Construction Materials Research Articles

A Review of the Utilization of Recycled Powder from Concrete Waste as a Cement Partial Replacement in Cement-Based Materials: Fundamental Properties and Activation Methods

Recycled powder (RP) is the primary by-product generated during the reclamation process of construction and demolition waste (CDW). There is existing literature on the use of RP as supplemental cementitious materials (SCMs) in cement-based materials, but a comprehensive evaluation on the characteristics of RP generated from concrete waste has been missing until now. This paper critically reviews the use of RP from concrete waste in cement-based materials, as concrete waste makes up a significant amount of CDW and other components have designated recycling methods. In this sense, this study conducted a critical analysis on the use of RP as an SCM, using detailed literature research. The technology used for producing RP is detailed along with its chemical, mineralogy, and microstructural characteristics. Fresh-state properties in cementitious matrices with RP are introduced with the view of mechanical grinding, thermal activation, carbonation, chemical treatment, biomineralization, mineral addition, nano activation, and carbonation. The review highlights the significant potential of utilizing RP in cement-based materials. Specifically, RP can be advantageously utilized in the production of value-added construction materials.

Shear Bond Strength in Stone-Clad Façades: Effect of Polypropylene Fibers, Curing, and Mechanical Anchorage.

This study investigates the shear bond strength between four widely used façade stones-travertine, granite, marble, and crystalline marble-and concrete substrates, with a particular focus on the role of polypropylene fibers in adhesive mortars. The research evaluates the effects of curing duration, fiber dosage, and mechanical anchorage on bond strength. Results demonstrate that Z-type anchorage provided the highest bond strength, followed by butterfly-type and wire tie systems. Extended curing had a significant impact on bond strength for specimens without anchorage, particularly for travertine. The incorporation of polypropylene fibers at 0.2% volume in adhesive mortar yielded the strongest bond, although lower and higher dosages also positively impacted the bonding. Furthermore, the study introduces a novel fuzzy logic model using the Dombi family of t-norms, which outperformed linear regression in predicting bond strength, achieving an R2 of up to 0.9584. This research emphasizes the importance of optimizing fiber dosage in adhesive mortars. It proposes an advanced predictive model that could enhance the design and safety of stone-clad façades, offering valuable insights for future applications in construction materials.

3DP for sustainable built environment – Synthesis and thermomechanical characterization of composite materials based on local soil and date palm fiber waste

There is an increasing demand for sustainable construction materials to address the challenges posed by the environmental impact of the built environment (BE), which is driven by climate change, population growth, and urbanization. Conventional construction materials like cement contribute significantly to carbon emissions during production, transport, use, and disposal phases, and their poor thermal conductivity hinders efforts to maintain comfortable indoor environments. To address these challenges, there is an urgent need for innovative, locally sourced thermal insulation materials specifically designed for regions with extreme climates and high energy demands to maintain building comfort. This research explores synthesizing novel, environmentally friendly building materials using locally sourced date palm fiber waste and clay. The study also investigates the developed material's 3D printing (3DP) capabilities and optimizes its printing parameters with lab-scale prototypes. Additionally, thermo-mechanical characterization is conducted to assess its suitability for built environment applications. Different concentrations, from 1 to 5 wt% of date palm fiber to clay ratio (Dpf/C), were studied regarding microstructural, thermal, and mechanical properties, dimensional accuracy, and feasibility for 3DP of BE structures. Results demonstrated a significant reduction in thermal conductivity by 73%, achieving 0.244 W/mK, and an increase in compressive strength by 106%, reaching 10.9 MPa at 5 wt% Dpf/C. The promising thermomechanical properties of these composites and their suitability for 3DP support their use in real-world applications in the future's sustainable built environment. This scalable methodology can be adapted to regions with similar sustainable local and waste resources, advancing the circular economy.

