首页期刊导航|Materials and structures
期刊信息/Journal information
Materials and structures
RILEM Publications
Materials and structures

RILEM Publications

1359-5997

Materials and structures/Journal Materials and structuresSCI
正式出版
收录年代

    Effect of K/Na on the alkali silica reaction of seawater and sea sand concrete

    Qizhi ZhangQingnan GongRong ChenMing Wang...
    1.1-1.18页
    查看更多>>摘要：Abstract In recent years, research into the properties of seawater and sea sand concrete (SWSSC) has emerged as a prominent area of investigation, and the alkali silica reaction (ASR) of SWSSC is an urgent issue to be solved. However, little attention has been paid to the effect of K/Na on the ASR of SWSSC. In order to fill this gap, the effects of different K/Na on ASR products, pore structure, pH and alkali ion content, and expansion of SWSSC were measured. The findings demonstrated that the composition of the amorphous product ASR-P1 (K0.52Ca1.16Si4O8(OH)2.84–1.5H2O) of SWSSC exhibited an inverse relationship with K/Na, whereas the crystalline product K-shlykovite (NaCaSi4O8(OH)3–2.3H2O) displayed a direct correlation with K/Na. The increase of K+ concentration leads to the decrease of silica dissolution, which is the main reason for the lowest ASR degree in the high K/Na group. The transformation of ASR-P1 to K-shlykovite also resulted in different main ASR products in different K/Na groups. The experimental data show that increasing the K/Na from 0.85 to 1.85 reduced the 14d expansion from 0.248 to 0.22% and 28d ASR expansion from 0.415 to 0.350%. Notably, the most significant suppression occurred in the high K/Na group, which exhibited the lowest expansion values at all ages. The findings of this study provide a foundation for the theoretical application of SWSSC in the field of ocean engineering. These results suggest that adjusting K/Na ratios could serve as a viable strategy to mitigate ASR induced damage in marine concrete structures. For such structures, this implies that material selection should prioritize potassium-rich binders, such as blended cements or SCMs like potassium feldspar, to naturally elevate the K/Na ratio. In mix design, controlled additions of KOH during mixing can adjust the alkali balance, while leveraging seawater with inherently higher K/Na ratios or supplementing seawater with potassium salts can help achieve the target K/Na ratio. The findings of this study provide a foundation for the theoretical application of SWSSC in the field of ocean engineering to enhance long-term durability in ocean engineering applications.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    RILEM TC 275-HDB: results of round-robin testing for the vapor permeability of hemp concrete

    Thibaut ColinartCamille Magniont
    1.1-1.17页
    查看更多>>摘要：Abstract Determining the hygrothermal properties of bio-based construction products on a material scale is a major challenge in order to highlight and guarantee their performances. These data are also essential to feed models at wall and building scales for prediction and optimization of their contribution to energy consumption and user’s comfort. Among these properties, water vapor permeability is commonly measured with the dry cup method. Despite the good repeatability and reproducibility of this test when performed in one lab, one can observe a high level of discrepancy in the literature values. To address the origin of these differences and establish recommendations for the characterization of highly hygroscopic and permeable bio-based materials, an interlaboratory test is therefore necessary. In the context of the activities of the RILEM TC 275-HDB, two interlaboratory campaigns have been launched to measure the water vapor permeability of bio-aggregate based building materials by means of cup test. The analysis of the results from six participating laboratories from different countries highlighted the main sources of discrepancy, in particular the progressive saturation of the desiccant during the experiment and the incompatibility of the “steady state” criterion and the air velocity recommended by the standard ISO 12572 in the case of highly permeable materials. Despite the many sources of uncertainties, recommendations are proposed to improve the accuracy of this measurement for permeable materials such as a continuous measurement of the vapor pressure within the air layer and the measurement of the air velocity above each cup to evaluate the local interface resistance.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Investigation of the hydration of clinker-reduced cementitious binders by 1H NMR relaxometry

