Polymers

Research

43 pages, 13313 KB

Open AccessArticle

Synergistic Impact of Bio-Based and Waste-Derived Contents on the Mechanical and Thermal Performance of Alkali-Activated Slag Mortars

by Hakan Sarıkaya, Gülşah Susurluk and Levent Bostanci

Polymers 2026, 18(16), 1966; https://doi.org/10.3390/polym18161966 - 12 Aug 2026

Viewed by 287

Abstract

The need to enhance both the mechanical and the thermal insulation performance of alkali-activated mortars has stimulated interest in natural fiber-based reinforcement strategies, particularly for sustainability-driven design and low-carbon construction. This study explores the combined effect of natural kapok fiber, petroleum coke (PC) [...] Read more.

The need to enhance both the mechanical and the thermal insulation performance of alkali-activated mortars has stimulated interest in natural fiber-based reinforcement strategies, particularly for sustainability-driven design and low-carbon construction. This study explores the combined effect of natural kapok fiber, petroleum coke (PC) and waste tire rubber powder (WTRP) on the mechanical, thermal, microstructural, mineralogical, and pore structure characteristics of alkali-activated slag-based mortars. While the beneficial effects of each of these bio-based and waste-derived materials have been widely reported, little attention has been paid to their combined use and the potential for them to work together in a way that is more effective than the sum of their parts. For this purpose, 20 different mortar mixtures were produced, incorporating kapok fibers at ratios of 0%, 0.5%, 0.75% and 1%. The beneficial effect of WTRP was investigated for the case of a 3% cement additive where natural sand was substituted by PC at ratios of 0%, 10% and 20%. The results indicated that the synergistic interaction enabled the development of a sustainable mortar with enhanced thermal insulation performance of up to 37% while maintaining flexural performance compared to the control case. Microstructural, mineralogical, pore structure and thermal analyses revealed that the bio-based and waste-derived contents significantly influenced the pore network, phase evolution and fiber–matrix interactions. Overall, the results highlight the potential of the proposed sustainable material system to produce mortars with enhanced thermal insulation, sufficient mechanical performance, and lowered environmental footprint. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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25 pages, 8515 KB

Open AccessArticle

Mechanical and Microstructural Performance of Concrete Incorporating Waste Tire Rubber and Recycled Steel Fibers Under Elevated Temperatures

by Ersin Ayhan, Mehmet Kadri Değer and Murat Doğruyol

Polymers 2026, 18(14), 1681; https://doi.org/10.3390/polym18141681 - 8 Jul 2026

Viewed by 447

Abstract

This study investigates the thermo-mechanical and microstructural performance of concrete incorporating waste tire rubber (WR) and recycled steel fibers (WS) under elevated temperatures. Four mixtures were prepared: plain concrete (PL), rubber-modified concrete (WR5), and hybrid mixtures containing 0.4% and 0.8% steel fibers (WS0.4WR5 [...] Read more.

This study investigates the thermo-mechanical and microstructural performance of concrete incorporating waste tire rubber (WR) and recycled steel fibers (WS) under elevated temperatures. Four mixtures were prepared: plain concrete (PL), rubber-modified concrete (WR5), and hybrid mixtures containing 0.4% and 0.8% steel fibers (WS0.4WR5 and WS0.8WR5). Specimens were exposed to temperatures of 400 °C, 600 °C, and 800 °C to simulate fire conditions. The results indicate that the incorporation of rubber reduces compressive strength at ambient temperature due to its lower stiffness and weak interfacial bonding. However, the addition of recycled steel fibers significantly improves crack resistance and enhances thermal stability. At 400 °C, the WS0.8WR5 mixture showed a retention rate of 92.9% (absolute strength: 44.32 MPa), compared to 72.2% for plain concrete (absolute strength: 44.11 MPa). Although the hybrid mixture has a lower ambient strength (47.68 MPa vs. 61.07 MPa), its superior retention makes it competitive in fire scenarios. Ultrasonic pulse velocity (UPV) measurements revealed a strong correlation with compressive strength degradation, confirming its effectiveness as a non-destructive indicator of internal damage. Microstructural analyses (SEM, XRD, and TGA-DTA) demonstrated that elevated temperatures lead to dehydration, phase transformation, and increased porosity, while steel fibers help maintain matrix integrity through crack-bridging mechanisms. The findings highlight a synergistic interaction between waste rubber and steel fibers, offering a sustainable and effective approach for improving the fire resistance of concrete. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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15 pages, 2766 KB

