Construction and Building Materials最新文献

Concrete mix design: Optimizing recycled asphalt pavement in Portland cement concrete 混凝土混合设计：优化波特兰水泥混凝土中的再生沥青路面

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-17 DOI: 10.1016/j.conbuildmat.2024.139180

Jirayut Suebsuk , Suksun Horpibulsuk , Veena Phunpeng , Panupong Panpipat , Komkorn Chaidachatorn , Wunchock Kroehong , Rattapon Somna

In contemporary construction projects, there is a growing trend towards incorporating Recycled Asphalt Pavement (RAP) into Portland Cement Concrete (PCC). However, a significant challenge lies in formulating the mixture to achieve the desired strength for practical applications. This study delves into the influence of RAP on formulation of PCC mixtures. Conventional aggregates were systematically substituted with RAP at proportions of 25 %, 50 %, 75 %, and 100 % relative to the overall weight of the mixture. The study comprehensively analyzed various parameters throughout both the initial and solidified phases, encompassing modulus of elasticity, unit weight, workability, and compressive strength. The efficacy of PCC incorporating RAP can be standardized through the application of an extended water/cement ratio approach. Moreover, the key factors influencing the strength development of PCC containing RAP were identified as the residual water content after hardening (w_u) and the asphalt fraction weight percentage in the aggregate mixture (θ_AS). A straightforward and precise technique for designing the strength of PCC using RAP was suggested. This document presents the design criteria and suggestions for using PCC including RAP. The outcomes offer crucial insights regarding the utilization of RAP as a greener material in PCC applications on a substantial scale.

在当代建筑项目中，将再生沥青路面（RAP）融入硅酸盐水泥混凝土（PCC）的趋势日益明显。然而，如何配制混合物以达到实际应用所需的强度是一项重大挑战。本研究探讨了 RAP 对 PCC 混合物配方的影响。系统地用 RAP 替代了传统的集料，比例分别为混合物总重量的 25%、50%、75% 和 100%。研究全面分析了初始阶段和凝固阶段的各种参数，包括弹性模量、单位重量、工作性和抗压强度。通过采用扩大水灰比的方法，可以规范掺入 RAP 的 PCC 的功效。此外，影响含有 RAP 的 PCC 强度发展的关键因素是硬化后的残余含水量（wu）和集料混合物中的沥青组分重量百分比（θAS）。本文提出了使用 RAP 的 PCC 强度设计的直接而精确的技术。本文介绍了使用含 RAP 的 PCC 的设计标准和建议。这些成果为在 PCC 大规模应用中使用 RAP 这种更环保的材料提供了重要的启示。

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引用次数: 0

Perforated cenospheres used to enhance the engineering performance of high-performance cement-slag-limestone ternary binder 用于提高高性能水泥-矿渣-石灰石三元粘结剂工程性能的穿孔仙人球

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-17 DOI: 10.1016/j.conbuildmat.2024.139084

Gui-Yu Zhang , Jingquan Wang , Yulong Zheng , Zenian Wang , Xiao-Yong Wang

Slag-limestone-cement ternary mixed binder is a new type of cementitious material. There are 1137 published literatures on this new type of cementitious material in the Scopus database, but so far, no papers have been published on the research of reactive internal curing of this new type of cementitious material. One kind of fly ash is called a cenosphere with a very thin outer shell and a hollow center. Cenospheres generate pores through chemical etching, thereby achieving the effect of self-curing. This article conducted multiple experimental studies to ascertain the impact of perforated cenospheres regarding the execution of cement-slag-limestone binder. The mixture samples with different dosage of perforated cenospheres and cenospheres are numbered C0 (control group), P3.3 (content of perforated cenospheres in the binder is 3.3 %), P6.6 (content of perforated cenospheres in the binder is 6.6 %), and C6.6 (content of perforated cenospheres in the binder is 6.6 %). Based on the results of autogenous shrinkage and compressive strength, perforated cenospheres as an internal curing agent not only reduces the autogenous shrinkage of cement-slag-limestone concrete, but also avoids a significant decrease in strength of cement-slag-limestone concrete. In fact, because of volcanic ash reactivity of advanced cenospheres and the internal curing effect, the compressive strength of P3.3 mixed mortar increased by 0.7 and 4 MPa compared to C0 mixed mortar at 7 and 28 days of age, achieving a dual effect of reducing shrinkage and improving strength. Secondly, the experimental results of Fourier transform infrared spectroscopy and X-ray diffraction showed that perforated cenospheres can undergo volcanic ash reaction with calcium hydroxide. The scanning electron microscope images indicate that the P3.3 and P6.6 mixed paste with added perforated cenospheres exhibit better and denser bonding between the perforated cenospheres and the matrix. In summary, the microscopic reactions of perforated cenospheres can enhance concrete's macroscopic qualities, which can be utilized as reactive internal curing materials.