    Sarah MunschWolfram SchmidtRenata LorenzoniMelissa Telong...
    1.1-1.23页
    查看更多>>摘要：Abstract In this paper, we demonstrate the value of 1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{1}$$\end{document}H NMR relaxometry for studying the hydration of clinker-reduced, climate-friendly cementitious binders. Our study includes white cement (WC), ordinary Portland cement (OPC), and samples incorporating reactive agro-waste based ashes and non-reactive biochars as supplementary cementitous materials (SCM). NMR measurements were performed over a period of up to 120 h during hydration with an echo time of 50 μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu$$\end{document}s and a relatively large sample size of 20 mL. The results were compared to heat flow calorimetry (HFC) data, and a detailed comparison with literature data was performed for pure OPC and WC. The results show that time-resolved NMR measurements, especially the analysis of individual NMR signal components assigned to defined 1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$^{1}$$\end{document}H reservoirs, are effective for studying hydration processes. They offer insights into the evolution of the microstrucure and specific chemical phases. NMR provides valuable information and serves as a good complement to HFC. The comparison with data obtained with shorter echo times (40 μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu$$\end{document}s or around 15–45 μ\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu$$\end{document}s with solid echo sequence) on much smaller samples showed almost identical developments with respect to the T2\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\hbox {T}_2$$\end{document} distributions. For the SCM samples, NMR results indicated partially accelerated hydration processes compared to classical OPC hydration. One SCM sample acted as a highly reactive pozzolan, showing a similar hydration process to OPC with the strongest effect observed when superplasticizer was added. Adding biochar delayed C-S-H gel pore formation but significantly increased capillary pores and even free water, likely due to the sponge-like structure.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Efficient carbon sequestration of seawater sea-sand recycled aggregate concrete: an experimental study

    Xiaolong HuJianzhuang XiaoKaijian ZhangTao Ding...
    1.1-1.17页
    查看更多>>摘要：Abstract Carbonation has long been considered harmful to the durability of steel reinforced concrete structures especially with the increasing CO2 and temperature globally. In coastal construction, the chloride ions even make it worse. By replacing the steel with chloride-insensitive reinforcement such as fiber reinforced polymer (FRP), sea sand is a potential alternative to river sand, even carbonation could be utilized due to the acid resistance of FRP. In this paper, seawater sea-sand recycled aggregate concrete (SSRAC) was prepared, which had different hydration and carbonation from ordinary concrete (OC). The test results showed that the carbonation depth at 28 days of SSRAC increased up to 179.13% of OC. A modified carbonation model based on pore evolution was established. On the other hand, the increasement of carbonatable material in SSRAC was up to 14.32%. Combined with this characteristic, the carbon emission and absorption assessment were carried out. It is found that the CO2 absorption of SSRAC can be up to 325% of OC in 10 years’ service, and the total carbon emission including carbon sequestration over the whole life of SSRAC with a salinity of 4% is 45.73% of OC. This research verifies that it is expected to achieve more CO2 sequestration rapidly in SSRAC, which could probably help design low-carbon concrete structures.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    The heterogeneous characteristics of the microstructure in cement stone under the effect of self-weight segregation

    Zhiheng WangXiuhao LiMeng WangYu’an Gong...
    1.1-1.15页
    查看更多>>摘要：Abstract Under the influence of self-weight segregation, the microstructure of cement stone exhibits significant heterogeneous characteristics, but the mechanisms of these variations have not been revealed. In this study, the pore size distribution and porosity of the cement stone with various water-to-cement (w/c) ratios and the initial height were measured using NMR methods. The relationships between cement stone porosity and height position were fitted using a simplified self-weight consolidation finite model and a small strain model. The results show that under the same w/c ratios, the density and porosity of the stones formed at the bottom of cement grout columns with different initial heights are essentially consistent. As the height increases, the amount of ettringite increases while the formation of C-S-H gels decreases, leading to a higher content of transitional and capillary pores, which primarily contributes to the overall increase in the porosity of the cement stone. The variation trend in the porosity of cement stone with a lower w/c ratio, such as 0.8, aligns with the predictions of the finite strain model. As the w/c ratio increases, like 1.0 or 1.2, the reduction in effective stress between particles delays the self-weight consolidation process, enhancing the influence of cement hydration. This ultimately makes the porosity change more consistent with the small strain model.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Unlocking clay’s potential: a comparative analysis of activation techniques for enhanced reactivity in SCMs

