Construction Materials

33 pages, 3644 KB

Open AccessReview

Sustainable Engineering of Recycled Aggregate Concrete: Structural Performance and Environmental Benefits Under Circular Economy Frameworks

by Bishnu Kant Shukla, Harshit Yadav, Satvik Singh, Shivam Verma, Anoop Kumar Shukla and Chetan Sharma

Constr. Mater. 2025, 5(3), 67; https://doi.org/10.3390/constrmater5030067 - 15 Sep 2025

Abstract

The transition toward sustainable infrastructure in the construction sector necessitates the practical integration of Circular Economy (CE) principles, particularly through the valorization of recycled materials in concrete applications. This review critically synthesizes recent advancements in the use of recycled polyethylene terephthalate (PET), glass [...] Read more.

The transition toward sustainable infrastructure in the construction sector necessitates the practical integration of Circular Economy (CE) principles, particularly through the valorization of recycled materials in concrete applications. This review critically synthesizes recent advancements in the use of recycled polyethylene terephthalate (PET), glass powder, and crumb rubber as partial replacements for conventional aggregates in Ordinary Portland Cement (OPC)-based concrete. The incorporation of these secondary materials has demonstrated the ability to reduce the environmental footprint of concrete production—achieving up to 25% reductions in greenhouse gas emissions and diverting significant volumes of waste from landfills—while maintaining structural viability with compressive strength retention levels exceeding 90% in several optimized mix designs. Enhanced ductility, thermal resistance, and reduced density further support their application in specialized construction scenarios. Beyond material characterization, the review systematically examines implementation enablers, including regulatory alignment, life-cycle-based procurement, and design-for-deconstruction strategies. It also highlights critical gaps such as the absence of harmonized standards, variability in recycled material quality, and systemic barriers to market uptake. Addressing these challenges is essential for scaling CE integration and achieving measurable sustainability gains across the built environment. This study aims to inform policy, practice, and research trajectories by linking material innovation with operational frameworks that support regenerative construction systems. Full article

(This article belongs to the Special Issue Advances in the Sustainability and Durability of Waste-Based Construction Materials)

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25 pages, 5162 KB

Open AccessArticle

Determining Performance, Economic, and Environmental Benefits of Pavement Preservation Treatments: Results from a Systematic Framework for PMS

by Anthony Brenes-Calderon, Adriana Vargas-Nordcbeck, Surendra Chowdari Gatiganti and Josué Garita-Jimenez

Constr. Mater. 2025, 5(3), 66; https://doi.org/10.3390/constrmater5030066 - 11 Sep 2025

Abstract

This study evaluated the benefits of pavement preservation treatments across two climatic zones using data from the National Center for Asphalt Technology (NCAT) Pavement Preservation Group Study. Longitudinal data analysis was conducted to quantify pavement performance over time. Results indicate that in the [...] Read more.

This study evaluated the benefits of pavement preservation treatments across two climatic zones using data from the National Center for Asphalt Technology (NCAT) Pavement Preservation Group Study. Longitudinal data analysis was conducted to quantify pavement performance over time. Results indicate that in the freeze zone, treatments significantly improved pavement smoothness, as evidenced by reductions in the progression of the International Roughness Index (IRI), whereas similar trends were not observed in the no-freeze region, highlighting the need for further research to quantify the benefits in these zones. Life cycle cost analysis (LCCA) showed that selected preservation treatments reduced user costs by 54–57% due to lower excess fuel consumption, particularly in high-traffic corridors. These treatments also contributed to reductions in greenhouse gas (GHG) emissions by decreasing fuel use. Despite these findings, comprehensive, high-quality data are needed to fully evaluate the economic and environmental benefits of preservation treatments at the project level and to improve decision-making in pavement management strategies. Full article

(This article belongs to the Special Issue Advances in Sustainable Construction Materials for Asphalt Pavements)

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15 pages, 2286 KB

Open AccessArticle

Development and Characterization of Colored Lime–Gypsum Mortars for Heritage Building Restoration in Humid Environments

by Faris J. Thyab, Zaid Hazim Al-Saffar, Anas Ghaiath Ibrahim and Helen Faris

Constr. Mater. 2025, 5(3), 65; https://doi.org/10.3390/constrmater5030065 - 11 Sep 2025

Abstract

Surface deterioration and paint peeling occur in historic buildings worldwide due to excessive moisture. Conventional coatings often fail to preserve these structures. In Mosul, Iraq, conventional paints often do not preserve historic structures. The article aims to use colored lime–gypsum mortar, which has [...] Read more.