Properties and Potential Application of Urban Sewage Sludge as Construction Material in Da Nang City

Research on sludge properties makes an important contribution to the management and reuse of sludge for different purposes. In this study, 60 sludge samples were sampled from the urban drainage river system in Da Nang city and analyzed for their physical and chemical properties. The results show that the composition of the sludge samples are mainly sand, ranging from 52.2 to 90.1%, pH at slightly acidic to neutral levels, ranged from 4.3 to 6.8, total organic carbon content ranged from 1.1 to 6.0% and there was a large difference within samples. The content of Cl-, SO42- ranges from 0.07 to 1.92%. There were 45/60, 31/60, and 26/60 samples with Zn, Pb and Hg contents exceeding the national technical regulation on sediment quality (QCVN 43:2017/BTNMT), respectively, from 1.04 - 2.52, 1.02 – 1.61, and 1.4 – 5.8 times. The As and Cd contents in all research samples were lower than the maximum allowable level (QCVN 43:2017/BTNMT). Ag, Co, and Se content were undetected in all samples. 48/60 sludge samples had phenol content exceeding QCVN 43:2017/BTNMT by 2.38 - 6.91 times. With this result, urban wastewater sludge in Da Nang city could be reused as bricked construction materials for a circular economy.

A numerical investigation on the conductive drying process for phosphate sludge

Phosphate production generates huge quantities of waste materials that pose both economic and environmental challenges. They are characterized by a high-water content, making disposal a very difficult task. To address this issue, conductive drying emerges as a viable solution to reduce the water content in the phosphate sludge to facilitate handling and specially recycling them as construction materials. This paper presents a simplified numerical model based on Fick's law, depicting heat and mass transfer in porous media to simulate the conductive drying process within the phosphate sludge. To provide more accuracy to the numerical model solution, the experimental data are integrated into the numerical model as boundary conditions, enabling the prediction of temperature profiles, thermal conductivity, and effective moisture diffusivity throughout the conductive drying process. The water evaporation capacity is found between 1.25 and 2.1 kg water/m2.h.These findings could be a tool for designing a suitable dryer for phosphate washing sludge.

Stakeholders’ perceptions of and willingness to pay for circular economy in the construction sector

Adopting Circular Economy practices in the construction industry can help reduce greenhouse gas emissions. However, many barriers exist to adoption, and current perceptions of and willingness to pay for circularity have yet to be quantified. This study seeks to understand the various perceptions of circularity in the construction industry, characterize uncertainties and risks, and identify economic incentives and opportunities that could accelerate circular adoption via an industry survey of three stakeholder groups. 58 stakeholders filled out part of the survey, and 42 stakeholders completed the majority of questions. Real estate developers are willing to pay an average premium of 10% for construction costs if there’s a minimum embodied carbon reduction of 53%. Design and construction professionals and material suppliers were also surveyed. Reasons for adopting circular practices were primarily driven by client, design team, and net zero goals. The results of this survey begin to characterize the economic landscape of what is needed for a circular transition in the built environment.

A Sustainability Study upon Manufacturing Thermoplastic Building Materials by Integrating Chicken Feather Fibers with Plastic Waste

The article explains how to make thermoplastic construction materials by combining waste from chicken feathers with plastic waste. The initial phase focused on a new and environmentally friendly method of sterilizing raw feathers using microwave radiation inside sealed ovens with circulating air. Additionally, composites containing varying feather amounts using two different polymer matrices were fabricated through an injection process, followed by mechanical and physical tests on the samples. Because of their excellent characteristics, products made from a combination of chicken feather waste and plastic waste could effectively replace traditional wood–plastic composites that are polyvinyl chloride-based. The recycling technology was assessed for its environmental impact, and sustainability was proven economically and environmentally.

Elucidating Rheological Properties of Cementitious Materials Containing Fly Ash and Nanosilica by Machine Learning.

Researching the rheology contributes to enhancing the physical and mechanical properties of concrete and promoting material sustainability. Despite the challenges posed by numerous factors influencing viscosity, leveraging machine learning in the era of big data emerges as a viable solution for predicting the general properties of construction materials. This study aims to create models to forecast the rheological properties of cementitious materials containing fly ash and nanosilica. Four models-Random Forest, XGBoost, ANN, and RNN (Stacked LSTM)-are employed to predict and assess shear rate versus shear stress and shear rate versus apparent viscosity curves. Through hyperparameter adjustments, RNN (Stacked LSTM) exhibits excellent performance, achieving a coefficient of determination (R2) of 0.9582 and 0.9257 for the two curves, demonstrating superior statistical parameters and fitting effects. The RNN (Stacked LSTM) exhibited a better generalization ability, suggesting it will be more reliable for future prediction in cementitious material viscosity.

