Properties and Strength Prediction Modeling of Green Mortar with Brick Powder Subjected to a Short-Term Thermal Shock at Elevated Temperatures

The cement industry is responsible for 8% of global CO₂ production. Therefore, a clear trend has been observed recently to replace to some extent the main binder of cement composites with environmentally friendly or recycled materials with a lower carbon footprint. This paper presents the effect of brick powder (BP) on the physico-chemical and mechanical properties of cement mortars. The effect of a short-term thermal shock on morphology and strength properties of green mortars was investigated. BP addition caused increase in porosity and decrease in compressive and flexural strength of mortars. The best results were obtained for samples with 5% wt. BP addition. Above this addition the strength decreased. The mechanical performance of the samples subjected to thermal loading increased compared to the reference samples, which is the result of a process called as the “internal autoclaving”. The BP addition positively affects the linear shrinkage, leading to its reduction. The lowest linear shrinkage value was achieved by the mortar with the highest BP addition. An intelligent modeling approach for the prediction of strength characteristics, depending on the ultrasonic pulse velocity (UPV) is also presented. To solve the model problem, a supervised machine-learning algorithm in the form of an SVM (support vector machines) regression approach was implemented in this paper. The results indicate that BP can be used as a cement replacement in cement mortars in limited amounts. The amount of the additive should be moderate and tuned to the features that mortars should have.     

Proposal of Major Environmental Impact Categories of Construction Materials Based on Life Cycle Impact Assessments

The “Korean New Deal” policy in South Korea emphasizes the necessity of a substantial and timely response to global climate change. In addition to carbon emissions, construction materials have various environmental impacts that necessitate serious considerations. Therefore, this study aimed to identify the major environmental impact categories of construction materials that reflect their diverse environmental impact characteristics using life cycle assessment. To this end, eight environmental impact categories were assessed for seven major construction materials. The contributions of all construction materials to these environmental impact categories were then analyzed to derive major environmental impact categories with contributions ≥95% or higher for each construction material. Consequently, global warming potential and abiotic depletion potential were derived as major environmental impact categories for all seven construction materials. In the case of ready-mixed concrete and cement, the photochemical oxidant creation potential was also found to be an environmental impact category that needs to be considered further. Thus, a study that defines environmental impacts must be considered in conjunction with the carbon emissions of building materials, and presenting the criteria for evaluating the defined environmental impacts is essential.     

Effects of Elevated Temperatures on the Properties of Cement Mortars with the Iron Oxides Concentrate

Using the waste materials in the production of the building materials limits the storage of the wastes, burdensome for the environment and landscape, and makes possible to manufacture the materials and products with the use of the less volume of the raw materials. Cement concretes and mortars as the basic building materials offer the broad prospects of utilization of the recyclable or waste materials. The wastes from the iron ore processing are the solid wastes resulting from the process of enrichment of the ore concentrate. The paper presents the results of testing three mortars, in which a part of fine aggregate was replaced with the iron oxide concentrate (IOC) resulting from such a process. IOC has been used as a substitute of 10%, 20% and 30% (by mass) of the fine aggregate. The effect of the concentrate on the mechanical performance of the mortars at the high temperature (up to 600 °C) was also investigated. The IOC is a neutral material, not affecting chemically the process of cement hydration. The addition of IOC slightly improves the strength of the cement mortars (by 5% to 10%). In the case of the larger amount (20–30%) of the addition, the use of superplasticizer is necessary. The IOC significantly improves the high temperature resistance of the cement mortars (300 °C). The cement mortars containing 30% of the IOC addition keep 80% of the initial flexural and compressive strength when exposed to the temperature 450 °C.     

Hydration Properties of Cement with Liquefied Red Mud Neutralized by Nitric Acid

An increasing amount of red mud (RM) is being generated globally due to the growth in aluminum production. To avoid RM pollution, low-cost methods for effectively recycling RM are being investigated. We propose a method for recycling RM as a construction material. Liquefied RM (LRM) was neutralized by nitric acid and added to cement paste, and the hydration heat, compressive strength, and hydration products were investigated. The cement paste with neutralized LRM had a higher compressive strength than that of plain cement paste and cement paste with LRM without neutralization at 1 day of aging; this indicates that nitric acid neutralization increases the early-age strength. Furthermore, the cement paste with 10% neutralized LRM showed 28 days-compressive strength and hydration heating curves similar to the plain mixture, indicating the positive impact of LRM neutralization on the strength. It was noted that a greater quantity of portlandite was produced earlier in cement paste with neutralized LRM than in that without. Therefore, the proposed method of using RM as a concrete additive has the potential to reduce the cost and environmental impact of both construction materials and RM waste management.     

