Dry Thermal Conductivity Research Articles

Development and performance evaluation of ultra-lightweight geopolymer foam insulation material

The preparation technology for new ultra-lightweight geopolymer insulation materials (ULGIM) has been developed based on the principle of alkaline activation, and ULGIM for building walls have been obtained. It has improved the problem of traditional inorganic foam insulation material that cannot balance density, insulation performance, mechanical performance and environmental performance. The composition of supplementary cementitious materials, the mass ratio between each component, and water to binder ratio (w/b) were used to analyze the thermal conductivity, dry density, volumetric water absorption, compressive strength, average pore diameter, and porosity of ULGIM. The life cycle assessment (LCA) method was employed to assess the environmental impact of ULGIM production. The test results showed that ULGIM achieved a dry density and thermal conductivity of ULGIM only 181.17 kg/m3 and 0.0427 W/(m·K), respectively, and the optimal compressive strength was 0.72 MPa at 7 d. ULGIM exhibited superior compressive strength, lower thermal conductivity, and smaller environmental impact in comparison to cement-based foamed materials with comparable dry density.

A simple two-phase approach to predict moisture-dependent thermal conductivity for porous materials

This study develops a generalized solution for moisture-dependent thermal conductivity (λeff) in porous media, utilizing readily available parameters. By introducing arbitrary dry and saturated phases, the tri-phase model (solid, gas, and water) is simplified into a two-phase model. Seven analytical solutions are adapted, including series-parallel, Maxwell-Eucken, Landauer's, exponential, and Somerton's relations. The proposed method requires only two parameters to predict λeff under different degrees of saturation (Sr): effective dry thermal conductivity (λdry, where Sr = 0) and effective saturated thermal conductivity (λsat, where Sr = 1). In the absence of direct λsat measurement, this λsat can be obtained using λdry and the parallel relation for highly porous media, and using Landauer's relation for medium-density materials. Validation results indicate that both Landauer's and exponential relations provide the upper bound and lower bounds, respectively, for λeff. For medium-density materials, the upper bound aligns with the parallel relation and the lower bound aligns with Landauer's relation.

Influence of the Addition of Palm (Borassus Aethiopum Mart.) Fibers on the Durability of Compressed Earth Blocks

This study aims to determine the influence of the content and length of the palm (borassus aethiopum mart.) fibers on the physical, mechanical and thermal properties of Compressed Earth Blocks (CEB). Three fiber contents (0.2%, 0.4% and 0.8%) of different lengths (10 mm, 20 mm, or 40 mm) were used to make CEB. CEB with 0% fiber content were manufactured to serve as control samples. CEB specimens stabilized with palm fibers or not were subjected to various tests according to standard XP P 13-901 for the determination of the following properties: dry density, water absorption, dry compressive strength, abrasion resistance and thermal conductivity. The results show that the dry density of CEB decreases from 4% to 7% when the content and length of the fibers increase respectively from 0.2% and 10 mm in length to 0.8% and 40 mm in length. The water absorption of fiber-containing CEBs ranges from 14% to 22% with increasing fiber content and length. The results also indicate that the mechanical and thermal properties are improved for well-chosen fiber contents. Thus, the dry compressive strength of the fibers increases by more than 13% for a fiber content of 0.2% and a length of 10 mm compared to CEB with 0% fibers. On the other hand, the optimal abrasion resistance values are obtained for a fiber content of 0.4% and a length of 40 mm. For all CEBs, the thermal conductivity values vary from 0.51 W/mK to 0.38 W/mK when the fiber content varies from 0.2% to 0.8%. Overall, palm fiber content has a greater influence on the measured physical, mechanical and thermal characteristics than fiber length.

A circular approach to stone wool: Alkali-activated lightweight aggregates

This study investigates the high-value recycling of stone wool from construction and demolition waste into alkali-activated lightweight insulation aggregates, designed for ground cover insulation. Various proportions of milled and as-is stone wools are alkali-activated to produce aggregates. The aggregates demonstrate loose bulk densities ranging from 720 to 850 kg m−3 and dry thermal conductivity from 0.075 to 0.094 W m−1·K−1, with moderate water sorption capacities. The fibre morphology of as-is stone wool influences rheology, introducing a greater number of pores or defects, which results in a decrease in mechanical strength. Hydrothermal simulations reveal that the floor assembly of the rehabilitated crawl space, partially filled with the fabricated aggregates, shows a reduction in water content and an increase in floor surface temperature. This observation suggests potential benefits for maintaining the structural integrity of buildings and enhancing occupant comfort.

