CEMENT最新文献

{"title":"Water-to-cement ratio of calcium sulfoaluminate belite cements: Hydration, setting time, and strength development","authors":"Lisa E. Burris ,&nbsp;Kimberly E. Kurtis","doi":"10.1016/j.cement.2022.100032","DOIUrl":"10.1016/j.cement.2022.100032","url":null,"abstract":"<div><p>Little published data is available to guide engineers in designing calcium sulfoaluminate belite (CSAB) cement mixtures with adequate workability, strength, and durability. This lack of understanding of design factors, especially the effect of varying w/c, represents a significant barrier to widespread CSAB use. In this study hydration, setting time, and strength development of two CSAB cements with w/c from 0.3 – 0.6 were evaluated. CSAB reaction kinetics varied with increased w/c depending on CSAB composition, specifically calcium sulfate content – with higher w/c increasing retardation in higher anhydrite/ye'elimite content cement, but reduced retardation in lower anhydrite/ye'elimite cement. For both cements, greater w/c led to greater total hydration, increased setting times, and reduced compressive strengths in the pastes and mortar samples. Setting time was linked more closely to anhydrite content than w/c, with greater sulfate volumes shortening setting times.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100032"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549222000123/pdfft?md5=7bd215f81bb7774c1c827e5fad80db1a&pid=1-s2.0-S2666549222000123-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88146042","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical properties and electrical resistivity of portland limestone cement concrete systems containing greater than 15% limestone and supplementary cementitious materials","authors":"Jose E. Garcia ,&nbsp;Nicolas B. Tiburzi ,&nbsp;Kevin J. Folliard ,&nbsp;Thanos Drimalas","doi":"10.1016/j.cement.2022.100026","DOIUrl":"10.1016/j.cement.2022.100026","url":null,"abstract":"<div><p>This investigation explored the feasibility of producing strong, good quality, durable concrete in low-clinker systems (less than 50% clinker in some cases). The low-clinker content was achieved by combining interground portland limestone cement (PLC) with high limestone contents and different supplementary cementitious materials (SCMs). Seven cements, with approximate limestone contents between 3% and 31%, from two cement plants were used, in combination with SCMs, in forty-two different mixtures with water-cementitious materials ratios (w/cm) of 0.40 and 0.45. The SCMs included Class F and C fly ashes, Grade 100 slag, and silica fume. Mechanical properties (compressive strength, tensile strength, elastic modulus) and electrical resistivity were measured at 1, 7, 28, and 91 days. Similar compressive strengths were observed for mixtures with equivalent effective w/cm ratios. Although, the combination of PLCs with SCMs for very low-clinker systems resulted in decreased compressive strength, an increase in electrical resistivity was observed. More importantly, strong, good-quality concrete can be produced without sacrificing environmental benefits.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100026"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549222000068/pdfft?md5=5bfc91c24335d9aad7c9eb3633dbe3d9&pid=1-s2.0-S2666549222000068-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83981766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of limestone fillers on CO2 and water vapour diffusion in carbonated concrete","authors":"Sarah Steiner ,&nbsp;Tilo Proske ,&nbsp;Frank Winnefeld ,&nbsp;Barbara Lothenbach","doi":"10.1016/j.cement.2022.100027","DOIUrl":"10.1016/j.cement.2022.100027","url":null,"abstract":"<div><p>Replacing Portland cement clinker partially with limestone powder offers economic and ecological benefits but may decrease the resistance against carbonation. The diffusivity of carbon dioxide and the moisture conditions in concrete significantly influence the carbonation rate. Thus a test method was developed to determine the effective CO₂ diffusion coefficient (<em>D_CO2</em>). Additionally, the water vapour diffusion coefficients (<em>D_H2O</em>) were analysed. <em>D_CO2</em> and <em>D_H2O</em> increase with increasing water-to-cement ratios (w/c, related to the CEM I content in the binder). At the same w/c ratio, higher amounts of limestone decrease <em>D_CO2</em> and <em>D_H2O</em> and increase compressive strength. <em>D_CO2</em> and <em>D_H2O</em> show a linear correlation for samples with w/c ≥ 0.6 but a non-linear relationship for dense concrete (w/c ≤ 0.5). <em>D_CO2</em> ranges from 2.6⁻⁹ m²/s to 1.9⁻⁷ m²/s for w/c of 0.5 and 1.25, respectively. <em>D_H2O</em> were between 2.8⁻⁸ m²/s and 4.5⁻⁷ m²/s. A model for estimating <em>D_CO2</em> in concrete with high limestone contents was derived based on the experimental analysis of the correlations between mix design, compressive strength, and CO₂ diffusion.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100027"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S266654922200007X/pdfft?md5=cbd303c0b6afd39e497dfcb43b3ef654&pid=1-s2.0-S266654922200007X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75485989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control the early-stage hydration of expansive additive from calcium sulfoaluminate clinker by polymer encapsulation","authors":"Malinee Nontikansak ,&nbsp;Phattarakamon Chaiyapoom ,&nbsp;Wanwipa Siriwatwechakul Ph.D. ,&nbsp;Passarin Jongvisuttisun Ph.D. ,&nbsp;Chalermwut Snguanyat","doi":"10.1016/j.cement.2022.100021","DOIUrl":"10.1016/j.cement.2022.100021","url":null,"abstract":"<div><p>Ye′elimite (C₄A₃<span><math><mover><mi>S</mi><mo>¯</mo></mover></math></span>), a main compound in calcium sulfoaluminate (CSA) clinker, is an important ingredient as expansive additive