Investigation of material cost of a propane-propylene rectification column

In this study a propane-propylene rectification column was investigated in terms of diameter of the column, number of trays, reflux ratio and the construction material costs of the column. During the calculations the reflux ratio was modified between 8 and 30. The chosen material of the column and trays was 1.4404 grade austenitic steel. The calculation has shown that with higher reflux ratio the diameter of the column and the number of trays were changing. Next, the necessary wall thickness of the shell of the column was determined with strength calculation. A material cost function was also determined with these parameters applying various reflux ratio values. From the results it can be concluded that the optimal reflux ratio is 12, because in this case the material cost function has a minimum point.

Comprehensive Review of Fly Ash: Environmental Impact and Applications

ABSTRACTFly ash (FyA), a byproduct from coal combustion in power plants, has become increasingly valuable due to its pozzolanic properties. Primarily, FyA finds applications in the construction industry, including road and brick construction, forest road building, and the cement industry. When added to concrete, it enhances splitting tensile strength, compressive strength, and workability, while also reducing the environmental impact of cement production. Beyond construction, FyA is utilized for air pollutant removal and serves as an adsorbent for various contaminants. It also plays a role in creating geopolymers and nanocomposites, promoting the development of eco‐friendly construction materials. This review article presents current data on thermal power plants (ThPPs) in India, the challenges in FyA management, and its environmental impact. It also discusses relevant Indian policies and highlights ongoing research aimed at improving the efficiency and expanding the applications of FyA in various industrial sectors, such as battery manufacturing, zeolite synthesis, and cenosphere extraction. These efforts underscore FyA's potential in supporting sustainable practices. The findings of this review address critical issues related to FyA. By reducing the environmental footprint of cement manufacturing, removing air pollutants, and acting as an adsorbent for various contaminants, FyA demonstrates significant potential in pollution mitigation. It also contributes to the development of eco‐friendly construction materials and promotes sustainability in the construction sector. Effective management practices are essential to minimize FyA's negative impact on human health and the environment. The article emphasizes the need for greater awareness and implementation of policies to address these issues comprehensively. By providing a detailed understanding of the benefits and challenges associated with FyA, it aims to pave the way for more effective and sustainable utilization of this industrial byproduct.

Valorization of Residue from Aluminum Industries: A Review.

Recycling and reusing industrial waste and by-products are topics of great importance across all industries, but they hold particular significance in the metal industry. Aluminum, the most widely used non-ferrous metal globally, generates considerable waste during production, including dross, salt slag, spent carbon cathode and bauxite residue. Extensive research has been conducted to recycle and re-extract the remaining aluminum from these wastes. Given their varied environmental impacts, recycling these materials to maximize residue utilization is crucial. The components of dross, salt slag, and bauxite residue include aluminum and various oxides. Through recycling, alumina can be extracted using processes such as pyrometallurgy and hydrometallurgy, which involve leaching, iron oxide separation, and the production of alumina salt. Initially, the paper will provide a brief introduction to the generation of aluminum residues-namely, dross, salt slag, and bauxite residue-including their environmental impacts, followed by an exploration of their potential applications in sectors such as environmental management, energy, and construction materials.

Enhancing bricks with titanium dioxide ore waste: Mechanical and environmental assessments