    Isabel Pol SeguraPeter A. JensenKiranmai SanagavarapuWilson R. Leal da Silva...
    1.1-1.22页
    查看更多>>摘要：Abstract Clays’ reactivity can be improved through different treatments that transform their crystalline structure into an amorphous state. This study compares thermal, mechanical, and chemical activation on three laboratory grade clays (kaolinite, halloysite and montmorillonite), investigating changes in particle morphology, composition, and evaluating their reactivity as supplementary cementitious materials (SCMs) in composite cement through compressive strength tests. Across all activation methods, harsher conditions (higher temperatures, grinding times or acid contents) resulted in larger particle sizes and lower specific surface areas, reducing the clays’ degree of mineral amorphization and pozzolanic activity. All activated clays were tested with a 20% replacement of CEM I, a water-to-binder ratio of 0.5, and compared against a baseline of 100% CEM I mortar. Our findings indicate that thermal activation, particularly at 750 °C, is most effective for kaolinites and halloysites, resulting in an average 28-day compressive strength increase of 40% and 30%, respectively. For montmorillonite, mechanical activation with a ball-to-powder ratio of 10 and a duration of 75 min works best, yielding a 23% increase in the 28-day strength. While chemical activation of montmorillonite led to a 15% 28-day strength gain, thermal activation had no significant impact on its performance compared to 100% CEM I baseline. However, challenges related to the scalability and safety of chemical activation hinder its industrial application. Overall, this study provides new insights into optimizing activation methods based on clay mineralogy to improve strength performance as SCMs in composite cement, while promoting the utilization of clays that are currently deemed unsuitable for composite cement production.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Influence of aggressive agents on properties of geopolymer concrete and corrosion behavior of steel in geopolymer concrete pore solution

    Leela Sai Rangarao MaradaniBulu Pradhan
    1.1-1.26页
    查看更多>>摘要：Abstract The effect of aggressive agents such as chloride and sulfate admixed salt (NaCl, NaCl + Na2SO4, and NaCl + MgSO4) on compressive strength, ionic concentration (Ca2+, Na+, and K+ ions) of geopolymer concrete (GeoPC) pore solution, and microstructural characteristics of fly ash (FA), and fly ash-ground granulated blast furnace slag GeoPC were investigated in the present study. In addition, the effect of aggressive ions on the electrochemical behavior of steel specimen was investigated by half-cell potential, linear polarisation (LPR), and potentiodynamic polarisation (PDP) tests. The results exhibited that the GeoPC admixed with NaCl plus MgSO4 showed lower strength than other GeoPC mixes. Further, variation in ionic concentrations of pore solution are in line with formation of binding gels. Microstructural investigations of GeoPC showed that the mixtures added with chloride-sulfate salt showed lower formation of binding gels than chloride admixed GeoPC which were substantiated with the strength results. The LPR and PDP test results indicated that the corrosion resistance of steel specimen was higher in pore solution of GeoPC added with NaCl plus Na2SO4 than NaCl plus MgSO4, and followed by NaCl.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Effect of monopotassium phosphate fineness on properties and micro-characteristics of magnesium potassium phosphate cements