Surface deterioration and paint peeling occur in historic buildings worldwide due to excessive moisture. Conventional coatings often fail to preserve these structures. In Mosul, Iraq, conventional paints often do not preserve historic structures. The article aims to use colored lime–gypsum mortar, which has significant potential to be used as a sustainable and appropriate candidate material for the restoration of historic structures. This is particularly relevant for the restoration of exterior elements or interior walls in humid environments. The flowability, strength (compressive, flexural, and tensile), and shrinkage cracking of several mortar mixtures with different lime–gypsum ratios and color additives were all part of the extensive testing. Every procedure closely followed the applicable international standards The mortar mixture identified as optimal (Mix A10), comprising a 1:1 lime-to-gypsum ratio with carefully calibrated pigment additives (0.5 g chromium oxide, 0.2 mL liquid oxide, and 0.5 g powder oxide), demonstrated superior mechanical properties and minimal shrinkage cracking. This composition was ideal due to its superior mechanical strength and reduced shrinkage cracking compared to pure gypsum mixtures. The colored lime–gypsum mortar is a sustainable material well-suited to the restoration of historic structures, and applicable to both interior and exterior elements in humid environments. Its low shrinkage cracking enhances durability and effectively prevents moisture ingress in moisture-sensitive cultural settings. Full article

(This article belongs to the Topic Green Construction Materials and Construction Innovation)

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20 pages, 4144 KB

Open AccessArticle

Design and Evaluation of Modified Asphalt with Enhanced Stripping Resistance Based on Surface Free Energy

by Tomohiro Fujinaga, Tomohiro Miyasaka, Yousuke Kanou and Shouichi Akiba

Constr. Mater. 2025, 5(3), 64; https://doi.org/10.3390/constrmater5030064 - 9 Sep 2025

Abstract

Latent stripping has become increasingly apparent in asphalt pavements, particularly in highway rehabilitation and international construction projects supported by Official Development Assistance (ODA) from the Government of Japan. Stripping accelerates structural deterioration, making countermeasures essential. However, in ODA projects, securing high-quality aggregates or [...] Read more.

Latent stripping has become increasingly apparent in asphalt pavements, particularly in highway rehabilitation and international construction projects supported by Official Development Assistance (ODA) from the Government of Japan. Stripping accelerates structural deterioration, making countermeasures essential. However, in ODA projects, securing high-quality aggregates or evaluating local materials is often difficult due to environmental and budgetary constraints. This study focused on Surface Free Energy (SFE) as a small-sample evaluation method and developed ten types of styrene–butadiene–styrene (SBS) polymers to enhance interfacial adhesion by targeting aggregate surface functional groups. The SFE of each Polymer-Modified Bitumen (PMB) and thirteen aggregates was measured, and the work of adhesion and moisture sensitivity index (MSI) were calculated for all combinations. Twenty-one Hot-Mix Asphalts (HMA) were then prepared and evaluated using the Hamburg Wheel Tracking Test (HWTT) based on load cycles to stripping initiation (LC_SN) and to 12.5 mm rut depth (LC_ST). The developed PMBs showed a higher work of adhesion, a lower MSI, and substantially increased LC_SN and LC_ST values. Strong negative correlations were observed between MSI and both HWTT indicators, confirming the utility of SFE-based MSI for material screening. This study demonstrates that interface-targeted PMBs can improve stripping resistance, thereby promoting the use of lower-quality aggregates in durable pavements. Full article

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21 pages, 2849 KB

Open AccessSystematic Review

A Decision Framework for Waste Foundry Sand Reuse: Integrating Performance Metrics and Leachate Safety via Meta-Analysis

by Ferdinand Niyonyungu, Aurobindo Ogra and Ntebo Ngcobo

Constr. Mater. 2025, 5(3), 63; https://doi.org/10.3390/constrmater5030063 - 8 Sep 2025

Abstract

The reuse of Waste Foundry Sand (WFS) in construction remains constrained by fragmented research, unclear regulatory pathways, and inconsistent assessments of environmental safety and material performance. This study introduces a novel decision-making framework that systematically integrates mechanical performance metrics and leachate toxicity data [...] Read more.

The reuse of Waste Foundry Sand (WFS) in construction remains constrained by fragmented research, unclear regulatory pathways, and inconsistent assessments of environmental safety and material performance. This study introduces a novel decision-making framework that systematically integrates mechanical performance metrics and leachate toxicity data to classify WFS into three categories: Approved, Reusable with Treatment, or Rejected. The framework is based on a bibliometric analysis of 822 publications and a meta-analysis of 45 experimental mix designs and 30 peer-reviewed leachate studies. Normalized compressive strength (NSR), water-to-cement (w/c) ratio, and heavy metal leachate concentrations are used as screening criteria. Thresholds are benchmarked against regulatory limits from the United States Environmental Protection Agency (EPA), the European Union Landfill Directive, and South Africa’s National Waste Standards. Validation using field data from a foundry in Gauteng Province, South Africa, confirms the framework’s practicality and adaptability. Results indicate that over 80 percent of WFS samples comply with environmental thresholds, and mixes with 10-to-30 percent WFS substitution often outperform control specimens in terms of compressive strength. However, leachate exceedances for cobalt and lead in certain chemically bonded sands highlight the need for batch-specific evaluation and potential treatment. The proposed framework supports data-driven, transparent reuse decisions that enhance environmental compliance and promote circular material flows in the built environment. Future work should focus on digital implementation, life-cycle monitoring, and expanding the framework to other industrial byproducts. Full article

