Search

As a result of firing pulverized coal in thermal power plants, enormous amounts of fly ash (FA) are produced as industrial waste. The release into the atmosphere and storage of this industrial waste remains one of the major environmental problems that threaten human health by contributing to air, water, and soil pollution. The recovery and reuse of FA in the construction industry is the only economic solution to the existing problem. In this study, the potential radiological risk caused by the usage of FA in concrete and cement production as a main component and its storage in landfill sites was evaluated for people and works by estimating radiological parameters (activity concentration and alpha index, annual effective doses, and the corresponding excess lifetime cancer risks) based on activity concentrations of terrestrial radionuclides in FA. Also, the radiological risk to the workers working in the FA landfill site was evaluated using the Residual Radioactivity Onsite 7.2 code. The average activity concentrations of terrestrial radionuclides in FA samples from the Tunçbilek lignite coal-fired thermal power plant at Kütahya province of Turkey were measured as 417, 156 and 454 Bq kg−1 for 226Ra, 232Th and 40K, respectively. When using up to 35% by mass of FA in cement and concrete, the average values of the radiological parameters revealed that they were within the recommended safety limits. However, code estimations showed that a regular worker in FA storage would be exposed to a total effective dose rate greater than 3 mSv y−1. [ABSTRACT FROM AUTHOR]

Artificial aggregate (AF), i.e., silico manganese (SiMn) slag aggregate, is a byproduct of ferromanganese and silico manganese alloy production. The utilization of industrial waste and industrial byproducts in construction has increased the aim of conserving natural resources to nurture a pollution-free environment. The current study examines the performance of the use of artificial aggregate (AF) and partial replacement of cement with fly ash (FA). The properties of fresh concrete, as well as the compressive and flexural strength and split tensile strength of concrete were evaluated. Seven mix proportions were prepared for M30-grade concrete. The first was a control mix (with 0% AF and FA), three other mixes contained varying amounts of AF (20%, 40%, and 60%) as a partial replacement of CA with AF. The average compressive strength of the control SCC was found to be 32.87 MPa (megapascals) at the age of 28 days, and after replacing 20% natural aggregate with artificial aggregate, the compressive strength increased by 8.27%, whereas for 40% and 60% replacement, it decreased by 4.46% and 12.55%, respectively. Further investigation was performed on the optimum value obtained by replacing 20% of CA with AF. At this percentage, cement was replaced by FA at (15%, 25%, and 35%) where at 15%, the average compressive strength increased by 7.41%, whereas for 25% and 35% replacement, it decreased by 7.47% and 17.19%, respectively. For SCAF20 and SCF15, all strengths were at maximum due to the increase in its density. The findings show that the development of advanced construction materials is environmentally sustainable. [ABSTRACT FROM AUTHOR]

Utilizing industrial wastes in concretes solves environmental issues such as disposal, depletion of natural resources, and CO2 emission. In this research, fly ash (FA) and ceramic tile waste (CTW) were used in making concrete. FA was used as a partial replacement for cement (30%), and CTW was used as a partial to total replacement for fine aggregate (10–100%). According to the experimental findings, 30% substitution of FA increased the compressive strength (10.05%), tensile strength (9.15%), flexural strength (6.9%), and elastic modulus (9.4%). The optimal level of CTW substitution in fly ash concrete was found to be 40%. At this level, compressive strength, tensile strength, flexural strength, and elastic modulus were increased by 10.56%, 9.3%, 6.9%, and 8.86%, respectively. The fly ash concrete mix with 40% CTW had higher electrical resistivity and reduced water absorption. The environmental sustainability of concrete mixes, as assessed by the CO2 emissions, was found to be lower by 21.5% in fly ash concrete as compared to reference concrete. With 100% CTW addition, the emission was lowered by 3.8%. The preparation cost for fly ash mix with 40% CTW was 14% less than the reference concrete. As an outcome of this research, the fly ash concrete with 40% CTW can be used with the benefits of improved strength, durability, sustainability, and cost savings. Box–Behnken design (BBD) models were developed to estimate the mechanical properties of the CTW-incorporated fly ash concrete, and excellent correlations were obtained between the predicted and experimental values. Effect of ceramic tile waste as fine aggregate in 30% fly ash additive concrete [ABSTRACT FROM AUTHOR]

In the context of the circular economy and the adoption of one of its business models, namely "resource recovery", this study presents an opportunity to valorize industrial and urban wastes using alkaline activation technology to produce hybrid binders. Several alkali-activated binders were produced using response surface methodology based on a mixture of 45/45/10 clay brick waste, fly ash, and Portland cement. The compressive strength and setting time of each were evaluated. The hybrid cementitious pastes achieved up to 45 MPa after 28 days of setting. Based on the experimental data, two binders were selected as the cementitious matrix for composites, with paper sludge as the lightweight aggregate. Incorporating up to 45% volume of paper sludge allowed extrusion of the materials. The addition of paper sludge reduced the compressive and flexural strength. These results were explained by the decrease in density and the increase in porosity. However, there was an improvement in the thermal properties of the composites; in particular, the thermal conductivity range between 0.35 and 0.49 W/mK. Finally, it was found that the composites with 25% volume of paper sludge had the best combination of properties, positioning them as potential construction materials. [ABSTRACT FROM AUTHOR]

The use of mineral additives, arising from industrial waste, for construction materials such as cement has environmental and economic importance. Also, there is a vital gap between research and issued standards in the wetting-drying field which is well-known as one of the most important corrosive environmental conditions. Only a few pieces of research report non-air entrained fly ash substituted composites exposed to freezing-thawing. In this study, 20% of cement was replaced with fly ash and 60 wetting-drying or freezing-thawing cycles were applied to the samples. For microstructural investigation, cement paste prisms were prepared in two groups of control and fly ash-cement mixtures with the dimension of 40 x 40 × 160 mm. Additionally, 150 x 150 × 150 mm cubes were molded to study the mechanical properties of fly ash-containing concrete subjected to the wetting-drying or freezing-thawing cycles. First series of control and fly ash-added samples after a 28-day curing period were exposed to the purposed cycles. Similarly, the second and third series after 56 and 90 days were exposed to wetting-drying or freezing-thawing cycles. Based on the obtained results, fly ash-containing samples performed better than control mixtures after a 90-day curing period with/without application of wetting-drying cycles since excessive CSH gel was produced as a prominent product of pozzolanic reaction decreased porosity of the mixtures and increased adherence between particles. After the exposure to freezing-thawing cycles, control composites displayed better performance than fly ash-containing samples at early ages. As an important achievement of this study, pozzolanic reactions required at least 90 days to be completed under normal curing conditions at the standard temperature. Due to the required long curing time, partial cement replacement with fly ash can be an efficient alternative for the production of prefabricating elements used in marine construction or other constructions exposed to cold weather. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The protection of the environment must be a priority in our society, and the construction sector can contribute significantly to this goal. Construction, being one of the industrial sectors that is more demanding in terms of raw materials, must reinforce its effort to implement, in a more profound and systematic way, the paradigm of the circular economy. In this sense, in recent years several studies have been trying to contribute solutions aimed at reintroducing industrial by-products or residues in new products for the construction industry. It should be noted that nowadays it is increasingly important to introduce a higher percentage of recycled materials in concrete. In this context, the present work addresses the appropriateness of a design procedure proposed to maximize the content of electric arc furnace slag (EAFS) and include recycled tire steel fibers (RTSF) in the production of more sustainable structural concretes. For this, the properties of various concrete mixtures at the fresh and hardened state, obtained by the substantial substitution of coarse and fine natural aggregates by EAFS and fly ash (FA), were investigated. The design of EAFS mixtures was based on two conventional reference mixtures (REF1 and REF2), and by using the modified Andreasen and Andersen particle packing model, these were optimized to achieve maximum packing density. Compressive strength, modulus of elasticity behavior, and fresh and physical properties were assessed in order to define the best mix proportions with respect to the predefined requirements of ordinary mixtures. Untreated recycled tire steel fibers (RTSF) were included in the developed sustainable concrete to perform a comparison of the physical properties with unreinforced concretes developed with natural aggregates (REF2) and with EAFS aggregates (EAFS8D1). This incorporation was intended to improve the physical behavior of unreinforced concretes with EAFS aggregates. Mixtures with high percentages of waste aggregates up to 70% (in weight), and 10% (in weight) of FA were obtained, showing competitive mechanical behavior compared to REF1 and REF2. These concrete compositions showed minimum and maximum compressive strengths between 9 MPa and 37 MPa, respectively. This study coverd the two major classes of concrete used as structural material, namely structural concrete and fiber reinforced concrete. [ABSTRACT FROM AUTHOR]