矿渣-石灰石-水泥三元混合粘结剂是一种新型胶凝材料。在 Scopus 数据库中有 1137 篇关于这种新型胶凝材料的文献，但迄今为止，还没有关于这种新型胶凝材料反应性内固化研究的论文。有一种粉煤灰被称为 "仙人球"，其外壳很薄，中心中空。仙人球通过化学蚀刻产生孔隙，从而达到自固化的效果。本文进行了多项实验研究，以确定穿孔的仙人球对水泥-矿渣-石灰石粘结剂的执行产生的影响。穿孔仙人球和仙人球用量不同的混合物样品分别编号为 C0（对照组）、P3.3（粘结剂中穿孔仙人球的含量为 3.3%）、P6.6（粘结剂中穿孔仙人球的含量为 6.6%）和 C6.6（粘结剂中穿孔仙人球的含量为 6.6%）。根据自生收缩和抗压强度的结果，穿孔仙人球作为内部养护剂不仅可以减少水泥-矿渣-石灰岩混凝土的自生收缩，还可以避免水泥-矿渣-石灰岩混凝土强度的显著下降。事实上，由于高级仙人球的火山灰反应性和内养护效果，P3.3 混合砂浆在 7 天和 28 天龄期时的抗压强度比 C0 混合砂浆分别提高了 0.7 和 4 兆帕，达到了减少收缩和提高强度的双重效果。其次，傅里叶变换红外光谱和 X 射线衍射的实验结果表明，穿孔仙人球能与氢氧化钙发生火山灰反应。扫描电子显微镜图像表明，添加了穿孔仙人球的 P3.3 和 P6.6 混合浆料的穿孔仙人球与基体之间的粘结更好、更致密。总之，穿孔仙人球的微观反应可提高混凝土的宏观质量，可用作反应性内部养护材料。

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引用次数: 0

Dynamic splitting tensile properties of crumb rubber modified ultra-high performance engineered cementitious composites (UHP-ECC) 屑橡胶改性超高性能工程水泥基复合材料（UHP-ECC）的动态劈裂拉伸性能

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-17 DOI: 10.1016/j.conbuildmat.2024.139183

Huzi Ye , Jinlong Pan , Binrong Zhu , Yuanzheng Lin , Jingming Cai

Ultra-high performance engineered cementitious composites (UHP-ECC) have been extensively researched as a promising material to evaluate their mechanical properties under quasi-static loads. However, further comprehensive research is necessary on their dynamic mechanical response at high strain rates. This paper systematically investigates the dynamic tensile mechanical properties and failure mechanisms of rubber-modified UHP-ECC. Dynamic mechanical tests were conducted using a split hopkinson pressure bar (SHPB) to obtain crucial dynamic mechanical parameters, including dynamic splitting tensile stress, dynamic increase factor (DIF), and energy absorption capacity for different UHP-ECC samples. It was observed that CR acts as pseudo-pores, enhancing the deformation capacity of the specimens at high strain rates. At high strain rates, CR reduces the stiffness of the matrix and the bond strength of the fibres, making a 5 % CR content more beneficial for improving the splitting toughness and energy absorption capacity of UHP-ECC. The findings of this study are significant for guiding infrastructure construction using CR modified UHP-ECC under high-velocity impact.

