An Experimental Investigation on Thermal Conductivity of Lightweight Foamcrete for Thermal Insulation

2013 ◽  
Vol 63 (1) ◽  
Author(s):  
Md Azree Othuman Mydin
Keyword(s):  
Thermal Conductivity ◽  
Construction Industry ◽  
Impact Resistance ◽  
High Impact ◽  
Void Size ◽  
Conventional Concrete ◽  
Freeze Thaw ◽  
Conductivity Property ◽  
Structural Applications ◽  
Molecular Constitution

Presently, the construction industry has shown considerable consciousness in utilizing lightweight foamcrete as a building material. The demand of lightweight foamcrete is becoming higher now where this material has increased many folds in recent years due to its intrinsic economies and advantages over conventional concrete in a range of structural and semi-structural applications. The major specialties of lightweight foamcrete are its excellent thermal conductivity, low self-weight, high impact resistance and good freeze thaw resistance. The aim of this experimental study is to investigate the thermal conductivity property of lightweight foamcrete with various densities. The main parameters that will be considered are density of lightweight foamcrete, the void size and porosity. The lightweight foamcrete samples are made with constant water-cement ratio of 0.5 and cement-sand ratio of 2:1. According to experimental results, lower densities lightweight foamcrete transforms to lower thermal conductivity values. Meanwhile, the density of lightweight foamcrete is controlled by the porosity where lower densities indicate larger porosity values. For this reason, thermal conductivity of lightweight foamcrete changes significantly with the porosity because air is the poorest conductor in comparison to solid and liquid owing its molecular constitution. The measured values of thermal conductivity should provide a useful database for evaluating the thermal performance of lightweight foamcrete structures.

scholarly journals Formulation and characterization of structural lightweight concrete containing residues of porcelain tile polishing, tire rubber and limestone

Cerâmica ◽  
2017 ◽  
Vol 63 (368) ◽  
pp. 530-535
Author(s):  
Z. L. M. Sampaio ◽  
A. E. Martinelli ◽  
T. S. Gomes
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Void Ratio ◽  
Lightweight Concrete ◽  
Fine Aggregate ◽  
Conventional Concrete ◽  
Tire Rubber ◽  
Increased Strength ◽  
Porcelain Tile

Abstract The recent increase in the construction industry has transformed concrete into an ideal choice to recycle a number of residues formerly discarded into the environment. Among various products, porcelain tile polishing, limestone and tire rubber residues are potential candidates to replace the fine aggregate of conventional mixtures. The aim of this study was to investigate the effect of the addition of varying contents of these residues in lightweight concrete where expanded clay replaced gravel. To that end, slump, compressive strength, density, void ratio, porosity and absorption tests were carried out. The densities of all concrete formulations studied were 10% lower to that of lightweight concrete (<1.850 kg/m³). Nevertheless, mixes containing 10 to 15% of combined residues reduced absorption, void ratio and porosity, at least 17% lower compared to conventional concrete. The strength of such formulations reached 27 MPa at 28 days with consistency of 9 to 12 cm, indicating adequate consistency and increased strength. In addition, the combination of low porosity, absorption and voids suggested improved durability.

scholarly journals Evolution of mantis shrimp telson armour and its role in ritualized fighting

2019 ◽  
Vol 16 (157) ◽  
pp. 20190203 ◽  
Author(s):  
Jennifer R. A. Taylor ◽  
Nina I. Scott ◽  
Greg W. Rouse
Keyword(s):  
Comparative Analysis ◽  
Impact Resistance ◽  
High Impact ◽  
Mantis Shrimp ◽  
Impact Forces ◽  
Drop Tests ◽  
Impact Parameters ◽  
Ritualized Combat ◽  
Stiff Spring ◽  
The Impact

Mantis shrimp possess both formidable weapons and impact-resistant armour that clash during ritualized combat. The telson is one of few biological structures known to withstand the repeated high impact forces of smashing mantis shrimp strikes, and it is hypothesized that this pairing of armour and weapon is associated with the evolution of telson sparring. We carried out a comparative analysis of telson impact mechanics across 15 mantis shrimp species to assess if the telsons of sparring species (i) are consistently specialized for impact-resistance, (ii) are more impact-resistant than those of non-sparring species, and (iii) have impact parameters that correlate with body size, and thereby useful for assessment. Our data from ball drop tests show that the telsons of all species function like a stiff spring that dissipates most of the impact energy, but none of the measured impact parameters are correlated with the occurrence of sparring behaviour. Impact parameters were correlated with body mass for only some species, suggesting that it is not broadly useful for size assessment during ritualized fighting. Contrary to expectation, sparring mantis shrimp do not appear to have coevolved telson armour that is more robust to impact than non-sparring species. Rather, telson structure is inherently impact-resistant.

