
Thermal Insulation Material

This work aims to provide an extensive evaluation on the use of polylactic acid (PLA) as a green, biodegradable thermal insulation material. The PLA was processed by melt extrusion followed by compression molding and then subjected to different annealing conditions. Afterwards, the thermal insulation properties and structural capacity of the PLA were characterized. Increasing the annealing time of PLA in the range of 0–24 h led to a considerable increase in the degree of crystallization, which had a direct impact on the thermal conductivity, density, and glass transition temperature. The thermal conductivity of PLA increased from 0.0643 W/(m·K) for quickly-cooled samples to 0.0904 W/(m·K) for the samples annealed for 24 h, while the glass transition temperature increased by approximately 11.33% to reach 59.0 °C. Moreover, the annealing process substantially improved the compressive strength and rigidity of the PLA and reduced its ductility. The results revealed that annealing PLA for 1–3 h at 90 °C produces an optimum thermal insulation material. The low thermal conductivity (0.0798–0.0865 W/(m·K)), low density (~1233 kg/m3), very low water retention (<0.19%) and high compressive strength (97.2–98.7 MPa) in this annealing time range are very promising to introduce PLA as a green insulation material.

scholarly journals A Compressive Peak Strength Model for CFRP-Confined Thermal Insulation Materials under Elevated Temperature

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 26 ◽  
Author(s):  
Yeou-Fong Li ◽  
Wai-Keong Sio ◽  
Ying-Kuan Tsai
Keyword(s):  
Compressive Strength ◽  
Elevated Temperature ◽  
Thermal Insulation ◽  
Thermal Softening ◽  
Peak Strength ◽  
Insulation Material ◽  
Strength Model ◽  
Test Results ◽  
Thermal Insulation Material ◽  
Insulation Materials

In this paper, a compressive peak strength model for CFRP-confined thermal insulation materials under elevated temperature was proposed. The thermal insulation material was made by Portland cement with different portions of perlite. The compressive strengths of four different perlite ratios in weight, such as 0%, 10%, 20%, and 30% of thermal insulation materials, confined by one-layer, two-layer, and three-layer carbon fiber-reinforced polymer (CFRP) composite materials, were obtained. The test results indicated that the specimen’s compressive strength decreased with an increase in the amount of perlite replacement and increased with an increase in the number of CFRP wrapping layers. Based on the test results, a theoretical compressive peak strength model with some parameters was proposed. In the meantime, the compressive strengths of the above four different perlite ratios of thermal insulation materials under elevated temperature, such as ambient temperature, 100 °C, 150 °C, 200 °C, 250 °C, and 300 °C, were obtained. For compression tests of specimens with a fixed amount of perlite, the test results indicated that the specimen’s compressive strength decreased with an increase in temperature, highlighting a thermal softening phenomenon. Based on the test results, a compressive peak strength model with a thermal softening parameter was proposed to predict the peak strength under elevated temperature. Finally, a compressive peak strength model for thermal insulation material with CFRP confinement under different elevated temperature was derived, and it achieved acceptable results in comparison to the experimental results.

Analysis on New Functional Material - Applied Research of Clothing Based on New Thermal Insulation Materials

2012 ◽  
Vol 580 ◽  
pp. 489-492
Author(s):  
Qin Fei Sun ◽  
Xue Wang
Keyword(s):  
Thermal Insulation ◽  
Applied Research ◽  
Science And Technology ◽  
Insulation Material ◽  
Functional Material ◽  
Thermal Insulation Material ◽  
Insulation Materials

The analysis on thermal insulation material of new functional material presented its application on clothing, clarified its superior characteristic on clothing is more and more popular with the development of science and technology, promoted people developing new functional material.

Effect of Material Constitution on the Properties of Thermal Insulation Materials

2014 ◽  
Vol 541-542 ◽  
pp. 141-145
Author(s):  
Bo Liu ◽  
Shou De Wang ◽  
Shuai Yang ◽  
Chen Chen Gong ◽  
Ling Chao Lu
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Thermal Insulation ◽  
Cementitious Materials ◽  
Cellulose Ether ◽  
Dry Density ◽  
Ratio Test ◽  
Insulation Material ◽  
Material Constitution ◽  
Insulation Materials