The Improvement of Durability of Reinforced Concretes for Sustainable Structures: A Review on Different Approaches

The topic of sustainability of reinforced concrete structures is strictly related with their durability in aggressive environments. In particular, at equal environmental impact, the higher the durability of construction materials, the higher the sustainability. The present review deals with the possible strategies aimed at producing sustainable and durable reinforced concrete structures in different environments. It focuses on the design methodologies as well as the use of unconventional corrosion-resistant reinforcements, alternative binders to Portland cement, and innovative or traditional solutions for reinforced concrete protection and prevention against rebars corrosion such as corrosion inhibitors, coatings, self-healing techniques, and waterproofing aggregates. Analysis of the scientific literature highlights that there is no preferential way for the production of “green” concrete but that the sustainability of the building materials can only be achieved by implementing simultaneous multiple strategies aimed at reducing environmental impact and improving both durability and performances.     

Development of Geopolymer-Based Materials with Ceramic Waste for Artistic and Restoration Applications

This contribution presents the preparation and characterization of new geopolymer-based mortars obtained from recycling waste deriving from the production process and the “end-of-life” of porcelain stoneware products. Structural, morphological, and mechanical studies carried out on different kinds of mortars prepared by using several types of by-products (i.e., pressed burnt and extruded ceramic waste, raw pressed and gypsum resulting from exhausted moulds) point out that these systems can be easily cast, also in complex shapes, and show a more consistent microstructure with respect to the geopolymer paste, with a reduced amount of microcracks. Moreover, the excellent adhesion of these materials to common substrates such as pottery and earthenware, even for an elevated concentration of filler, suggests their use in the field of technical-artistic value-added applications, such as restoration, conservation, and/or rehabilitation of historic monuments, or simply as materials for building revetments. For all these reasons, the proposed materials could represent valuable candidates to try to overcome some problems experienced in the cultural heritage sector concerning the selection of environmentally friendly materials that simultaneously meet art and design technical requirements.     

Analysis of the Embodied Energy and CO2 Emissions of Ready-Mixed Concrete: A Case Study in Cuenca,Ecuador

Concrete is the most commonly construction material used worldwide. In contrast to other countries, Ecuador lacks studies that determine the environmental impact of the production of construction materials. This research presents a quantification of embodied energy and CO₂ emissions associated with the concrete production, using as a case study a ready-mixed concrete plant in the city of Cuenca, Ecuador. The study was based on the Life Cycle Assessment methodology established by ISO 14040 and ISO 14044, and the 2006 Intergovernmental Panel of Experts on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories. The production of ready-mixed concrete was considered for one year, with a “gate to gate” approach including the “transport of raw material” to the concrete plant and the subsequent “transport of final product” to the construction site. The results revealed that to produce 1 m³ of ready-mixed concrete, its production required 568.69 MJ of energy, accompanied by 42.83 kg CO₂. Indirect transport generates the greatest environmental impact, especially the “transport of raw materials”, which represents approximately 80% of the embodied energy and 79% of CO₂ emission.     

Granite Powder vs. Fly Ash for the Sustainable Production of Air-Cured Cementitious Mortars

The partial replacement of cement in concrete with the addition of granite powder and fly ash can help to reduce the carbon dioxide (CO₂) emissions into the atmosphere associated with cement production. The aim of the article is to compare the performance of granite powder and fly ash for the sustainable production of air-cured cementitious mortars. The morphological, chemical, and granulometric properties of these additives were first compared with the properties of cement. Afterward, a series of mortars modified with the addition of granite powder and fly ash was made. The properties of the fresh mixes and the mechanical properties of the hardened composites were then tested. Finally, based on the obtained results, a cost analysis of the profitability of modifying cementitious composites with granite powder or fly ash was investigated. The obtained results allow similarities and differences between granite powder and fly ash in relation to cement to be shown. To conclude, it should be stated that both of these materials can successfully be used for the sustainable production of air-cured cementitious composites. This conclusion has a significant impact on the possibility of improving the natural environment by reducing the amount of cement production. More sustainable production of cement-based materials could enable CO₂ emissions to be decreased. The use of granite powder for the production of cementitious mortars can significantly reduce the amount of this material deposited in landfills.     