    Yizhou ZhaoBiwan Xu
    1.1-1.16页
    查看更多>>摘要：Abstract Hydration of magnesium potassium phosphate (MKP) cements is a dissolution–precipitation process. Compared to magnesia, the dissolution effect of monopotassium phosphate (KH2PO4) has been gained less attention and remains unclear. In this study influence of two KH2PO4 materials with different fineness on properties and micro-characteristics of the MKP cement pastes at Mg/PO4 molar ratio of 4 and 8 was investigated. Compared with the pastes without boric acid, the effect of KH2PO4 fineness was more obvious with the presence of boric acid due to the slowed-down reactions. The combined use of boric acid and the coarse KH2PO4 better slowed down the reactions, thus led to longer setting time but to reduced flowability, higher shrinkages and great strength losses. In contrast, the combined use of boric acid and the fine KH2PO4 facilitated a better dissolution and consumption of KH2PO4 and formations of robust K-struvite hydrates, resulting in less detrimental capillary pores, lower shrinkages and higher strengths, although the reaction could be faster. To guarantee a full consumption of KH2PO4 and mitigate strength loss over long-term, Mg/PO4 molar ratio > 4 and fine KH2PO4 are commended for those pure MKP cements.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Effects of single and hybrid fiber incorporation on the toughness, mechanical properties and microstructure of fiber-reinforced mortar

    Xuesong ZhangYanrong ZhangKai WuBaoyuan Yang...
    1.1-1.23页
    查看更多>>摘要：Abstract In order to study the influence of fiber types and their ℓ/d ratios on the mechanical and microstructural properties of fiber reinforced mortar (FRM), four-point bending test and compressive test were carried out on FRM prisms to study their flexural toughness and mechanical strength at the ages of 3 and 28 days. Additionally, mercury intrusion porosimetry and electron scanning microscopy were applied to study the mechanisms responsible for the mechanical performance and mesoscopic failure modes of two types of polypropylene (PP) fiber, termed PP1 and PP2, and a polyvinyl alcohol (PVA) fiber, and their hybrids, used as mortar reinforcement. The results indicated that the improvement in the mortar's equivalent flexural toughness due to fiber incorporation followed the order: PP1 > PP2 > PVA, that in the equivalent flexural strength followed the order: PVA > PP2 > PP1. The PP1 fibers loosened the fiber-matrix interfacial transition zone (ITZ) and weakened the bond, resulting in easy fiber pull out. The ITZ of hydrophilic PVA fiber was relatively dense. The moduli, fracture elongations, and surface properties of PVA and PP1 fibers differed, resulting in a lack of synchronization in limiting FRM crack propagation at 3 days, as each fiber contributed to stress resistance at different stages. However, they exhibited complementary characteristics. PVA fibers restricted the initiation and development of early cracks, encouraging the formation of multiple cracks, while PP1 fibers prevented unstable crack growth in the strain-softening stage of FRM.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature

    Effect of nano silicon nitride on the microstructural characteristics and mechanical properties of ultra-high-performance steel fiber reinforced concrete

    J. D. Ruiz MartínezJ. D. RíosE. M. Pérez-SorianoH. Cifuentes...
    1.1-1.22页
    查看更多>>摘要：Abstract This study investigates the incorporation of an innovative nano-reinforcement, nano silicon nitride (NSIN), to enhance the workability and mechanical performance of ultra-high-performance fiber reinforced concrete. The addition of NSIN at dosages of 0.25, 0.5, 0.75, and 1.5 wt% of cement was analyzed to evaluate its impact on the distribution and interaction between steel fibers and the cementitious matrix. Experimental analyses, including thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and scanning electron microscopy (SEM), were conducted to establish a relationship between the microstructural modifications, fiber-matrix interactions, and the resulting mechanical behavior. The findings revealed that NSIN increased workability and extended setting time, enabling improved steel fiber dispersion and interaction with the matrix. This, in turn, reduced macroporosity around the fibers, enhancing the matrix integrity. TGA indicated a reduction in free calcium hydroxide, corroborating the observed strengthening of the matrix. Furthermore, the addition of 0.75 wt% NSIN yielded the optimal results, with a 17.3% improvement in compressive strength and a 66% increase in crack propagation resistance during the elastic phase. These results highlight the potential of NSIN as a nano-reinforcement to significantly improve the mechanical and microstructural properties of UHPFRC.
      原文链接:
    • NETL
    • NSTL
    • Springer Nature