Open AccessArticle

Investigation of the Influence of Pine Cone and Pine Resin Addition on the Properties of Plaster Composites

by Ayse Bicer, Celal Kistak, Ali Taskiran and Nevin Celik

Polymers 2026, 18(12), 1501; https://doi.org/10.3390/polym18121501 - 16 Jun 2026

Viewed by 485

Abstract

The physical characteristics of gypsum plaster composites made from agricultural wastes of pine cones (PCs) and pine resin (PR), as sustainable substitutes for traditional natural fillers, are examined in this work. Particle sizes of 3–5 mm, 0–3 mm, and powder were used to [...] Read more.

The physical characteristics of gypsum plaster composites made from agricultural wastes of pine cones (PCs) and pine resin (PR), as sustainable substitutes for traditional natural fillers, are examined in this work. Particle sizes of 3–5 mm, 0–3 mm, and powder were used to classify the PCs after grinding. First, gypsum plaster was replaced with PC particles at 20%, 40%, 60%, and 80% by weight for each group to produce resin-free specimens. To create artificial porosity and improve the matrix’s binding strength, 1% PR by total weight was then added to duplicate mixes, yielding 24 different sample combinations. In resin-free samples, the addition of 3–5 mm, 0–3 mm, and powder PC (in ratios ranging from 20% to 80%) reduced the thermal conductivities by 35.16%, 33.84%, and 34.97%, respectively, and the compressive strength values by 82.00%, 77.18%, and 77.50%. Further decreases in thermal conductivity (29.36%, 32.05%, and 33.66%) and compressive strength (76.89%, 75.64%, and 75.48%) were observed in PR-modified samples. The results show that adding PCs and PR to gypsum plaster considerably improves the plaster’s thermal insulation while marginally reducing its compressive strength loss. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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19 pages, 17532 KB

Open AccessArticle

Investigation of Temperature-Field Evolution and Microstructural Response in Bituminous Waterproofing Membranes Under Low-Temperature Flexibility Testing Conditions

by Jun Tan, Lei Geng, Dong Zhang, Chen Li and Chao Zhang

Polymers 2026, 18(11), 1294; https://doi.org/10.3390/polym18111294 - 25 May 2026

Viewed by 348

Abstract

Low-temperature conditioning is a key procedure in the flexibility evaluation of waterproofing membranes and directly affects the reliability of subsequent performance assessments. However, the internal unsteady-state heat transfer kinetics and the thermal gradient evolution mechanisms in multi-layer composite membranes under transient cold shocks [...] Read more.

Low-temperature conditioning is a key procedure in the flexibility evaluation of waterproofing membranes and directly affects the reliability of subsequent performance assessments. However, the internal unsteady-state heat transfer kinetics and the thermal gradient evolution mechanisms in multi-layer composite membranes under transient cold shocks require further investigation. Focusing on commonly utilized 3 mm and 4 mm thick SBS (Styrene–Butadiene–Styrene)-modified bitumen waterproofing membranes as subjects, this study investigated the internal dynamic temperature fields and microstructural response of bituminous waterproofing membranes under standard low-temperature flexibility testing conditions. By accurately pre-embedding micro-temperature sensors in situ at the interface between the surface layer and the reinforcement matrix, the transient thermal response profiles of specimens with varying specifications in a −25 °C liquid environment were quantified. Simultaneously, a three-dimensional transient heat conduction finite element model was established to elucidate the dynamic evolution of internal spatial temperature gradients. The congruence between experimental and numerical results demonstrates that upon exposure to extreme cold, composite membranes of different thicknesses exhibit a pronounced “surface-to-core” heat transfer lag effect. The cooling rate maximized within the initial 10 min of exposure. Conversely, the internal interface layer—acting as a high-thermal-resistance zone and the most unfavorable point for heat conduction—necessitated 10~20 min of nonlinear thermal dissipation to stabilize at the target ambient temperature. This study clarifies the transient thermal response and temperature-field evolution laws of bituminous waterproofing membranes, providing a robust theoretical framework for elucidating low-temperature embrittlement mechanisms and informing the material design and application of waterproofing projects in cold regions. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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25 pages, 4687 KB

Open AccessArticle

Finite-Element Analysis of the Quasi-Static Response of Concrete Specimens Containing Polymeric Self-Healing Microcapsules

by Todor Zhelyazov

Polymers 2026, 18(11), 1289; https://doi.org/10.3390/polym18111289 - 24 May 2026

Viewed by 570

Abstract

Healing agent encapsulated in polymeric microcapsules has proven its ability to seal surface and internal cracks. Focused on mitigating the negative impact of capsules on the properties of fresh cement paste and hardened cementitious matrix, uncertainties in self-healing triggering, and poor control of [...] Read more.