Mortar Bond Strength: A Brief Literature Review,Tests for Analysis,New Research Needs and Initial Experiments

Despite technological advances in the production processes of the materials for ceramic façade coatings, the problems of detachments are still frequent. Therefore, this work aims to investigate, through a literature review, the existing gaps related to the adhesion ability of adhesive mortars, identifying new research needs that can better explain the behavior of the material. In addition, an experimental procedure was developed to evaluate the mechanical capacity of adhesive mortars when subjected to cyclic stresses. Dynamic stress measurements are presented for several blocks of mortar and on similar blocks but with a slot drilled prior to measurements (intended to represent failure). From these data we calculated values of stress energy, elastic energy, and dissipated energy. The experimental results showed that the energy involved in the test process accompanied the load values and current stress values. The mortar samples with the previous failure absorbed and dissipated less energy than mortars without failure, showing that materials that have less energy to dissipate, are materials that have developed less capacity to adhere, that is, to keep their parts together.     

Effect of High-Dispersible Graphene on the Strength and Durability of Cement Mortars

Graphene’s outstanding properties make it a potential material for reinforced cementitious composites. However, its shortcomings, such as easy agglomeration and poor dispersion, severely restrict its application in cementitious materials. In this paper, a highly dispersible graphene (TiO₂-RGO) with better dispersibility compared with graphene oxide (GO) is obtained through improvement of the graphene preparation method. In this study, both GO and TiO₂-RGO can improve the pore size distribution of cement mortars. According to the results of the mercury intrusion porosity (MIP) test, the porosity of cement mortar mixed with GO and TiO₂-RGO was reduced by 26% and 40%, respectively, relative to ordinary cement mortar specimens. However, the TiO₂-RGO cement mortars showed better pore size distribution and porosity than GO cement mortars. Comparative tests on the strength and durability of ordinary cement mortars, GO cement mortars, and TiO₂-RGO cement mortars were conducted, and it was found that with the same amount of TiO₂-RGO and GO, the TiO₂-RGO cement mortars have nearly twice the strength of GO cement mortars. In addition, it has far higher durability, such as impermeability and chloride ion penetration resistance, than GO cement mortars. These results indicate that TiO₂-RGO prepared by titanium dioxide (TiO₂) intercalation can better improve the strength and durability performance of cement mortars compared to GO.     

Regional Waste Streams as Potential Raw Materials for Immediate Implementation in Cement Production

There is an urgent need to apply available technologies to reduce the environmental impact of the construction industry. One of the possible solutions that can be implemented immediately is the industrial symbiosis between the waste-producing industries on the one hand and the cement industry, which consumes enormous amounts of raw materials for its production, on the other. In order for the industry to accelerate the use of these available materials and technologies, the potential of these materials must be disclosed. The present study shows a systematic approach to assess the potential of waste materials, by-products, and other raw materials available in the South East Europe that can be used in cement production. Their evaluation included the analysis of their availability, their chemical and physical properties, their chemical reactivity, and their contribution to the mortar’s strength. Based on the results and the analyses carried out, a recommendation for immediate use in the construction sector is given for each of the materials collected.     

Microstructural,Mechanical and Radiological Characterization of Mortars Made with Granite Sand

The study reported the effect of granite sand on strength and microstructural developments in mortars prepare from OPC with a high coal fly ash (FA) content or from hybrid alkaline cements. The radiological behaviour of the resulting mortars was compared to materials prepared with siliceous sand (with particles sizes of <2 mm) and the relationship between such radiological findings and mortar microstructure and strength was explored. A new method for determining natural radionuclides and their activity concentration Index (ACI) on cement mortars (specifically to solid 5-cm cubic specimens) was applied and validated. The microstructural changes associated in mortars have no effect on mortar radiological content measurements. The mortars with granite sand exhibited very high ACI > 0.96, which would ultimately limit their use. A conclusion of interest is that where information is at hand on the starting materials (OPC, FA, sand, admixtures), their proportions in the mortar and the mixing liquid content (water or alkaline activators) their radiological content is accurately predicted. The inference is that a mortar’s radiological content and ACI can be known prior to mixing, providing a criterion for determining its viability. That in turn lowers environmental risks and the health hazards for people in contact with such materials.     

Using Converter Dust to Produce Low Cost Cementitious Composites by in situ Carbon Nanotube and Nanofiber Synthesis

Carbon nanotubes (CNTs) and nanofibers (CNFs) were synthesized on clinker and silica fume particles in order to create a low cost cementitious nanostructured material. The synthesis was carried out by an in situ chemical vapor deposition (CVD) process using converter dust, an industrial byproduct, as iron precursor. The use of these materials reduces the cost, with the objective of application in large-scale nanostructured cement production. The resulting products were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) and were found to be polydisperse in size and to have defective microstructure. Some enhancement in the mechanical behavior of cement mortars was observed due to the addition of these nano-size materials. The contribution of these CNTs/CNFs to the mechanical strength of mortar specimens is similar to that of high quality CNTs incorporated in mortars by physical mixture.     

