The Effect of Biochar on the Properties of Alkali-Activated Slag Pastes

This paper examines the influence of biochar on the properties of alkali-activated slag pastes using two activator solutions, namely NaOH and Na2CO3. The biochar demonstrated different absorption kinetics in the mixture of slag and the two activator solutions. The pastes with biochar showed a delay in the heat flow peak, compared to the pastes without biochar, but the cumulative heat release in these pastes at later hours was increased, compared to the pastes without biochar. It was found that the use of biochar reduced autogenous shrinkage in the pastes and the reduction in autogenous shrinkage was more pronounced in the alkali-activated slag with NaOH, compared to Na2CO3. The void structure of the pastes was investigated using x-ray micro-computed tomography. It was found that refined pore structure due to reduced effective solution/slag in the pastes with biochar was able to compensate for the decreasing effect of biochar voids on compressive strength. The electrical resistivity was shown to be lower in the pastes with biochar.

Microencapsulated Phase Changing Materials for Gypsum Plasters: A Practical Approach

Several studies have shown the feasibility and thermal potential of gypsum plaster with microspheres of PCM, but very few of them investigated an approach with practical and standards concern. In this work, different characterizations are performed according to European standards on a standard gypsum plaster and two different gypsum plasters formulated with 20 wt.% of PCM microspheres. A material is experimentally made by mixing conventional gypsum and PCM microspheres, whereas the other is an already prepared commercial mix. For the laboratory material, the addition of PCM increases the consistency of the fresh paste of plaster. In order to reach a consistency in agreement with the standards more water is required. This higher amount of water causes further issues on the densification and cohesion properties. In contrary, the properties of the commercial mix are closer to a common plaster. It is therefore assumed that the commercial material incorporates thinner additives. In view of these results, it is assumed that most of the drawbacks due to the addition of PCM microspheres in gypsum plasters could effectively be encountered by adequate addition of additives in order to reduce the amount of water, and binding resins in order to improve the adhesion and mechanical properties.

Non-Linear Numerical Modelling of Sustainable Advanced Composite Columns Made from Bamboo Culms

The present article uses the finite element analysis (FEA) software ABAQUS to model a bamboo-based advanced composite column for construction. Different numerical models were analysed to be able to predict the behaviour of a bamboo-based composite column tested by the same group. Bamboo-based composites maintain the inherent excellent mechanical properties of raw bamboo whilst adding a certain degree of processing and engineering. Thus, the composite individual samples are more consistent and reliable when compared with their raw counterparts. A buckling analysis is carried out to determine the response of the composites to axial compressive loading. Different modelling elements and imperfection parameters were implemented separately in different FEA models so that the efficacy of each could be established and suggestions could be made with regard to the modelling elements and size of imperfection that should be used in future models. The results are compared to empirical findings, giving insights into the quality of results that can be obtained using numerical modelling. This also allowed for an evaluation of the methods and assumptions applied in the model. The load at rupture and displacements obtained by the numerical model were comparable to the experimental findings, with only minor differences observed.

Clay as a Sustainable Binder for Concrete—A Review

The negative environmental impacts of Portland cement as a binder in the construction industry have created a growing impetus to develop sustainable alternative binders. Various types of clay have been considered as potential cement replacements. The impact of clays as cement replacement depends on the dosage and treatment methods. This paper presents a comprehensive review to determine the effects of different types of clay on the fresh and hardened properties of concrete mixtures by analyzing the experimental database reported by the literature, including raw, calcined, modified, nano, and organo. This study intends to show the process of optimizing the use of clay in concrete, the reason behind converting raw clay to modified types, and research gaps through a comparison study between different types of clays. The present review study shows that clay-based concrete mixtures have higher thixotropy and yield stress values, improving shape stability. This results in lower early-age shrinkage of the concrete. However, the high floc strength of clay-based concrete causes a reduction in flowability. Treatment methods of raw clay, such as calcination and nano-sized clay particles, improve concrete compressive strength. General results of the previous studies highlight that all types of clay investigated positively affect the resistance of concrete to environmental attack.

Environmental Protection with HDPE Geomembranes in Mining Facility Constructions

The present work evaluated two high-density polyethylene (HDPE) geomembranes exhumed from mining facility constructions in Brazil. The MIN sample was exhumed from a pond for water use for the iron ore process after 7.92 years of exposure. The MIN2 sample was exhumed from a spillway channel of a ferronickel tailing dam after 10.08 years of service. The physical evaluations showed high depletion for antioxidants that work in the temperature range of 200 °C. The samples presented brittle tensile behavior and had similar behaviors between stress cracking and tensile. Low tensile elongation values and low-stress crack resistance were noted. The MIN2 sample presented a higher melt flow index (MFI) value and lower stress crack resistance. Thermogravimetric curves (TG) under synthetic air purge gas evaluation showed that both samples presented a similar behavior during the evaluation but had several mass losses. The results showed that exothermic and endothermic events occurred with loss of mass and showed no combustion events in the differential thermal analysis (DTA) curve evaluation. Differential scanning calorimetry (DSC) analysis showed no changes in the samples’ behavior. Thus, the results of tensile, stress cracking, and viscosity properties can demonstrate that changes in polymer structure occurred after field exposures.