Healing agent encapsulated in polymeric microcapsules has proven its ability to seal surface and internal cracks. Focused on mitigating the negative impact of capsules on the properties of fresh cement paste and hardened cementitious matrix, uncertainties in self-healing triggering, and poor control of the released quantity, researchers report technological improvements in predominantly experimental studies. However, practical applications will necessitate lightweight models that capture all the characteristics of practical importance. Analysis of the scientific literature reveals the lack of such models adapted for cementitious composites. In this paper, a model rooted in continuum damage mechanics, tuned based on empirical data, is used in the finite element analysis of concrete specimens containing polymer self-healing microcapsules to quantify self-healing efficiency and local damage-healing behavior. The predicted increase in the self-healing rate is more pronounced for specimens subjected to compression compared to that for elements subjected to four-point bending. Thus, for a 20% increase in healing efficiency, strength recovery in compression increases from 18.5% to 32% for C25 and C30, respectively, whereas the corresponding values for tension in the tension-be-flexure setup are 3.5% and 5.3%. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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28 pages, 11090 KB

Open AccessArticle

Boron Nitride-Modified Hemp Nanofiber Reinforced Slag-Based Geopolymer Composites: Mechanical, Microstructural and Fire Resistance Performance

by Ahmet Filazi, İsmail Melih Tezcan, Reyhan Akat, Deniz Doğan and Ümit Erdem

Polymers 2026, 18(11), 1288; https://doi.org/10.3390/polym18111288 - 24 May 2026

Cited by 1 | Viewed by 546

Abstract

This study investigates the mechanical performance, high-temperature resistance, and microstructural characteristics of ground granulated blast furnace slag (GGBFS)-based geopolymer composites reinforced with boron nitride (BN)-modified hemp nanofibers. BN-modified hemp nanofibers (PVA-mBN/Hemp) were produced via electrospinning and incorporated into geopolymer mixtures at varying ratios [...] Read more.

This study investigates the mechanical performance, high-temperature resistance, and microstructural characteristics of ground granulated blast furnace slag (GGBFS)-based geopolymer composites reinforced with boron nitride (BN)-modified hemp nanofibers. BN-modified hemp nanofibers (PVA-mBN/Hemp) were produced via electrospinning and incorporated into geopolymer mixtures at varying ratios ranging from 0 to 4 wt%. The effects of nanofiber content on composite properties were evaluated through mechanical testing, ultrasonic pulse velocity (UPV) measurements, and exposure to elevated temperatures (300–1200 °C), supported by SEM-EDS, FTIR, and XRD analyses. The results indicate that low nanofiber additions (0.5–1 wt%) improve flexural strength by up to 15%, although compressive strength is slightly reduced due to increased porosity. UPV measurements confirm the changes in internal structure. At elevated temperatures, nanofiber-reinforced samples exhibit enhanced residual strength compared to the control specimens, particularly at moderate temperatures, whereas significant degradation occurs above 900 °C. Microstructural analyses reveal improved fiber-matrix interaction, reduced crack propagation, and enhanced thermal stability attributed to BN modification. Overall, the incorporation of 0.5–1 wt% BN-modified hemp nanofibers provides an effective balance between mechanical performance and high-temperature resistance, highlighting their potential for use in sustainable and fire-resistant construction materials. This study contributes to the United Nations Sustainable Development Goals (SDGs), particularly SDG 9 (Industry, Innovation, and Infrastructure), SDG 11 (Sustainable Cities and Communities), and SDG 12 (Responsible Consumption and Production). Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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19 pages, 3061 KB

Open AccessArticle

Design and Manufacturing of Artificial Composite Stone Using Waste Limestone and Glass-Based Reinforcements

by Şükrü Çetinkaya

Polymers 2026, 18(9), 1040; https://doi.org/10.3390/polym18091040 - 24 Apr 2026

Viewed by 911

Abstract

Artificial composite stones have recently attracted attention as multifunctional materials for construction and defense-related applications. In this study, a novel composite stone was developed using waste limestone as the primary mineral filler, combined with an unsaturated polyester resin matrix and reinforced with glass [...] Read more.

