Search Results (17)

This study investigates the fire resistance capabilities of newly developed loose-fill thermal insulation materials crafted from annual plants such as wheat straw, corn stalk, and water reed. Three processing methodologies were employed: mechanical crushing (raw, size ≤ 20 mm), chemi-mechanical pulping (CMP) using 4% sodium hydroxide, and steam explosion (SE). An admixture of boric acid (8%) and tetraborate (7%) was added to all treated materials to enhance fire retardancy. The fire reaction characteristics of the insulation materials were assessed using a cone calorimeter measuring the key parameters like time to ignition, total heat release, heat release rate, and total smoke production. The findings indicate that nearly all tested insulation samples, apart from the raw and SE water reed, demonstrated fire resistance comparable to commercial cellulose insulation, surpassing the fire performance of various synthetic foams and composite materials. Furthermore, the single-flame source fire tests indicated that the developed insulation materials achieved a fire classification E, except for the SE water reed sample. Thus, the fire performance results approve the suitability of developed plant-based insulation materials for competing materials in building constructions. Full article

Loose-fill thermal composite insulation produced from surface-modified wood scobs has been explored as a potential fire-resistant material for building envelopes. This work involves fire resistance behavior comparisons between four coating systems consisting of liquid glass, liquid glass-tung oil, liquid glass-expandable graphite, and liquid glass-tung oil-expandable graphite. The techniques of thermogravimetric and differential thermogravimetric analyses, gross heat combustion via a calorimetric bomb, cone calorimetry, SEM imaging of char residues, and energy dispersive spectrometry for elemental analysis, as well as propensity to undergo continuous smoldering, were implemented. The coating technique resulted in greater thermal stability at a higher temperature range (500–650 °C) of the resulting loose-fill thermal composite insulation, reduced flame-damaged area heights after the exposure of samples at 45° for 15 s and 30 s, with a maximum of 49% decreased gross heat combustion, reduced heat release and total smoke release rates, improved char residue layer formation during combustion and changed smoldering behavior due to the formation of homogeneous and dense carbon layers. The results showed that the highest positive impact was obtained using the liquid glass and liquid glass-expandable graphite system because of the ability of the liquid glass to cover the wood scob particle surface and form a stable and strong expanding carbon layer. Full article

The increasing requirements concerning the consideration of the environmental impact of building materials, along with the simultaneous preservation and enhancement of building thermal parameters, have led to a surge in interest in insulations based on organic or recycled materials. Despite the growing interest in these materials, there remains a scarcity of scientific studies regarding their hygrothermal properties. Within the scope of the research described in the text, the insulation properties of loose-fill materials (hemp shives, cellulose fibers, loose wood wool, and mineral wool as a reference) in wooden frame walls were analyzed. The authors simulated walls with the same U value filled with these materials using Delphin 6.1 software. The simulation time was 3 years, considering the appropriate climatic conditions of Olsztyn and different microclimatic conditions inside the rooms. Insulations made of natural organic can absorb and reveal moisture to the internal environment, while mineral wool transports the moisture to the outside, which may cause condensation problems. Insulations made of hemp shives or wood wool do not increase the level of accumulated moisture over time, which results in thermal stability. In contrast, cellulose and mineral wool store more moisture, which in wet conditions increases the heat flux by 6.9% and 5.2%, respectively. Full article

Three-dimensional concrete printing (3DCP) is of great interest to scientists and the construction industry to bring automation to structural engineering applications. However, studies on the thermal performance of three-dimensional printed concrete (3DPC) building envelopes are limited, despite their potential to provide a long-term solution to modern construction challenges. This work is a numerical study to examine the impact of infill geometry on 3DPC lattice envelope thermal performance. Three different lattice structures were modeled to have the same thickness and nearly equal contour lengths, voids, and insulation percentages. Additionally, the effects of filament width and the application of granular insulating materials (expanded polystyrene beads and loose-fill perlite) were also studied. Finally, the efficacy of insulation was established. Results show that void area affects the thermal performance of 3DPC envelopes under stagnant air conditions, while web length, filament width, and contact (intersection) area between the webs and face shells affect the thermal behavior when cavities are filled with insulating materials due to thermal bridging. The thermal efficiency of insulation, which shows the effective use of insulation, varies between 26 and 44%, due to thermal bridges. Full article