(This article belongs to the Special Issue Design, Process, Energy, and Evaluation in Construction Material Science)

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20 pages, 6556 KB

Open AccessArticle

Comprehensive Analysis of Microstructure and Mechanical, Operational, and Technological Properties of AISI 321 Austenitic Stainless Steel at Electron Beam Freeform Fabrication

by Sergey V. Panin, Mengxu Qi, Dmitry Yu. Stepanov, Mikhail V. Burkov, Valery E. Rubtsov, Yury V. Kushnarev and Igor Yu. Litovchenko

Constr. Mater. 2025, 5(3), 62; https://doi.org/10.3390/constrmater5030062 - 30 Aug 2025

Abstract

The aim of this study was to investigate microstructure and the mechanical and operational characteristics of thick and thin walls 3D-built by electron beam additive manufacturing (EBAM). In addition, the milling parameters (rotation speed, feed, and cutting width) were optimized based on simultaneous [...] Read more.

The aim of this study was to investigate microstructure and the mechanical and operational characteristics of thick and thin walls 3D-built by electron beam additive manufacturing (EBAM). In addition, the milling parameters (rotation speed, feed, and cutting width) were optimized based on simultaneous assessments of Ra roughness on the machined surfaces and material removing rate values. The wall dimensions did not exert a noticeable effect on their chemical compositions, as compared with the original wires used for 3D printing. In comparison, the strength characteristics of the wrought steel (cold-rolled plate) were higher due to finer grains, with both ferrite content and dislocation density being greater as well. In the 3D building process, multiple thermal cycles gave rise to the formation of elongated columnar grains, reducing the strength characteristics. The corrosion rate of the wrought steel was almost twice those of the 3D-printed blanks because of the higher content of both ferrite and twins. By assessing the machinability of the EBAM-built blanks using the stationary milling machine, the cutting forces were comparable due to similar mechanical properties (including microhardness). To improve the removing rate values and reduce the cutting forces, it is recommended to enhance the cutting speeds while not increasing the feeds. For the semi-industrial milling machine, both linear multiple regression and nonlinear neural network models were applied. An integrated approach was proposed that rationally determined both additive manufacturing and post-processing parameters based on a combination of express assessment and analysis of the mechanical, operational, and technological characteristics of built products within a single laboratory complex. Full article

(This article belongs to the Special Issue Mineral and Metal Materials in Civil Engineering)

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11 pages, 2977 KB

Open AccessArticle

Cryogenic Thermal Properties of Mineral Fiber Insulation: Efficiency in Low-Temperature Storage Systems

by Sergey Gutnikov and Pavel Pastushkov

Constr. Mater. 2025, 5(3), 61; https://doi.org/10.3390/constrmater5030061 - 29 Aug 2025

Abstract

Hydrogen is emerging as a crucial energy carrier, yet effective insulation for liquid hydrogen (LH2) storage remains a significant challenge. This study focuses on evaluating the thermal properties of mineral fiber insulation at cryogenic temperatures, utilizing the guarded hot plate method to determine [...] Read more.

Hydrogen is emerging as a crucial energy carrier, yet effective insulation for liquid hydrogen (LH2) storage remains a significant challenge. This study focuses on evaluating the thermal properties of mineral fiber insulation at cryogenic temperatures, utilizing the guarded hot plate method to determine thermal conductivity values between 223 K (−150 °C) and 573 K (300 °C). The measured effective thermal conductivities ranged from 0.0147 to 0.2113 W/mK, varying with temperature. Notably, while high-density materials can be accurately modeled using linear approximations, low-density materials exhibit significant nonlinearity, with discrepancies in thermal conductivity estimates reaching up to 30%. The implications of this research highlight the necessity for precise thermal property assessments in the design of cryogenic systems, emphasizing their potential impact on energy efficiency and reduced carbon emissions. Ultimately, these findings provide essential insights for advancing cryogenic insulation technologies, supporting the broader transition to sustainable hydrogen energy solutions. Full article

(This article belongs to the Special Issue Mineral and Metal Materials in Civil Engineering)

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17 pages, 1288 KB

Open AccessArticle

Effect of Different Plastics on Mechanical Properties of Concrete

by Madiha Z. J. Ammari, Halil Sezen and Jose Castro

Constr. Mater. 2025, 5(3), 60; https://doi.org/10.3390/constrmater5030060 - 25 Aug 2025

Abstract

In this research work, five different types of post-consumer plastics were mechanically ground into fine aggregate, and each type was used to prepare 2 in. (50 mm) mortar cubes by partial volumetric replacement of the sand. The purpose is to evaluate the effect [...] Read more.