Using residues, generated in various production chains of goods and services through developing new materials for civil construction, has proven to be a promising approach to addressing environmental issues. The residue generated during titanium dioxide (TiO2) production, commonly called Unreacted Ore Waste (UOW), presents potential utilization routes in the ceramic materials production chain, thereby avoiding disposal in industrial landfills. This study aimed to investigate the effects of combining UOW with ceramic blocks for any beneficial results. The properties of ceramic blocks obtained from the mixture of clay and UOW were evaluated after adding 5 %, 10 %, 15 %, and 20 % of UOW relative to the clay’s total mass. The ceramic blocks produced were assessed for their mechanical, photocatalytic, morphological, granulometric, mineralogical, and chemical properties. The results indicated that UOW did not negatively affect the structural properties studied. The addition of UOW led to a significant 9 % increase in the self-cleaning efficacy of the ceramic block produced. The textural parameter values of the ceramic blocks decreased with UOW incorporation due to more efficient particle packing. The surface area reduced from 16.6 to 9.1 m2/g, and the pore volume decreased from 0.045 to 0.025 cm3/g for samples from 0 % to 20 % UOW, respectively. Decreased porosity values contributed to increased compressive strength, resulting in a 6.5 MPa increment. The results suggested that the addition of UOW causes an increase in Al concentrations in leachate samples, from 647.64 to 5128.92 ppb for samples from 0 % to 20 % UOW, respectively. The presence of leachate and solubilized components from UOW impaired the germination of Lactuca sativa seeds. Based on the results, although the addition of UOW resulted in toxicity from the leachate/solubilized components, it did not adversely affect any fundamental properties of the ceramic materials. It can be incorporated up to 20 % into the process, replacing traditional raw materials. This suggests promising future trends in sustainable construction, with broader applications in the development of eco-friendly building materials.

Environmental Sustainability Assessment of Cold Storage Panel Production

Today's ever-increasing environmental sustainability concerns have led to a major shift in construction sites and industrial sectors. In this context, the choice of construction materials for important structures such as cold storages plays an important role in terms of both environmental impacts and energy efficiency. The aim of this study is to evaluate the environmental loads of cold storage panels with thicknesses of 80 mm, 100 mm, 120 mm, 150 mm, 180 mm and 200 mm. In order to reveal the production inputs that cause these loads, the environmental effects were examined specifically for the 100 mm thick cold storage panel. Environmental impacts were analyzed using the Life Cycle Assessment (LCA) method in accordance with the ISO 14040/44 methodology as a system boundary "cradle to gate". This study focused on three different environmental impact categories of cold storage panels produced in Türkiye: global warming potential (GWP), cumulative energy demand (CED) and water footprint. In the evaluation of environmental impacts, production inventory information obtained from the panel manufacturer was used. For analyses, Simapro v. 8.5 LCA software was used. Analysis results show that the use of galvanized sheet metal in cold storage panel production is a hot spot in terms of global warming effect. It has been determined that the largest share in the water footprint belongs to polyurethane used as insulation material. Additionally, according to the CED, non-renewable fossil and non-renewable nuclear were determined to be the most affected categories, and the use of galvanized sheet metal and polyurethane were determined to be the most important hot spots in terms of non-renewable and renewable resources. To help improve the environmental performance of the cold storage panel, it is recommended to use bio-based and less environmentally impactful raw materials in production and to measure their environmental impact on a life cycle basis from cradle to grave.

Modelling Nigerian residential dwellings: bottom-up approach and scenario analysis

Nigeria’s residential buildings consume a substantial amount of the country’s energy, so achieving a net-zero building sector with a rapidly growing population is a key challenge. To bridge the gap in research at a national level and support Nigeria’s commitment to an unconditional 20% reduction in emissions by 2030, this study develops bottom-up archetype models of different residential building typologies to estimate the energy and material use of Nigerian residential buildings. This creates an overview of the residential stock and how different archetypes perform. The study calculates a baseline energy and material use of Nigeria’s residential building stock using the BuildME tool and converts these data into CO2 emissions using a life-cycle assessment. Scenarios are modelled for 2020. Nigeria’s residential dwellings use approximately 0.3 kt of material per dwelling over a lifetime of 50 years and 2404 kWh/yr of energy per dwelling. Annualised, dwellings emit 2500 kgCO2-eq per dwelling due to material and energy use. Scenarios proposed for meeting Nigeria’s emissions targets will require improved energy efficiency, decarbonising the building envelope through a shift in construction materials and decarbonising grid electricity. Policy relevance This study provides a comprehensive analysis of the energy and material use of residential buildings in Nigeria, focusing on achieving the country’s commitment to a 20% reduction in emissions by 2030. It employs a bottom-up approach to model energy and material use, revealing the peculiarities of the dwelling stock across Nigeria’s four climatic zones. The study explores the implications of different policy scenarios on sustainable housing. The research suggests that meeting Nigeria’s emissions targets requires improved energy efficiency, a shift in construction materials and decarbonisation of grid electricity. It also highlights the potential benefits of a policy switch to materials such as timber, earthen blocks, adobe bricks and clay, which could significantly reduce construction-related emissions. These changes could improve the quality of life of households in Nigeria, combat climate change on a global scale and bring economic advantages to Nigeria.