The direction of construction science that is associated with the development of the theory and practice of creating a new generation of foam concrete is particularly interesting and relevant. The development of improved structural foam concrete using polypropylene fiber and industrial waste, namely fly ash (FA), is prompted by the existing environmental threat posed by FA; this threat is a result of the operation of the fuel energy industry, as well as the possibility of using foam concrete not only as thermal insulation, but as the main material for load-bearing structures that have a certain level of responsibility. The aim of this work was to create and optimize the recipe technological parameters to produce non-autoclaved fiber foam concrete (FFC) using FA as a component. The study used standardized methods for assessing the properties of FFC, and the method of optical microscopy to analyze the structural characteristics of the material. It has been revealed that the replacement of cement with FA in an amount of 10% to 40% helps to reduce the dry density (DD) of FFC. The lowest DD was recorded for samples with 40% FA. The best results for the compressive strength (CS) and flexural strength (FS) were recorded for FFC samples with 10% FA instead of cement. The increase in CS was 12%, and the increase in FS was 23%. The best thermal insulation properties of FFC, and in terms of resistance to freezing and thawing, were recorded in samples with a 10% replacement of cement with FA. The maximum decrease in thermal conductivity was 14%. [ABSTRACT FROM AUTHOR]

Concrete is the most used construction material in the world. Sustainable construction practice demands durable material. A particular type of concrete that flows and consolidates under its weight is proposed to reduce labor dependency during construction, called self-compacting concrete. It is installed without vibration due to its excellent deformability and flowability while remaining cohesive enough to be treated without difficulty. Evaluating its compressive strength is essential as it is used in important construction projects. An artificial neural network (ANN) is a predicting tool that can predict output in various sectors. This study evaluated the compressive strength of industrial waste such as fly ash and silica fume incorporated in self-compacting concrete at various ages. A non-linear relationship was used to develop the model relating mix composition and SCC compressive strength using an Artificial Neural Network (ANN). The experimental and expected outcomes were compared with the model prediction to evaluate the predictive capacity, generalize the generated model, and observe suitable matches. The developed ANN network can predict the desired output, i.e., compressive strength incorporating industrial waste. Furthermore, the influence of individual parameters viz. cement, silica fume, and fly ash, w/b were also evaluated using parametric analysis, which shows the sensitivity of various materials on the compressive strength of Self-compacting concrete. As a result, a higher correlation coefficient of 0.9835 with a smaller value of MAPE (0.0347) and RMSE (2.4503) is obtained. Finally, a process of creating tools for practical engineers and field users is proposed, which would be very handy and fast for predicting the strength of SCC. [ABSTRACT FROM AUTHOR]

Zinc tailing waste material is generated during the extraction of zinc metal. Its deposit is increasing year after year posing a threat to the environment and occupying large precious land. The present research explores the possibility of its application in road construction and filling. Physical and chemical tests were carried out, viz. SEM, EDS, X-ray diffraction and toxicity characteristics leachate procedure. The geotechnical characterisation was carried out and compared with similar types of materials, viz. soil and industrial wastes (fly ash and jarofix). Stress-settlement behaviour was studied by using a small scale physical model and validated by a numerical model test. Tailing was further mixed with cement to improve its properties for application in stabilised layers. Tailing is a porous, multi-phase and non-swelling cohesionless fine-grained material. It contains mainly oxides of silica, alumina, magnesium, calcium and less concentration of heavy metals. It has a high dry density (18.62 kN/m3), California Bearing Ratio (11%) and angle of internal friction (34°) compared to soil which makes it suitable for road construction. Cement stabilised tailing can be used in sub-base layer and can save about 170 mm thickness of the aggregate layer. Modulus value (18.17 MPa) indicates that it is a stiff material which leads to less settlement as a structural fill. [ABSTRACT FROM AUTHOR]

Nowadays, the use of environmentally friendly, long-lasting building materials with minimal energy and carbon dioxide emissions are highly recommended. Some of these materials can be made from industrial and agricultural wastes. By replacing ordinary Portland cement (OPC) with large volume of fly ash waste (FA), environmental issues associated with landfill disposal and cement manufacture can be mitigated. Nonetheless, using a high amount of FA (up to 50 %) to replace cement resulted in poor strength performance, particularly during early age. This experimental study created an increased strength cement mortar containing a high volume of FA (60 %) and bottle glass waste nanoparticles (BGWNPs). In this experiment BGWNPs were prepared and 2, 4, 6, 8 and 10 vol% of them were used as a replacement of OPC-FA binder. According to the results, by adding 0–6 % of BGWNPs to a high-volume FA matrix considerably increased the bond strength (from 12.5 % to 39.1 %). On the other hand, the findings revealed that the addition of nanoparticles (up to 6 %) caused a modest reduction in strength values. Other engineering and microstructure properties showed a similar pattern. The matrix with 6 % BGWNPs displayed the best performance when compared to other levels. The results also showed that replacing OPC by high volume FA incorporating BGWNPs significantly improved the durability of proposed mortar, such as reduction in drying shrinkage and increased acid attack and abrasion resistance. Related to the environment benefits, the proposed mortars contributed in a reduction of carbon dioxide emission, energy consumption and cost of binder by 61.9 %, 54.3 % and 50.6 % compared to OPC, respectively. To conclude, the use of BGWNPs make it possible to produce high volumes of FA-based cement mortars with acceptable mechanical and durable properties for concrete repair applications in the construction industry. Additionally, sustainability can be attained by lowering pollution, recycling waste, and finding solutions to landfill problems. • Mortars with high fly ash level showed excellent performance as eco-friendly concrete repair materials. • The bond performance of prepared mortar enhanced with inclusion nanoparticles. • Potential use of waste materials to enhance the cement properties and reduce the environment impact. [ABSTRACT FROM AUTHOR]