Physical Properties of Building Blocks from Hemp Shives Aggregate and Cementitious Binder, Manufactured in the Expanded Clay (Vibro Pressing) Production Line

2017 ◽  
Vol 908 ◽  
pp. 118-122 ◽  
Author(s):  
Giedrius Balčiūnas ◽  
Viktor Kizinievič ◽  
Justinas Gargasas
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Physical Properties ◽  
Production Line ◽  
Scientific Literature ◽  
Building Blocks ◽  
Freeze Thaw ◽  
Cementitious Binder ◽  
Pressing Technology

Scientific literature mostly aims at investigation of composites with fibre hemp shives (FHS) aggregate and lime binder, although, such materials are characterised by pretty low mechanical properties. In order to obtain higher mechanical properties of a composite, it is appropriate to use cementitious binder. This work investigates physical properties of blocks from hemp shives aggregate and cementitious binder, manufactured in the expanded clay production line using vibro pressing technology. Following properties of the blocks are determined: freeze-thaw resistance, compressive strength, thermal conductivity and density. Thermal resistance according to EN ISO 6946 for the block with cavities is calculated as well. It is found that compressive strength of FHS-cement blocks may be up to 3.18 MPa when the density is of ~850 kg/m3 and thermal conductivity up to 0.135 W/(m∙K). It is found as well that the decrease of compressive strength is 8.7% after 25 freeze-thaw cycles.

scholarly journals Experimental Cryoablation of Thyroid Gland with Propilthiouracyl-Induced Diffuse Hyperplasiae

2021 ◽  
Vol 31 (2) ◽  
pp. 168-179
Author(s):  
Kostiantyn Pobielienskyi ◽  
◽  
Oleksandr Pakhomov ◽  
Gurina Tetyana Gurina Tetyana ◽  
Liliia Pobielienska ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thyroid Gland ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Freeze Thaw ◽  
Model Experiments ◽  
Endoscopic Control ◽  
The One ◽  
Benign Nodules

Cryoablation under endoscopic control is considered to be a promising approach in therapy of benign nodules of thyroid gland (TG). However, pathologically altered TG tissue differs in thermal conductivity and heat capacity from normal one, therefore the model experiments in animals are necessary to determine the cryoablation parameters. In this research, the changes of temperature during cryoablation of experimental rat TG under normal conditions and the one with propylthiouracil (PTU)-induced diffuse hyperplasia (DH) were comparatively assessed. TG was cryo-ablated in rats, previously received a 0.1% PTU solution within 90 days, using a copper cryoprobe, cooled to liquid nitrogen temperature. The process was controlled using thermocouples placed at different distances from the iceball. Differences between thermograms of intact TG tissue and the samples with PTU-induced DH were established. To achieve the destruction effect of TG with DH to a depth of more than 1 mm, the need of implementing two freeze-thaw cycles with 120-second cryoprobe exposure was proven.

scholarly journals ASSESSING THE SUITABILITY OF TIGER NUT FIBRE FOR STRUCTURAL APPLICATIONS

2020 ◽  
Vol 3 (01) ◽  
pp. 32-38
Author(s):  
Uduakobong Okorie ◽  
Ubong Robert ◽  
Ubong Iboh ◽  
Grace Umoren ◽  
Grace Umoren
Keyword(s):  
Thermal Conductivity ◽  
Cost Effective ◽  
Waste Recycling ◽  
Cassava Starch ◽  
Fibre Content ◽  
Raw Material ◽  
Structural Applications ◽  
The Mean ◽  
Thermal Absorptivity ◽  
Reduce Health Risk

In this work, the properties of the composite produced from waste carton with various tiger nut fibre contents having cassava starch slurry as binder were investigated. The results obtained showed the ranges of the mean thermal conductivity, bulk density, specific heat capacity, thermal diffusivity, thermal absorptivity, nailability, flexural strength  and compressive strength values to be (0.0447 – 0.0603) Wm-1K-1, (683.62 – 746.32) kgm-3, (1439.811 – 1840.554) J/kg/K, (5.612 - 3.553) 10-8 m2s-1, (25.456 – 31.993) m-1, (23.9 – 100)%, (1.58 – 1.86) MPa and (2.16 – 2.78) MPa respectively between  8.3% and 43.1% of the fibre content.  It was generally observed that with a choice variation in the fibre content, the performance of the developed board can be optimized for structural applications. Hence, instead of discarding the fibre as waste, recycling it can help to provide raw material for the production of cost effective and environmentally friendly materials. This will in turn reduce health risk caused by environmental pollution due to improper waste disposal practice of such material.

Experimental and Modeling Study on High Velocity Penetration of a Carbon/Epoxy Composite Laminate

2021 ◽  
Vol 904 ◽  
pp. 167-173
Author(s):  
Fang Yu Chen ◽  
Ding Feng Ma ◽  
Xiao Ming Zhou
Keyword(s):  
Impact Loading ◽  
High Velocity ◽  
Composite Laminate ◽  
Epoxy Composite ◽  
Good Choice ◽  
High Impact ◽  
Light Weight ◽  
Specific Strength ◽  
High Specific Strength ◽  
Structural Applications

In many structural applications, such as marine, aircraft and so on, structures are designed to withstand high impact loading, because they may be subjected to impact of the projectiles with high velocity [1,2] . Fabrics become good choice to resist impact of ballistic [3] because of light weight and high specific strength .

scholarly journals Structural Applications of Thermal Insulation Alkali Activated Materials with Reduced Graphene Oxide