The present study evaluates the mold fungal resistance of newly developed loose-fill thermal insulation materials made of wheat straw, corn stalk and water reed. Three distinct techniques for the processing of raw materials were used: mechanical crushing (Raw, ≤20 mm), thermo-mechanical pulping (TMP) with 4% NaOH and steam explosion pulping (SEP). An admixture of boric acid (8%) and tetraborate (7%) was applied to all processed substrates due to their anti-fungal properties. The fourth sample group was prepared from SEP substrates without added fungicide (SEP*) as control. Samples from all treatments were separately inoculated by five different fungal species and incubated in darkness for 28 days at 28 °C and RH > 90%. The highest resistance to the colonization of mold fungi was achieved by TMP and SEP processing, coupled with the addition of boric acid and tetraborate, where molds infested only around 35% to 40% of the inoculated sample area. The lowest mold fungi resistance was detected for the Raw and SEP* samples, each ~75%; they were affected by rich amount of accessible nutrients, suggesting that boric acid and tetraborate additives alone did not prevent mold fungal growth as effectively as in combination with TMP and SEP treatments. Together, the achieved fungal colonization scores after combined fungicide and pulping treatments are very promising for the application of tested renewable materials in the future development of thermal insulation products. Full article

This research aimed to compare the transport capacity of loose-fill mineral wool, cellulose fibers, and wood wool to transfer moisture under steady-state conditions. The tests were carried out in the heat flow meter apparatus, which created a constant thermal field, limiting samples of sorptive moistened materials. The thermal conductivity, stabilization time, and moisture content of the samples were measured. Based on the variation in the results, the dynamism of moisture transport in the materials was determined. Mineral wool samples showed the lowest sorption. As a result, the moisture transport in this material stopped the fastest. In the case of cellulose and wood fibers, moisture transport continued throughout the whole test procedure. It was noted that the amount of moisture transport is influenced primarily by the structure of the fibers, the moisture content, and the possible presence of air in the pores. The wetter the material, the faster the transport. The dynamism of moisture transport according to trends of thermal conductivity changes over time was analyzed. The greater the slope of the linear regression line, the greater the dynamics of change. The smallest dynamics of change were found for mineral wool, for which the measured slope was between −0.008 and −0.033. For cellulose and wood wool, the range of slope was from −0.141 to −0.210, and from −0.162 to −0.211, respectively. The results of this research may provide the basis for further work on buffering moisture in the adjacent internal layers of the frame walls. Full article

Loose-fill thermal insulations in timber-frame structures are designed to provide efficient thermal protection with the ability to fill intricate details. In a previous study, we detected several air cavities formed in timber-framed wall samples filled with loose-fill mineral fiber insulation. This discovery led us to retrofit the walls by adding appropriate insulation, thus enabling us to evaluate the importance of proper amendment. This paper focuses on a wall fragment with an 80 mm high air gap at the top and a 30 mm high cavity in the middle of the wall height. The following paper compares data collected before the discovery and after the replenishment (refill of air gaps with additional insulation), evaluating potential thermal performance improvement. We were able to quantify the impact of these defects on the external wall exposed to realistic conditions. Based on temperature and relative humidity measurements, the results show significant advancement in the middle of wall thickness with an 8 °C and 45% difference. The results show that although this defect did not directly affect the energy balance of the building, it significantly increases the risk of mold growth due to thermal bridging. Full article

