Calcium Silicate Board Research Articles

Thermal performance assessment of sandwich wall panel fabricated with polyurethane foam and natural husk

The demand for enhancing thermal efficiency in building construction has accelerated the evolution of sandwich wall panels in recent years. In this study, the novel sandwich panel is developed using Polyurethane (PU) as core and PU replaced with Rice husk (RH) and Coconut Husk (CH) at varying percentage (10, 20, 30, 40 and 50 %) with calcium silicate board as outer material. Dimension of sandwich panel is 30 × 30 cm with 3 cm as a core thickness is tested for compressive strength. The panel owing highest compressive load with combination of Polyurethane foam Coconut Husk panel at 20 % (PUC3–20 %) and polyurethane foam Rice husk panel at 30 % (PUR3–30 %) was taken further for thermal analysis. The temperature study was carried out on a prototype model using IR thermographic camera showing the temperature difference of indoor and outdoor of the sandwich panel. The PUR3–30 % shows the thermal conductivity of 0.28 w/mk and the difference of thermal heat flux was 10.42 W/m2. Regression analysis was carried out to validate the experimental results and the correlation accuracy of R2 > 0.90 was obtained. A residential building (G+3) was created in Autodesk Revit to conduct an energy analysis audit, where all the data of fabricated sandwich panel was added as new material and the analysis was carried out in green building studio. The annual energy and annual fuel end use for Heating Ventilation and Air Conditioning (HVAC) has been decreased by 3.5 and 4.5 % using PUC3–20 % and PUR3–30 % panels compared to the base material.

Preparation of a lightweight calcium silicate board using chlorine-containing Ti-extraction blast furnace slag and diatomite

Preparation of a lightweight calcium silicate board using chlorine-containing Ti-extraction blast furnace slag and diatomite

Bending analysis of textile reinforced concrete sandwich panels: Experimental and numerical evaluation

Textile reinforced concrete (TRC) is a combination of a cementitious matrix and a textile reinforcement that has good mechanical properties. This makes a highly promising composite material for a wide range of construction practices. One notable application of this innovative composite deals with the production of thin sandwich panels. Hence it is noteworthy to examine the control parameters (depth & number of layers) that affect the mechanical properties of TRC sandwich panels with chosen fibre meshes and core material.Initially, 24 different TRC panels were cast and modelled with varying depths (45 mm, 55 mm and 65 mm) and layers (3, 4, 5 and 6), incorporating two different fibre mesh reinforcements. The flexural behavior of these panels was studied both experimentally and numerically using ABAQUS software. The optimized control parameters was obtained from the results was TRC panel of 5 layers of Aramid fibre mesh having 55 mm depth.Further exploration focused on the effect of overall depth variation on the flexural behavior of TRC sandwich panels. A panel with Aramid fibre reinforcement and a calcium silicate board core, featuring a 55 mm overall depth, exhibited a remarkable 69.49 % increase in bending stress compared to a panel with a depth of 118 mm. These findings underscore the significance of optimized control parameters, showcasing the potential for enhancing the mechanical performance of TRC sandwich panels in construction practices.

CO2-Cured Fiber-Reinforced Board from Low-Calcium Clinker: Key Synthesizing Factors, Carbonation Products, and Comparison to Autoclaved Calcium Silicate Board

CO2-Cured Fiber-Reinforced Board from Low-Calcium Clinker: Key Synthesizing Factors, Carbonation Products, and Comparison to Autoclaved Calcium Silicate Board

Experimental studies on the mechanical behaviors of cold-formed thin-walled steel-foam concrete composite walls

This paper presents experimental studies to investigate the compressive and shear behaviors of cold-formed thin-walled steel-foam concrete composite walls. Three compressive walls and three shear walls were tested. The failure mode and load-displacement curve of the specimen were obtained from the compressive experiment. The compressive wall infilled with foam concrete mainly experienced distortion buckling of the end stud and local crushing failure of the concrete. The stud openings had a limited effect on the compressive bearing capacity of the composite wall. The failure mode and load-deformation curve were obtained in shear tests. The ductility index, shear stiffness, yield load, peak load, energy dissipation, and stiffness degradation were analyzed. The shear composite wall filled with foam concrete mainly occurred concrete crushing failure, local or distortional buckling failure of the end stud, and cracking failure of the calcium silicate board. The shear stiffness, shear capacity, ductility, and energy dissipation of the composite wall could be significantly improved after filling with foam concrete.