Preparation and Properties of Lightweight Geopolymer by Bio-Based Foaming Agent.

Lightweight geopolymers have the advantages of a wide source of raw materials, chemical corrosion resistance, high mechanical strength and excellent durability, and are expected to replace traditional building insulation materials. In this paper, a green bio-based foaming agent with a small 1 h settlement distance, high average foaming multiple and low bleeding ratio was obtained by a Cetyltrimethylammonium Bromide/yeast solution. When the amount of Cetyltrimethylammonium Bromide is 0.50 wt%, the foam prepared by the yeast and Cetyltrimethylammonium Bromide solution exhibits the improved 1 h settlement distance, the large average foaming multiple, the small bleeding ratio and uniform foam size. Subsequently, a lightweight geopolymer based on metakaolin and fly ash (or silica fume) was successfully prepared by the bio-based foaming agent, and the effects of different foam content on the properties of the geopolymer, such as dry density, water absorption, thermal conductivity, compressive strength and morphology, were studied. With an increase in foam content, the dry density, thermal conductivity and compressive strength of the geopolymer gradually decrease, the water absorption increases, regardless of whether silica fume or fly ash are added. Herein, it is confirmed that the foaming agent based on yeast can be effectively used to prepare lightweight geopolymers, which can provide vast opportunities to turn into candidates for novel inorganic thermal insulation materials.

Selection of suitable cellulose nanofibers derived from eco-friendly sources for the production of lightweight cementitious composites with tuned rheological, mechanical, and microstructure properties

Different cellulose nanofibers (CNF) and ordinary Portland cement (OPC) were combined to prepare CNF-OPC composite pastes at different water to cement ratios (W/C) to optimize density, thermal conductivity, and mechanical strength. The rheological data of CNF-OPC composites showed that the viscosity and yield stress of the mixtures were abruptly increased in comparison to those of OPC pastes at equal W/C. Rheological and morphological data showed that the uniformity of the CNF and degree of fiber entanglement plays a significant role in tuning the composite properties. CNF suspensions with short fibers were observed to improve the mechanical properties of the composite while suspensions with entangled fiber networks were found to decrease density and thermal conductivity. Loss of flexural strength of CNF-OPC compared to OPC was found to be to a lesser extent than loss of compressive strength. The dry density and thermal conductivity of the CNF-OPC composites were substantially reduced to the range of 750 (kg/m3) and 0.1 (W/m−1K−1) at W/C = 2. CNF caused a reduction in peak temperature and postponed the hydration peak by more than 2 h compared to OPC.

Synergistic effect of fly ash and polyvinyl alcohol fibers in improving stability, rheology, and mechanical properties of 3D printable foam concrete

Foam concrete, a lightweight cellular cementitious mixture has gained significant attention globally due to its multifunctional properties. Employing such multifunctional material to additive manufacturing helps in reducing the material wastage, time for construction and cost of production. However, there are various challenges encountered in employing such material with conflicting attributes in 3D concrete printing technology. Therefore, it is important to address these challenging requirements (i.e. stability along with printability). In this study, fly ash and polyvinyl alcohol fibers are employed as sand replacement and reinforcing material respectively to improve stability, rheology and mechanical characteristics of 3D printable foam concrete. Initially, printability of the mixture is achieved through moderation of slump and slump flow. Further, these mixtures are studied for fresh density, rheological properties and buildability. Essential hardened properties like oven dry density, compressive strength, flexural strength, bond strength, and thermal conductivity are studied. Later, microstructural studies are conducted to analyze the variations in hardened properties. Results show that replacement of sand with fly ash has significant influence (more than 100%) in improving the printability (for both 1300 and 1000 kg/m3 densities), however it has negative impact on the stability of foam. Stability of foam concrete could be counteracted by adding the fibers which forms networks with the foam bubbles and reduced the breakage and coalescence. Nonetheless, addition of fly ash increased the mechanical performance and thermal conductivity, but the dry density is increased due to bubble breakage. Addition of fibers reduced dry density with significant reduction in thermal conductivity and minimal compromise in mechanical performance.