Geopolymer (GP) concrete is a novel construction material that can be used in place of traditional Portland cement (PC) concrete to reduce greenhouse gas emissions and effectively manage industrial waste. Fly ash (FA) has long been utilized as a key constituent in GPs, and GP technology provides an environmentally benign alternative to FA utilization. As a result, a thorough examination of GP concrete manufactured using FA as a precursor (FA-GP concrete) and employed as a replacement for conventional concrete has become crucial. According to the findings of current investigations, FA-GP concrete has equal or superior mechanical and physical characteristics compared to PC concrete. This article reviews the clean production, mix design, compressive strength (CS), and microstructure (Ms) analyses of the FA-GP concrete to collect and publish the most recent information and data on FA-GP concrete. In addition, this paper shall attempt to develop a comprehensive database based on the previous research study that expounds on the impact of substantial aspects such as physio-chemical characteristics of precursors, mixes, curing, additives, and chemical activation on the CS of FA-GP concrete. The purpose of this work is to give viewers a greater knowledge of the consequences and uses of using FA as a precursor to making effective GP concrete. [ABSTRACT FROM AUTHOR]

The large volume of industrial by-products and wastes from the construction, timber and paper industries has become a serious challenge worldwide. Recycling these industrial wastes as functional materials in the construction industry is an efficient approach for sustainable development. This study presents a pretreatment approach for recycling construction and demolition waste (CDW) and industrial side-streams (such as green liquor sludge, fiber waste, flotation sand and fly ash) in order to produce a geopolymer for the 3D printing of construction materials. A treatment approach was developed for screening the residues from CDW with a maximum size of 16 mm and for a combined line treatment for industrial side streams. The treatment processes utilized suitable and economical separation techniques for the recycling of waste materials. The crushing of the screened residues resulted in a homogeneous material size that facilitates the separation of mixed wastes and simplifies the classification of materials. The combined plant enabled the cost-effective treatment of various industrial wastes in a single process unit. The results show that the economic and environmental impact of the chosen techniques, in terms of their energy consumption, is highly dependent on the treatment line, separation technique and quantity of the individual waste that is processed. These recycled industrial wastes can be used as sustainable materials for the production of geopolymer concrete, contributing to the sustainability of the construction industry. [ABSTRACT FROM AUTHOR]

A main global challenge is finding an alternative material for cement, which is a major source of pollution to the environment because it emits greenhouse gases. Investigators play a significant role in global waste disposal by developing appropriate methods for its effective utilization. Geopolymers are one of the best options for reusing all industrial wastes containing aluminosilicate and the best alternative materials for concrete applications. Waste wood ash (WWA) is used with other waste materials in geopolymer production and is found in pulp and paper, wood-burning industrial facilities, and wood-fired plants. On the other hand, the WWA manufacturing industry necessitates the acquisition of large tracts of land in rural areas, while some industries use incinerators to burn wood waste, which contributes to air pollution, a significant environmental problem. This review paper offers a comprehensive review of the current utilization of WWA with the partial replacement with other mineral materials, such as fly ash, as a base for geopolymer concrete and mortar production. A review of the usage of waste wood ash in the construction sector is offered, and development tendencies are assessed about mechanical, durability, and microstructural characteristics. The impacts of waste wood ash as a pozzolanic base for eco-concreting usages are summarized. According to the findings, incorporating WWA into concrete is useful to sustainable progress and waste reduction as the WWA mostly behaves as a filler in filling action and moderate amounts of WWA offer a fairly higher compressive strength to concrete. A detail study on the source of WWA on concrete mineralogy and properties must be performed to fill the potential research gap. [ABSTRACT FROM AUTHOR]

Natural and artificial pozzolans are widely used in building materials and play an increasingly important role in minimizing costs and mitigating environmental effects in the manufacturing of building materials. These pozzolans can be obtained as by-products from various industries, generally they are wastes without any application or added value. However, when implemented in cement mixtures, their effectiveness is somewhat questionable. Therefore, it is necessary to determine the properties, characteristics, and behavior of these materials. This study aims to summarize the main pozzolans used in building materials. Volcanic pozzolans, pozzolans of sedimentary origin, fly ash, blast furnace slag, silica fume, metakaolin, ceramic wastes, demolition, and construction wastes, rice husk ash, bagasse ash, biomass ash, and paper sludge were considered. The chief characteristics studied were particle size, specific area chemical composition, and mineralogical composition. In addition, the impact on mechanical properties and durability in cement mixtures using pozzolans was analyzed. It was observed that the mechanical properties of cement mixtures change by increasing pozzolan replacement. The maximum percentage of replacement depends on the characteristics of the pozzolan. In the case of durability, pozzolans decrease absorption and permeability by reducing the porosity of the binder. This decreases acid diffusion and autogenous shrinkage, thus improving concrete durability. Finally, future studies are suggested to consider the implementation of artificial intelligence techniques and machine learning algorithms to improve the properties of the concrete mixtures. [ABSTRACT FROM AUTHOR]

The construction industry is the world's largest emitter of greenhouse gases. The CO2 emission levels in the atmosphere are already reaching a tipping point and could cause severe climate change. An important element is the introduction of a technology that allows for the capture and sequencing of carbon dioxide levels, reducing both emissions and the carbon footprint from the production of Portland cement and cement-based building materials. The European Union has started work on the European Climate Law, establishing the European Green Deal program, which introduces the achievement of climate neutrality in the European Union countries. This includes a new policy of sustainable construction, the aim of which is to develop products with a closed life cycle through proper waste management. All efforts are being made to create generated waste and thus to support their production and/or use as substitutes for raw materials to produce biocomposites. This article reviews environmental issues and characterizes selected waste materials from the agri-food, mineral, and industrial sectors with specific properties that can be used as valuable secondary raw materials to produce traditional cements and biocomposite materials, while maintaining or improving their mechanical properties and applications. [ABSTRACT FROM AUTHOR]

This review systematically introduces the current status and development trend of inorganic industrial solid waste (IISW)-based materials. IISWs have the characteristics of wide sources, large land occupation, low utilization rate, and high environmental risk. In this paper, IISWs from different sources are introduced firstly, including coal (coal fly ash, coal gangue, flue gas desulfurization gypsum), metallurgy (steel slag, blast furnace slag, electrolytic manganese residue, red mud, etc.), chemistry (phosphogypsum, lithium slag), construction (waste glass, ceramic waste), mining (tailings) and other industries. Then the main research progress of IISWs in building material preparation (cement, aggregate, glass, ceramic, road, brick), water/air treatment (catalyst and adsorbent), and soil improvement (fertilizer and remediation agent) is discussed in detail. At the same time, the role of IISWs in material systems and the solidification/stabilization (S/S) mechanisms of heavy metals in IISW-based materials are emphasized. Finally, the challenges of IISWs material utilization are discussed, and prospects for the development of this field are proposed. Overall, the construction industry is expected to achieve large-scale and comprehensive utilization of IISWs, while the research in other fields requires more value-oriented and industrialized exploration. More importantly, the migration and transformation of heavy metals in IISWs during material utilization need full attention. [Display omitted] • Recycling of IISW in material preparation is comprehensively introduced. • Characteristics of IISW and the role IISW played in derived material are summarized. • S/S mechanisms of heavy metals in IISW are emphasized. • Challenges and prospects of IISW-based materials are presented. [ABSTRACT FROM AUTHOR]