超高性能工程水泥基复合材料（UHP-ECC）作为一种前景广阔的材料，已被广泛研究，以评估其在准静态载荷下的机械性能。然而，有必要对其在高应变速率下的动态机械响应进行进一步的综合研究。本文系统地研究了橡胶改性 UHP-ECC 的动态拉伸机械性能和失效机理。使用分体式霍普金森压力棒（SHPB）进行了动态力学测试，以获得不同 UHP-ECC 样品的关键动态力学参数，包括动态劈裂拉伸应力、动态增大因子（DIF）和能量吸收能力。研究发现，CR 可作为伪孔，增强试样在高应变速率下的变形能力。在高应变速率下，CR 会降低基体的刚度和纤维的结合强度，因此 5% 的 CR 含量更有利于提高 UHP-ECC 的劈裂韧度和能量吸收能力。本研究的发现对于在高速冲击下使用 CR 改性超高压-ECC 指导基础设施建设具有重要意义。

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引用次数: 0

Durability against cyclic wetting-drying of cement-stabilized loess subgrade for railway in tropical semi-arid regions 用于热带半干旱地区铁路的水泥稳定黄土路基对周期性湿-干作用的耐久性

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-17 DOI: 10.1016/j.conbuildmat.2024.139123

Narongdet Yangsukkasem , Jirayut Suebsuk , Apichit Kampala , Akkharadet Siriphan , Rattapon Somna , Weeraphan Jiammeepreecha , Prinya Chindaprasirt

This research investigates the effect of soaking times, number of wetting-drying (W-D) cycles, saturation levels, sample dimensions, and cement contents on the durability performance of cement-stabilized loess for railway subgrade. To imitate the extreme environment in tropical semi-arid regions, the samples were soaked in water and dried in an oven to create the cyclic W-D state. Microstructure tests were used to confirm the cement hydration reaction in the cemented loess sample after the cyclic W-D. The soaking time was observed as the key factor controlling the depth of water infiltration and degree of saturation of W-D samples. At the same soaking time, the small sample reached a higher saturation level than the large sample. Increasing the amount of cement enhanced stability by strengthening cementation bonds and improving water retention capacity. The increase in cement content not only enhanced the strength but also improved the water resistance and reduced the weight loss of soil samples. The unconfined compressive strength (UCS) in high cement content samples increased notably during 6–12 cycles of W-D due to the cement hydration, as proved by the microstructure tested results. The correlation of the UCS after cyclic W-D of the sample with a diameter of 50 mm and that of 101.6 mm was proposed. The durability index was suggested to facilitate the design of cement-stabilized loess mixes effectively while extending the service life. The results could provide valuable guidance for sustainably designing cement-stabilized loess as a subgrade for railway and other geotechnical structures in tropical semi-arid regions.

本研究探讨了浸泡时间、湿润-干燥（W-D）循环次数、饱和度、样品尺寸和水泥含量对铁路路基水泥稳定黄土耐久性能的影响。为了模拟热带半干旱地区的极端环境，样品被浸泡在水中并在烘箱中干燥，以形成循环 W-D 状态。微观结构测试用于确认循环 W-D 后胶结黄土样品中的水泥水化反应。浸泡时间是控制 W-D 样品渗水深度和饱和度的关键因素。在相同的浸泡时间内，小样本的饱和度高于大样本。增加水泥用量可通过加强胶结键和提高保水能力来增强稳定性。水泥含量的增加不仅提高了强度，还改善了土样的耐水性，减少了土样的重量损失。由于水泥水化作用，高水泥含量土样的无压抗压强度（UCS）在 6-12 个 W-D 循环期间显著增加，这一点已被微观结构测试结果所证实。提出了直径为 50 毫米和 101.6 毫米试样循环 W-D 后 UCS 的相关性。提出的耐久性指数有助于有效设计水泥稳定黄土混合料，同时延长其使用寿命。研究结果可为可持续地设计水泥稳定黄土作为热带半干旱地区铁路和其他岩土结构的路基提供宝贵的指导。