A novel cement mortar comprising natural zeolite/dodecyl alcohol shape stable composite phase change material for energy effective buildings

Investigations into Phase Change Materials (PCMs) for heat storage in facilities have gained significance, contributing to indoor temperature regulation, decreased energy usage, and improved building efficiency, thereby supporting sustainability initiatives. However, the issue of PCM leakage during the heating phase has constrained its thermal energy storage (TES) prospective at large scaled-practices. Addressing this concern, the present study emphases on elimination of the leakage problem of dodecyl alcohol (DA) as a PCM with appropriate melting temperature for building TES request by its impregnating into the natural zeolite (NZ) as a low cost host matrix. In the second stage of the work, using the developed shape stable-NZ/DA (SS-NZ/DA) composite PCM in cement mortar instead of sand, novel cementitious mortars with enhanced thermal properties were created by incorporating different weight percentages (25 %, 50 %, 75 %, and 100 %) compared to the mortar comprising NZ. Experimental works were carried out to analyze the shape-stability, TES features, cycling TES stability and thermal endurance of the SS-NZ/DA composite as well the physical properties, mechanical strength, and solar temperature regulation performance of the SS-NZ/DA included mortars. The SS-NZ/DA demonstrated the melting enthalpy of 107.5 J/g at 19.47 °C and a freezing enthalpy of 106.1 J/g at 19.86 °C. The performance test results obtained under real weather conditions indicated that the integration of SS-NZ/DA into mortar presented maximum drop of 10 % and 9.26 % in peak indoor temperature at the SS-CPCM slab surface and the center of SS-CPCM slab-cabin, respectively, accompanied by an approximate 3-hour time delay. Mortars with SS-NZ/DA composite PCM exhibited a decreased dry unit weight (1189 kg/m3) and thermal conductivity (0.394 W/mK) while experiencing a moderate strength loss (4.5 MPa). These favorable physico-mechanical properties, TES characteristics and thermal management capability make the novel cementitious mortar containing composite PCM as an energy-efficient material for creating thermo-regulative building components. In this study, the natural, economical, and environmentally friendly nature of the NZ material used for PCM impregnation, its ability to contain a high percentage of PCM (up to 45 %) without any leakage issues, is the most fundamental and important characteristic of the composite used. The most unique feature of this composite mortar is the ability to achieve sufficient mechanical and thermal properties in cementitious mortars produced using this composite material without any leakage problems.

Shrinkage Reduction in Nanopore-Rich Cement Paste Based on Facile Organic Modification of Montmorillonite.

The organic modification of montmorillonite was successfully achieved using cetyltrimethyl ammonium bromide under facile conditions. The modified montmorillonite was subsequently used for the fabrication of montmorillonite-induced nanopore-rich cement paste (MNCP), and the shrinkage behavior and fundamental performance of MNCP were also investigated. The results indicate that alkali cations on a montmorillonite layer surface were exchanged by using CTAB under 80 °C, successfully achieving the organic modification of montmorillonite. As a pore-forming agent, the modified montmorillonite caused a reduction in shrinkage: the 28-day autogenous shrinkage at a design density of 400 kg/m3 and 800 kg/m3 was reduced to 2.05 mm/m and 0.24 mm/m, and the highest reduction percentages during the 28-day drying shrinkage were 68.1% and 62.2%, respectively. The enlarged interlamellar pores and hydrophobic effects caused by the organic modification of montmorillonite aided this process. Organic-modified montmorillonite had a minor influence on dry density and thermal conductivity and could contribute to an enhancement of strength in MNCP.

Preparation of autoclaved-aerated concrete with waste ash of petroleum coke gasification

ABSTRACT In this paper, a novel route for the utilisation of petroleum coke gasification ash in the preparation of autoclaved-aerated concrete (AAC) is presented. The waste ash along with quartz sand, cement, lime, and gypsum are used as the primary raw materials, with aluminium powder paste serving as the pore-forming agent. The effect of incorporating petroleum coke gasification ash on the dry density and thermal conductivity of the resulting AAC was investigated. The results indicate that the thermal insulation performance of AAC is significantly enhanced by reducing the thermal conductivity coefficient upon the addition of treated petroleum coke gasification ash. At a 40% ash content, the AAC exhibits remarkable performance that meet the requirements of A2.5B05 in GB 11,968-2006, with compressive strength higher than 2.5 MPa and dry density lower than 525 kg m−3. Furthermore, the study examined the optimal calcium silicon ratio after the addition of the ash, with the results demonstrating that AAC prepared with a ratio of 0.25–0.26 exhibits the best compressive strength and dry density. The present study offers a novel perspective on waste management, which carries substantial significance for both the environmental and construction industries.

