CEMENT

Pub Date : 2025-09-01 Epub Date: 2025-07-20 DOI: 10.1016/j.cement.2025.100151

Richard Caron , Ravi A. Patel , Andreas Bogner , Frank Dehn

This study focuses on a multiscale characterization of basic creep behavior of two AAS creep mixes with high (hS) and low (lS) slag content, loaded at 28 days. Nano-indentation tests are performed to investigate creep properties of individual phases and classical creep tests to analyze the creep behavior of concrete. An analytical multiscale micromechanics-based model is applied to downscale creep properties of the reaction product foam at nano-scale to compare it with results from nano-indentation. The creep at nanoscale of reaction product foam is modeled with a compliance function considering only deviatoric component consisting of Kelvin–Voigt chain for short term behavior and logarithmic function to account for long-term behavior. Comparing downscaled compliance with creep modulus measured from nano-indentation it is concluded that nano-indentation captures long-term behavior of reaction product foam. In terms of two mix tested, while at nano-scale mix hS has a higher creep modulus, presence of more capillary porosity and micro-cracks counteracts this and as a result concrete with mix hS shows higher creep. The creep modulus of AAS product foam obtained from nano-indentation is significantly lower compared to the OPC products. Additionally, higher amount of gel water and fewer crystalline secondary products could explain higher creep observed for AAS concrete compared to OPC concrete.

本研究的重点是对两种高（hS）和低（lS）渣含量的AAS蠕变混合料在加载28天时的基本蠕变行为进行多尺度表征。采用纳米压痕试验研究了混凝土各相的徐变特性，采用经典徐变试验分析了混凝土的徐变特性。采用多尺度细观力学模型分析了反应产物泡沫在纳米尺度下的蠕变特性，并与纳米压痕结果进行了比较。用仅考虑由Kelvin-Voigt链组成的偏差分量的柔度函数和考虑长期行为的对数函数来模拟反应产物泡沫在纳米尺度上的蠕变。通过对比纳米压痕测量的蠕变模量和缩尺顺应性，得出纳米压痕能够捕获反应产物泡沫的长期行为的结论。两种配合比的试验结果表明，在纳米尺度下，hS配合比具有较高的徐变模量，但更多的毛管孔隙和微裂缝的存在抵消了这一作用，使得hS配合比混凝土表现出更高的徐变模量。纳米压痕制备的AAS产品泡沫的蠕变模量明显低于OPC产品。此外，较高的凝胶水量和较少的结晶二次产物可以解释AAS混凝土比OPC混凝土观察到的更高的徐变。

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引用次数: 0

Condition assessment of pre-tensioning prestressed concrete sleepers distressed by internal swelling reactions (ISR) 内膨胀反应（ISR）下预张预应力混凝土枕木状态评价

CEMENT

Pub Date : 2025-09-01 Epub Date: 2025-07-23 DOI: 10.1016/j.cement.2025.100154

R. Medeiros , D.J. De Souza , L.F.M. Sanchez , A.C. Santos

Concrete sleepers worldwide have been affected by internal swelling reactions (ISR), primarily alkali-silica reaction (ASR) and internal sulfate attack (ISA). While numerous studies have focused on diagnosing ISR-affected sleepers, most emphasize identifying the cause rather than estimating the extent of deterioration, which is critical for informed decision-making. This study presents a comprehensive condition assessment of concrete sleepers displaying numerous ages and environmental exposure conditions through visual inspection (i.e., crack measurements) followed by the implementation of the multi-level assessment protocol, composed of microscopic (i.e., damage rating index-DRI) and mechanical (i.e., stiffness damage test-SDT) testing procedures. Results evidenced the multi-level protocol efficiency in estimating the cause(s) (i.e., ASR+ISA), further confirmed through SEM-EDS analysis, and quantifying the deterioration extent. These findings reveal gaps in current specification to prevent ISR damage in new sleepers and the importance of considering environmental conditions in condition assessment of existing sleepers, demonstrating an urgent need to review specifications/protocols.