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引用次数: 0

Lightweight, high-strength, thermal- and sound-insulating reed scraps/portland cement composite using extruded resin particles 使用挤压树脂颗粒的轻质、高强度、隔热和隔音芦苇碎片/波特兰水泥复合材料

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-17 DOI: 10.1016/j.conbuildmat.2024.139248

Shuanggang Yang, Hao Wu, Yingfeng Zuo, Xingong Li, Yiqiang Wu

The development of a lightweight composite made from reed scraps, Portland cement, and polystyrene particles can simultaneously address issues related to reed waste, environmental pollution, and carbon emissions produced by the construction industry. However, standard polystyrene particles have low bonding strength with Portland cement and reed scraps, giving the resulting composites inferior mechanical properties and thermal and acoustic insulation characteristics. To overcome these limitations, nano-silicon expanded resin particles (NSERP), composed of polyvinyl alcohol, polystyrene, nano-silicon, and various modifiers, were introduced to replace traditional polystyrene particles in the composite. These novel particles enhanced the interfacial bonding strength and improved the mechanical properties, as well as the thermal and acoustic insulation capabilities of the composites. This study investigated the effects of the water-cement ratio, reed scraps-to-cement ratio, and NSERP dosage on the composite's properties through single-factor experiments. The optimized composite had a density of 0.66 g/cm³ and a compressive strength of 2.5 MPa, and its sound absorption coefficient in the middle and high-frequency bands was 0.7, which was approximately 4.3 times higher than that of conventional silicate composites. Its thermal insulation performance surpassed that of standard composites. This lightweight, high-strength, thermally insulating, environmentally friendly, and energy-efficient multifunctional composite has potential applications in building energy conservation, traffic noise reduction, and new energy battery insulation.

开发一种由芦苇下脚料、波特兰水泥和聚苯乙烯颗粒制成的轻质复合材料，可以同时解决与芦苇废料、环境污染和建筑业产生的碳排放有关的问题。然而，标准的聚苯乙烯颗粒与波特兰水泥和芦苇下脚料的粘合强度较低，导致复合材料的机械性能、隔热和隔音性能较差。为了克服这些局限性，我们引入了由聚乙烯醇、聚苯乙烯、纳米硅和各种改性剂组成的纳米硅发泡树脂颗粒（NSERP），以取代复合材料中的传统聚苯乙烯颗粒。这些新型颗粒增强了界面粘合强度，改善了复合材料的机械性能以及隔热和隔音能力。本研究通过单因素实验研究了水灰比、芦苇碎屑与水泥比以及 NSERP 用量对复合材料性能的影响。优化后的复合材料密度为 0.66 g/cm³，抗压强度为 2.5 MPa，其中高频段吸声系数为 0.7，是传统硅酸盐复合材料的约 4.3 倍。其隔热性能超过了标准复合材料。这种轻质、高强、隔热、环保、节能的多功能复合材料有望应用于建筑节能、交通降噪和新能源电池隔热等领域。

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引用次数: 0

A multidisciplinary evaluation of mixtures of municipal solid waste incineration bottom ash and mine tailings for sustainable geotechnical solutions 对城市固体废物焚烧底灰和矿山尾矿混合物进行多学科评估，以寻找可持续岩土工程解决方案

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-17 DOI: 10.1016/j.conbuildmat.2024.139139