The reduction of CO2 emission has recently become a global concern. The use of Portland cement has been responsible for the main global warming effects in the construction industry, Geo-polymers have emerged as a new generation of alternatives. Construction has been most important human activity since early ages. The main aim is to study strength characteristics and flexural behaviour of Geo-polymer concrete with Construction Demolition Waste. In this study, Geo-polymer concrete is produced with fly ash, GGBS, and sodium hydroxide and sodium silicate is used as a binder. The mix design is carried out for 12M concentration of sodium hydroxide. Alkaline activator solution ratio of 2.5 and alkaline liquid to fly ash ratio 0.4 is selected for this investigation. The specimen of size 100x100x100mm cubes 100x200mm cylinders and 1200x150x100mm beam were casted and the specimens of Geo-polymer concrete are cured at ambient temperature for 3days, 7 days and 28 days. The cured specimens were then tested for compressive strength, split tensile strength and flexural strength respectively. [ABSTRACT FROM AUTHOR]

We carried out physicochemical and mechanical characterization studies of glass-ceramic materials obtained from industrial waste of slag, fly ash and glass cullet. These studies were performed through the sintering process of powder by means of cold compaction, in concentrations of 10% slag, 70% fly ash and 20% glass cullet. A total of 230 pellets of 15 mm diameter by 5 mm thickness were produced. Later, 15 pellets were heat treated with a heating ramp of 10 °C/min up to 1000 °C and held for 2 hours, followed by a cooling rate of 10 °C/min. The remaining 15 pellets were heat treated with a heating ramp of 10 °C/min up to 1050 °C, followed by the same hold and cooling times. The increase in temperature favored the mechanical resistance of the glass-ceramic and the phases formed after the thermal treatments were anorthite, augite, gehlenite, and cordierite. The highest porosity found in this process was 40%; in terms of bulk densities, these were 2.36 and 2.57 g/cm3. In contrast to the observations of mechanical resistance, crystalline phases, apparent porosity, bulk density and chemical resistance. They showed that the temperature increase decreased the percentage of porosity and increased the values of densities and mechanical properties. Scanning electron microscopy images using backscattered electrons confirmed the homogenization of the mixtures in both heat treatments and mechanical properties similar to those reported for glass-ceramic materials for construction industry applications. [ABSTRACT FROM AUTHOR]

Featured Application: Mortars formulated with different types of industrial wastes with improved mechanical properties can be obtained and used in civil engineering applications. Short chopped fibers coated by epoxy resin of different length (5 to 10 mm length) were added at low volume content (about 4.6% on the composite) to alkali-activated fly ash or metakaolin mortars. These uncured scraps derive from the production of carbon fiber-reinforced polymer composites and they are not presently recycled, despite their outstanding mechanical properties. The workability, microstructure, porosity, and physical and mechanical properties (mainly flexural strength) of the derived materials were investigated. Superior flexural strength and increased toughness were obtained. An acid treatment of the scraps further improved the mechanical properties of the mortars by changing the chemical structure of the surface, thus increasing the interaction with the inorganic phase. These results foster the use of these wastes to improve the performance of low carbon footprint building materials such as alkali-activated composites in the building industry. [ABSTRACT FROM AUTHOR]

Novel building materials were manufactured and analyzed for 226Ra, 232Th and 40K using an HPGe gamma-ray spectrometer. The results show that the highest value of 40K was 4530 Bq per kg which was measured in a sample containing fly ashes from olive stones. The highest values of 226Ra and 232Th activities were 181 and 185 Bq per kg, which were measured in a sample with fly ashes from the co-combustion of coal and coke, respectively. On the other hand, the lowest values of 40K, 226Ra and 232Th activities were obtained for samples incorporating mussel shells. The radiological health hazard parameters, such as radium equivalent activity (Raeq), activity concentration index (I), absorbed and effective dose rates, associated with these radionuclides were evaluated. These values are within the EU recommended limits in building materials, except for samples of concrete containing fly ashes from olive stones, coal and coke. This study has contributed to the inclusion of industrial wastes that have not been collected previously in the Naturally Occurring Radioactive Material (NORM) databases on radioactivity of building materials. [ABSTRACT FROM AUTHOR]

Concrete is one of the most utilized and preferred construction materials in almost all the regions of the world. It is mainly known for its compressive strength. Several megastructures such as bridges, spillways, high-rise buildings, dams, etc. require sufficient compressive strength to suitably bear the upcoming large load on them. At the same time, in recent years, a lot of industrial by-products that are dumped as an industrial waste have attracted attention on concrete technologists. To safeguard the land from becoming the dumping zone/landfill sites, several researchers have come up and utilized these wastes as a supplementary cementitious material (SCM) in concrete. These SCMs can be used either in addition or in replacement of cement. In this paper, the effect of varying particle size and proportion of SCMs on compressive strength of concrete has been reviewed. Efforts have been made to showcase the effective utilization of various industrial by-products in manufacture of concrete with comparable compressive strength. [ABSTRACT FROM AUTHOR]

35207993 10 Cheng Z., Cheng X., Xie Y., Ma Z., Liu Y. Strength Tests and Numerical Simulations of Loess Modified by Desulfurization Ash and Fly Ash. This Special Issue, titled "Research and Development of Building Materials Based on Industrial Waste", is focused on the preparation and description of the properties of new building materials based on industrial waste that are to be used in practice in civil engineering and engineering construction. 35009234 12 Liu H., Tian Z., Fan H. A Study on the Relationships between Water Film Thickness, Fresh Properties, and Mechanical Properties of Cement Paste Containing Superfine Basalt Powder (SB). [Extracted from the article]

This paper focused on the optimization of the C40 fly ash concrete pavement, which was considered as a measure to accelerate the consumption of industrial solid wastes such as fly ash, committing to the goal of zero waste. By comparing with three groups of ordinary mix proportion, the performances (e.g., mechanical properties, durability, and brittle property) of the optimized mix proportion were evaluated via multiple mechanical and physical tests. Their air voids' structure was characterized by the BJH method (a method to calculate pore size described by Barrett, Joyner, and Halenda), and the results were combined with the road performances of concrete to analyze the formation mechanism of high durability of optimized fly ash pavement concrete. As for the experimental results for the optimized, its 28 d compressive strength peaked at 50.8 MPa together with corresponding 28 d flexural strength at 8.2 MPa, which indicated a favorable mechanical performance for wide application in pavement construction. Except for the mechanical properties, the better durability indicators obtained after optimization also provided a more compact pore structure for the optimized. The raw materials and construction technology of the two kinds of pavements were compared. Promoting the use of optimized fly ash pavement concrete can break the situation of the asphalt pavement monopolizing heavy-haul highway and greatly reduce the industrial wastes which can be used as raw materials in the production of cement, such as blast furnace slag and fly ash. It was proved that the optimized fly ash concrete pavement can be used to replace the asphalt pavement under the premise of achieving the same working performances. [ABSTRACT FROM AUTHOR]