混凝土轨枕在世界范围内受到内部膨胀反应（ISR），主要是碱-硅反应（ASR）和内部硫酸盐侵蚀（ISA）的影响。虽然许多研究都集中在诊断受isr影响的睡眠者，但大多数研究都强调确定原因，而不是估计恶化的程度，这对明智的决策至关重要。本研究通过目视检查（即裂缝测量）对混凝土枕木进行了全面的状态评估，显示了许多年龄和环境暴露条件，随后实施了多层次评估方案，由微观（即损伤等级指数- dri）和力学（即刚度损伤测试- sdt）测试程序组成。结果证明了多级协议在估计原因（即ASR+ISA）方面的效率，并通过SEM-EDS分析进一步证实，并量化了恶化程度。这些发现揭示了当前规范在防止新枕木的ISR损伤方面存在的差距，以及在对现有枕木进行状态评估时考虑环境条件的重要性，表明迫切需要审查规范/协议。

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引用次数: 0

Enhancing efficiency in evaluating alkali-silica reaction (ASR) damage: an automated approach to point-count microscopy 提高评估碱-硅反应（ASR）损伤的效率：点计数显微镜的自动化方法

CEMENT

Pub Date : 2025-09-01 Epub Date: 2025-07-27 DOI: 10.1016/j.cement.2025.100153

Cassandra Trottier , Laurent Ramos Cheret , Haoye Lu , Anthony Allard , Maia Fraser , Leandro F.M. Sanchez

The damage rating index (DRI) is a valuable microscopy tool for collecting and counting data on different types of concrete cracks, such as those associated with alkali-silica reaction (ASR) induced deterioration. Yet, the procedure presents drawbacks such as time consumption and variability linked to operator experience, which has sparked debates about the subjectivity of its outcomes. Embracing the forefront of technological advancements, this study explores the practicality of automating the DRI's data collection through artificial intelligence (AI) and machine learning. Like many image processing and analysis applications that use AI, the DRI is an object classification and segmentation task. This study represents a step forward in leveraging automation to enhance the objectivity and efficiency of ASR damage characterization in concrete through point-count microscopy, along with proposing a set of tools to evaluate the outcomes from the application’s perspective for more efficient training data selection. Results show that despite obtaining acceptable performance individually, where the detector-classifier performance was found to have an accuracy of 0.744, and the crack counter accuracy was 0.988, the current version of the proposed machine still displays high variability in detecting, classifying, and counting distinct crack types. Overall, the machine overestimates ASR-induced damage, which was further verified through the Chi-square goodness of fit test, indicating that further training and enhancement of the proposed machine are required.

损伤等级指数（DRI）是一种有价值的显微工具，用于收集和计数不同类型的混凝土裂缝数据，例如与碱-硅反应（ASR）引起的恶化有关的裂缝。然而，该方法存在一些缺点，如耗时和与操作人员经验相关的可变性，这引发了关于其结果主观性的争论。拥抱技术进步的前沿，本研究探索了通过人工智能（AI）和机器学习实现DRI数据收集自动化的可行性。像许多使用人工智能的图像处理和分析应用程序一样，DRI是一个对象分类和分割任务。这项研究代表了利用自动化技术通过点计数显微镜来提高混凝土ASR损伤表征的客观性和效率的一步，同时提出了一套工具来从应用程序的角度评估结果，以更有效地训练数据选择。结果表明，尽管单独获得了可接受的性能，其中检测器-分类器性能的准确率为0.744，裂纹计数器精度为0.988，但当前版本的机器在检测，分类和计数不同的裂纹类型方面仍然表现出很高的可变性。总的来说，机器高估了asr引起的损伤，卡方拟合优度检验进一步验证了这一点，表明需要进一步训练和增强所提出的机器。

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引用次数: 0

Hydration of portland cement and slag cement mixtures with insights on AFm phases and reaction mechanism 硅酸盐水泥和矿渣水泥混合料的水化及其AFm相和反应机理

CEMENT

Pub Date : 2025-09-01 Epub Date: 2025-08-21 DOI: 10.1016/j.cement.2025.100155

Mohsen Torabi , Peter C Taylor

Hydration of Portland cement + slag blends with different slag replacements at various hydration times has been studied. Findings from QXRD, TGA, ESEM(EDS) & NMR have provided us with insights into the hydration mechanisms and phase assemblage of cement and slag mixtures. Phase assemblage and quantification of the AFm phases has been made possible using the parallel beam X-ray diffraction and it was observed that AFm formation is favored in these blends in direct proportion with the slag level. In fact, AFm formation after pozzolanic reaction can be considered as one of the consumers of portlandite in portland cement+slag blends. Hydrocalumite has been observed to be present among the hydration phases of these blends at various hydration times and its concentration has been observed to increase with increasing slag replacement. The presence of this phase might have implications on the durability aspects of the resulting concrete. Furthermore, some chemical reactions during slag hydration as well as its interactions with hydration of clinker phases have also been proposed.