In this research work, five different types of post-consumer plastics were mechanically ground into fine aggregate, and each type was used to prepare 2 in. (50 mm) mortar cubes by partial volumetric replacement of the sand. The purpose is to evaluate the effect of the plastic type and its shape on the density and the compressive strength of concrete. The plastic products used in this study are usually not collected by curbside recycling facilities and are discarded in landfills or incinerated. The different types of plastics investigated were Polyethylene terephthalate (PET), High-Density Polyethylene (HDPE), Polypropylene (PP), Polystyrene (PS), and Acrylonitrile Butadiene Styrene (ABS). A total of 180 cubes with 5%, 10%, and 15% replacement were prepared and tested for their densities at the age of 28 days and their compressive strengths at the ages of 7 and 28 days. This work concluded by proposing general equations to predict the reduction in the density and compressive strength of the mortar with the increment in the plastic replacement. Full article

(This article belongs to the Special Issue Design, Process, Energy, and Evaluation in Construction Material Science)

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14 pages, 1562 KB

Open AccessArticle

Pozzolanic Assessment of Recycled Waste Glass for Use as a Supplementary Cementitious Material

by Samuel Ramírez-Arellanes, Fernando Montejo-Alvaro, Heriberto Cruz-Martínez, Hugo Rojas-Chávez, Jose Manuel Mendoza-Rangel and Víctor Alberto Franco-Luján

Constr. Mater. 2025, 5(3), 59; https://doi.org/10.3390/constrmater5030059 - 21 Aug 2025

Abstract

The manufacture of Portland cement (PC) emits a significant amount of CO₂ into the atmosphere. Therefore, the partial replacement of PC by supplementary cementitious materials (SCMs) possessing pozzolanic properties is considered a viable strategy to reduce its environmental impact. Recently, waste glass [...] Read more.

The manufacture of Portland cement (PC) emits a significant amount of CO₂ into the atmosphere. Therefore, the partial replacement of PC by supplementary cementitious materials (SCMs) possessing pozzolanic properties is considered a viable strategy to reduce its environmental impact. Recently, waste glass (WG) has been explored as a potential SCM. However, due to the wide variety of glass types and their differing physical and chemical properties, not all WG can be universally considered suitable for this purpose; therefore, this study investigates the use of recycled WG as an SCM for the partial replacement of PC. Two types of WG were evaluated: green waste glass from wide bottles (GWG) and laboratory waste glass (LWG), and their performance was compared to that of fly ash (FA). The physical, mechanical, and pozzolanic properties of the materials were assessed. Results show that both types of WG exhibit particle size distributions comparable to PC and have contents of SiO₂, Al₂O₃, and Fe₂O₃ exceeding 70%. Chemical, mineralogical, and pozzolanic analyses revealed that both GWG and LWG presented higher pozzolanic activity than FA, particularly at later ages. Notably, LWG demonstrated the most significant contribution to mechanical strength development. These findings suggest that recycled waste glass, especially LWG, can serve as a viable and sustainable SCM, contributing to the reduction of the environmental footprint associated with Portland cement production. Full article

(This article belongs to the Special Issue Mineral and Metal Materials in Civil Engineering)

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32 pages, 9996 KB

Open AccessArticle

Innovative Composite Aggregates from Thermoplastic Waste for Circular Economy Mortars

by Abdelhak Badache, Noureddine Latroch, Mostefa Hacini, Ahmed Soufiane Benosman, Mohamed Mouli, Yassine Senhadji and Walid Maherzi

Constr. Mater. 2025, 5(3), 58; https://doi.org/10.3390/constrmater5030058 - 20 Aug 2025

Abstract

This study investigates sustainable mortars using lightweight synthetic sand (LSS), made from dune sand and recycled PET bottles, to replace natural sand (0–100% by volume). This aligns with circular economy principles by valorizing plastic waste into a construction aggregate. LSS is produced via [...] Read more.