L.S.V.E. Monteiro , B.S. Bandarra , M.J. Quina , P.A.L.F. Coelho

Waste generation has been a source of environmental concern in case of inadequate management. However, the potential for resource recovery from waste has been highlighted, and circular economy strategies have been greatly promoted to achieve sustainability goals. Municipal solid waste incineration bottom ash (IBA) and mine tailings represent two relevant waste streams under study for geotechnical applications. The present work aims at investigating the physical, mechanical, chemical, and ecotoxicological characteristics of two mixtures of 90 % bottom ash and 10 % of two different mine tailings (one of iron and another of tungsten, tin, and copper) to evaluate their safe utilization. The results indicated that mixtures of IBA and mine tailings have good compressibility, permeability, and shear strength properties, comparable to granular soils. Additionally, adding 10 % mine tailings in the mixtures had minimal effect on the mechanical behaviour of IBA alone. No substantial concentration of potentially toxic metals or relevant ecotoxic effects were found in any of the analysed materials and their eluates. These results suggest that mixing IBA with mine tailings for geotechnical use, e.g., in embankments or road base/subbase may be a safe option. This represents a promising alternative for valorising both waste streams while promoting sustainable and circular solutions.

如果管理不善，废物的产生一直是环境问题的根源。然而，从废物中回收资源的潜力已得到强调，为实现可持续发展目标，循环经济战略已得到大力推广。城市固体废物焚烧底灰（IBA）和矿山尾矿是岩土工程应用研究中的两种相关废物流。本研究旨在调查两种混合物的物理、机械、化学和生态毒理学特征，这两种混合物分别含有 90% 的底灰和 10% 的两种不同矿山尾矿（一种含铁，另一种含钨、锡和铜），以评估其安全利用情况。结果表明，IBA 和矿山尾矿的混合物具有良好的压缩性、渗透性和剪切强度特性，可与颗粒土相媲美。此外，在混合物中添加 10% 的矿山尾矿对 IBA 本身的机械性能影响很小。在所有分析过的材料及其洗脱液中都没有发现大量潜在有毒金属，也没有发现相关的生态毒性影响。这些结果表明，将 IBA 与矿山尾矿混合用于岩土工程（如堤坝或路基/路基）可能是一种安全的选择。这是在促进可持续和循环解决方案的同时提高两种废物流价值的一种有前途的替代方法。

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引用次数: 0

Understanding the synergetic effect of SAP and nano-silica on the mechanical properties, drying shrinkage and microstructures of alkali-activated slag/fly ash-based concrete 了解 SAP 和纳米二氧化硅对碱激活矿渣/粉煤灰基混凝土的力学性能、干燥收缩和微观结构的协同效应

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-16 DOI: 10.1016/j.conbuildmat.2024.139223

Dongtao Xia , Nana Song , Biao Li , Yi Zheng , Wenyuan Guo , Jiani Wu , Songbo Wang

Superabsorbent polymers (SAP) have been commonly used to mitigate the shrinkage of alkali-activated materials through internal curing, but may cause some strength loss in the materials. To overcome this issue, nano-silica (NS) is used in this paper. The synergetic effect of SAP and NS on the mechanical properties and drying shrinkage behavior of slag/fly ash-based alkali-activated concrete (AAC) was investigated. The corresponding hydration reaction kinetics and microstructures were simultaneously examined to reveal the shrinkage-mitigating mechanism. The results revealed that, the incorporation of SAP induces a compressive strength deterioration of AAC, but mitigates the drying shrinkage of AAC, with the reducing amplitudes of 12.4–32.7 % at 56 d. The internal relative humidity (IRH) of 83 % is deemed as a critical node for the internal curing by SAP, and the additional moisture can maintain the IRH of AAC above 74 %, which improves the geopolymerization reaction around the SAP particles and reduces the proportion of capillary pores. The NS and SAP show a synergetic strengthening impact on the mechanical properties, drying shrinkage and microstructures of AAC, with the pores left by SAP water release filled and compensated by NS. In addition, the induction hydration period and its delay effect due to SAP can be reduced by NS, which decreases the initial and final setting times of AAC. From the results obtained in this work, AAC shows better mechanical performance and shrinkage-mitigating effect with the SAP and NS content of 0.2 % and 2 %, respectively. The research outcomes provide a new possibility for the drying shrinkage control without strength loss of AAC.