Artificial composite stones have recently attracted attention as multifunctional materials for construction and defense-related applications. In this study, a novel composite stone was developed using waste limestone as the primary mineral filler, combined with an unsaturated polyester resin matrix and reinforced with glass powder and chopped glass fibers. The influence of binder content and reinforcement type on physico-mechanical and microstructural behavior was investigated. Experimental characterization included water absorption, compressive strength, abrasion resistance, acid resistance, and optical microscopy. The results demonstrated that fine fillers improved matrix densification and reduced porosity, while short glass fiber reinforcement enhanced load-bearing capacity. Abrasion resistance and durability were found to depend on binder content and particle packing characteristics. Overall, the developed composite material exhibits promising mechanical performance, low water absorption, and improved durability, suggesting its potential as a candidate material for applications requiring environmental resistance, including potential use in defense-related camouflage applications. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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21 pages, 13844 KB

Open AccessArticle

Influence of Polycarboxylate Superplasticizer on Rheological Behavior and Early Interfacial Evolution of Phosphogypsum-Based Supersulfated Cement

by Dafu Wang, Lehuan Kuang, Shaoyang Ding, Yudong Sun, Yuejing Li, Ziyu Chen, Jun Ren and Xincheng Li

Polymers 2026, 18(9), 1021; https://doi.org/10.3390/polym18091021 - 23 Apr 2026

Viewed by 601

Abstract

Driven by global carbon reduction targets, supersulfated cement has emerged as a promising low-carbon cementitious material. This study investigates the influence of a polycarboxylate superplasticizer (PCE) on the rheological behavior and early interfacial evolution of phosphogypsum-based supersulfated cement (PSSC). Rheological measurements, pore solution [...] Read more.

Driven by global carbon reduction targets, supersulfated cement has emerged as a promising low-carbon cementitious material. This study investigates the influence of a polycarboxylate superplasticizer (PCE) on the rheological behavior and early interfacial evolution of phosphogypsum-based supersulfated cement (PSSC). Rheological measurements, pore solution ion analysis, hydration heat analysis, X-ray diffraction (XRD), and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM–EDS) are employed to correlate early hydration processes with structural development. The results indicate that the incorporation of PCE significantly reduces the initial yield stress and moderates the structural build-up rate. At a PCE dosage of 0.3 wt.%, the initial static yield stress decreases from 1313 Pa to approximately 125 Pa, while the structural build-up index I_s_,s reaches 10.19, indicating improved particle dispersion while maintaining progressive structural reconstruction during hydration. Phosphogypsum (PG) functions not only as a sulfate source but also as an active interfacial substrate that promotes the preferential nucleation of AFt on its surface. In the absence of PCE, continuous Ca–P-enriched layers form on PG particles, accompanied by localized AFt accumulation. After the incorporation of PCE, the primary crystalline phases remain unchanged; however, gypsum dissolution and AFt formation are delayed. Meanwhile, Ca–P enrichment shifts from continuous coverage to a more dispersed distribution, promoting the spatially separated growth of AFt crystals rather than dense localized aggregation. Overall, PCE influences the evolution of the structure and properties of the system by regulating early interfacial reactions and the spatial organization of hydration products. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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33 pages, 6006 KB

Open AccessArticle

An Experimental and Modeling Study on the Interaction of Cements with Varying C₃A Ratios and Different Water-Reducing Admixtures Using the op-ANN and Various Machine Learning Methods

by Veysel Kobya, Hasan Tahsin Öztürk, Kemal Karakuzu, Ali Mardani and Naz Mardani

Polymers 2026, 18(5), 656; https://doi.org/10.3390/polym18050656 - 7 Mar 2026

Cited by 1 | Viewed by 781

Abstract

This study investigates the interaction between polycarboxylate-based water-reducing admixtures (WRAs) and various types of CEM I 42.5R Portland cements, focusing on optimizing input parameters in cementitious systems. Despite the widespread use of WRAs to enhance concrete’s workability, strength, and durability, their compatibility with [...] Read more.