Cement-based foam insulation board is a lightweight thermal insulation and have a characteristic of energy saving. The effects of material constitution on the properties of mechanical properties, dry densityand thermal conductivity for thermal insulation materials. The subject of fast hardening sulphoaluminate cement as cementitious materials, polystyrene particles as a lightweight thermal insulation material, adding a certain amount of water reducer, cellulose ethers, air entraining agent to make thermal insulation materials. The experimental results shows that the appropriate material constitution is following: the cement-bead ratio is 12, the ratio is 0.65, the water-cement ratio is 0.4, the content of water reducer is 0.5%, the content of cellulose ether is 0.4%, the content of the air entraining agent is 0.4% .This mix ratio test of mechanical properties are: flexural strength is 0.72MPa, compressive strength is 1.24MPa, dry density is 375kg/m3, water content is 2.3%, water absorption is 10.8%, softening coefficient is 0.95 and coefficient of thermal conductivity is 0.053 W/ (m K).

scholarly journals Investigation and Preparation of the Plastering Mortar for Autoclaved Aerated Blocks Walls

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 175
Author(s):  
Tao Feng ◽  
Lingling Xu ◽  
Xin Shi ◽  
Jian Han ◽  
Pan Zhang
Keyword(s):  
Water Absorption ◽  
Hydroxypropyl Methylcellulose ◽  
Ethylene Vinyl Acetate ◽  
Strength Loss ◽  
High Water ◽  
Dry Density ◽  
Pore Characteristics ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle

The increase in the use of aerated concrete blocks (AAB) in construction walls has increased the demand for specialized plastering mortar, which should have the characteristics of high water retention, low water absorption, low thermal conductivity and high toughness. This study scrutinized the potential of expanded and vitrified small ball (EVSB) and expanded perlite as lightweight aggregates, and the beneficial effect of a modifying additive based on a mixture of ethylene-vinyl acetate (EVA), hydroxypropyl methylcellulose (HPMC) and fibers has been proved. The dry density, consistency, water absorption, mechanical strength, pore characteristics and micro morphology of the plaster mortar were evaluated. It is manifested by enhanced toughness, reduced dry density, and optimized pore structure characteristics. The relationship between mass water absorption and freeze-thaw cycle resistance is established, which shows that when the mass water absorption is 20%, the mortar exhibits better freeze resistance. After 25 freeze-thaw cycle tests, the mass loss was 0.26% and the strength loss was 1.41%. Through the comparison of test results, a new composition of plastering mortar is provided: cement: fly ash: water: heavy calcium carbonate: quartz sand: EVSB: EVA: HPMC (100,000 mPa·s): fiber = 70: 30: 76: 12: 250: 24: 2: 0.3: 0.2.

scholarly journals Characterization of Thermal Bio-Insulation Materials Based on Oil Palm Wood: The Effect of Hybridization and Particle Size

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3287
Author(s):  
Indra Mawardi ◽  
Sri Aprilia ◽  
Muhammad Faisal ◽  
Samsul Rizal
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Particle Size ◽  
Water Absorption ◽  
Thermal Insulation ◽  
Oil Palm ◽  
Bending Strength ◽  
Fine Particles ◽  
Biomass Waste ◽  
Insulation Materials

Oil palm wood is the primary biomass waste produced from plantations, comprising up to 70% of the volume of trunks. It has been used in non-structural materials, such as plywood, lumber, and particleboard. However, one aspect has not been disclosed, namely, its use in thermal insulation materials. In this study, we investigated the thermal conductivity and the mechanical and physical properties of bio-insulation materials based on oil palm wood. The effects of hybridization and particle size on the properties of the panels were also evaluated. Oil palm wood and ramie were applied as reinforcements, and tapioca starch was applied as a bio-binder. Panels were prepared using a hot press at a temperature of 150 °C and constant pressure of 9.8 MPa. Thermal conductivity, bending strength, water absorption, dimensional stability, and thermogravimetric tests were performed to evaluate the properties of the panels. The results show that hybridization and particle size significantly affected the properties of the panels. The density and thermal conductivity of the panels were in the ranges of 0.66–0.79 g/cm3 and 0.067–0.154 W/mK, respectively. The least thermal conductivity, i.e., 0.067 W/mK, was obtained for the hybrid panels with coarse particles at density 0.66 g/cm3. The lowest water absorption (54.75%) and thickness swelling (18.18%) were found in the hybrid panels with fine particles. The observed mechanical properties were a bending strength of 11.49–18.15 MPa and a modulus of elasticity of 1864–3093 MPa. Thermogravimetric analysis showed that hybrid panels had better thermal stability than pure panels. Overall, the hybrid panels manufactured with a coarse particle size exhibited better thermal resistance and mechanical properties than did other panels. Our results show that oil palm wood wastes are a promising candidate for thermal insulation materials.

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