Volcanic Ash as a Sustainable Binder Material: An Extensive Review

The construction industry is affected by the constant growth in the populations of urban areas. The demand for cement production has an increasing environmental impact, and there are urgent demands for alternative sustainable solutions. Volcanic ash (VA) is an abundant low-cost material that, because of its chemical composition and amorphous atomic structure, has been considered as a suitable material to replace Portland cement clinker for use as a binder in cement production. In the last decade, there has been interest in using alkali-activated VA material as an alternative material to replace ordinary Portland cement. In this way, a valuable product may be derived from a currently under-utilized material. Additionally, alkali-activated VA-based materials may be suitable for building applications because of their good densification behaviour, mechanical properties and low porosity. This article describes the most relevant findings from researchers around the world on the role of the chemical composition and mineral contents of VA on reactivity during the alkali-activation reaction; the effect of synthesis factors, which include the concentration of the alkaline activator, the solution-to-binder ratio and the curing conditions, on the properties of alkali-activated VA-based materials; and the mechanical performance and durability properties of these materials.     

Reutilisation of Water Contaminated by Mining Waste for the Encapsulation of Potentially Toxic Elements

Mining activities are essential for a population’s development; however, they also produce negative effects such as the production of waste, an impact on flora and water pollution. On the other hand, construction is one of the sectors which is most demanding of raw materials, with one of the main such materials being water. For this reason, this research evaluates the feasibility of incorporating water contaminated by mining waste into ceramic materials for bricks. In this way, the use of water is reduced and, on the other hand, the contaminating elements of the mining water are encapsulated in the ceramic matrix. To achieve this, the clay used and the contaminated water were first analysed, then different families of samples were conformed with different percentages of contaminated water. These samples were tested to determine their physical and mechanical properties. At the same time, leachate tests were carried out to determine that the ceramic material created did not cause environmental problems. The test results showed that the physical and mechanical properties of the ceramics were not influenced by the addition of contaminated water. On the other hand, the leachate tests showed that encapsulation of most of the potentially toxic elements occurred. However, the use of contaminated water as mixing water for ceramics could only be performed up to 60%, as higher percentages would leach impermissible arsenic concentrations. Accordingly, a new way of reusing water contaminated by mining activities is developed in this study, taking advantage of resources, avoiding environmental pollution and creating economic and environmentally friendly end products.     

Influence of Cement Replacement with Sewage Sludge Ash (SSA) on the Heat of Hydration of Cement Mortar

The amount of fly ash from the incineration of sewage sludge is increasing all over the world, and its utilization is becoming a serious environmental problem. In the study, a type of sewage sludge ash (SSA) collected directly from the municipal sewage treatment plant was used. Five levels of cement replacement (2.5%, 5%, 7.5%, 10% and 20%) and unchanged water-to-binder (w/b) ratio (0.55) were used. The purpose of the study was to evaluate the effect of sewage sludge ash (SSA) on the hydration heat process of cement mortars. The heat of the hydration of cement mortars was monitored by the isothermal calorimetric method for 7 days at 23 °C. The analysis of chemical composition and particle size distribution was performed on the tested material. The tests carried out have shown that SSA particles have irregular grain morphology and, taking into account the chemical composition consists mainly of oxides such as CaO, P₂O₅, SiO₂ and Al₂O₃. The concentration of these compounds affects the hydration process of cement mortars doped with SSA. In turn, the content of selected heavy metals in the tested ash should not pose a threat to the environment. Calorimetric studies proved that the hydration process is influenced by the presence of SSA in cement mortars. The studies showed that the rate of heat generation decreased (especially in the initial setting period) with the increasing replacement of cement by SSA, which also reduced the amount of total heat compared to the control cement mortar. With increasing mass of the replacement of cement with SSA up to 20%, the 7-day compressive strength of the mortar samples decreases.     