This study investigates the interaction between polycarboxylate-based water-reducing admixtures (WRAs) and various types of CEM I 42.5R Portland cements, focusing on optimizing input parameters in cementitious systems. Despite the widespread use of WRAs to enhance concrete’s workability, strength, and durability, their compatibility with cement remains a critical challenge, often leading to performance issues such as low initial flow, bleeding, and rapid slump loss. This research addresses two significant gaps in the literature: the unexplored use of input parameter reduction in cementitious systems and the application of novel metaheuristic algorithms in optimizing these systems. In this study, 25 WRA were first synthesized to enrich the inputs of machine learning (ML) models. Then, a dataset of 750 entries was generated, and advanced prediction models were developed. To ensure scientific rigor and eliminate data leakage, a triple-split dataset strategy (Training–Validation–Test) and 5-fold cross-validation were implemented. Among the machine learning techniques analyzed, the Optimized Artificial Neural Networks (opANN) architecture decisively demonstrated the highest prediction performance on the isolated test dataset. In the opANN process, 10 different metaheuristics were tested to evaluate their effectiveness in hyperparameter optimization. As a result, the Kepler Optimization (KOA) algorithm was determined as the algorithm with the highest performance in ANN hyperparameter optimization. Furthermore, Shapley Additive Explanations (SHAP) analysis was utilized to bridge the gap between empirical observations and algorithmic predictions, quantitatively corroborating the rheological roles of phosphate and sulfonate groups. The results offer new insights into WRA–cement compatibility and present advanced, interpretable modeling approaches that enhance predictive accuracy, contributing to more reliable and sustainable concrete practices. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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22 pages, 5421 KB

Open AccessArticle

Probabilistic Modeling and Prediction of Continuous FRP Degradation Curves Based on CSDI Diffusion Models

by Yuan Yue, Ming-Li Zhou, Hui Shen, Wen-Wei Wang, Lei Zhang, Jing-Xian Shi and Bai-Chun Liang

Polymers 2026, 18(5), 587; https://doi.org/10.3390/polym18050587 - 27 Feb 2026

Cited by 1 | Viewed by 572

Abstract

Traditional FRP durability forecasting predominantly treats performance evolution as a discrete “point-to-point” regression, inherently overlooking temporal coherence and stochastic uncertainty. This study proposes a novel probabilistic framework based on the CSDI diffusion model to reconstruct continuous FRP degradation curves. By formulating long-term forecasting [...] Read more.

Traditional FRP durability forecasting predominantly treats performance evolution as a discrete “point-to-point” regression, inherently overlooking temporal coherence and stochastic uncertainty. This study proposes a novel probabilistic framework based on the CSDI diffusion model to reconstruct continuous FRP degradation curves. By formulating long-term forecasting as a conditional imputation task, the methodology generates physically consistent performance trajectories from sparse experimental observations. Results from a multi-factor database demonstrate that CSDI enables a paradigm shift to continuous sequence generation, achieving high predictive accuracy (RMSE = 0.332, R² = 0.86) and robust probabilistic calibration (CRPS = 0.170) at a 30% missing ratio. This approach establishes a reliable probabilistic risk envelope, providing a scientific tool for the life-cycle reliability assessment of FRP structures under small-sample constraints. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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19 pages, 4479 KB

Open AccessArticle

Pine Resin as a Natural Polymer Binder in Pine Cone-Reinforced Lightweight Concrete

by Celal Kistak, Araz Muhammed Hassan, Ayse Bicer and Nevin Celik

Polymers 2026, 18(3), 364; https://doi.org/10.3390/polym18030364 - 29 Jan 2026

Cited by 3 | Viewed by 1527

Abstract

The aim of this study is to investigate the potential applications of pine cones as plant-based waste material in the construction industry. In order to achieve this target, the pine cone particles (PCP) are mixed with cement to create new lightweight concretes. Furthermore, [...] Read more.