Experimental study on preparation and performance of the Corn Straw Fiber (CSF) reinforced EPS concrete

With the full factor experimental design method carried out, 20 sets of EPS concrete specimens with different mass fractions of Corn Straw Fiber (CSF) and Expanded-Polystyrene (EPS) particles were designed to study their density, water absorption, compressive strength, flexural strength, splitting tensile strength, mass loss and strength loss after freeze-thaw cycles, and changes in thermal conductivity, to evaluate the effect of CSF content and EPS content on the properties of EPS cement-based composites. The experimental results show that adding CSF can improve the mechanical properties of EPS concrete while reducing its density, the maximum increase rate of compressive strength is 69.7 %, with a maximum value of 1.12 MPa; The maximum improvement rate of flexural strength is 127.38 %, with a maximum value of 0.885 MPa; The maximum improvement rate of splitting tensile strength is 68.07 %, and the maximum value is 0.256 MPa. After 50 standard freeze-thaw cycles, straw fibers can delay the quality loss of EPS concrete, but show adverse effects on its strength loss, the maximum quality loss rate is 4.23 %, and the maximum loss rates for the three strengths are 24.46 %, 24.22 %, and 24.61 %, respectively. In addition, in terms of improving the thermal insulation performance of EPS concrete, the role of the two aggregates is manifested as EPS > CSF, and the thermal conductivity coefficient values under different aggregate dosages were obtained, when the content of EPS is 1.4 % and the content of CSF is 4 %, the minimum thermal conductivity value is 0.0402 W/(m·°C), and the thermal conductivity coefficient of calcium silicate board is 0.0378 W/(m °C) by the thermal conductivity coefficient formula of composite materials. which can serve as a reference for selecting building insulation materials in areas with high temperature differences.

Experimental study on the fire resistance of all-composite and hybrid web-core sandwich panels for building floors

Fibre-reinforced polymer (FRP) composites and polymeric foams used in construction are susceptible to elevated temperatures, but little is known about the behaviour of composite sandwich panels under fire exposure. This paper presents an experimental study on the fire resistance of web-core composite sandwich panels with polyurethane foam infill for building floors. Two panel variants were considered: (i) an all-composite panel, with glass-FRP (GFRP) face sheets and webs; and (ii) a hybrid panel, with an additional fibre reinforced concrete (FRC) top layer. Five full-scale specimens were loaded in a four-point bending configuration, subjected to a constant service load, and subsequently exposed to a standard fire (ISO 834) on their bottom face. The effectiveness of passive fire protection systems, consisting of calcium silicate boards installed either adherent to the panels or forming an air cavity, was assessed. The following features were investigated: (i)temperature progression across the thickness of the panels, (ii)their mechanical response, (iii)failure modes, and (iv)fire resistance. The results obtained indicate that despite the vulnerability of composite sandwich panels to fire, relatively high fire resistances of 44 min and 49 min were obtained for the unprotected web-core all-composite and hybrid variants, respectively. The failure mechanism of the sandwich panels generally involved local compression and in-plane shear failure of the webs. The use of suitable passive fire protections provided significant fire resistance increases of at least 45 min (adherent) and 60 min (with air cavity), allowing to exceed the 90 min threshold.