This paper addresses the plastic waste management challenge by proposing a sustainable solution for the building sector. The proposed solution uses Loose-Fill Plastic Waste (LFPW) as a thermal insulation material, the world’s first in plastic waste recovery. To investigate the potential of this new path, an experimental study was conducted on test cells in Reunion Island’s cold and wet climate. It was revealed that LFPW (size between 3 and 4 mm with 8 cm thickness) can reduce surface temperatures by nearly 3.2 °C, with a maximum difference by almost 22.2 °C. The thermal phase shift is significant (190 mn) and comparable to conventional thermal insulation solutions. The study results suggest that LFPW can provide an effective and economical solution to the challenge of plastic waste management while promoting sustainable development. Full article

Lignocellulosic biomass (LCB)-based thermal insulation materials available in the market are more expensive than conventional ones and consist mainly of wood or agricultural bast fibers which are primarily used in construction and textile industries. Therefore, it is crucial to develop LCB-based thermal insulation materials from cheap and available raw materials. The study investigates new thermal insulation materials from locally available residues of annual plants like wheat straw, reeds and corn stalks. The treatment of raw materials was performed by mechanical crushing and defibration by steam explosion process. Optimization of thermal conductivity of the obtained loose-fill thermal insulation materials was investigated at different bulk density levels (30–45–60–75–90 kg m⁻³). The obtained thermal conductivity varies in range of 0.0401–0.0538 W m⁻¹ K⁻¹ depending on raw material, treatment mode and a target density. The changes of thermal conductivity depending on density were described by the second order polynomial models. In most cases, the optimal thermal conductivity was revealed for the materials with the density of 60 kg m⁻³. The obtained results suggest the adjustment of density to achieve an optimal thermal conductivity of LCB-based thermal insulation materials. The study also approves the suitability of used annual plants for further investigation towards sustainable LCB-based thermal insulation materials. Full article

The current study presents the results of monitoring the behavior of loose-fill thermal insulating material for buildings made of wood scobs (WS), which were coated with one, two, and three component-based coatings from liquid glass (LG), tung oil (TO), and expandable graphite (EG). The thermal conductivity of samples in the dry state and under normal laboratory conditions, short-term water absorption by partial immersion, surface wettability, and water vapor permeability were evaluated, and regression equations describing the variations in numerical values of specified properties under different amounts of each coating component were presented. It was shown that LG and TO act as hydrophobic layers that, in conjunction, reduce water absorption by a maximum of 274%, have a contact angle equal to 86°, and lower thermal conductivity by 55% in the dry state due to the specifics of the layer formed on the surface of WS. The addition of EG to LG coating resulted in insignificantly changed water absorption and thermal conductivity values, indicating the potential of this material to be used to improve the fire resistance of wood-based composites in the future. The results showed that the three-component layer of LG/TO/EG reduces water absorption by a maximum of 72%, increases thermal conductivity in the dry state by a minimum of 0.4%, and increases the contact angle to 81° at 100 wt.% LG. The changes in water vapor permeability of all compositions were determined to be insignificant. Full article

The article presents the results of studies concerning raw hemp shives obtained from the Polish crop of industrial hemp as a loose-fill thermal insulation material. The study focuses mainly on the measurements of the pore size distribution, thermal conductivity and air permeability of material. An increase in the value of the thermal conductivity coefficient (0.049–0.052 W/(m·K)) was demonstrated with an increase in the bulk density. The porosity of the individual pieces of shives is 78.7% and the predominant number of pores is in the diameter range of 0.9–3 μm. The paper also presents an example of the use of the tested material as thermal insulation of the wooden frame wall. The heat flow analysis was performed in various wall variants (insulation thickness: 100, 200 and 300 mm and pressure difference 0, 5, 10 and 15 Pa). A clear influence of the variables on the temperature distribution was observed. Full article