This study investigates sustainable mortars using lightweight synthetic sand (LSS), made from dune sand and recycled PET bottles, to replace natural sand (0–100% by volume). This aligns with circular economy principles by valorizing plastic waste into a construction aggregate. LSS is produced via controlled thermal treatment (250 ± 5 °C, 50–60 rpm), crushing, and sieving (≤3.15 mm), leading to a significantly improved interfacial transition zone (ITZ) with the cement matrix. The evaluation included physico-mechanical tests (density, strength, UPV, dynamic modulus, ductility), thermal properties (conductivity, diffusivity, heat capacity), porosity, sorptivity, alkali–silica reaction (ASR), and SEM. The results show LSS incorporation reduces mortar density (4–23% for 25–100% LSS), lowering material and logistical costs. While compressive strength decreases (35–70%), these mortars remain suitable for low-stress applications. Specifically, at ≤25% LSS, composites retain 80% of their strength, making them ideal for structural uses. LSS also enhances ductility and reduces dynamic modulus (18–69%), providing beneficial flexibility. UPV decreases (8–39%), indicating improved acoustic insulation. Thermal performance improves (4–18% conductivity reduction), suggesting insulation applicability. A progressive decrease in sorptivity (up to 46%) enhances durability. Crucially, the lack of ASR susceptibility reinforces long-term durability. This research significantly contributes to the repurposing of plastic waste into sustainable cement-based materials, advancing sustainable material management in the construction sector. Full article

(This article belongs to the Topic Innovations in Sustainable Building Materials and Structural Design for Net-Zero Carbon Emissions)

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32 pages, 4492 KB

Open AccessReview

Foundry Sand in Sustainable Construction: A Systematic Review of Environmental Performance, Contamination Risks, and Regulatory Frameworks

by Ferdinand Niyonyungu, Aurobindo Ogra and Ntebo Ngcobo

Constr. Mater. 2025, 5(3), 57; https://doi.org/10.3390/constrmater5030057 - 20 Aug 2025

Abstract

The significant expansion of the construction sector and corresponding depletion of natural sand resources have intensified the search for sustainable alternatives, with waste foundry sand (WFS) emerging as a promising candidate. This systematic review evaluates the environmental performance and engineering feasibility of using [...] Read more.

The significant expansion of the construction sector and corresponding depletion of natural sand resources have intensified the search for sustainable alternatives, with waste foundry sand (WFS) emerging as a promising candidate. This systematic review evaluates the environmental performance and engineering feasibility of using WFS as a substitute for natural sand in construction. A PRISMA-guided search identified 152 peer-reviewed studies published between 2001 and 2024, which were categorized into four thematic areas: material characterization, construction applications, environmental impacts, and regulatory frameworks. The findings indicate that substituting 10–30% of natural sand with WFS in concrete and asphalt can deliver compressive strength within ±5% of control mixes and reduce water absorption by 5–15% at optimal replacement levels. However, contamination risks remain a concern, as chromium and copper concentrations in raw WFS have been reported at up to 931 mg/kg and 3318 mg/kg, respectively. To address these risks and ensure responsible reuse, a six-stage framework is proposed in this study, comprising end-of-waste classification, contaminant assessment, material preprocessing, certification, and regulatory monitoring. A comprehensive decision tree is also presented to guide the feasibility assessment of WFS reuse based on contaminant levels and material performance. Full article

(This article belongs to the Special Issue Advances in the Sustainability and Durability of Waste-Based Construction Materials)

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15 pages, 1470 KB

Open AccessArticle

Predicting Compressive Strength of Sustainable Concrete Using Machine Learning and Artificial Neural Networks

by Francois Mouawad, Farah Homsi, Fadi Geara and Rayan Mina

Constr. Mater. 2025, 5(3), 56; https://doi.org/10.3390/constrmater5030056 - 18 Aug 2025

Abstract

The integration of sustainable materials such as fly ash, blast-furnace slag, recycled aggregates, and seawater into concrete mixes offers significant potential for reducing the environmental impact of construction. However, traditional experimental methods for determining the compressive strength of these concrete mixes are time-consuming [...] Read more.

The integration of sustainable materials such as fly ash, blast-furnace slag, recycled aggregates, and seawater into concrete mixes offers significant potential for reducing the environmental impact of construction. However, traditional experimental methods for determining the compressive strength of these concrete mixes are time-consuming and resource-intensive. This study leverages Artificial Neural Networks (ANNs) and Machine Learning (ML) to develop a predictive model for the compressive strength of sustainable concrete, using a dataset of 768 concrete mix samples. Input variables include the concrete age as well as concrete composition, including cement, water, fine and coarse aggregates, seawater, fly ash, blast-furnace slag, and superplasticizer contents, while the output is the compressive strength. The developed model captures the non-linear relationships among these variables to predict compressive strength efficiently. The best ANN model achieved a test loss of 0.051, demonstrating its ability to accurately predict compressive strength and reduce reliance on traditional testing methods. Moreover, the model’s results were compared with those of alternative algorithms to ensure its validity. These findings highlight the potential of machine learning in advancing sustainable construction practices. A relevant future research direction is to analyze feature importance in machine learning models to identify key variables and guide more effective optimization and decision-making, in addition to extending their application to other material properties and advanced concrete mixes. Full article

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18 pages, 10727 KB

Open AccessArticle

Time Series Transformer-Based Modeling of Pavement Skid and Texture Deterioration

by Lu Gao, Zia Ud Din, Kinam Kim and Ahmed Senouci

Constr. Mater. 2025, 5(3), 55; https://doi.org/10.3390/constrmater5030055 - 14 Aug 2025

Abstract

This study investigates the deterioration of skid resistance and surface macrotexture following preventive maintenance using micro-milling techniques. Field data were collected from 31 asphalt pavement sections located across four climatic zones in Texas. The data encompasses a variety of surface types, milling depths, [...] Read more.