Impact of air entrapment on capillary absorption in porous building materials

When the water content of a porous material is high, air entrapped in the pore space is expected to affect water transfer through the pores. To understand the effects of air entrapment on water transfer in porous building materials in the high-water-saturation region, we examined the water transfer characteristics corresponding to significantly small air entrapment effects. First, we conducted two sets of water uptake experiments. In the first experiment, using three building materials, the time evolution of the amount of water absorption was measured at a low air pressure near vacuum (several kPa). In the second experiment, the water content profile during water uptake was measured using the gamma-ray attenuation method. The experimental results showed that low air pressure accelerated the water uptake by the brick and aerated concrete specimens, whereas water uptake by the calcium silicate board specimens was not significantly affected. These differences among materials were analyzed from a pore structure viewpoint. Moreover, gamma-ray attenuation measurements confirmed that the obtained water content profile was qualitatively similar at atmospheric and low air pressures, although the low air pressure increased both the water content of the material after capillary absorption and the wetting front propagation rate. Finally, simultaneous water and air transfer calculations based on the air and liquid water balance in a material reproduced the measured water absorption rates well, confirming that air entrapment and pressure development in the pores can significantly reduce the rate of water uptake and water content after capillary absorption. The calculation results also indicated that the air pressure in a material did not significantly increase at early water uptake stages where local water content was not high, which supported the general assumption that treating the liquid-water transfer in porous building materials as a one-component flow is valid in most cases.

Axial performance of cold-formed steel single-stud wall panels with dissimilar fibre-cement and calcium silicate boards sheathing configuration

In practical applications, it is typical for different types of sheathings (referred to as dissimilar) to be connected at both flanges of the stud (lipped channel-section) in cold-formed steel (CFS) panelised construction (e.g. one-side has interior sheathing and the other exterior sheathing). However, limited studies are available on the axial behaviour of CFS studs with different combinations of sheathings present at both-flanges of a stud. This novel experimental study investigates the structural behaviour of fourteen (14) CFS panels with sheathing on one-side only and different sheathing on both flanges of the wall panel using combinations of seven (7) different sheathing boards [fibre-cement boards (FCB) (8 mm/10 mm/12 mm thick); calcium silicate boards (CSB) (12 mm thick); and heavy duty FCB (6 mm/9 mm/12 mm thick)]. The ultimate axial strength, load-deformation behaviour and failure patterns are the parameters compared. Analytical/semi-analytical design methodologies namely; Rayleigh-Ritz (R-R) method, finite-strip method based on direct strength method (DSM) and differential equation of equilibrium method (DEEM) are validated based on the experiments. Limited studies are available to verify the efficacy of these methods to estimate the axial strength of CFS wall panels with dissimilar sheathing on both flanges. Results establish that DSM may be used efficiently rather than the R-R method and DEEM.

Three-dimensional finite element modelling of the fire response of passive and prestressed near-surface mounted (NSM)-CFRP-strengthened reinforced concrete slab strips

This paper presents a numerical study about the fire behaviour of reinforced concrete (RC) slab strips strengthened with passive and prestressed carbon fibre reinforced polymer (CFRP) laminates installed according to the Near-Surface Mounted (NSM) technique. 3D finite element models were developed to simulate fire resistance tests in which the NSM-CFRP-strengthened-RC slab strips were simultaneously subjected to a service load and the ISO834 fire. The CFRP-concrete interface was modelled through temperature-dependent bi-linear bond-slip laws. In addition to the prestress levels applied to the CFRP (0%, 25% and 50% of their tensile strength), the presence/geometry of fire protection (calcium silicate boards) was also assessed. The comparison between numerical and previous experimental results showed the models accuracy in predicting the thermo-mechanical response of fire exposed passive and prestressed NSM-CFRP-strengthened-RC slab strips, presenting a fire resistance decrease when the prestress increased from 0% to 50%, from 13to 6 min when no fire protection was used, and from 152to 127 min with fire protection. The numerical results allowed predicting the decrease of critical temperature in the CFRP anchorages with the prestress increase: 3.4–3.6Tg, 3.0Tg, and 2.1–2.4Tg respectively for prestress levels of 0%, 25% and 50% (Tg – adhesive’s glass transition temperature).