The aim of this study is to investigate the potential applications of pine cones as plant-based waste material in the construction industry. In order to achieve this target, the pine cone particles (PCP) are mixed with cement to create new lightweight concretes. Furthermore, pine tree resin (PTR), acting as a natural bio-polymer binder, is incorporated into selected samples to ascertain its potential as a binder. The pine cones are cut into particles of 2–4 cm, 0–2 cm, and ground into a powder. A series of critical tests is conducted on the novel produced samples, including thermal conductivity, specific heat, density, compressive strength, water absorption rate, and drying rate. The experiments show that thermal conductivity, specific heat capacity, and thermal expansion coefficient decrease as the weight ratio and size of PCP increase. The presence of PTR increases porosity, further decreasing thermal conductivity, specific heat, and thermal expansion coefficients for the majority of samples. The compressive strength values decrease with the presence of PTR and PCP. Regarding durability, the water absorption ratios remain below the critical 30% threshold, making the material suitable for internal applications or external facades protected by coating/plaster or as external coverings. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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19 pages, 4639 KB

Open AccessArticle

Effect of Dehydration on the Resilient Modulus of Biopolymer-Treated Sandy Soil for Pavement Construction

by Ahmed M. Al-Mahbashi and Abdullah Almajed

Polymers 2025, 17(20), 2738; https://doi.org/10.3390/polym17202738 - 13 Oct 2025

Cited by 3 | Viewed by 1173

Abstract

Biopolymers have recently been introduced as eco-friendly alternatives to other chemical cementitious additives for sandy soil stabilization, especially in pavement construction. The resilient modulus (M_R) is a key metric considered in the mechanistic design of pavement layers that ensures a safe [...] Read more.

Biopolymers have recently been introduced as eco-friendly alternatives to other chemical cementitious additives for sandy soil stabilization, especially in pavement construction. The resilient modulus (M_R) is a key metric considered in the mechanistic design of pavement layers that ensures a safe and economic design based on guaranteed accurate values. This study investigated the effects of dehydration on the M_R of biopolymer-treated sand. Prepared specimens were subjected to two different curing conditions. The first set underwent closed-system curing (CSC) for periods of 7, 14, and 28 days. The second set of specimens was cured at different levels of suction by controlling relative humidity (RH) using different salt solutions (0.27, 1.0, 9.7, 21.0, 54.6, 113.7, and 294 MPa), referred to as dehydration curing (DC). The soil water retention curve (SWRC) was measured over the entire suction range to evaluate the dehydration curing and to link the results of suction levels and dehydration regime. M_R tests were conducted on both sets of specimens using a dynamic triaxial system to simulate different confining, traffic, and dynamic stresses. The results showed a significant increase in M_R (i.e., up to eight times) for specimens cured under DC conditions that was proportional to the suction level across different zones of the SWRC. Scanning electron microscopy revealed a phase change from hydrogel to film, which enhanced cementation and bonding between particles. in addition, CSC treatment resulted in a 10–30% reduction in M_R. A new regression model is proposed to predict the M_R of biopolymer-treated sand as a function of confining stresses, dynamic stresses, and suction. These findings will assist pavement engineers and designers in achieving safe, sustainable, and economic designs. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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46 pages, 29512 KB

Open AccessArticle

From Research Trend to Performance Prediction: Metaheuristic-Driven Machine Learning Optimization for Cement Pastes Containing Bio-Based Phase Change Materials

by Leifa Li, Wangwen Sun, Lauren Y. Gómez-Zamorano, Zhuangzhuang Liu, Wenzhen Zhang and Haoran Ma

Polymers 2025, 17(18), 2541; https://doi.org/10.3390/polym17182541 - 19 Sep 2025

Cited by 8 | Viewed by 1980

Abstract

This study presents an integrated approach combining bibliometric analysis and machine learning to explore research trends and predict the performance of cement pastes containing bio-based phase change materials. A bibliometric review of 5928 articles from the Web of Science Core Collection was conducted [...] Read more.