研究了不同矿渣替代量的硅酸盐水泥+矿渣在不同水化时间下的水化性能。QXRD， TGA， ESEM（EDS）和NMR的研究结果为我们提供了水泥和矿渣混合物水化机制和相组合的见解。利用平行束x射线衍射可以进行相组合和AFm相的量化，并观察到在这些混合料中，AFm的形成与炉渣水平成正比。事实上，在硅酸盐水泥+矿渣共混物中，火山灰反应后形成的AFm是硅酸盐的消耗者之一。在不同的水化时间，在这些混合物的水化相中观察到水矾土的存在，并观察到其浓度随着矿渣置换量的增加而增加。这一阶段的存在可能会对混凝土的耐久性产生影响。此外，还提出了渣水化过程中的一些化学反应及其与熟料相水化的相互作用。

引用次数: 0

Modelling and visualizing the impact of metakaolin on the alkali concentration in cement paste pore solution 偏高岭土对水泥浆孔溶液中碱浓度影响的建模和可视化

CEMENT

Pub Date : 2025-09-01 Epub Date: 2025-06-11 DOI: 10.1016/j.cement.2025.100148

Ana Bergmann , Klaartje de Weerdt , Maxime Ranger , Miriam E. Krüger , Petter Hemstad , Barbara Lothenbach

This study investigates the effects of replacing Portland cement (PC) with metakaolin (MK) on the pore solution composition of cementitious binders. Using the empirical Taylor model and a thermodynamic model (GEMS), the required replacement levels of PC by MK are computed to achieve different threshold alkali metal concentrations. GEMS predicts that similar amounts of MK (15–20 %) are required regardless of w/b-ratio and PC alkali content, which does not match with the experimental evidence. The Taylor model captures better the effect of these variables, predicting replacement levels ranging from 0 to 40 %. Results are visualized through contour and 3D plots, highlighting the complex interactions and effects of SCMs on concrete durability.

本文研究了偏高岭土（MK）替代硅酸盐水泥（PC）对胶凝粘合剂孔隙溶液组成的影响。利用经验Taylor模型和热力学模型（GEMS），计算了达到不同阈值碱金属浓度所需的PC置换水平。GEMS预测，无论w/b比和PC碱含量如何，都需要相同数量的MK(15 - 20%)，这与实验证据不符。泰勒模型更好地捕捉了这些变量的影响，预测更替水平在0到40%之间。结果通过等高线和3D图可视化，突出了scm对混凝土耐久性的复杂相互作用和影响。

引用次数: 0

Comparisons of quarry by-products as a partial replacement of portland cement in pastes and mortars 采石场副产品在膏体和砂浆中部分替代波特兰水泥的比较

CEMENT

Pub Date : 2025-09-01 Epub Date: 2025-07-17 DOI: 10.1016/j.cement.2025.100152

Tu-Nam Nguyen , Michael Lowry , Thien Q. Tran , Ketki Phadke , Elizabeth Bise , Alexander S. Brand

Quarry by-products (QB), including screenings, pond fines, and baghouse fines, present a significant surplus, since they are not significantly utilized in other markets and industries. This study explores the use of seven different QB as direct replacements of limestone powder in a portland limestone cement for paste and mortar applications. Cement replacements ranging from 5 % to 20 % by volume were explored, and testing included compressive and flexural strengths, isothermal calorimetry, pore solution analysis, alkali-silica reaction, and reactivity analysis. Expectedly, the results demonstrated that not all QB yielded equivalent performance. All mortars with 5 % and 15 % QB substitution had lower compressive strengths than the control, with the 15 % QB substitution performing worse. However, the mortars with QB had higher flexural strengths than the control. The 5 %, 10 %, 15 %, and 20 % QB substitution samples decreased the cumulative heat at 24 h, 48 h, and 72 h, with a higher substitution having a stronger decreasing effect. QB 2 and QB 7 were found to only slightly decrease the cumulative heat at 5 % substitution. Furthermore, QB 2 was found to significantly accelerate the silicate and aluminate heat evolution peaks, while QB 1, QB 3, QB 4, QB 5, and QB 7 only slightly accelerated the silicate and/or aluminate peaks. The pore solution of mortars with 5 % and 15 % QB substitution were found to have a lower pH and, in general, increased calcium and silicon contents. QB 2 was found to be moderately ASR reactive, while QB 7 was found to be ASR reactive. All QB were found to be non-pozzolanic; however, they may still be of use in other portland cement applications.