This study investigates the deterioration of skid resistance and surface macrotexture following preventive maintenance using micro-milling techniques. Field data were collected from 31 asphalt pavement sections located across four climatic zones in Texas. The data encompasses a variety of surface types, milling depths, operational speeds, and drum configurations. A standardized data collection protocol was followed, with measurements taken before milling, immediately after treatment, and at 3, 6, 12, and 18 months post-treatment. Skid number and Mean Profile Depth (MPD) were used to evaluate surface friction and texture characteristics. The dataset was reformatted into a time-series structure with 930 observations, including contextual variables such as climatic zone, treatment parameters, and baseline surface condition. A comparative modeling framework was applied to predict the deterioration trends of both skid resistance and macrotexture over time. Eight regression models, including linear, tree-based, and ensemble methods, were evaluated alongside a time series Transformer model. The results show that the Transformer model achieved the highest prediction accuracy for skid resistance (R² = 0.981), while Random Forest performed best for macrotexture prediction (R² = 0.838). The findings indicate that the degradation of surface characteristics after preventive maintenance is non-linear and influenced by a combination of environmental and operational factors. This study demonstrates the effectiveness of data-driven modeling in supporting transportation agencies with pavement performance forecasting and maintenance planning. Full article

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23 pages, 5951 KB

Open AccessArticle

Study on the Application Potential and Environmental Impact of Fly Ash and Calcined Coal Gangue in Cementitious Materials

by Zhaochang Zhang, Yudong Luo, Yonghong Miao, Enquan Zhou, Zhiwei Yan and Guiyu Zhang

Constr. Mater. 2025, 5(3), 54; https://doi.org/10.3390/constrmater5030054 - 14 Aug 2025

Abstract

Coal is still China’s primary energy source, and the production process of coal produces industrial byproduct coal gangue. This study explores the possibility of using industrial byproducts of thermal power generation, fly ash (FA) and calcined coal gangue (CCG), as a partial (10% [...] Read more.

Coal is still China’s primary energy source, and the production process of coal produces industrial byproduct coal gangue. This study explores the possibility of using industrial byproducts of thermal power generation, fly ash (FA) and calcined coal gangue (CCG), as a partial (10% and 20%) substitute for cement in construction materials. Methodical research was conducted to determine how these two substances affect the microstructure and macroscopic characteristics of cement-based materials. Macroscopic performance test findings indicate that replacing 20% of cement with CCG had no discernible effect on the specimens’ performance. At the same time, adding FA required 28 days to be comparable to the control group. Mercury intrusion porosimetry (MIP) test results show that using CCG can refine microscopic pores. Additional hydration products could be produced by these materials, according to analyses using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The production of hydration products by CCG to fill the microscopic pores was further demonstrated by scanning electron microscopy (SEM) pictures. After 28 days of hydration, a layer of hydration products developed on the surface of FA. When supplementary cementitious materials (SCMs) were added, calcium hydroxide (CH) was consumed by interacting with FA and CCG to form additional hydration products, according to thermogravimetric analysis (TG) data after 28 days. Furthermore, an evaluation of FA and CCG’s effects on the environment revealed that their use performed well in terms of sustainable development. Full article

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21 pages, 5621 KB

Open AccessArticle

Establishing Rational Processing Parameters for Dry Finish-Milling of SLM Ti6Al4V over Metal Removal Rate and Tool Wear

by Sergey V. Panin, Andrey V. Filippov, Mengxu Qi, Zeru Ding, Qingrong Zhang and Zeli Han

Constr. Mater. 2025, 5(3), 53; https://doi.org/10.3390/constrmater5030053 - 5 Aug 2025

Abstract

The study is motivated by the application of dry finish milling for post-build processing of additive Ti6Al4V blanks, since the use of neither lubricant nor coolants has been attracting increasing attention due to its environmental benefits, non-toxicity, and the elimination of the need [...] Read more.