in shrinkage compensating cement. This study proposes to modify the expansive additive by encapsulating it with polyethylene glycol (PEG). The polymer provides a matrix structure, in which the ye′elimite particles are embedded. When the modified expansive additive come into contact with water, the polymer matrix acts as a water barrier, but can dissolve away. This slowly exposed C₄A₃<span><math><mover><mi>S</mi><mo>¯</mo></mover></math></span> to hydration, resulting in gradual early-stage ettringite formation; hence control early expansion in expansive cement. The study compared the ettringite formation between the unmodified and the modified expansive additive using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and scanning electron microscopy (SEM) from 1 hour to 3 days. The results show that the unmodified expansive additive generated more ettringite than the modified ones at the same hydration time. The study subsequently investigated the mortar properties with the unmodified and modified expansive additives admixtures. The results showed that the modified expansive cement showed superior flowability and drying shrinkage behaviours, while the compressive strength of the finished products underperformed that of the untreated expansive additives.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100021"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549222000019/pdfft?md5=a7d4097d9d87552513d6539339330b1c&pid=1-s2.0-S2666549222000019-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74684453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Ground Granulated Blast Furnace Slag on the compressive strength and ductility of Ultra High-performance fibre reinforced cementitious composites","authors":"Gideon Ayim-Mensah ,&nbsp;Milan Radosavljevic","doi":"10.1016/j.cement.2022.100030","DOIUrl":"10.1016/j.cement.2022.100030","url":null,"abstract":"<div><p>The mechanical properties of Ultra High Performance Fibre Reinforced Cementitious Composite (UHPFRCC) is basically influenced by the type of fibres and reactive binders used. Fibres primarily influence the ductility whereas reactive binders influence the compressive strength of UHPFRCC. Among the commonly used reactive binders, Ground Granulated Blast Furnace Slag (SL) with its vitreous nature has the ability of influencing both the compressive strength and ductility of UHPFRCC. This study discussed the microstructure and mechanical properties of six different mixtures made up of 0%, 20%, 40%, 60% 75% and 90% cement replacement of SL. The XRD results indicated that, increased levels of C-S-H and ettringite retard the hydration process leading to lower compressive strength and vice versa. The SL-cementitious composite can achieve a compressive strength of up to 108.1MPa and ductility of up to 1.67% without the use of fibres. The maximum compressive strength and ductility were achieved with 40% SL replacement of cement whereas the minimum compressive strength and ductility were achieved with 60% and 20% SL contents, respectively. Moreover, the optimum mechanical properties (i.e. compressive strength, tensile strength, flexural strength, and tensile strain) were achieved with a 40% SL replacement of cement in the cementitious composite.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100030"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S266654922200010X/pdfft?md5=843c8c5bef096d390f0233828b8dd33a&pid=1-s2.0-S266654922200010X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81650133","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Designing corrosion resistant systems with alternative cementitious materials","authors":"Prasanth Alapati ,&nbsp;Mehdi Khanzadeh Moradllo ,&nbsp;Neal Berke ,&nbsp;M. Tyler Ley ,&nbsp;Kimberly E. Kurtis","doi":"10.1016/j.cement.2022.100029","DOIUrl":"10.1016/j.cement.2022.100029","url":null,"abstract":"<div><p>Alternative cementitious materials (ACMs) may exhibit superior mechanical properties and durability to certain environments, and that also may be produced with relatively less environmental impact compared to traditional portland cement. Differences in ACM composition, reaction products, and microstructure produces variations in their performance, including their resistance to fluid and ion and to corrosion of embedded steel. Understanding relationships between composition, structure, and corrosion performance in ACM systems is essential for designing durable reinforced concrete from these materials. Here, five commercially available ACMs are evaluated and compared against ordinary portland cement (OPC). The five ACMs include one calcium aluminate cement (CAC); one ternary blend of calcium aluminate, portland cement, and calcium sulfate (CACT); one calcium sulfoaluminate cement (CSA) as well as the same CSA cement with polymer-modification (CSAP); and one activated aluminosilicate binder system (AA). Water sorption, chloride ion ponding, bulk conductivity, formation factor measurements, and accelerated corrosion tests were performed to evaluate the porosity, mass transport, chloride ion binding capacity, and resistance to corrosion of embedded reinforcement. The results demonstrate that mixtures with high pore structure interconnectivity and low binding capacity (such as CSA and CAC investigated in this paper) or mixtures with significantly low binding capacity (such as AA investigated in this paper) should be avoided to minimize damage due to chloride-induced corrosion. Polymer addition could be an important strategy to improve the corrosion resistance of mixtures that have high interconnectivity. Overall, one ACM, CACT, evaluated in this study showed the best corrosion resistance among the materials considered – including OPC.