The utilization of industrial waste as a partial replacement in construction materials has been increasing rapidly in recent years. This Paper investigates the performance of reinforced concrete columns comprising of recycled aggregates, fly ash and synthetic fibres in varying percentage, under monotonic and thermal loads. Ten full scale reinforced concrete columns of size 150 x 150 x 750 mm were experimentally studied under compressive loads. Results of the experiment showed that the polypropylene (PP) fibre reinforced fly ash column with recycled aggregate consisting of 1.5% PP fibre, 15% fly ash and 25% recycled aggregates exhibited better load carrying and deflection capacities and was further considered for numerical analysis. The conventional column was modelled as a control specimen and the behaviour of polypropylene fibre-reinforced fly ash column with recycled aggregate was comparatively studied under the action of thermal loads in ABAQUS. In order to understand the effect of fibre-reinforced polymer (FRP) rebar reinforcement in columns under thermal loads, a parametric study was carried out by varying the type of reinforcement, using carbon fibre-reinforced polymer rebar (CFRP) and glass fibre-reinforced polymer rebar (GFRP). The polypropylene fibre-reinforced fly ash column with recycled aggregate reinforced with CFRP rebars exhibited better performance under thermal loads. [ABSTRACT FROM AUTHOR]

The paper presents the researches undertaken for the superior capitalization, in the context of the circular economy, of the power plant ashes and other industrial wastes, in the construction materials industry. Taking into account the specific properties of the ash from the thermal power plant, a technological scheme was elaborated through which the recovery of iron oxides was pursued (their share being significant). Due to the hydraulic properties of power plant ash, similar to those of classical construction materials, laboratory research was conducted in order to develop a material usable in the construction materials industry with superior characteristics. [ABSTRACT FROM AUTHOR]

The application of industrial waste in construction reduces the dependency on natural resources. The materials, including red mud (RM) and fly ash (FA), proved to be favorable materials. However, the materials potential together as a geopolymer composite for road applications has rarely been explored. This study will examine the possibility of the replacement of natural materials in subgrade applications. To achieve this, the geopolymer compositions will be prepared by replacing RM with FA at replacement rates of 10%, 20%, and 30% by dry weight basis. The alkaline activator solution of 8 M will be prepared using sodium hydroxide (NaOH) and sodium silicate to develop geopolymer composites. The strength properties will be studied using the California Bearing Ratio (CBR) and unconfined compression strength (UCS) and validated with microstructural analysis using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The results reveal that geopolymer composites could achieve a maximum CBR value of 12% and UCS of 2,700 kPa. The microstructural analysis revealed that the formation of dense calcium aluminate hydrate (C-A-H) and calcium silicate hydrate (C-S-H) are the reason for strength improvement. The leaching studies show that the toxic elements were within the permissible limits. Overall, the test results confirmed that the geopolymer composites meet the required strength and could be used as a subgrade material in road construction. [ABSTRACT FROM AUTHOR]

Owing to the increased population in developing country like India, the demand of sustainable building material is likewise increased to meet its excessive consumption. In the present study, non-autoclaved aerated geopolymer (NAAG) blocks were developed using industrial waste [fly ash, granulated blast furnace slag (GGBS)], foam and aerating agents with less concentration of alkaline solution (i.e. 1.5–4 M) and tested for their physio-mechanical properties. These NAAG blocks achieved up to 13.5 MPa compressive strength. Optimized samples were tested for thermal and durability related properties. Performance evaluation of NAAG blocks exhibited low thermal conductivity and durable nature as compared to the clay bricks. This developed NAAG block is proven to be a cost-effective and energy effective solution and can be used as building material. [ABSTRACT FROM AUTHOR]

Blast furnace slag (BFS) is commonly used as a substitute for cement clinker due to its hydration properties. However, the demand for BFS is outpacing the supply, and its price is rising steadily. Moreover, the significant accumulation of industrial waste with potential hydration properties poses a severe environmental threat. To address these challenges, this paper aimed to prepare high-performance composite blast furnace slag powder (CBFS) by incorporating red mud (RM), fly ash (FA), desulfurization gypsum (DG) and BFS, guided by the synergistic effects and the theory of medium-calcium systems. This paper reveals that the primary activation methods of the amorphous silicon-aluminum mineral phases in CBFS are alkali activation and sulfate activation. The optimal results demonstrate that the compressive strength of CBFS-cementitious material (50% CBFS + 50% cement) can reach 52.8 MPa, meeting the standards of Portland Cement PO 42.5. Additionally, RM, FA and DG account for 66% of CBFS and the hydration activity of CBFS is better than that of S95-grade BFS. Furthermore, the CBFS-cementitious material effectively immobilizes hazardous elements of the raw materials, and the leachate meets drinking water standards. The application of CBFS facilitates the recycling of industrial solid wastes, improves the quality of construction materials and reduces the construction industry's dependence on BFS. [Display omitted] • CBFS was prepared using RM, FA, DG, and BFS, aiming to achieve integrated clean production in multiple industries. • The total content of RM, FA and DG in CBFS reaches 66%, and its properties meet the requirements of S95-grade BFS. • RM, FA, DG and BFS showed a positive synergistic effect in CBFS, which enhanced the strength of the matrix (52.8 MPa). • CBFS can reduce carbon emissions in the cement industry and solidify the hazardous elements in the raw materials. [ABSTRACT FROM AUTHOR]

• The focus of this investigation was on development of a new sustainable class of hydraulic binder that relies upon the robust nature of alkali aluminosilicate binder chemistry to make value-added and large-volume use of industrial wastes of rice husk ash, municipal waste solid ash (MSW) and coal fly ash as primary raw materials. • In an effort to produce a hydraulic binder that requires only the addition of water (in lieu of alkaline solutions in traditional geopolymerization), the blend of raw materials was subjected to mechanochemical processing. • The binder chemistry used here yields hydration products with desirable capabilities for stabilization of heavy metals. Rice husk ash, Municipal Solid Incineration Ash and coal fly ash was served as aluminosilicate precursor in synthesis of one-part alkali activated geopolymer binder. These by-products industrial wastes were subjected to physio-chemical processing of materials (mechanochemical synthesis) together with different naturally originated sources of alkaline earth metal cations into one-part alkali activated (geopolymer) binder binders. The binder of hydraulic binders was assessed based on their strength development attributes and morphology with respect to silica content, diffusion of Calcium ions and compositions of Alkali activator. The particle size distribution, the chemical composition, mineralogy, bond environment, of binder particles and effective immobilization of heavy metals of hydrated binder pastes were also inspected. The results highlighted that the ternary blend of combustion ashes to produce hydraulic binders with strength development qualities and safe disposal as material for building construction. [ABSTRACT FROM AUTHOR]

• Alkali-activated fly ash with pozzolanic reaction reached 60 MPa at ambient condition. • Silica fume enhanced reaction participation of Ca2+ in alkaline environment. • Significant contribution to strength development was induced from pozzolanic reaction. • Physical filling effect by addition of silica fume was negligible in tested mix proportions. Despite considerable efforts focused on the utilization of industrial wastes, the application of low-calcium fly ash to the construction industry is limited to the partial substitution to ordinary Portland cement. High-temperature curing is a method via which fly ash can be completely utilized as an alkali-activated construction material; however, additional energy is required. In this study, the dual reaction of alkali activation and the pozzolanic reaction was proposed to manufacture ambient-condition-curable structural mortars. For this purpose, calcium hydroxide was used in fly ash activated by sodium hydroxide and sodium silicate solutions. A series of experiments, including compressive strength tests, X-ray diffraction, thermogravimetric analysis, heat of reaction, and mercury intrusion porosimetry, were conducted. The continuous pozzolanic reaction on the pre-formulated geopolymeric skeleton was found to significantly enhance the material properties. By the addition of silica fume and a 7:3 mixture of sodium hydroxide and sodium silicate solutions, the material strength increased to greater than 60 MPa at 56 days. The added silica fume as well as the reduced alkali content of the solution enhanced the reactions due to the active participation of the calcium ion supplied by the added hydrated lime in a high pH environment. [ABSTRACT FROM AUTHOR]