采石场副产品（QB），包括筛分、池粉和袋粉，呈现出显著的盈余，因为它们在其他市场和工业中没有得到显著利用。本研究探讨了七种不同的QB作为石灰石粉在波特兰石灰石水泥中的直接替代品，用于膏体和砂浆应用。水泥替代量从5%到20%不等，测试包括抗压和抗弯强度、等温量热法、孔溶液分析、碱-硅反应和反应性分析。意料之中的是，结果表明并非所有QB都产生了相同的性能。5%和15% QB替代砂浆的抗压强度均低于对照，15% QB替代砂浆的抗压强度更差。但掺加QB的砂浆抗折强度高于对照。5%、10%、15%和20% QB取代的样品在24 h、48 h和72 h时降低累积热量，取代率越高，降低效果越强。qb2和qb7在5%的取代量下仅能略微降低累积热量。此外,QB 2被发现明显加快硅酸盐和铝酸盐放热峰,而QB 1, QB 3, QB 4、QB 5, QB 7稍微加快了硅酸铝酸和/或峰值。QB取代率为5%和15%的砂浆孔隙溶液pH值较低，钙和硅含量总体上有所增加。发现qb2具有中度ASR反应，而qb7具有ASR反应。所有QB均为非火山灰；然而，它们可能仍然在其他波特兰水泥应用中使用。

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引用次数: 0

Moisture dynamics and influence on alkali-silica reaction induced expansion: A comprehensive laboratory study 水分动力学及其对碱-硅反应诱发膨胀的影响：一项综合实验室研究

CEMENT

Pub Date : 2025-06-01 Epub Date: 2025-05-23 DOI: 10.1016/j.cement.2025.100146

O.D. Olajide , M.R. Nokken , L.F.M. Sanchez

Moisture availability is crucial for initiating and progressing alkali-silica reaction (ASR) in concrete. As a result, moisture control has often been adopted as a mitigation strategy in maintaining ASR-affected concrete. Selecting effective maintenance strategies requires a deep understanding of the moisture dynamics between internal moisture in concrete and its environment, and influence on ASR, which remains incompletely explored. To evaluate this interplay, 180 concrete cylinders incorporating a reference reactive aggregate (i.e., Spratt) were manufactured and stored at distinct conditions: i.e., three different temperatures (21°C, 38°C and 60°C) and five relative humidities (100 % RH, 90 % RH, 82 % RH, 75 % RH, and 62 % RH). The internal and external relative humidity, length, and mass change were monitored for up to a year. Results indicate that the amount of water used for cement hydration is sufficient to trigger the reaction, regardless of the subsequent exposure condition. However, the rate of ASR-induced development is influenced by the internal relative humidity, which changes with time based on the external relative humidity and temperature. Additionally, the minimum moisture (i.e., RH threshold) required to cause significant deleterious effects from ASR was assessed and confirmed to be temperature-dependent.

水分的可用性对于混凝土中碱-硅反应（ASR）的发生和发展至关重要。因此，在维护受asr影响的混凝土时，通常采用湿度控制作为缓解策略。选择有效的维护策略需要深入了解混凝土内部水分与其环境之间的水分动态，以及对ASR的影响，这方面的研究尚未完全深入。为了评估这种相互作用，制造了180个包含参考反应性骨料（即Spratt）的混凝土圆柱体，并在不同的条件下储存：即三种不同的温度（21°C， 38°C和60°C）和五种相对湿度（100% RH, 90% RH, 82% RH， 75% RH和62% RH）。内部和外部的相对湿度，长度和质量变化监测长达一年。结果表明，无论随后的暴露条件如何，用于水泥水化的水量足以引发反应。然而，asr诱发的发育速率受内部相对湿度的影响，内部相对湿度在外部相对湿度和温度的基础上随时间变化。此外，对引起ASR显著有害影响所需的最小湿度（即RH阈值）进行了评估，并确认其与温度有关。