This study presents an integrated approach combining bibliometric analysis and machine learning to explore research trends and predict the performance of cement pastes containing bio-based phase change materials. A bibliometric review of 5928 articles from the Web of Science Core Collection was conducted using CiteSpace (v.6.3.R1) to identify research hotspots. A dataset of 100 experimental samples was compiled, including nine input variables and three output properties identified as thermal conductivity (Tc), latent heat capacity (LH) and compressive strength (CS). Four machine learning algorithms (SVR, RF, XGBoost, and CatBoost) were optimized using five metaheuristic algorithms (GA, PSO, WOA, GWO, and FFA), resulting in 24 optimized hybrid models. Of all the models considered, CatBoost-WOA achieved the best overall performance, with R² values of 0.927, 0.955, and 0.944, and RMSEs of 0.0057 W/m·K, 1.84 J/g, and 2.91 MPa for Tc, LH, and CS. Additionally, SVR-GWO and XGBoost-WOA also showed strong generalization and low error dispersion. The developed models provide a transferable and data-driven modeling pipeline for predicting the coupled thermal and mechanical behavior of cement pastes containing bio-based phase change materials. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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21 pages, 4651 KB

Open AccessArticle

Phosphogypsum and Borogypsum as Additives for Sustainable and High-Performance 3D-Printable Concrete

by Yeşim Tarhan and Berrin Atalay

Polymers 2025, 17(18), 2530; https://doi.org/10.3390/polym17182530 - 19 Sep 2025

Cited by 4 | Viewed by 1742

Abstract

3D-printable concretes often require high binder content. This study evaluates the use of industrial gypsum by-products, phosphogypsum (PG) and borogypsum (BG), as partial cement replacements to enhance sustainability without compromising printability. PG and BG were incorporated at 2.5–10 wt% to replace the gypsum [...] Read more.

3D-printable concretes often require high binder content. This study evaluates the use of industrial gypsum by-products, phosphogypsum (PG) and borogypsum (BG), as partial cement replacements to enhance sustainability without compromising printability. PG and BG were incorporated at 2.5–10 wt% to replace the gypsum fraction in cement-based mortars containing fly ash (FA) or ground granulated blast-furnace slag (GGBS), with and without fibers. The fresh properties (spread flow diameter, open time, air content, density, and pH) and compressive strength were measured. At 28 days, the highest strength was achieved with a 7.5% PG addition to the GGBS system (~51 MPa), which exceeded the strength of the GGBS control C1 (~47.6 MPa). In the FA system, 2.5% PG reached 42.5 MPa, comparable to the FA control C2 (41.2 MPa). BG caused pronounced strength penalties at ≥7.5% across both binder systems, indicating a practical BG ceiling of ≤5%. Open time increased from ~0.75 h in the controls to ~2–2.5 h in BG-FA mixes with fibers, whereas PG mixes generally maintained a stable, printable window close to control levels. Overall, adding 5–7.5% PG, particularly in the presence of GGBS, improved mechanical performance without compromising workability. However, BG should be limited to ≤5% unless extended open time is the primary objective. These findings provide quantitative guidance on selecting PG/BG dosages and FA/GGBS systems to balance strength and printability in cement-based, 3D-printable concretes. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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27 pages, 6450 KB

Open AccessArticle

Durability and Microstructural Evaluation of Geopolymer Mortars Exposed to Sulphuric Acid Using Industrial By-Product Fillers

by Ouiame Chakkor

Polymers 2025, 17(17), 2310; https://doi.org/10.3390/polym17172310 - 26 Aug 2025

Cited by 5 | Viewed by 1837

Abstract

Rapid urbanization and industrialization have increased atmospheric pollution, particularly via sulfur oxides (SO_x) that form sulfuric acid and accelerate the degradation of cementitious materials. While Portland-cement systems have been widely studied, less is known about the acid resistance of geopolymer mortars. [...] Read more.

Rapid urbanization and industrialization have increased atmospheric pollution, particularly via sulfur oxides (SO_x) that form sulfuric acid and accelerate the degradation of cementitious materials. While Portland-cement systems have been widely studied, less is known about the acid resistance of geopolymer mortars. This study investigates the durability and microstructural evolution of metakaolin–red mud geopolymer mortars incorporating limestone, marble, and basalt powders as partial sand replacements (5, 10, and 15 wt %). Specimens were immersed in 3% H₂SO₄ for 30, 60, and 90 days, with performance evaluated via compressive and flexural strength, weight loss, and ultrasonic pulse velocity (UPV), alongside scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). After 90 days, the optimal basalt-filled mix (15 wt %) retained 84% of its initial compressive strength (46.8 MPa), compared with 61% for the control; mass loss decreased from 6.4% (control) to 3.2%, and UPV degradation was reduced by 35%. Microstructural analyses indicate denser gel phases and reduced microcracking in basalt- and marble-filled mixes. These results demonstrate that industrial by-product fillers can significantly improve sulfuric-acid resistance while supporting more sustainable binder technology. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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28 pages, 5794 KB