Current environmental crisis calls for sustainable solutions in the building industry. One of the possible solutions is to incorporate timber-framed constructions into designs. Among other benefits, these structures are well established in many countries, originating in traditional building systems. This paper focuses on experimental timber-frame walls. Different wall assemblies vary in thermal insulation materials and their combinations. We investigated ten experimental wall structures that have been exposed to natural external boundary conditions since 2015. The emphasis was on their state in terms of visual deterioration, mass moisture content, and thermal conductivity coefficient. We detected several issues, including defects caused by inappropriate realization, causing local moisture increase. Material settlement in loose-fill thermal insulation was another issue. Concerning was a significant change in the thermal conductivity of wood fiber insulation, where the current value almost doubled in one case compared to the design value determined by the producer. Full article

Pumice quarried by LAVA MINING & QUARRYING SA from Yali island, Dodecanese, is used, domestically and abroad, in applications such as concrete lightweight aggregate, masonry units constituent, road substrate, and loose soil stabilization. It is a porous natural volcanic rock with low density, low thermal and noise transmission, and higher strength among all the natural or artificial lightweight materials of mineral origin. Nowadays, pumice is of additional interest, as it has a reduced CO₂ footprint because thermal energy is not required for its expansion compared with artificial lightweight aggregates. In this context, HERACLES Group is launching a new product in the market under the brand name MASTER FLOOR^®, a commercial bagged product for floor or wall fillings with lightweight and insulating properties. Full article

The paper presents the results of research concerning three fiber materials—mineral wool, hemp fiber and wood wool—as loose-fill thermal insulation materials. The analysis used the material parameters determined in previous works conducted by the authors, such as thermal conductivity and air permeability in relation to bulk density. These materials exhibit open porosity; thus, convection is an essential phenomenon in the heat transfer process. The paper aimed at conducting thermal simulations of various frame wall variants which were filled with the above-mentioned insulation materials. The simulations were performed with the Control Volume Method using the Delphin 5.8 software. The studies accounted for the effect of wind pressure and the time of its influence on a wall insulated by means of fiber material with a thickness of 150 as well as 250 mm. The simulation enabled us to obtain such data as maximal R-value reduction and time to return to equilibrium after filtration for the analyzed materials. The study proved that heat transfer in these insulations strongly depends on the bulk density, thickness of the insulation and wind pressure. The decrease in R is reduced as the density increases. This results from the decreased air permeability characterizing the material. Wind washing causes lower R reduction than air filtration in all models. The greater the thickness, the longer it takes for the models to return to the equilibrium state following air filtration (and wind washing). This period is comparable for air filtration and wind washing. Hemp fibers were characterized with the strongest susceptibility to air filtration; in the case of wood wool, it was also high, but lower than for hemp fibers, while mineral wool was characterized with the lowest. Full article

Currently, the recycling potential of wood waste (WW) is still limited, and in a resource efficiency approach, recycling WW in insulation materials, such as polyurethane (PUR), appears as an appropriate solution. It is known that the quality of WW is the main aspect which influences the stability of the final products. Therefore, the current study analyses different WW-based fillers as possible modifiers for polyurethane biocomposite foams for the application as loose-fill materials in building envelopes. During the study of WW-based fillers, it was determined that the most promising filler is wood scobs (WS) with a thermal conductivity of 0.0496 W/m·K, short-term water absorption by partial immersion—12.5 kg/m², water vapour resistance—0.34 m²·h·Pa/mg and water vapour diffusion resistance factor—2.4. In order to evaluate the WS performance as a filler in PUR biocomposite foams, different ratios of PUR binder and WS filler (PURb/WS) were selected. It was found that a 0.40 PURb/WS ratio is insufficient for the appropriate wetting of WS filler while a 0.70 PURb/WS ratio produced PUR biocomposite foams with the most suitable performance: thermal conductivity reduced from 0.0523 to 0.0476 W/m·K, water absorption—from 5.6 to 1.3 kg/m², while the compressive strength increased from 142 to 272 kPa and the tensile strength increased from 44 to 272 kPa. Full article