To study the processes of interaction and formation of the phase composition in slag-alkali binders based on fly ash, the alkaline ingredient solution was proportioned after 28 days of aging and after heat treatment, steam curing or setting in natural conditions. The products of interaction of slags and soda-sulfate mixture with highly basic additives were studied. Their phase composition was determined by the type of slag, additives, and setting conditions. The increase in density of alkaline ingredient solution from 1,100 to 1,300 kg/cm³ resulted in a 1.7-2 times higher compressive strength of set binder, which is 30.7, 47.1 and 45.9 MPa, depending on the liquid glass module. When the soda-sulfate mixture was introduced into the formula, the compressive strength of the steam-cured samples was 7-22% higher than that of the samples exposed to dry heat treatment. The strength of slag-alkali binders based on fly ash depended on the fineness of fly ash. The developed binding formulas can be used for the preparation of high-strength concretes and building materials. [ABSTRACT FROM AUTHOR]

The study of the deformability of building structures, especially bending elements, is an integral part of a full study of structures, because it is often the deformability determines the size of the cross section of the element, to ensure the necessary rigidity of building structures. For beam elements, the most important during exploitation are vertical displacement - deflections. For application (especially under the influence of aggressive environment) as a material of production of the building structures we offer rubber concrete-polymer concrete which has favorable deformation and strength characteristics, high adhesion to metal surfaces. It is important to note that the composition of fibrorubcon used industrial waste such as fly ash and fibers steel cord. It was established experimentally that the strength of fibrorubcon corresponds to the class of high-strength concrete, but the modulus of elasticity of rubcon corresponds to the modulus of elasticity of traditional concrete. To study the deformability of rubcon and fibrorubcon bending elements we have made a beam with a longitudinal reinforcement percentage μ = 0...8.4%. The beams were tested for pure bending - the most characteristic type of loading for such elements. On the basis of the tests, a limit on the percentage of longitudinal reinforcement to satisfaction the requirements of the current standards for maximum deflections of fibrorubcon and rubcon beams was set. [ABSTRACT FROM AUTHOR]

Abstract Fly ash and glass cullet - two materials, which are produced in quite large amounts. This paper presents the new way the high calcium fly ash (HCA) and the industrial glass waste powder (GP) disposal in building materials technology as main components of binders. Samples were examined over the period up to 6 years of maturity. There were used only two kinds of waste materials (GP + HCA) and water to produce pastes. Fine grinded glass was used as alkaline activator. The HCA was used to induce alkaline activation and dissolution of the glass powder in HCA – GP mixtures. Materials were mixed in three different proportions to prepare the samples. The mechanical strength, microstructure, phase composition and expansion were examined. Results showed that the HCA in connection with GP gave a good alkali activated binding materials for some special applications. In addition to that, the GP + HCA mixtures could be prepared with neither Portland cement nor any additional activator using exclusively waste materials. This is important for the perspective of reducing the CO 2 emission. Presented materials were prepared. This is the first work which presents the usage of GP as an alkali activator. Highlights • A binders composed exclusively of waste materials is presented (powdered glass cullet and high calcium fly ashes). • Glass powder and high calcium fly ashes were used as mutual alkaline activators. • Long-term (six years) performance of ground glass and high calcium fly ashes was presented. • SO3/Al2O3 is a key factor controlling the late expansion of ground glass – high calcium fly ash binder. [ABSTRACT FROM AUTHOR]

This study investigates the potential approach of utilising CO 2 to produce carbonated fly ash (CFA) in a cement blend for new ‘green’ construction materials. The aqueous fly ash (FA) carbonation experiments are performed in a batch bench-scale glass reactor to study the effect of different CO 2 flow rates (of 2 and 4 ml/min) and water-to-FA ratios (15 and 7.5 ml/g) on the carbonation process. A longer carbonation time is obtained for the water-to-solid ratio of 7.5 ml/g compared with 15 ml/g at the same CO 2 flowrate while a faster carbonation process is achieved at higher CO 2 flowrate at the same solid dosage. The maximum carbonation efficiency of 16.9% is calculated for water-to-solid ratio of 15 ml/g based on the variation in the Ca 2+ ions concentration in the liquid phase. However, using the carbonate content of the solid samples results in a much higher carbonation efficiency of 83.5% corresponding to a final CO 2 uptake of around 3.2%, i.e. 32 g CO 2 /kg FA. The CFA is then used to prepare cement paste blends in which Portland cement (PC) is replaced with CFA at different replacement levels of 10 and 30% (w/w) using the water-to-cementitious material ratio of 0.4. Mechanical strengths of CFA-PC mortars, cured for 14 days under ambient conditions, are compared with those prepared from pure PC in order to investigate the effect of FA pre-carbonation on the performance of green cement with low-carbon footprint. The results show that the CFA-PC mortars containing 10% CFA has slightly lower compressive strength than that of the pure cement, however with increasing the CFA replacement level to 30%, significant reduction in the compressive strength of mortars is observed. [ABSTRACT FROM AUTHOR]

Construction materials are being used primarily for the humans' basic shelter needs since the beginning of history. Also, construction sector continues to evolve with the constantly advancing technology and it is one of the most important and largest sectors together with textile and food in the world. Gas concrete, which is a type of lightweight concrete's, usage has increased due to its minimal energy losses and light weight. With the additives that uses in gas concrete and creating pores with them, the structure can gain lightness and insulating properties. In this study, the gas concrete samples have been prepared with different methods using various industrial wastes as aggregate. Two different mixing types including by hand and with mechanical stirrer were used to see the impact of mixing type to the strength. Characterization and compressive strength values of the prepared samples were determined by comparing the best aggregate types. Gas concrete has been prepared both under the pressure and temperature in autoclaved conditions and the room conditions separately to see the effect of using the autoclave. According to analysis result, the gas concrete sample prepared from Afsin Elbistan fly ash and sand mixture had the best compressive strength of 1.09 N/mm² and it was classified as G1 class regarding to TS 453. [ABSTRACT FROM AUTHOR]

A new kind of foamed cement (FC) made of Portland cement (PC), fly ash (FA), steel slag (SS), and foam agent has been developed with the purpose of preparing energy-saving building materials. The effect of SS and FA on the properties such as bulk density and compressive strength of base mix was systematically investigated. The results indicated that the base mix with 50% PC, 30% FA and 20% SS showed the optimum properties. By proper control in dosage of foam agent, a series of FC with a range of bulk densities (350–1340 kg/m 3 ) were obtained for the further experimental measurement. The corresponding thermal conductivity ( k e ) of the samples was measured by a guarded hot plate apparatus. In addition, k e was also predicted by a modified model. Comparison with the previous model, the modified model had better accuracy and shorter calculated time. Finally the predictions were compared with the experimental data and other existing analytical models. The results indicated that the predicted results agree well with the measured values. [ABSTRACT FROM AUTHOR]