Determination of Physicomechanical Characteristics of the Cement Mortar with Added Fiberglass Waste Treated with Hydrogen Plasma

Solving the environmental problems and the economic aspects of the construction sector represent a global priority. The considerable quantities of raw materials and the energy consumed by this sector make it one of the most polluting economic activities. Fiberglass in various forms is widely used in the construction sector. In the manufacturing process and during the usage of fiberglass products, a significant amount of indestructible waste results, negatively impacting the environment. An innovative solution for utilizing this type of waste is the treatment with hydrogen plasma. This process results in two products: the first in the gaseous state used to obtain synthetic fuel and the second in solid-state, named slag. The composition of solid waste contains chemical compounds that can increase their strength if used as additives in mortars or concretes. This study presents the laboratory tests on mortars, in which a part of the cement amount was replaced with the solid component resulting from the plasma treatment of glass fiber waste. The results showed that replacing a part of the cement with these materials is a solution that minimizes the ecological footprint of the buildings.     

Geopolymer Ceramic Application: A Review on Mix Design,Properties and Reinforcement Enhancement

Geopolymers have been intensively explored over the past several decades and considered as green materials and may be synthesised from natural sources and wastes. Global attention has been generated by the use of kaolin and calcined kaolin in the production of ceramics, green cement, and concrete for the construction industry and composite materials. The previous findings on ceramic geopolymer mix design and factors affecting their suitability as green ceramics are reviewed. It has been found that kaolin offers significant benefit for ceramic geopolymer applications, including excellent chemical resistance, good mechanical properties, and good thermal properties that allow it to sinter at a low temperature, 200 °C. The review showed that ceramic geopolymers can be made from kaolin with a low calcination temperature that have similar properties to those made from high calcined temperature. However, the choice of alkali activator and chemical composition should be carefully investigated, especially under normal curing conditions, 27 °C. A comprehensive review of the properties of kaolin ceramic geopolymers is also presented, including compressive strength, chemical composition, morphological, and phase analysis. This review also highlights recent findings on the range of sintering temperature in the ceramic geopolymer field which should be performed between 600 °C and 1200 °C. A brief understanding of kaolin geopolymers with a few types of reinforcement towards property enhancement were covered. To improve toughness, the role of zirconia was highlighted. The addition of zirconia between 10% and 40% in geopolymer materials promises better properties and the mechanism reaction is presented. Findings from the review should be used to identify potential strategies that could develop the performance of the kaolin ceramic geopolymers industry in the electronics industry, cement, and biomedical materials.     

The Influence of Cement Substitution by Biomass Fly Ash on the Polymer–Cement Composites Properties

The generation of energy for the needs of the population is currently a problem. In consideration of that, the biomass combustion process has started to be implemented as a new source of energy. The dynamic increase in the use of biomass for energy generation also resulted in the formation of waste in the form of fly ash. This paper presents an efficient way to manage this troublesome material in the polymer–cement composites (PCC), which have investigated to a lesser extent. The research outlined in this article consists of the characterization of biomass fly ash (BFA) as well as PCC containing this waste. The characteristics of PCC with BFA after 3, 7, 14, and 28 days of curing were analyzed. Our main findings are that biomass fly ash is suitable as a mineral additive in polymer–cement composites. The most interesting result is that the addition of biomass fly ash did not affect the rheological properties of the polymer–cement mortars, but it especially influenced its compressive strength. Most importantly, our findings can help prevent this byproduct from being placed in landfills, prevent the mining of new raw materials, and promote the manufacture of durable building materials.     

Evaluation of Stresses on Implant,Bone, and Restorative Materials Caused by Different Opposing Arch Materials in Hybrid Prosthetic Restorations Using the All-on-4 Technique

The long-term success of dental implants is greatly influenced by the use of appropriate materials while applying the “All-on-4” concept in the edentulous jaw. This study aims to evaluate the stress distribution in the “All-on-4” prosthesis across different material combinations using three-dimensional finite element analysis (FEA) and to evaluate which opposing arch material has destructive effects on which prosthetic material while offering certain recommendations to clinicians accordingly. Acrylic and ceramic-based hybrid prosthesis have been modelled on a rehabilitated maxilla using the “All-on-4” protocol. Using different materials and different supports in the opposing arch (natural tooth, and implant/ceramic, and acrylic), a multi-vectorial load has been applied. To measure stresses in bone, maximum and minimum principal stress values were calculated, while Von Mises stress values were obtained for prosthetic materials. Within a single group, the use of an acrylic implant-supported prosthesis as an antagonist to a full arch implant-supported prosthesis yielded lower maximum (Pmax) and minimum (Pmin) principal stresses in cortical bone. Between different groups, maxillary prosthesis with polyetheretherketone as framework material showed the lowest stress values among other maxillary prostheses. The use of rigid materials with higher moduli of elasticity may transfer higher stresses to the peri implant bone. Thus, the use of more flexible materials such as acrylic and polyetheretherketone could result in lower stresses, especially upon atrophic bones.