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1052
Author(s):  
Wu-Jian Long ◽  
Can Lin ◽  
Xiao-Wen Tan ◽  
Jie-Lin Tao ◽  
Tao-Hua Ye ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Energy Consumption ◽  
Reduced Graphene Oxide ◽  
Thermal Insulation ◽  
Expanded Polystyrene ◽  
Information Modeling ◽  
Reduced Graphene ◽  
Structural Applications ◽  
Alkali Activated

Development of low thermal conductivity and high strength building materials is an emerging strategy to solve the heavy energy consumption of buildings. This study develops sustainable alkali activated materials (AAMs) for structural members from waste expanded polystyrene (EPS) beads and reduced graphene oxide (rGO) to simultaneously meet the thermal insulation and mechanical requirements of building energy conservation. It was found that the thermal conductivity of AAMs with 80 vol.% EPS and 0.04 wt.% rGO (E8–G4) decreased by 74% compared to the AAMs without EPS and rGO (E0). The 28-day compressive and flexural strengths of E8–G4 increased by 29.8% and 26.5% with the addition of 80 vol.% EPS and 0.04 wt.% rGO, compared to the sample with 80 vol.% EPS without rGO (E8). In terms of compressive strength, thermal conductivity, and cost, the efficiency index of E8–G4 was higher than those of other materials. A building model made from AAMs was designed using building information modeling (BIM) tools to simulate energy consumption, and 31.78% of total energy consumption (including heating and cooling) was saved in the building operation period in Harbin City, China. Hence, AAMs made of waste EPS beads and rGO can realize the structural and functional integrated application in the future.

scholarly journals High impact resistance in graphyne

RSC Advances ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 1697-1703 ◽  
Author(s):  
Yang Yang ◽  
Qiang Cao ◽  
Yang Gao ◽  
Shuting Lei ◽  
Sheng Liu ◽  
...  
Keyword(s):  
Impact Resistance ◽  
High Impact ◽  
Electrical Performance

Graphyne was recently facilely synthesized with superior mechanical and electrical performance.

scholarly journals Gypsum, Geopolymers, and Starch—Alternative Binders for Bio-Based Building Materials: A Review and Life-Cycle Assessment

2020 ◽  
Vol 12 (14) ◽  
pp. 5666 ◽  
Author(s):  
Girts Bumanis ◽  
Laura Vitola ◽  
Ina Pundiene ◽  
Maris Sinka ◽  
Diana Bajare
Keyword(s):  
Thermal Conductivity ◽  
Life Cycle Assessment ◽  
Life Cycle ◽  
Environmental Impact ◽  
Construction Industry ◽  
Building Materials ◽  
Initial Moisture Content ◽  
Limited Application ◽  
Ecological Building ◽  
Thermal Conductivity Λ

To decrease the environmental impact of the construction industry, energy-efficient insulation materials with low embodied production energy are needed. Lime-hemp concrete is traditionally recognized as such a material; however, the drawbacks of this type of material are associated with low strength gain, high initial moisture content, and limited application. Therefore, this review article discusses alternatives to lime-hemp concrete that would achieve similar thermal properties with an equivalent or lower environmental impact. Binders such as gypsum, geopolymers, and starch are proposed as alternatives, due to their performance and low environmental impact, and available research is summarized and discussed in this paper. The summarized results show that low-density thermal insulation bio-composites with a density of 200–400 kg/m3 and thermal conductivity (λ) of 0.06–0.09 W/(m × K) can be obtained with gypsum and geopolymer binders. However, by using a starch binder it is possible to produce ecological building materials with a density of approximately 100 kg/m3 and thermal conductivity (λ) as low as 0.04 W/(m × K). In addition, a preliminary life cycle assessment was carried out to evaluate the environmental impact of reviewed bio-composites. The results indicate that such bio-composites have a low environmental impact, similar to lime-hemp concrete.

Formwork Pressure of Self-Consolidating Concrete in Tall Wall Field Applications

2005 ◽  
Vol 1914 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Fernando Tejeda-Dominguez ◽  
David A. Lange ◽  
Matthew D. D'Ambrosia
Keyword(s):  
Hydrostatic Pressure ◽  
Use Of Self ◽  
Conventional Concrete ◽  
Concrete Material ◽  
Self Consolidating Concrete ◽  
Structural Applications ◽  
Formwork Pressure ◽  
High Column

The growing interest in the use of self-consolidating concrete (SCC) for a wide variety of structural applications has initiated a reexamination of its properties and current construction practices and how they compare with those of conventional concrete. One property of interest is the formwork pressure of SCC and how it relates to that of conventional concrete. This work presents the results for three tall walls (28, 21.7, and 13 ft tall) cast slowly with SCC and a 10.6-ft-high column poured quickly by using the same concrete used in one of the walls. The research demonstrates that the pressure of SCC against the formwork drops quickly just after the concrete material is placed. Measurements from the walls poured slowly show that the maximum recorded pressure falls far below the hydrostatic pressure and is closely related to the pouring rate. The experiments also reveal that the formwork pressure exerted by SCC can be revitalized if the SCC is vibrated, even if stiffening is already in progress.

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