The fabrication of bricks commonly consumes relatively high natural resources. To reduce the carbon footprint in the brick production industry, repurposing industrial wastes in the making of sustainable bricks is a recent trend in research and application. Local wastes, such as oil palm shell (OPS), palm oil fuel ash (POFA), and quarry dust (QD), are massively produced annually in the palm oil-exporting countries. Moreover, QD from mining industries is hazardous to both water and air quality. For better waste management in marching towards sustainability, these wastes should be given their second life as construction materials. Therefore, this paper investigates the possibility of incorporating agro-industrial wastes into the brick mixture by examining their properties by means of several standardized tests. For the mix design, a 100% replacement of coarse aggregate with OPS, 20% replacement of cement with POFA, 20% cement weight of limestone as admixture, and 0 to 50% replacements of fine aggregate with QD are experimentally considered. The optimum mix of these wastes is preliminarily determined by focusing on high compressive strength as an indicator. Other examinations include splitting tensile, flexural strength, water absorption, and efflorescence tests. Although the agro-industrial waste cement brick is 18% lower in the strength to weight ratio compared to that of conventional, it is observed that it has better late strength development due to its POFA pozzolanic properties. Moreover, the proposed green cement brick is further checked for compliance with several standards for feasible use in the construction industry. Financially, the cost for the brick with the new mix design is almost equivalent to that of conventional. Hence, this green cement brick is reasonable to be employed in the construction industry to promote material sustainability for better waste management. [ABSTRACT FROM AUTHOR]

[Display omitted] • Area of bloating clays by Riley and Wilson is used to assess the bloatablity of CDW to make LWA. • Brick and fly ash in Vietnam is suitable for producing LWAs, GBFS is not. • SiC is suitable as a blowing agent to produce LWAs from CDW and fly ash. • Optimum sintering temperature to make LWA from CDW is 1220–1250 °C. • Necessary residence time for burning is 6–9 min. The amount of construction and demolition waste and industrial by-products are increasingly high in Vietnam recently. The recycling of these wastes as new construction materials is an effective solution for sustainable development. This paper presents a method for the recycling of construction and demolition waste and other industrial by-products, such as fly ash and slag in Vietnam to produce lightweight aggregate. Experimental results show that masonry wastes including brick and mortar as well as fly ash are suitable materials for producing lightweight aggregates with a granule density of less than 1000 kg/m3 with the optimum sintering temperatures and the residence time in the range from 1220 °C to 1250 °C and, 6 to 9 min, respectively. These recycled lightweight aggregates can be used as valuable substitutes for natural aggregates to make lightweight concrete for new structures and therefore contribute to the construction industry's sustainability. [ABSTRACT FROM AUTHOR]

• Foamed geopolymer was successfully produced from industrial wastes. • Foamed geopolymer consisted of geopolymer binders, unreacted and nonreactive phases. • The factors influencing the mechanical properties of geopolymer were studied. The characteristics of strong alkalinity and concentrated heavy metals make it difficult to dispose and re-utilize Bayer red mud (RM). As for another industrial waste, ZSM-5 (Zeolite Socony Mobil-5) waste is deactivated ZSM-5 catalysts that was formed from the industrial cycles. Herein, a new kind of foamed geopolymer composite (containing various ratios of RM/FA) with micropores was fabricated at elevated temperature from three industrial wastes: Bayer red mud (RM), fly ash (FA) and ZSM-5 waste. The final geopolymer products were characterized by compressive strength tests, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, FT-IR spectral analysis, and mercury intrusion porosimetry to evaluate the relationship between their microstructure, geopolymerization reactions and mechanical properties. ZSM-5 waste has the strong ability to foam because it contains ZSM-5 that possesses numerous mesoporous. The addition of ZSM-5 waste generates a microporous structure. Higher RM/FA ratios generally result in a lower compressive strength owing to the lower reactivity of the RM; however, excessive RM particles may cause the negative effect. The compressive strength in overall decreases from 10.7 to 8.0 MPa and the bulk density increases from 1.04 to 1.26 g/cm−1 with the increased RM/FA ratios of 0.4–1.0, respectively. Microscopic morphology analysis demonstrates that the final products are composites consisting of geopolymer gels and unreacted phases, such as mullite and hematite phases, as fillers. This research can shed light on the utilization and mechanisms of industrial RM and ZSM-5 waste into the construction and building materials. [ABSTRACT FROM AUTHOR]

Fly and bottom ash(es) are the most abundant generated by-products of coal combustion in thermal power plants. This investigation offers a sustainable solution of a double and circular use of industrial waste material in civil engineering practices; i.e., fly ash (FA) as an eco-efficiently, low-cost material for As(V) adsorption, as well as an additive in building materials. A goethite impregnated sample (FAG) was synthesized and optimized using the column precipitation procedure, then thoroughly, structurally and morphologically characterized using liquid nitrogen porosimetry (BET), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and Mössbauer spectroscopy (MS) techniques. The data from the equilibrium adsorption were fitted by linear and non-linear isotherm models; the optimal capacity of FAG/As(V) removal was calculated from the Langmuir model at 31.742 mg g−1 for 45 °C. The kinetics of adsorption process has shown the pseudo-second-order kinetic model (PSO). The Weber-Morris model was applied to determine the intra-particle diffusion as a limiting step of reaction. The low pH dependant FAG leaching confirmed the efficient use of non-hazardous waste material in arsenic removal; furthermore, it also validated the new added value of the used/spent adsorbent as an adhesive in building materials possessing advanced mechanical properties. • Goethite modified fly ash (FAG) was used as an eco-efficiently adsorbent. • The sorption capacity of FAG/As(V) separation medium was 31.742 mg g−1. • The exhausted adsorbent FAG/As(V) was (re)used as an additive in building material. • Leaching tested building material was inert and non-hazardous to the environment. • The 'closed loop' of industrial waste valorization and practice was achieved. [ABSTRACT FROM AUTHOR]

Residential consumption dominates the energy expenditure of heating and cooling systems, especially in tropical climates where building envelopes play an important role in energy efficiency. The thermal properties of concrete that are commonly employed as the building envelope material affect directly human comfort in a building. In addressing both the concrete thermal performance and industrial waste issues, this paper experimentally studies the concrete compressive strength and thermal properties used later for comparative energy analysis for human comfort. Four design mixes and a conventional concrete as control specimen are considered utilizing industrial wastes; palm oil fly ash (POFA), lightweight expanded clay aggregate (LECA), oil palm shell (OPS), and quarry dust, as constituents. These mixes are cast for cube compressive strength (to ensure the achievement of structural concrete requirement) and small-scaled wall tests. The measurement of surface temperatures of scaled wall tests is conducted in a polystyrene box to determine the concrete time lag and decrement factor. It is found that the density of concrete governs the compressive strength and that air pockets in the concrete matrix play an essential role as far as the thermal properties are concerned. From the energy analysis, structural lightweight concrete may save approximately 50% of the residential energy consumption. [ABSTRACT FROM AUTHOR]