Hygrothermal Optimization for Excavated Soil Reuse in Various Climate Buildings: A Global Literature Meta-Analysis

This article investigates the hygrothermal properties of earth-based materials by analyzing experimental data from 88 articles spanning 32 countries worldwide. The focus is determining effective techniques for leveraging the use of excavated soil in construction, particularly emphasizing enhancement of hygrothermal comfort in specific climates. Based on statistical analysis, the study presents a comprehensive classification of earth production techniques, incorporating additives, and examines their impacts on hygrothermal properties of excavated soils. Additionally, it explores the intricate relationship between the climatic conditions of a region and the chosen earth-material production techniques. The analysis aims to propose standard parameters for earthen materials and identify gaps in both methods and experimental studies. Therefore, this study will provide valuable insights by proposing new design tools (ternary diagrams) to maximize the use of excavated soils in construction practices. The proposed diagrams illustrate the intricate relation linking either hygrothermal properties, the climate zone, and manufacturing techniques, or the relation between the most studied manufacturing techniques (compaction, fibered, and stabilization) and expected dry thermal conductivity. Thereby, results from this meta-analysis and critical review will contribute to advancing sustainable construction practices.

Experimental Analysis of Moisture-Dependent Thermal Conductivity, and Hygric Properties of Novel Hemp-shive Insulations with Numerical Assessment of Their In-Built Hygrothermal and Energy Performance.

The use of lime as a binder in hemp-lime considerably increases the drying time of hemp-lime after casting. Furthermore, lime is a non-renewable mineral resource. As such, this paper explores the effectiveness of using an alternative non-mineral binder instead of lime to formulate a novel hemp-shive insulation. The moisture-dependent thermal conductivity, adsorption isotherm, vapour diffusion resistance factor, and in-built hygrothermal performance of four variants of a novel bio-based insulation were investigated. The hygrothermal performance of the novel hemp-shive insulation was compared with that of a previously developed novel hemp-lime insulation. No significant variation in thermal conductivity of hemp-shive insulations between the equilibrium moisture contents (EMC) at 0% and 50% relative humidity (RH) was observed, but there was a substantial increase in thermal conductivity hemp-shive insulations when the material reached the EMC at 98% RH. The average dry thermal conductivity values of hemp-shive and hemp-lime insulations were also similar. The adsorption isotherms of hemp-shive insulations were determined at 0%, 20%, 50%, 70%, 90%, and 98% relative humidity steps. At 98% RH, the moisture adsorption capacity of hemp-shive insulations was 4-to-5-times higher than that of hemp-lime insulation. Hemp-shive insulations' vapour diffusion resistance factor (µ value) was about double the µ value of hemp-lime insulation. Hemp-shive insulations exhibited 4-to-5-times higher water absorption resistance than that of hemp-lime insulation. Numerically determined porosity values of hemp-shive agree with the values of wood-based insulation materials of similar density. Finally, using all experimentally acquired data as inputs, dynamic whole-building hygrothermal simulations were carried out and the results show that novel hemp-shive insulation materials perform at a similar level to the hemp-lime insulation in terms of heating and cooling energy demand but require 45% less energy for humidification. However, the relative humidity inside the hemp-shive wall remains higher than 70%, which can potentially induce mould growth.

Experimental and Numerical Study on the Thermal Response of the Lightweight Aggregate Concrete Panels Integrated with MPCM

This paper determines the best design parameters and uses conditions of lightweight aggregate concrete panels containing microencapsulated phase change materials (MPCM-LWAC panels). The main work of this paper includes the followings: (1) The fundamental properties (dry density, thermal conductivity, and specific heat capacity) of MPCM-LWAC were researched to reveal the effect of MPCM dosage on these properties. (2) A model test was carried out to quantify the effect of MPCM dosage on the thermal response of the MPCM-LWAC panel exposed to realistic climate conditions. (3) The numerical simulation was conducted to investigate the effect of MPCM dosage, panel thickness, and outdoor temperature conditions on the thermal response of the MPCM-LWAC panel, which helps to determine its optimum design parameters and use condition. The results showed that the incorporation of MPCM results in lower dry density and thermal conductivity of MPCM-LWAC but higher specific heat capacity. The more MPCM dosage in the MPCM-LWAC panel with a thickness of 35 mm, the lower the energy demand to keep a comfortable interior temperature. Most notably, when the panel thickness exceeds 105 mm, the MPCM-LWAC panel with 5% MPCM only delays the peak temperature. Moreover, the optimal use condition for MPCM-LWAC panels is an average outdoor temperature of 25 °C, which makes the energy demand attain a minimum.