In-situ temperature monitoring of an internal insulated wall in a historic building

The subject of the contribution is the evaluation of in-situ monitoring of an internally insulated wall in a historical building in Levoča. The paper compares the development of surface temperatures, temperatures under the thermal insulation and temperatures in the masonry at a depth of 100 mm when using calcium silicate board and phenolic foam. The temperatures of the insulated walls are compared with the reference temperatures of the uninsulated wall. As part of the measurements, the parameters of the internal environment are also monitored. The aim of the contribution is to quantify the effect of internal insulation on the development of temperatures in the perimeter structure and its effect on the quality of the internal environment.

Transforming oyster shell and rice husk biowaste into functional calcium silicate board with highly-efficient photo-enhanced antimicrobial activities

Green construction materials based on biomass waste are attracting tremendous research attention in recent years as a means to satisfy the low-cost and sustainable construction requirements in the modern building industry. In this work, the use of oyster shell and rice husk biowaste as raw materials for the environment-friendly preparation of calcium silicate boards is presented. To endow the calcium silicate boards with an antimicrobial functionality, CuSe/CaCO3 is incorporated. The antimicrobial effect is credited to the presence of CuSe nanoparticles, which are capable of inhibiting microbial growth through light-induced generation of radicals, release of copper ions, and photothermal heating. The fabrication process of the antimicrobial calcium silicate boards is optimized by studying the effect of different loading amounts and processing conditions. It was determined that the calcium silicate board that exhibits the most satisfying flexural strength and antimicrobial efficacy can be prepared using the following parameters: Ca/Si ratio of 0.83, molding pressure of 30 MPa, curing temperature of 180 ℃, curing time of 10 h, and 10 wt% of CuSe/CaCO3. Our work might shed light on the sustainable preparation of functional calcium silicate boards through valorization of biowaste. The utilization of biowaste as building materials can significantly aid in mitigating environmental pollution and in lowering the overall cost of construction.

The Study of Carbonyl Emissions and Ozone Removal on Green Recycled Building Materials

Green recycled building materials (GRBMs) have the potential to reduce carbon footprint but with insufficient emission information. The increasing application of GRBMs may affect human health due to potential primary and/or secondary emissions. This study centers on assessing carbonyl emissions and ozone removal on green recycled building materials under ozone exposure circumstances. Tested materials include gypsum board (GB), waterproof gypsum board (WGB), fiber cement board (FCB), and calcium silicate board (CSB). Among all the observed carbonyls, methacrolein and formaldehyde were the only two that could be found on all four recycled building materials. All carbonyl compounds had relatively high emission factors at the beginning of the experiment and decreased to a relatively lower level one month later. Carbonyl emissions were about 33.3%, 38.9%, 42.0%, and 8.0% of their original values for WGB, FCB, CSB, and GB, respectively. The ozone removal efficiencies at the beginning and one month later were 63.26±6.11% and 61.59±5.46% on CSB, 55.74±4.94% and 47.16±7.97% on FCB, 54.59±6.50% and 34.93±6.77% on GB, and 53.63±8.40% and 23.49±6.63% on WGB, respectively. CSB seems to be a healthier recycled building material compared with WGB, GB, and FCB in terms of low carbonyl emissions and high ozone removal efficiency.

Capillary condensation redistribution (CCR) test: measurement results of 5 materials and comparison to modelling

To improve the accuracy of hygrothermal modelling, a capillary condensation redistribution (CCR) has been proposed to help distribute the share of vapour and liquid conductivity functions based on a wider experimental dataset. This paper aims to provide further data by presenting the CCR test measurement results of 2 calcium silicate (CaSi) boards, 2 aerated autoclaved concrete (AAC) boards and spruce (the latter both perpendicular and parallel to the grain). A variation of the CCR test setup is described. The measurement results agree with those from literature where some of the materials presented here were also tested. Modelling results using previously available material properties are compared to measurement results: none of the AAC and longitudinal spruce material properties can reproduce the moisture content levels achieved in the study, while CCR-optimized CaSi material data is close to the measured results. The best agreement between measurements and modelling of spruce perpendicular to grain are achieved with material properties which discard liquid conductivity and presume increased vapour permeability due to increase of moisture content instead.