• Mechanical properties and reinforcement interaction with rammed earth were studied. • Poisson's ratio, shear and flexural strengths should follow concrete design rules. • Elastic modulus and tensile strength should use existing rammed earth estimations. • Reinforcement bond can be measured using a 'push-out' test. Developing low-embodied energy building materials can significantly contribute to reducing global greenhouse gas emissions. However, these new building materials must be properly understood before they can or will be adopted by the construction industry. Rammed earth materials with low greenhouse gas emissions have been developed based on the principles of alkali-activated stabilisation as replacements for conventional construction materials. In previous work by the authors, the strength development, durability and sustainability, via life cycle assessment, of these new materials have already been studied. However, how these materials interact with and affect embedded reinforcement is poorly understood, as are methods to test these properties. Their applicability in modern construction is therefore currently limited. This paper extends the understanding of these materials through flexural and push-out testing of specimens reinforced with steel and glass-fibre reinforced polymer bars. We determine mechanical properties of the alternatively-stabilised rammed earth materials and study the composite behaviour of the reinforced materials. The suitability of current testing standards for elastic modulus, Poisson's ratio, and indirect tensile, bond, shear and flexural strengths, originally designed for concrete specimens, were evaluated for RE materials. These were compared with design rules and predictions made using concrete standard AS 3600 and rammed earth standards (NZS 4297-4299), handbook (HB 195) and rammed earth and concrete literature. Results showed that existing testing procedures specified for concrete specimens were appropriate for estimating Poisson's ratio and shear modulus as well as for determining flexural and shear strengths for rammed earth. Existing rammed earth recommendations given in NZS 4297 for estimating elastic modulus should continue to be followed. An alternative compressive reinforcement bond test, similar to RILEM AAC 8.2 push-out standard for autoclaved aerated concrete, was proposed; however, more work is required to establish a better prediction model for bond strength. Results indicated that current expressions to relate indirect tensile to unconfined compressive strength are suitable for compressive strengths up to 20 MPa. [ABSTRACT FROM AUTHOR]

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials. [ABSTRACT FROM AUTHOR]

• CO 2eq emissions of alkali- and lime-activated rammed earth (RE) were measured. • Recycled materials can be incorporated, reducing waste. • Use of a local base material is essential to reduce transport-related emissions. • Best material choices may vary with time and location. • Adopting alkali-activated RE could reduce Australia's greenhouse gas emissions. As the Paris Agreement target year of 2030 draws nearer, it is becoming increasingly evident that neither Australia nor many other nations are progressing at a rate sufficient to meet greenhouse gas emissions targets. One area in which to improve performance is in the use of low embodied energy construction materials. Rammed earth (RE) is often considered to be one such material. However, many modern RE variations incorporate cement: a significant contributor to global CO 2 emissions. RE materials with low greenhouse gas emissions have been developed as replacements for conventional construction materials. In this series, we examine the strength development, durability and sustainability, via life cycle assessment, of these new materials. This paper explores the cradle-to-gate greenhouse gas emissions of RE materials incorporating recycled waste (crushed brick and concrete), industrial by-products (ground granulated blast furnace slag, fly ash and silica fume) and either NaOH or hydrated lime. These are then compared to construction techniques conventionally used in Australia (cavity brick and brick veneer). Attributional life cycle assessments were carried out for hypothetical building envelopes suitable for climate zones 1–7, assuming construction in metropolitan Perth and 600 km inland (Kalgoorlie, WA). Results showed that greenhouse gas emissions per vertical square metre of wall could be reduced by 73% or 57% respectively when compared to traditional cavity brickwork or brick veneer. This is in contrast to RE incorporating cement, which produced a saving of just 15% compared to brick veneer. If this construction technique were adopted across Australia for new, detached dwellings constructed during 2021–2030, this could represent a greenhouse gas reduction of 11.3 million tonnes CO 2eq , or 1.2–1.3% of the cumulative emissions reductions required in 2021–2030 to meet Australia's Paris Agreement targets. [ABSTRACT FROM AUTHOR]

• Durability properties of alkali-, lime- and self-activated rammed earth were assessed. • All tested stabilised rammed earth (RE) materials have adequate durability properties. • The water repellent, Plasticure, improved immersed absorption of cement-stabilised RE. • The water repellent improved initial rate of absorption of RE with all stabiliser types. Rammed earth (RE) materials with low greenhouse gas emissions have been developed as replacements for conventional construction materials. In this series, we examine the strength development, durability and sustainability, via life cycle assessment, of these new materials. In this paper, we present findings for material durability with and without the addition of the water repellent admixture, Tech-Dry 'Plasticure'. Understanding of durability properties is essential to verify the suitability of the RE materials for building. The study assessed four distinct RE materials, all based on a substrate of crushed limestone: a control mix, cement-stabilised RE (the industry standard in Western Australia) and three alternative stabilisers, i) alkali-, ii) lime-, and iii) self-activated RE. The alternative RE stabilisers incorporated industrial by-products fly ash, ground granulated blast furnace slag and silica fume, in combination with sodium hydroxide, hydrated lime or no activator (respectively, by mix). Durability was assessed using initial rate of absorption, immersion and wire brush testing. Both with and without Plasticure, all materials either passed these tests or, where pass/fail criteria were unavailable, were found to be comparable to conventional building materials. Scanning electron microscopy and energy dispersive spectroscopy showed that greater maturity in terms of reaction of raw materials was associated with lower absorption. Those materials with Plasticure had lower initial rate of absorption than those without, especially in the case of lime- and self-activated RE. Plasticure was shown to improve durability properties of all tested RE mixes. [ABSTRACT FROM AUTHOR]

• Suitability of CSEB stabilized with cement and fly ash is assessed in terms of strength and durability. • Inclusion of fly ash is effective in reducing the cement content significantly. • Optimum fly ash content is 15% for 5–7% cement content. • Fly ash is effective in reducing water absorption capacity. • Fly ash and cement stabilized CSEBs are more suitable compared to fired clay bricks from economic standpoint. For saving natural resources, reducing pollution and increasing energy efficiency, Compressed Stabilized Earth Block (CSEB) can serve as a suitable alternative to conventional Fired Clay Brick (FCB). In this study, suitability of industrial waste, Fly Ash (FA) is assessed along with cement as stabilizers for producing CSEBs with coarse grained soil. Different combination of cement and FA (5–10% cement and 5–25% FA; by weight of dry soil) was considered to prepare CSEBs for finding the optimum mix composition in terms of strength, durability, deformation characteristics and cost effectiveness. Furthermore, strength and durability test results are compared to the design criteria reported in Indian Standard, Sri Lankan Standard, Standard Australia, British Standard and Malaysian Standard for assessing its viability as construction material. With the increase in cement content, strength of the blocks gradually increases; however, at a definite cement content, addition of FA increases strength up to a certain limit and then begins to drop. Inclusion of 7–8% cement and 15–20% FA is found to provide adequate dry compressive strength (>5 MPa), wet-to-dry compressive strength (>0.33) and enough durability in terms of water absorption (<20%) as recommended by British Standard and Standards Australia. The behavior of the CSEBs were also analyzed through microstructural investigation, where SEM images were taken to ascertain the morphologic and anatomic changes that occurred at different fly ash contents. At a definite cement content, with the increase of FA, peak strain and failure strain increase; thereby indicating an improved straining capacity of the blocks due to inclusion of FA. Moreover, modulus of elasticity improves with increasing amount of cement and FA for both dry and wet state. Furthermore, economic analysis of a typical house constructed with CSEBs and FCBs was performed and compared with literature. Considering all the parameters it can be concluded that CSEBs prepared with cement and fly ash as stabilizers can be used as a sustainable construction material. [ABSTRACT FROM AUTHOR]