Lebanese Cedar, Skeuomorphs, Coffins, and Status in Ancient Egypt

In ancient Egypt, as with many cultures, funerary objects often communicated aspects of access, power, and social status. Lebanese cedar, for instance, was selected as a particularly desirable material from which to craft the coffins of Egypt’s upper echelons. This imported timber was both structurally superior to local woods and had important social and religious significance. For the slightly lower-ranking elite of Egypt, for whom cedar was inaccessible, local wood skeuomorphs that imitated cedar coffins were created in their place. The skeuomorphs enabled these individuals to demonstrate their knowledge of elite styles and tastes, and, due to the power of the image in ancient Egypt, also allowed for them to borrow the religious power of cedar wood to protect and enhance their own coffins. In this paper, a selection of Old to Middle Kingdom coffins are discussed to demonstrate the ways that cedar was emphasized as a construction material by the upper elite and mimicked by the middle and lower elite. This helps to demonstrate both the value of cedar in ancient Egypt, as well as the means by which imagery could be manipulated to gain access to the power of this potent material.

Axial compressive properties of round bamboo-fiber reinforced phosphogypsum composite short columns

Bamboo is an ideal green building material with excellent mechanical properties. Phosphogypsum (PG) is a kind of solid waste residue which is in urgent need of resource utilization and has been used as construction material. In this paper, a kind of round bamboo-fiber reinforced phosphogypsum composite short column was proposed. Axial compression tests of pure bamboo columns, bamboo columns filled with phosphogypsum inside, bamboo columns with phosphogypsum outside and bamboo columns with phosphogypsum inside and outside were carried out to explore the failure mode and mechanical properties of the short columns. The effects of the parameters include bamboo node, hose hoops, size of the bamboo tube and the strength of phosphogypsum on the mechanical properties of the short columns were analyzed, and the theoretical calculation method of the bearing capacity of the short columns was put forward. The results show that the bamboo nodes and hose hoops can improve the bearing capacity, initial stiffness and ductility of the column. The larger the size of the bamboo tube, the better the mechanical properties of the short column. The bearing capacity of round bamboo—phosphogypsum composite short column is higher than that of pure bamboo column. The ductility of bamboo columns with phosphogypsum outside is obviously higher than that of pure bamboo columns. The finite element analysis results are in good agreement with the test results. The theoretical calculation method of the bearing capacity of columns considering the strength reduction coefficient, the bamboo node effect coefficient and the constraint effect in this paper has high accuracy.

FoCa – Free of Carbon Architecture –an educational and informational online platform supporting the decarbonization of the construction sector in Poland and Turkey

Wrocław University of Science and Technology, in consortium with the Polish Association of Ecological Buildings (PLGBC), the Institute of Building Technology (ITB) and research and scientific units from Turkey, started the international project FoCA – Free of Carbon Architecture. Its aim is to create a publicly available tool – an interactive internet platform providing information on the environmental properties of construction materials and products available in Poland and Turkey. The platform allows users to compare and evaluate the environmental impact of selected building materials. As part of the platform's development, information is collected about building materials or products available on local markets, in the form of data describing their selected environmental impacts (GWPfossil, GWPbiogenic, GWPtotal, TRPE, TNRPE, WD). The platform allows to compare building materials and perform analyzes for conceptual building designs. In addition, producers of building materials can also benefit from the project because they will receive information about the environmental properties of some of their products. The platform will be available in the second half of 2024.