Open AccessArticle

Polymers in Sustainable Construction Composites: Rheology, Mechanical Performance, and Durability

by Yahya Kaya, Veysel Kobya, Murteda Ünverdi, Naz Mardani and Ali Mardani

Polymers 2025, 17(16), 2186; https://doi.org/10.3390/polym17162186 - 9 Aug 2025

Cited by 4 | Viewed by 1255

Abstract

Today, various strategies are being adopted to produce more environmentally friendly cementitious systems. A commonly adopted strategy is the enhancement of energy efficiency in the clinker grinding process through the use of grinding aids (GAs). Another approach is to reduce cement consumption by [...] Read more.

Today, various strategies are being adopted to produce more environmentally friendly cementitious systems. A commonly adopted strategy is the enhancement of energy efficiency in the clinker grinding process through the use of grinding aids (GAs). Another approach is to reduce cement consumption by partially replacing cement with mineral additives such as fly ash. The literature has highlighted that the use of GAs during clinker grinding can narrow the particle size distribution, thereby promoting higher rates of mineral additive replacement. Nevertheless, the literature still lacks comprehensive insight into how the combined application of commonly used GAs influences the substitution levels of mineral additives. In this regard, this study thoroughly examined the influence of varying proportions and dosages of Triethanolamine (TEA) and Triisopropanolamine (TIPA)—two commonly employed grinding aids—on the hydration kinetics, compressive strength development, and life cycle performance of fly ash (FA)-blended cementitious systems. The mixtures prepared with the cements produced were analyzed through XRD, TGA, and SEM techniques, and the compressive strength results were evaluated using the Taguchi method. The results demonstrated that, irrespective of the type of additive used, the use of GAs enhanced pozzolanic activity and compressive strength. In particular, the GA combination containing 75% TIPA and 25% TEA proved the most superior results in terms of hydration kinetics, mechanical strength, and environmental performance. It was demonstrated that the combined use of TEA and TIPA in specific proportions creates a synergistic effect, enabling the development of more efficient binder systems. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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Open AccessArticle

Performance and Mechanism of Polycarboxylate Superplasticizer in Red Mud Blended Cementitious Materials

by Lei Yang, Pengfei Wang, Shuqiong Luo, Yaxin Wang and Shengye Xu

Polymers 2025, 17(13), 1738; https://doi.org/10.3390/polym17131738 - 22 Jun 2025

Cited by 7 | Viewed by 3573

Abstract

The utilization of red mud by blending it into cement paste is still facing poor workability issues due to the finer particle size and higher water absorption of red mud, which can be solved by the addition of polycarboxylate superplasticizer (PCE) to effectively [...] Read more.

The utilization of red mud by blending it into cement paste is still facing poor workability issues due to the finer particle size and higher water absorption of red mud, which can be solved by the addition of polycarboxylate superplasticizer (PCE) to effectively maintain the working performance. However, the specific mechanisms by which different topologies of PCEs, in terms of water-reducing (WR)- and slump-retaining (SR)-type PCEs, influence red mud blended cement paste require further clarification. This research investigates the effect of WR-PCE and SR-PCE on the rheological properties, mechanical properties, and microscopic morphology of red mud blended cement paste under different red mud contents. The results demonstrated that at saturated dosages of 0.5% WR-PCE and 0.75% SR-PCE, both types of PCEs improved paste fluidity and reduced plastic viscosity and shear stress. Moreover, the time-dependent fluidity loss rate of the SR-PCE-incorporated paste was lower to that of the WR-PCE-incorporated paste at 30 and 60 min. With 0% and 25% red mud contents, the compressive strengths at 1, 3, 7, and 28 days were higher for WR-PCE than for SR-PCE due to the enhanced hydration of C₂S and C₃S. Furthermore, hydration products in the WR-PCE-incorporated paste were more uniformly distributed compared to the SR-PCE-incorporated paste. However, a 50% red mud content negatively impacted paste strength, likely due to the high alkalinity destabilizing the PCE. This study aims to elucidate the mechanistic relationship between PCE topology and the improved performance of red mud blended cement paste. Full article

(This article belongs to the Special Issue Application of Polymers in Cementitious Materials)

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