The study is motivated by the application of dry finish milling for post-build processing of additive Ti6Al4V blanks, since the use of neither lubricant nor coolants has been attracting increasing attention due to its environmental benefits, non-toxicity, and the elimination of the need for additional cleaning processes. For end mills, wear patterns were investigated upon finish milling of the SLM Ti6Al4V samples under various machining conditions (by varying the values of radial depth of cut and feed values at a constant level of axial depth of cut and cutting speed). When using all the applied milling modes, the identical tool wear mechanism was revealed. Built-up edges mainly developed on the leading surfaces, increasing the surface roughness on the SLM Ti6Al4V samples but protecting the cutting edges. However, abrasive wear was mainly characteristic of the flank surfaces that accelerated peeling of the protective coatings and increased wear of the end mills. The following milling parameters have been established as being close to rational ones: Vc = 60 m/min, Vf = 400 mm/min, a_p = 4 mm, and a_e = 0.4 mm. They affected the surface roughness of the SLM Ti6Al4V samples in the following way: max cutting thickness—8 μm; built-up edge at rake surface—50 ± 3 μm; max wear of flank surface—15 ± 1 μm; maximum adherence of workpiece. Mode III provided the maximum MRR value and negligible wear of the end mill, but its main disadvantage was the high average surface roughness on the SLM Ti6Al4V sample. Mode II was characterized by both the lowest average surface roughness and the lowest wear of the end mill, as well as an insufficient MRR value. Since these two modes differed only in their feed rates, their values should be optimized in the range from 200 to 400 mm/min. Full article

(This article belongs to the Special Issue Mineral and Metal Materials in Civil Engineering)

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13 pages, 1636 KB

Open AccessArticle

Mechanical Performance of Sustainable Asphalt Mixtures Incorporating RAP and Panasqueira Mine Waste

by Hernan Patricio Moyano-Ayala and Marisa Sofia Fernandes Dinis-Almeida

Constr. Mater. 2025, 5(3), 52; https://doi.org/10.3390/constrmater5030052 - 4 Aug 2025

Abstract

The increasing demand for sustainable practices in road construction has prompted the search for environmentally friendly and cost-effective materials. This study explores the incorporation of reclaimed asphalt pavement (RAP) and Panasqueira mine waste (greywacke aggregates) as full replacements for virgin aggregates in hot [...] Read more.

The increasing demand for sustainable practices in road construction has prompted the search for environmentally friendly and cost-effective materials. This study explores the incorporation of reclaimed asphalt pavement (RAP) and Panasqueira mine waste (greywacke aggregates) as full replacements for virgin aggregates in hot mix asphalt (HMA), aligning with the objectives of UN Sustainable Development Goal 9. Three asphalt mixtures were prepared: a reference mixture (MR) with granite aggregates, and two modified mixtures (M15 and M20) with 15% and 20% RAP, respectively. All mixtures were evaluated through Marshall stability, stiffness modulus, water sensitivity, and wheel tracking tests. The results demonstrated that mixtures containing RAP and mine waste met Portuguese specifications for surface courses. Specifically, the M20 mixture showed the highest stiffness modulus, improved moisture resistance, and the best performance against permanent deformation. These improvements are attributed to the presence of stiff aged binder in RAP and the mechanical characteristics of the greywacke aggregates. Overall, the findings confirm that the combined use of RAP and mining waste provides a technically viable and sustainable alternative for asphalt pavement construction, contributing to resource efficiency and circular economy goals. Full article

(This article belongs to the Special Issue Advances in the Sustainability and Durability of Waste-Based Construction Materials)

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22 pages, 8767 KB

Open AccessArticle

Experimental and Numerical Investigation of Shear Performance of RC Deep Beams Strengthened with Engineered Cementitious Composites

by Hamsavathi Kannan, Sathish Kumar Veerappan and Madappa V. R. Sivasubramanian

Constr. Mater. 2025, 5(3), 51; https://doi.org/10.3390/constrmater5030051 - 31 Jul 2025

Abstract

Reinforced concrete (RC) deep beams constructed with low-strength concrete are susceptible to sudden splitting failures in the strut region due to shear–compression stresses. To mitigate this vulnerability, various strengthening techniques, including steel plates, fiber-reinforced polymer sheets, and cementitious composites, have been explored to [...] Read more.

Reinforced concrete (RC) deep beams constructed with low-strength concrete are susceptible to sudden splitting failures in the strut region due to shear–compression stresses. To mitigate this vulnerability, various strengthening techniques, including steel plates, fiber-reinforced polymer sheets, and cementitious composites, have been explored to confine the strut area. This study investigates the structural performance of RC deep beams with low-strength concrete, strengthened externally using an Engineered Cementitious Composite (ECC) layer. To ensure effective confinement and uniform shear distribution, shear reinforcement was provided at equal intervals with configurations of zero, one, and two vertical shear reinforcements. Four-point bending tests revealed that the ECC layer significantly enhanced the shear capacity, increasing load-carrying capacity by 51.6%, 54.7%, and 46.7% for beams with zero, one, and two shear reinforcements, respectively. Failure analysis through non-linear finite element modeling corroborated experimental observations, confirming shear–compression failure characterized by damage in the concrete struts. The strut-and-tie method, modified to incorporate the tensile strength of ECC and shear reinforcement actual stress values taken from the FE analysis, was used to predict the shear capacity. The predicted values were within 10% of the experimental results, underscoring the reliability of the analytical approach. Overall, this study demonstrates the effectiveness of ECC in improving shear performance and mitigating strut failure in RC deep beams made with low-strength concrete. Full article