Study on the effect of cinder ash as an auxiliary additive mineral in hydrated lime treatment for expansive sub-grade soil in road construction

Expansive soils pose significant challenges to road construction globally due to their tendency to expand and contract with changes in moisture content, leading to pavement failure. In the construction industry, finding an economical and cost-effective alternative to conventional road construction materials is crucial. The use of a natural cinder ash and hydrated lime mixture as reinforcement has proven to be effective in addressing this issue. Cinder ash, a readily available waste material in countries like Ethiopia, is adaptable and water-resistant, making it an ideal choice for reinforcing expansive soil. This article investigates the strength performance of a cinder ash and hydrated lime mixture as a reinforcement material for expansive soil. The study involves mixing 0%, 20%, 25%, 30%, and 35% of cinder ash with soil stabilized with 2–5% hydrated lime. Expansive soil samples are prepared according to the ASSHTO & ASTM method and tested for compressive strength, California bearing ratio, bulk density, and water absorption. The findings reveal a 448.62%, and 374% increase in compressive strength and California Bearing Ratio respectively for the specimen containing 5% hydrated lime and 35% cinder ash, cured for 28 days. The water absorption is minimized at 15.23% for the 5% hydrated lime and 35% cinder ash mixture; while the maximum density of the soil is observed at 1.774 kg/m3 for the optimal combination of 5% hydrated lime and 35% cinder ash mix. The study suggests that using 5% hydrated lime and 35% cinder ash content for the stabilization of expansive soil significantly enhances the strength characteristics of compressed stabilized soil.

Study on the mechanical property and durability of alkali-activated seawater and sea sand recycled aggregate concrete

This study investigates the potential of Alkali-Activated Seawater Sea Sand Recycled Aggregate Concrete (ASSRAC) as a novel sustainable construction material. By utilizing recycled aggregates from construction and demolition waste, seawater, sea sand, and alkali-activated materials such as fly ash and blast furnace slag, this innovative concrete aims to mitigate carbon emissions from cement production and optimize resource usage. The impact of recycled aggregate replacement rate, water-to-binder ratio, and sand type on the compressive strength of ASSRAC was examined through analysis of variance. Cylindrical axial compression and prism flexural tests were conducted to evaluate the long-term performance of ASSRAC under seawater immersion. The results indicate a decrease in compressive strength with higher recycled aggregate replacement rates and water-to-binder ratios, with recycled aggregates being the primary weak link. Additionally, increasing the water-to-binder ratio hampers hydration by diluting alkali activators, weakening polycondensation reactions. Under seawater immersion, ongoing reactions foster denser C-(A)-S-H structures, enhancing compressive strength and elastic modulus over time. Moreover, higher recycled aggregate replacement rates result in improved ductility, attributed to reactions between the old mortar on recycled aggregate surfaces and slag/fly ash at interfaces. For specimens immersed for 0 and 90 days, most theoretical models accurately predict results, except for the CEB-FIP model, which only accurately reflects the stress-strain curve at 180 days. The seawater-sea sand group's flexural strength initially exceeds that of the freshwater-river sand group due to accelerated early hydration, but this advantage diminishes over time due to high salt content.

Assessment of indoor radon levels at multiple floors of an apartment building in the historic center of Rome (Italy): a comprehensive study

The urbanized area of Rome is largely built over volcanic deposits, characterized by a significant radionuclides content and consequently a high radon emanation potential. An accurate monitoring of workplaces and residential dwellings constitutes a first step towards mitigating the indoor radon exposure. Since radon diffusion dynamics involves complex interactions among many environmental parameters on different time scales, a proper assessment of radon concentration variations can be better achieved by means of active monitoring approaches. We present here the results of 1 year of continuous measurements conducted in six premises (five apartments and a basement) at different floors of the same building in the Esquilino district, in the historical center of Rome. Collecting annual series of radon concentration enables us to identify fluctuations over a seasonal scale, with radon generally decreasing in the warm season. The simultaneous tracking of different floors should cancel the influence of geogenic radon and of building characteristics like age, typology, and construction materials. While the basement shows the highest radon concentration, indicating a major contribution from the ground, we observe indoor radon levels comparable at all the upper floors, questioning the common belief that high-risk exposure be limited to the lowest storeys. The use of active devices makes it possible to discriminate between average indoor radon measured during the day and overnight, when residents are more likely to be at home. Our analysis provides the characterization of the dynamics of the gas emanation and transport inside the buildings and of its temporal fluctuations, in relation to the environmental and meteorological conditions. Since the experiment was performed in the Roman urban contest, we cannot ignore the specificity of the retrieved data, affected not only by endogenous factors like life habits relative to ventilation and conditioning of the apartments, but also by exogenous factors, among which the warmer microclimate compared to the surrounding suburban and rural areas, due to the effects of urbanization (urban heat island effect).