Hygrothermal Modelling of one-dimensional Wall Assemblies: inter-model Validation between WUFI and DELPHIN

Various Heat-Air-and-Moisture models may give divergent results for the same case, due to differences in assumptions, simplifications, or approximations. Inter-model comparisons have been used as ‘peer review’, but common limitations and/or mistakes may remain concealed. Recent validation efforts, confronting simulations with measured datasets, use limited materials, configurations, and boundary conditions. A thorough and stepwise assessment is still lacking. In this study, dedicated hygrothermal experiments on four wall assemblies (comprising calcium silicate board, mineral wool, wood fiber board and vapor barrier in different configurations) are conducted in a hot box-cold box at KU Leuven, Belgium as a benchmark. Temperatures, relative humidity, heat fluxes and moisture mass are monitored while the thermal and hygric properties of the materials from the same batch are measured. One dimensional simulations in WUFI and DELPHIN are employed to reproduce the experiments in three stages: (1) “similar” materials (with the closest properties) from respective databases provide realistic trends but also significant deviations; (2) “same” materials (attained by mathematical translation) give better agreement but uncertainties in material properties and simplifications still have great influence; (3) monitored datasets are employed to compare with simulated results using measured material properties, based on which a collaborative inter-model blind-box validation has been initiated.

Water uptake of porous building materials with extremely small air entrapment effects

When a porous material is near capillary saturation, entrapped air is expected to affect water transfer through the pores. Based on the results of water absorption tests at reduced air pressure, Janssen et al. (Energy Procedia, 2015) demonstrated that air entrapment prevents water absorption above capillary saturation. In this study, to understand the air entrapment effects on water transfer in the high-water-saturation region, we further examined the water transfer characteristics corresponding to extremely small air entrapment effects. First, using three common porous building materials, water uptake experiments were conducted at low air pressure near vacuum (several kilopascals), and the time evolution of the water absorption was measured. The results show that low air pressure accelerates water uptake by brick and aerated concrete specimens, whereas the water uptake by calcium silicate board specimens is not significantly affected. These differences among the materials are discussed from the viewpoint of the pore structure. Furthermore, the results of simultaneous water and air transfer calculations confirm that air entrapment and pressure development in the pores can significantly reduce the rate of water uptake and the water content that a material can reach after capillary absorption.

Fabrication of a sandwich panel by integrating coconut husk with polyurethane foam and optimization using R2

As the need for a sustainable solution increase, waste materials are gaining popularity in building applications to reduce the environmental impact. This study aims to utilize the waste Coconut Husk (CH) and Calcium Silicate Board (CSB) in a sandwich panel where Polyurethane Foam (PU) is used as a binding material which consists of A (isocyanate) and B (polyol) with a mixing ratio of A: B at 1:1.2. CH is obtained as a residue from the production of coconut shells aggregate. The PU has been replaced with CH at 10, 20, 30, 40 and 50 %, to identify the optimum replacement level. Sandwich panels of dimension 30 × 30 cm with a core thickness of 2 and 3 cm was prepared and tested to categorize their mechanical properties, thermal properties, durability properties, characterization study and sound absorption coefficient. The results show that the PU replaced with 20 % of CH has higher compression and flexural properties, owing as an optimum percentage. The inclusion of CH in the PU reduces the cell size and yields a significant improvement in acoustic behavior up to a frequency of 1600 Hz. The regression model was analyzed with the experimental data and validated by the suitable R2 threshold accuracy as R2 > 0.90.