超吸水性聚合物（SAP）通常用于通过内部固化缓解碱激活材料的收缩，但可能会导致材料强度下降。为了克服这一问题，本文采用了纳米二氧化硅（NS）。研究了 SAP 和 NS 对矿渣/粉煤灰碱活性混凝土（AAC）力学性能和干燥收缩行为的协同效应。同时研究了相应的水化反应动力学和微观结构，以揭示其缓解收缩的机理。结果表明，掺入 SAP 会导致 AAC 的抗压强度下降，但会减轻 AAC 的干燥收缩，56 d 时的收缩幅度为 12.4-32.7%。内部相对湿度（IRH）为 83% 是 SAP 内部固化的关键节点，额外的水分可使 AAC 的内部相对湿度保持在 74% 以上，从而改善 SAP 颗粒周围的土聚合反应，减少毛细孔的比例。NS 和 SAP 对 AAC 的力学性能、干燥收缩率和微观结构具有协同强化作用，SAP 释水留下的孔隙由 NS 填充和补偿。此外，NS 还能缩短诱导水化期及其因 SAP 而产生的延迟效应，从而缩短 AAC 的初凝和终凝时间。从研究结果来看，当 SAP 和 NS 的含量分别为 0.2 % 和 2 % 时，AAC 具有更好的机械性能和收缩缓解效果。这些研究成果为在不损失 AAC 强度的情况下控制其干燥收缩提供了新的可能性。

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引用次数: 0

Laboratory investigation on anisotropic shear behavior of natural and splitting joints under different normal stresses 不同法向应力下自然接头和劈裂接头各向异性剪切行为的实验室研究

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-16 DOI: 10.1016/j.conbuildmat.2024.139140

Wei Sun , Wei Zhang , Linggen Kong , Shaohui Tang , Qi Zhang

Mechanical splitting test has been widely used to generate splitting joint for investigating shear behaviors in the laboratory. In fact, some differences are within shear behavior between splitting joint and natural joint, especially anisotropic characteristics. To quantitatively compare these differences, the 3D engraving technique was employed in the present study to repeatedly reconstruct three natural joints and three splitting joints. Then direct shear tests were conducted to analyze their shear behaviors under different shear directions and normal stresses. The results indicated that there were substantial dissimilarities between two types of joints in shear behavior. For the splitting joints, the peak shear strength exhibited slight variations in different shear directions under low normal stress. These variations were less pronounced compared to natural joints. As the normal stress increased, the anisotropy of peak shear strength in splitting joints gradually diminished. For the natural joints, the anisotropy intensified in as the normal stress increased. Additionally, the dip angle of micro-asperities of splitting joint surface mainly presented a normal distribution. The shape of directional parameter, θ*_max/(C + 1), was circular. The joint surface was uniform damage under different shear directions. During shear test process, most micro-asperities contributed to the shear behavior without displaying obvious anisotropy. There were no key micro-asperities on the splitting joint surface. Conversely, the dip angle of micro-asperities of natural joint surface exhibited a predominantly irregular distribution. The shape of the directional roughness parameter was also irregular. The damage on joint surfaces presented strip-shaped failure, indicating pronounced anisotropy. These damage areas consisted of the micro-asperities with high height or high dip angle, which were key micro-asperities influencing the shear failure. The nonuniform distribution of these key micro-asperities of natural joints contributed to the prominent anisotropy in shear behavior.

机械劈裂试验已被广泛用于产生劈裂接头，以研究实验室中的剪切行为。事实上，劈裂接头与天然接头的剪切行为存在一些差异，尤其是各向异性特征。为了定量比较这些差异，本研究采用三维雕刻技术反复重建了三个自然接头和三个劈裂接头。然后进行直接剪切试验，分析它们在不同剪切方向和法向应力下的剪切行为。结果表明，两类接头的剪切行为存在很大差异。对于劈裂接头，在低法向应力下，不同剪切方向的峰值剪切强度略有不同。与自然接头相比，这些变化并不明显。随着法向应力的增加，劈裂接头峰值剪切强度的各向异性逐渐减弱。而对于天然接缝，各向异性随着法向应力的增加而增强。此外，劈裂接头表面微孔的倾角主要呈正态分布。方向参数θ*max/(C + 1)的形状呈圆形。在不同的剪切方向上，接合面均呈均匀破坏。在剪切试验过程中，大多数微孔都对剪切行为做出了贡献，但没有表现出明显的各向异性。在劈裂的接合面上没有关键的微孔。相反，自然接合面微孔的倾角主要呈不规则分布。方向粗糙度参数的形状也不规则。接合面上的损伤呈条状破坏，显示出明显的各向异性。这些损伤区域包括高高度或高倾角的微观粗糙度，它们是影响剪切破坏的关键微观粗糙度。天然接缝中这些关键微观粗糙度的不均匀分布导致了剪切行为的显著各向异性。