Reuse of wood biomass ash to improve thermal behavior of gypsum plasters

Huge amounts of waste are generated each year in the world. In addition, the construction sector is one of the larger producers of residues and a huge energy consumer. Thus, architects, engineers and other actors of the building sector should give solutions in order to reduce that problem. In that sense, the idea of finding solutions for the end of the service life of materials, in order to promote circularity, has been studied by several researchers. In this study, biomass wood ash has been used as aggregate for the generation of new eco-efficient gypsum plasters, for its application in new buildings and rehabilitation works. In order to conduct an exhaustive characterization of the new composites, an experimental campaign of the plasters has been conducted: dry bulk density and thermal conductivity of the plasters have been measured. The results showed that it was possible to add up to 25% of wood ash without modifying the water/gypsum ratios. Moreover, thermal conductivity of the plasters has improved up to18% when the ash was added to the mixture. Finally, the effects of using the new gypsum composites in the thermal envelope of buildings was analyzed by its usage in a rehabilitation case study simulation.

Multisource solid waste development of low-carbon ultra-light foamed insulation materials: A feasibility study

The continuous increase in building energy consumption, and the increasing types and quantities of solid waste have seriously hindered the rapid development of social economy. Therefore, reducing building energy consumption while realizing the recycling of waste has become the mainstream topic of environmental protection construction in the new era. An alkali-activated ultra-light foamed insulation material (AFIM) for building walls was prepared using EPS particles as lightweight aggregates. The effects of EPS dosage, particle size, and gradation on the compressive strength, dry density, thermal conductivity, and volumetric water absorption of AFIM were studied. The results showed that while ensuring good mechanical properties of AFIM, EPS particles can significantly reduce the dry density, thermal conductivity, and volumetric water absorption of AFIM. Excitingly, the optimal thermal conductivity and dry density of AFIM were 0.0408 W/(m·K) and 127.03 kg/m3, respectively. The microscopic morphology results showed that there was good compatibility between EPS particles and AFIM slurry, and the interface transition zone (ITZ) between them was dense and without obvious cracks. In addition, the feasibility of AFIM was evaluated from four aspects: performance, energy consumption, carbon emissions, and life cycle cost (LCC). It was encouraged that the performance of AFIM was comparable to that of traditional insulation materials, and showed significant advantages in energy conservation, emission reduction and economic benefits compared to traditional insulatin materials.

Development of ultra-light foamed insulation materials and interfacial bond behavior with fiber-reinforced alkali-activated composites

Due to the complex construction process, short service life and serious environmental pollution, the traditional insulation engineering and formwork engineering have caused great challenges and obstacles to the realization of the " dual carbon " goal. This study developed a new green external insulation system that integrates insulation and formwork based on alkali activation technology. The preparation technology of ultra-light foam insulation material (ULFIM) and the interface design method between ULFIM and fiber reinforced alkali-activated composite material (FRAC) were proposed. The effects of rice husk ash (RHA) and polyethylene (PE) fiber content on the dry density, thermal conductivity, compressive strength, volumetric water absorption, and pore structure parameters of ULFIM were studied. The effects of groove width, groove depth, groove spacing, and groove density on the interfacial bond behavior of FRAC-ULFIM were discussed. The microstructure of ULFIM and the interface transition zone morphology of FRAC-ULFIM and FRAC-extruded polystyrene (XPS) were observed using scanning electron microscopy (SEM), and the mechanism of influencing factors on the corresponding indicators were revealed. The results showed that adding an appropriate amount of RHA and PE fiber had a significant positive effect on improving the performance of ULFIM. In the past, the optimal dry density and thermal conductivity of ULFIM were only 191.5 kg/m3 and 0.0494 W/(m·K), respectively, and the compressive strength at 7 d could be as high as 0.49 MPa. In addition, interface shear performance test results have shown that the "bridging effect" of PE fiber can effectively improve the shear strength and ductility of FRAC-ULFIM, which was 23.7% higher than the interface shear strength of FRAC-XPS under the same conditions. The groove treatment increased the interfacial shear strength of FRAC-ULFIM from 74.59 kPa to 266.37 kPa, with a maximum increase rate of 257.11%. The proposed new green external insulation system has significant potential application value.