Comparative Analysis of Recycled Plaster Composition Determined by X-ray Powder Diffraction and Thermogravimetric Analyses

Plaster is primarily used as a building material obtained by the calcination of gypsum. Its rapid setting time (time for the mixture to solidify) and the low quality of labor generate a large amount of nonused material. Due to its solubility in water, wasted gypsum cannot be disposed of in the environment, and its recycling process is encouraged. In this work, quantitative phase analyses (QPA) using X-ray powder diffraction (XRPD) data and the Rietveld method were carried out to determine the amounts of each compound present in commercial, hydrated, and laboratory-recycled plasters, and the results compared with those obtained by thermogravimetric analysis (TGA). It was inferred that the Rietveld method associated with XRPD data is quite efficient since it identifies compounds not seen in the TGA. Furthermore, the amount of water used in the preparation of hydrated samples influences the proper hydration of the material and, consequently, the recycled composition of the samples.

A Decommissioned Wind Blade as a Second-Life Construction Material for a Transmission Pole

This paper demonstrates the concept of adaptive repurposing of a portion of a decommissioned Clipper C96 wind turbine blade as a pole in a power transmission line application. The current research program is aimed at creating a path towards sustainable repurposing of wind turbine blades after they are removed from service. The present work includes modelling and analysis of expected load cases as prescribed in ASCE 74 and NESC using simplified boundary conditions for tangent pole applications. Load cases involving extreme wind, concurrent ice and wind, extreme ice, differential ice, broken conductor, and broken shield have been analyzed and governing load cases for bending, shear, and torsion have been examined. Relative stiffnesses of different parts forming the wind blade’s cross section (i.e., shell, web, and spar cap) are determined. The corresponding stresses associated with each part under the governing loads are compared to allowable strength values which are determined from composite laminate theory and modelling of the known laminate structure of the E-Glass FRP material. Stresses and deflections obtained are compared with governing reliability-based design criteria and code requirements. The results of the structural analysis indicate that the wind blade can resist the expected loads with reasonable safety factors and that the expected deflections are within permissible limits. Recommendations are provided for detailing and modification of the wind blade for a power pole application in which crossarm and davit connections are highlighted, and foundation details are emphasized.

Numerical Study of the In-Plane Seismic Response of RC Infilled Frames

Reinforced Concrete (RC) buildings with masonry infills are a very common structural typology worldwide for civil, strategic, or productive use. Damage to infills may cause danger for human lives and strongly affects economic losses, as shown during past earthquakes. In the current literature, different approaches are available for modeling the in-plane response of infilled frames and different constitutive laws generally calibrated on experimental tests. On the contrary, few and recent studies proposed formulas that account for the main properties of infills influencing their in-plane behavior to lateral forces. This paper presents a study finalized to derive a reliable model that is able to predict the monotonic and cyclic response of RC infilled masonry frames. To this end, after a critical analysis of the available literature, the authors combine among them two models, one for the monotonic response and the other for the cyclic one, by showing their reliability with reference to different experimental cases. Then, at the end of the paper, the derived models are employed to assess the seismic vulnerability of infills throughout a proposed procedure based on the common pushover analysis approach.

A New High-Standard Journal Contributing to the Development of Sustainable Construction Materials

Materials for construction have evolved over the years, but they still need improvement in order to be environmentally and technically better [...]

Glass-Ceramic Materials Obtained by Sintering of Vitreous Powders from Industrial Waste: Production and Properties

Glass-ceramics are advanced inorganic silicate materials that can be obtained by sintering glass powders using a careful temperature control to result in the densification, nucleation, and crystallization of the material. In the current work, three different samples were obtained starting from amorphous silicate materials derived from mixtures of metallurgical slag, coal fly ash, and glass cullet, mixed in different proportions. The as-received waste samples were heat-treated to high temperatures to achieve complete melting at 1200, 1300, and 1400 °C for two hours, performing a rapid cooling in order to yield an amorphous material (glass). The obtained frit was ball-milled to a powder, which was then cold pressed to obtain compact pellets. The thermal treatment of pellets was carried out at 800–1100 °C for 2 h followed by a cooling rate of 10 °C/min to obtain the final glass-ceramics. The microstructure of samples was evaluated with scanning electron microscopy (SEM), which showed heterogeneous conglomerates and clusters of ~20 microns. The formation of crystalline phases was corroborated by means of X-ray diffraction (XRD) analysis, showing the presence of anorthite in all samples. Depending on the sample composition, other crystalline phases such as augite, enstatite, and diopside were detected. Using the Debye–Scherrer equation, it was possible to find the average size of the nano-crystalline domains. The quantification of the non-crystalline or amorphous fraction was also performed. Additionally, the density and porosity of the materials were calculated using the procedures defined in the ASTM C373 and ASTM C20 standards, measuring density values in the range 2.2–3.1 g·cm−3. The apparent porosity was approx. 33% in the three materials. Raman spectroscopy analysis showed characteristic signals associated with crystalline phases containing alumina, silica, iron, and calcium. Overall, the study confirmed the possibility of obtaining glass-ceramics with fine (nanometric) crystal sizes from a combination of silicate waste and the capability of modifying the crystalline composition by changing the proportions of the different wastes in the initial formulations.