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引用次数: 0

Study on the hydration kinetics and microstructure of the sulphate-alkali composite activated slag pastes 硫酸盐-碱复合活性渣浆的水化动力学和微观结构研究

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-16 DOI: 10.1016/j.conbuildmat.2024.139221

Miaomiao Wu , Minghui Huang , Weiguo Shen , Mengxia Zhou , Tiangang Zhou , Deqiang Zhao , Chaozheng Chai , Zhiyue Yang , Jiangwei Li , Zuhua Zhang , Zihan Wang

In this study, the phosphogypsum (PG) was successfully applied to prepare the sulphate-alkali activated slag (SAAS) pastes to reduce carbon emissions and production costs. The set-hardening properties of SAAS samples with PG were optimized using response surface methodology. Then, several in-situ measurements and several characterization methods were applied to monitor the hydration behavior and study the microstructure evolution. Furthermore, the hydration kinetics were analyzed to further reveal the new insight into the activation mechanism of the sulphate-alkali composite. The results showed that the optimized ratio was obtained at 2.7 % alkali dosage (AD) and 11.8 % PG, where the initial setting time and 28d strength valued 162 min and 56 MPa, respectively. It was also found that heat flow was accelerated but mitigated, and autogenous shrinkage was gradually mitigated with increasing PG content due to its additional activation effect as sulphate. Samples with 5 % PG require a higher AD to obtain a sufficient degree of hydration. While lower AD would produce more ettringite and CASH gels with higher degree of polymerization for samples with 15 % PG. Hydration kinetic analysis showed that addition of 5 % PG would make the nucleation process of CASH gels difficult. While the addition of 15 % PG would increase the nucleation density by almost 10 times, the growth rate would be greatly reduced, resulting in a slower but continuous development of the microstructure. Thus, it was demonstrated that the use of PG in SAAS pastes is reasonable and has great potential.

本研究成功地将磷石膏（PG）用于制备硫酸盐-碱活性渣（SAAS）浆料，以减少碳排放和生产成本。采用响应面方法优化了含有 PG 的 SAAS 样品的凝固硬化性能。然后，采用多种原位测量和表征方法监测水化行为并研究微观结构演变。此外，还对水化动力学进行了分析，以进一步揭示硫酸盐-碱复合材料活化机理的新见解。结果表明，在碱用量（AD）为 2.7 %、PG 为 11.8 % 的条件下获得了最佳配比，其初始凝固时间和 28d 强度值分别为 162 分钟和 56 兆帕。研究还发现，随着 PG 含量的增加，热流会加快，但会减弱；由于 PG 具有硫酸盐的附加活化效应，自生收缩也会逐渐减弱。PG 含量为 5% 的样品需要更高的 AD 才能获得足够的水化程度。而对于含 15% PG 的样品，较低的 AD 会产生聚合度更高的埃曲沸石和 CASH 凝胶。水合动力学分析表明，添加 5 % PG 会使 CASH 凝胶的成核过程变得困难。虽然添加 15 % PG 会使成核密度增加近 10 倍，但生长速度会大大降低，从而导致微观结构的发展缓慢但持续。由此可见，在 SAAS 浆料中使用 PG 是合理的，并且具有巨大的潜力。

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引用次数: 0

Service life evaluation of marine reinforced concrete structures in coastal soda residue soil subjected to chloride attack 受氯化物侵蚀的沿海碱渣土壤中海洋钢筋混凝土结构的使用寿命评估