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引用次数: 0

Cation uptake by fine aggregate in hardened cement mortar and its effect on electrical properties 水泥硬化砂浆中细骨料对阳离子的吸收及其对电性能的影响

CEMENT

Pub Date : 2025-06-01 Epub Date: 2025-05-29 DOI: 10.1016/j.cement.2025.100147

Atolo A. Tuinukuafe , Anuj Parashar , Xiaoqiang Hou , Jason H. Ideker

Electrical resistivity tests can be used to evaluate the transport properties of concrete and provide a durability assessment. However, the electrical resistivity is largely dependent on the pore solution composition and recent work suggests that some aggregates have the capacity for cation uptake. This study first aims to provide further evidence for adsorption of cations on aggregate surfaces, without formation of reaction products (e.g. alkali-silica reaction). Secondly, hardened mortar samples were prepared using a fine aggregate with a high alkali affinity and a non-reactive fine aggregate as a control. The electrical resistivity of mortars was measured, and the pore solution of these mortars was obtained through high-pressure extraction. The effect of aggregate moisture dilution on the pore solution was decoupled by using a pore partitioning model. The results indicate that aggregate minerology can influence the pore solution composition through cation uptake. Specific minerals of minor quantity, like biotite, may be responsible for cation exchange. While adsorbed cations strongly affected pore solution and formation factor measurement, the bulk resistivity measurements on hardened mortar were only marginally influenced. Research on other implications of similar aggregate interactions with pore solutions are an intriguing area for future research.

电阻率试验可用于评估混凝土的输送性能，并提供耐久性评估。然而，电阻率在很大程度上取决于孔隙溶液组成，最近的研究表明，一些聚集体具有阳离子吸收能力。本研究首先旨在提供进一步的证据，证明在不形成反应产物（如碱-硅反应）的情况下，阳离子在聚集体表面吸附。其次，以高碱亲和性细骨料和无反应性细骨料为对照，制备硬化砂浆样品。测定了砂浆的电阻率，并通过高压萃取得到了砂浆的孔隙溶液。利用孔隙分配模型解耦了骨料水分稀释对孔隙溶液的影响。结果表明，骨料矿物学通过阳离子吸收影响孔隙溶液组成。少量的特殊矿物，如黑云母，可能负责阳离子交换。虽然吸附阳离子对孔隙溶解度和地层系数的测量有强烈影响，但硬化砂浆的体电阻率测量仅受轻微影响。研究类似聚集体与孔隙溶液相互作用的其他含义是未来研究的一个有趣的领域。

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引用次数: 0

Influence of fineness modulus of fine aggregate on the durability properties of alkali-activated slag composites: An exprimental and statistical study 细骨料细度模量对碱活性矿渣复合材料耐久性能影响的实验与统计研究

CEMENT

Pub Date : 2025-06-01 Epub Date: 2025-04-24 DOI: 10.1016/j.cement.2025.100144

Adams Balade Abubakar, Waleed Hassan Khushefati

The consideration of sustainability has become a very important factor, because of the negative impacts posed by the production of Ordinary Portland Cement (OPC). This study investigates the influence of fine aggregate fineness modulus (FM) on the durability properties of AACs exposed to harsh environmental conditions (high temperatures, sea water, and sulfate solutions). Furthermore, this paper aims to statistically derive and validate a linear model that can be utilized in predicting the compressive strength (CS) of AACs of ground granulated blast furnace slag (GGBFS) using ultrasonic pulse velocity (UPV) a non-destructive evaluation. The FM of 2.4, 2.8, and 3.2, which represent fine, medium, and coarse particle sizes of fine aggregate, respectively, were adopted in this study, with other parameters kept constant. GGBFS was activated with a combined alkaline activating solution of sodium silicate (Na₂SiO₃) and a 12 M concentration of sodium hydroxide (NaOH) in a 2 to 1 ratio. The CS, UPV, density, and microstructural morphology as well as statistical analysis investigating linear relationships between UPV and CS were all evaluated in different harsh environments. The results showed that specimens immersed in 7 % magnesium sulfate (MgSO₄)and sea water after 6 months exhibited an increase in densities, CS, and UPV, with 2.4 FM having the highest enhancements, followed by 3.2 FM due to void filling action. However, mixes containing 2.8 FM were more resistant to residual incremental change produced by 7 % MgSO₄ and sea water. The statistical analysis shows that; besides the simplicity and robustness of the linear model, it also gives a higher coefficient of determination compared to an exponential model, making it a better fit for the UPV and CS relationship.