(This article belongs to the Topic Rehabilitation and Strengthening Techniques for Reinforced Concrete)

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19 pages, 7574 KB

Open AccessArticle

Effect of Natural Fiber Characteristics on Properties of Cementitious Composites: A Comparison of Recycled Pulp from Beverage Cartons, Bamboo, and Eucalyptus Fibers

by Phouthanouthong Xaysombath, Nattakan Soykeabkaew, Darunee Wattanasiriwech and Suthee Wattanasiriwech

Constr. Mater. 2025, 5(3), 50; https://doi.org/10.3390/constrmater5030050 - 31 Jul 2025

Abstract

This study evaluates the influence of fiber type, geometry, and interfacial behavior on the physical and mechanical performance of cementitious composites reinforced with recycled pulp from beverage cartons (RPBC), bamboo fiber (BF), and eucalyptus fiber (EF) as the sole reinforcing agents. The BF [...] Read more.

This study evaluates the influence of fiber type, geometry, and interfacial behavior on the physical and mechanical performance of cementitious composites reinforced with recycled pulp from beverage cartons (RPBC), bamboo fiber (BF), and eucalyptus fiber (EF) as the sole reinforcing agents. The BF was rounded in shape and had the highest aspect ratio, while the ribbon-shaped EF exhibited the highest tensile strength index. The RPBC fibers were fibrillated and the shortest, with a ribbon shape. Flexural strength results showed that RPBCC achieved a maximum strength that was 47.6% higher than the control specimen (0% fiber), outperforming both BF- and EF-reinforced counterparts. This superior performance is attributed to the higher fibrillation level of the ribbon-shaped RPBC fibers, which promoted better fiber–matrix bonding. As the fiber content increased, the bulk density of EFC and BFC decreased linearly, while RPBC composites showed only a modest decrease in density. Porosity steadily increased in EFC and BFC, whereas a non-linear trend was observed in RPBCC, likely due to its unique morphology and fibrillation. Conversely, EFC exhibited significantly higher maximum fracture toughness (3600 J/m² at 10 wt.%) compared to PBFCC (1600 J/m² at 14 wt.%) and BFC (1400 J/m² at 14 wt.%). This enhancement is attributed to extensive fiber pullout mechanisms and increased energy absorption during crack propagation. Overall, all composite types demonstrated flexural strength values above 4 MPa, placing them in the Grade I category. Those reinforced with 10–14% RPBC exhibited strengths of 11–12 MPa, categorizing them as Grade II according to ASTM C1186-02. Full article

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32 pages, 5440 KB

Open AccessReview

A Review of the Performance Properties of Geopolymer Pavement-Quality Concrete

by Saikrishna Chelluri, Nabil Hossiney, Sarath Chandra, Patrick Bekoe and Mang Tia

Constr. Mater. 2025, 5(3), 49; https://doi.org/10.3390/constrmater5030049 - 25 Jul 2025

Abstract

The construction of concrete pavements has increased due to their better durability, lifespan, and lower maintenance costs. However, this has resulted in the increased consumption of Portland cement, which is one of the major contributors to carbon emissions. Consequently, the research on alternative [...] Read more.

The construction of concrete pavements has increased due to their better durability, lifespan, and lower maintenance costs. However, this has resulted in the increased consumption of Portland cement, which is one of the major contributors to carbon emissions. Consequently, the research on alternative binders such as geopolymer concrete has increased in recent times. There are several research studies that investigate the feasibility of geopolymer concrete as a construction material, with limited studies exploring its application in concrete pavements. Therefore, this review study explores the material properties of geopolymer concrete pertinent to the performance of concrete pavements. It also discusses the potential of various industrial and agricultural waste as precursor material in geopolymer concrete. The findings of this paper show that most of the studies used fly ash and ground granulated blast furnace slag (GGBFS) as precursor material in geopolymer pavement-quality concrete, and there is a vast scope in the exploration of other industrial and agricultural waste as precursor material. The mechanical and durability properties of geopolymer pavement-quality concrete are superior to conventional pavement concrete. It is also observed that the drying shrinkage and coefficient of thermal expansion of geopolymer pavement-quality concrete are lower than those of conventional pavement concrete, and this will positively benefit the long-term performance of concrete pavements. The results of fatigue analysis and mechanical load test on the geopolymer pavement-quality concrete indicate its improved performance when compared to the conventional pavement concrete. Full article

(This article belongs to the Special Issue Innovative Materials and Technologies for Road Pavements)

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