Influence of coconut husk on mechanical properties as a filler with polyurethane foam in the sandwich panel—an experimental study

To reduce the environmental impact of construction, use of waste materials has become popular in building applications. In this study, waste coconut husks (CHs) and calcium silicate boards (CSB) are incorporated into a sandwich panel using polyurethane foam (PU) as binding material. PU is made up of A (isocyanate) and B (polyol), which are mixed at a ratio of 1:1.2. To determine the optimum replacement level, PU was replaced with CH at 10, 20, 30, 40 and 50%. A sandwich panel with an outer dimension of 30 × 30 cm and a core thickness of 2 and 3 cm was prepared and tested for its mechanical properties, thermal properties, durability properties and characterization study. The microscopic image showed that the replacement of PU with CH at 50% showed maximum reduction in porous size, but its composite has achieved higher compressive strength at 20%. Hence the optimum percentage of replacing PU with CH is found to be 20%. Further, analytical work was carried out to validate the experimental results through regression analysis and suitable threshold with an accuracy of R2 > 0.90 was obtained.

Fire behaviour of reinforced concrete slab strips strengthened with prestressed NSM-CFRP laminates

Carbon fibre reinforced polymer (CFRP) composites are now widely used to strengthen reinforced concrete (RC) structures. Among the strengthening systems available, near-surface mounted (NSM)-prestressed CFRP laminates offer several advantages, as they significantly increase the load carrying capacity and also the serviceability performance of RC structures. However, as for other CFRP systems, there is a concern about their behaviour at elevated temperature and under fire exposure due to the glass transition process undergone by their polymeric components. Nevertheless, the fire performance of NSM-prestressed-CFRP strengthening systems has not yet been investigated. This paper presents an experimental study about the fire resistance behaviour of RC slab strips strengthened with prestressed NSM-CFRP laminates; the slabs were simultaneously subjected to a mechanical (fire) load and the ISO 834 fire curve, and the influence of the following parameters on their fire resistance behaviour was assessed: (i) the prestress level (0 %, 25 % and 50 % of the CFRP tensile strength), and (ii) the presence of passive fire protection, comprising up to 48 mm thick calcium silicate (CS) boards. The results obtained showed that: (i) without fire protection, the strengthening system remained effective during a very low period of fire exposure, which significantly decreased with the prestress level, from 16 min (0 %) to less than 5 min (50 %); (ii) with fire protection, even with 50 % of prestress, the strengthening system remained effective for more than 120 min; and (iii) the “critical” temperatures in the anchorages of the strengthening systems were found to be about 2.5Tg, 2.0Tg and 1.5Tg, for the prestress levels of 0 %, 25 % and 50 %, respectively, with Tg being the glass transition temperature of the adhesive.

Preparation of calcium silicate board from tobermorite-rich residue for energy conservation in buildings

The tobermorite-rich residue was derived from coal fly ash after alumina extraction via a hydrothermal process, which was used to prepare calcium silicate board for energy conservation in buildings. By employing a formulation comprising 94 wt% tobermorite-rich residue and 6 wt% pulp, the resultant calcium silicate board exhibited notable characteristics when subjected to a compression pressure of 20 MPa, including a bending strength of 6.75 MPa, a bulk density of 0.63 g/cm3, and a thermal conductivity of 0.14 W/(m·K). Tobermorite within the residue predominantly exhibited a fibrous morphology and formed porous aggregations, which proved advantageous in preparing calcium silicate board of high bending strength and good thermal insulation performance. Furthermore, the tobermorite retained its fibrous morphology even at elevated temperatures exceeding 650 °C, this thermal stability conferred excellent fire resistance performance upon the resulting calcium silicate board. Conclusively, the calcium silicate board prepared from tobermorite-rich residue demonstrated superior performances like good thermal insulation, exceptional fire resistance, light weight and high strength, etc., which would show great potential for use in buildings.