由于普通硅酸盐水泥（OPC）的生产所带来的负面影响，可持续性的考虑已成为一个非常重要的因素。本研究探讨了细骨料细度模量（FM）对暴露于恶劣环境条件（高温、海水和硫酸盐溶液）下的AACs耐久性的影响。此外，本文旨在统计推导并验证一个线性模型，该模型可用于利用超声脉冲速度（UPV）一种无损评价方法预测高炉磨粒渣AACs的抗压强度（CS）。本研究采用细骨料的细、中、粗粒度FM分别为2.4、2.8、3.2，其他参数保持不变。用水玻璃（Na2SiO3）和12 M浓度的氢氧化钠（NaOH）按2比1的比例组合碱性活化液活化GGBFS。在不同的恶劣环境下，CS、UPV、密度和微观结构形态以及调查UPV和CS之间线性关系的统计分析都进行了评估。结果表明，浸泡在7%硫酸镁（MgSO4）和海水中6个月后，样品的密度、CS和UPV均有所增加，其中2.4 FM增强最大，其次是3.2 FM，这是由于空隙填充作用。然而，含有2.8 FM的混合物更能抵抗7% MgSO4和海水产生的残余增量变化。统计分析表明；除了线性模型的简单性和鲁棒性外，与指数模型相比，它还具有更高的决定系数，使其更适合UPV和CS关系。

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引用次数: 0

Phase assemblage and microstructure of burnt oil shale-containing blended cements 含焦化油页岩混合胶结物相组合及微观结构

CEMENT

Pub Date : 2025-06-01 Epub Date: 2025-04-03 DOI: 10.1016/j.cement.2025.100139

Federica Boscaro , Diana Londono-Zuluaga , Peter Kruspan , Michael Plötze , Karen Scrivener , Robert J. Flatt

Burnt oil shale (BOS), obtained from the combustion of oil shale, is a promising supplementary cementitious material (SCM) based on its chemistry and mineralogy. This paper summarizes the use of BOS and its hydration in blended cements. It presents new data on the effect of combinations of alkali activators and Ca(NO₃)₂ in blended cements containing 50 % Portland cement (OPC) where BOS is combined with limestone, fly ash and ground granulated blast furnace slag. These chemical admixtures increase the slope of the correlation between compressive strength and heat of hydration of BOS containing mixes, providing an increase in compressive strength from 1 to 7 days for similar heat release to the control system. In contrast, the slope is not affected in absence of BOS. The change is due to a higher volume of hydrates from BOS increased hydration for a given C₃S degree of hydration, likely from a less exothermic dissolution of BOS amorphous component. These admixtures increase the reactivity of both BOS and OPC at different curing times and depending on the type of alkali activator. They promote ettringite and portlandite precipitation, inducing a refinement of the microstructure, particularly around BOS particles. The information presented should pave the way to a broader and more effective use of BOS in blended cements with particularly low clinker contents.

焦化油页岩（BOS）是由油页岩燃烧得到的一种很有前途的补充胶结材料（SCM）。本文综述了BOS及其水化作用在混合水泥中的应用。它提供了碱活化剂和Ca(NO3)2组合对含有50%波特兰水泥（OPC）的混合水泥的影响的新数据，其中BOS与石灰石，粉煤灰和磨碎的粒状高炉渣混合。这些化学外加剂增加了含BOS混合物的抗压强度与水化热之间的相关性斜率，在控制系统释放类似热量的情况下，抗压强度从1天增加到7天。相反，在没有BOS的情况下，斜率不受影响。这种变化是由于来自BOS的水合物体积增加了C3S水化程度的增加，可能是由于BOS非晶组分的放热溶解减少。这些外加剂提高了BOS和OPC在不同固化时间和碱活化剂类型下的反应性。它们促进钙矾石和波特兰石的沉淀，导致微观结构的细化，特别是在BOS颗粒周围。所提供的信息应该为在熟料含量特别低的混合水泥中更广泛和更有效地使用BOS铺平道路。

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引用次数: 0

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