Revealing the impact of isolated pores on the properties of foam cement using hollow microspheres

Since foam concrete inevitably leads to foam bursting and merging during the molding process, the relationship between specific pore connectivity and pore diameter distribution on foam concrete properties is still difficult to characterize exactly. This study intentionally introduced hollow microspheres of three sizes (40 µm, 60 µm, and 80 µm) into foam concrete to control the number and diameter of isolated pores. The influence of isolated porosity and pore diameter distribution on the properties of foam concrete were evaluated by dry density, mechanical property and thermal conductivity. Meanwhile, the SEM and X-CT technologies were employed to assess the pore structure of the sample, and the measured thermal conductivity was compared with the theoretical thermal conductivity calculated by the formula based on the isolated porosity. Finally, the correlation between isolated pores and heat transfer paths were analyzed by the calculated tortuosity. The results of the dry density and mechanical tests indicated that the dry density tended to be lower with the increase of isolated pores’ diameter, which 80 µm hollow microspheres resulted in a notable reduction in the dry density within the three size groups, whereas 28 days compressive strength trended oppositely. The 40 µm hollow microsphere specimen with a dry density of 400 kg/m3 exhibited the better mechanical property among three groups, which was 1.82 MPa, due to the uniform distribution within the matrix, preventing fusion between foams. Specifically, the trend of the theoretical value calculated by the formula was consistent with that of the measured value, proving that the decrease in thermal conductivity of sample can be attributed to the increase of isolated porosity. The lowest thermal conductivity and highest tortuosity were achieved by specimens mixed with 80 µm hollow microspheres at the dry density of 300 kg/m3, which were 0.07045 W/(m·K) and 2.015, respectively, demonstrating that specimens mixed with 80 µm hollow microspheres exhibited a more complex heat transfer path than the other two groups.

Extended hygrothermal characterization of unstabilized rammed earth for modern construction

Although hygrothermal properties of rammed earth represent great potential for improving thermal comfort during hot summers, still little knowledge is available about this topic. The literature lacks complete sets of hygrothermal characteristics of rammed earth, although they are fundamental for heat and moisture transfer modeling necessary to predict earthen building performances. The present work reports the results of a large collaboration between four academic laboratories in order to obtain an extended hygrothermal characterization of rammed earth, focusing on the material used in a modern construction in Lyon, France. The aim of the article is to provide for the same kind of soil an extend characterization on a large span of relative humidity to provide complete set of material properties for heat and moisture transfer simulation. The hygrothermal measurements cover adsorption and desorption isotherm, intermediate isotherm loop, specific heat capacity, dry thermal conductivity, moisture-dependent thermal conductivity and water vapor resistance factor for a large span of relative humidity. In addition, the capillary rise test was performed to estimate the liquid transport coefficient for suction and redistribution. The results show that variations in the density of the samples have a low impact on sorption isotherm, while they have a non-negligible impact on thermal conductivity and water vapor permeability. Surprisingly, variations in the grain size distribution do not produce a significant modification in the sorption isotherm, while hysteresis slightly reduces when bigger grains are added to the soil composition. Approximation of empirical model coefficients for the determination of moisture-dependent thermal conductivity is proposed for rammed earth materials.

Some properties of thermal insulating cement mortar using Ponza aggregate

Abstract Lightweight aggregate (LWA) mortar is made using lightweight or low-density aggregate, which improves properties such as thermal insulation, durability for freezing and thawing, fire and temperature resistance, and sound insulation. This research aims to use lightweight fine aggregate obtained from crushing natural rocks that are locally called “Ponza” to produce LWA mortar with different mix proportions to study the possibility of using it to produce blocks that can be erected on the outer side of the walls of old buildings to provide good thermal insulation. It also presents a study about the internal curing property of the produced cement mortar, which comes from the absorbed water by the used surface-saturated dry Ponza aggregate. The process includes using three mix proportions (1:1, 1:0.7, and 1:0.5) by weight of cement: fine aggregate. The samples were cured by dividing them into five groups, including moist curing for 1, 3, 7, and 28 days and the fifth group was moist cured for 1 day and then covered by a thin layer of flan coat. Dry density, compressive strength, flexural strength, and thermal conductivity for ages (7, 28, and 56 days) have been tested. The findings indicate that it is possible to produce thermal insulating lightweight cement mortar with mixtures of 1:0.7 or 1:0.5 cement to LWA, using Ponza aggregate, since the results showed an acceptable range of compressive and flexural strengths reaching about 14.75 and 2.91 MPa, respectively, a bulk density of less than 1,600 kg/mm3, and a lower thermal conductivity than many building materials.

Thermal conductivity of dried biocemented sand at higher calcification

Thermal conductivity of dried biocemented sand at higher calcification