IF 7.4 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials

Pub Date : 2024-11-16 DOI: 10.1016/j.conbuildmat.2024.139222

Linjian Wu, Han Jiang, Xueli Ju, Mingwei Liu, Yutao Di, Yue Zhao, Zhouyu Xiang

In chloride salt environments, the corrosion of steel reinforcements due to chloride ions intrusion into concrete is the main cause of the durability failure of reinforced concrete structures (RCSs). The chloride content included in coastal soda residue soil (SRS) foundations with a high moisture content has been measured to be 2–3 times that of seawater, which seriously threatens the durability of RCSs built in the SRS environment. Compared with marine tidal environments, the influence of SRS corrosive environment with a high moisture content and high chloride ions content on the chloride ions transport behaviours and the service life for the marine RCSs remains unclear. Therefore, for this paper, an indoor experimental study on chloride ions intrusion into the marine concrete specimens in a coastal SRS environment was carried out. The concentration profiles and transport characteristics of chloride ions within concrete in a real SRS environment with a semi-buried zone (SBZ) and a fully buried zone (FBZ) and in a simulated salt solution (SSS) environment of SRS were revealed. The measured results of chloride transport in concrete specimens exposed to the marine tidal zone (MTZ) were used as the control group to quantify the differences in chloride transport behaviours between concrete buried in the coastal SRS environment and that in the MTZ (marine tidal zone). Chloride transport models of concrete in coastal SRS and MTZ (marine tidal zone) environments were built by means of the Fick's second law of diffusion. Taking a certain marine RCS as an example, the service lives of this structure in coastal SRS and MTZ (marine tidal zone) environments were evaluated via this paper’s proposed chloride transport models and then compared. Results indicated that the predicted service life of the RCS in the FBZ (fully buried zone) is the longest, followed by that in the MTZ (marine tidal zone), and that in the SBZ (semi-buried zone) is the shortest. The service lives of the marine RCSs in the FBZ (fully buried zone) and MTZ (marine tidal zone) were approximately 1.37 times and 2.76 times that of the SBZ (semi-buried zone), respectively.

在氯盐环境中，氯离子侵入混凝土导致的钢筋腐蚀是钢筋混凝土结构（RCS）耐久性失效的主要原因。据测量，含水量较高的沿海苏打渣土（SRS）地基中的氯离子含量是海水的 2-3 倍，这严重威胁着在 SRS 环境中建造的钢筋混凝土结构（RCS）的耐久性。与海洋潮汐环境相比，高含水量和高氯离子含量的 SRS 腐蚀环境对氯离子迁移行为和海洋遥控卫星使用寿命的影响尚不清楚。因此，本文对氯离子侵入沿海 SRS 环境中的海工混凝土试件进行了室内实验研究。研究揭示了半埋区（SBZ）和全埋区（FBZ）的真实 SRS 环境以及 SRS 模拟盐溶液（SSS）环境中混凝土内氯离子的浓度分布和迁移特性。暴露在海洋潮汐区（MTZ）中的混凝土试件的氯离子迁移测量结果被用作对照组，以量化埋在沿岸 SRS 环境中的混凝土与埋在 MTZ（海洋潮汐区）中的混凝土在氯离子迁移行为上的差异。根据菲克第二扩散定律，建立了沿岸 SRS 和 MTZ（海洋潮汐区）环境中混凝土的氯化物迁移模型。以某海洋 RCS 为例，通过本文提出的氯离子迁移模型对该结构在沿海 SRS 和 MTZ（海洋潮汐区）环境中的使用寿命进行了评估和比较。结果表明，FBZ（全埋区）中的 RCS 预测使用寿命最长，其次是 MTZ（海洋潮汐区）中的 RCS，而 SBZ（半埋区）中的 RCS 预测使用寿命最短。FBZ（全埋区）和MTZ（海洋潮汐区）的海洋遥控卫星的使用寿命分别约为SBZ（半埋区）的1.37倍和2.76倍。

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引用次数: 0