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100029"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549222000093/pdfft?md5=55043b25fb8e4900c287ff95d04fc2e4&pid=1-s2.0-S2666549222000093-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91268085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The efficacy of portland-limestone cements with supplementary cementitious materials to prevent alkali-silica reaction","authors":"Krishna Siva Teja Chopperla ,&nbsp;Jeremy A. Smith ,&nbsp;Jason H. Ideker","doi":"10.1016/j.cement.2022.100031","DOIUrl":"10.1016/j.cement.2022.100031","url":null,"abstract":"<div><p>This paper details a study on the efficacy of portland-limestone cements (PLCs) in combination with supplementary cementitious materials (SCMs) to prevent expansion due to alkali-silica reaction (ASR). The PLCs studied include both interground (10–15% limestone by mass) and interblended (10% limestone by mass) systems. In this study, ASTM Type II/V cements, five different SCMs, two very-highly reactive fine aggregates, and six SCM combinations were investigated. A total of 100 mixtures were assessed using three different accelerated laboratory test methods to investigate if the SCM combinations that are used with OPCs can be utilized as-is, increased, or decreased when used instead with PLCs. The test methods used to evaluate ASR included the Pyrex mortar bar test (PMBT, ASTM C441), the accelerated mortar bar test (AMBT, ASTM C1567), and the miniature concrete prism test (MCPT, AASHTO T 380). The difference in performance between PLCs with SCMs and parent OPCs with SCMs in the MCPT conditions was further evaluated using pore solution alkalinity and electrical resistivity analysis. The efficacy of the SCM combinations to prevent ASR was also evaluated with a pozzolanic reactivity test. The expansion results from the accelerated laboratory test methods revealed that the mixtures with PLCs and SCMs had similar or better overall performance when compared to the mixtures with the parent OPCs and SCMs. It was observed that the particle size of the added limestone in interblended PLC with SCM mixtures could have a significant influence on the ASR expansion that may alter the output of the test (pass/fail). Consequently, the SCM combinations that are used with OPCs can likely be utilized as-is when used with interground PLCs with up to 15% limestone to prevent ASR. The pore solution and bulk electrical resistivity analysis showed that the lower pore solution alkalinity and higher resistance to mass transport are the main contributing factors towards PLCs’ overall improved performance for ASR mitigation in the presence of SCMs.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"8 ","pages":"Article 100031"},"PeriodicalIF":0.0,"publicationDate":"2022-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549222000111/pdfft?md5=c38d67f918a1547be2aaa2217548e1af&pid=1-s2.0-S2666549222000111-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87918540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrostatic compression and pressure phase transition of major Portland cement constituents – Insights via molecular dynamics modeling","authors":"Ingrid M. Padilla Espinosa,&nbsp;Nirmalay Barua,&nbsp;Ram V. Mohan","doi":"10.1016/j.cement.2021.100017","DOIUrl":"10.1016/j.cement.2021.100017","url":null,"abstract":"<div><p>The complex composite material cement paste (CP) is under high pressures in underwater applications and when impact loading occurs. The mechanical behavior of cement paste to hydrostatic compression results from mechanical deformations of each phase, including unhydrated and hydrated minerals. Molecular Dynamics was used to study the atomistic deformation of individual unhydrated cement phases with increasing hydrostatic pressures. The pressure-specific volume Birch-Murnaghan equation of state (EoS) and the bulk modulus at zero pressure were determined for each phase. Results show that the bulk modulus and compressibility are pressure dependent. For tricalcium silicate (C₃S), dicalcium silicate (C₂S), and tricalcium aluminate (C₃A), the bulk modulus increases, while the volume compression decreases with increasing pressure. The C₃S and C₃A phases are stable during hydrostatic compression and exhibit isotropic behavior. The C₂S phase is not stable and shows anisotropic behavior. These results explain the effect of unreacted cement clinkers on cement paste mechanical behavior under high pressure based on the response of individual phases.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"7 ","pages":"Article 100017"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549221000141/pdfft?md5=a33f95fab9df10e800344575a682d53e&pid=1-s2.0-S2666549221000141-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75922014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase changes during the drying of calcium aluminate cement bond castables – the influence of curing and drying conditions","authors":"A. Koehler,&nbsp;J. Neubauer,&nbsp;F. Goetz-Neunhoeffer","doi":"10.1016/j.cement.2021.100020","DOIUrl":"https://doi.org/10.1016/j.cement.2021.100020","url":null,"abstract":"<div><p>This study presents the influence of different curing temperatures and the availability of unbound H₂O on the phase changes during the drying process of a simplified calcium aluminate cement bond castable. A mixture of CAC and alumina was hydrated for 48 h at 5, 23 and 40 °C, which represents different working conditions during casting. After the curing process, these samples were heated up to 180 °C, and in some of them, the remaining unbound H₂O had been removed by vacuum drying beforehand. The quantitative phase composition was determined by QXRD. Thermogravimetric analysis and gravimetric measurements were also used to characterize the differently cured samples. While the mineral phases in the samples cured at 40 °C were barely affected by the heating process in the investigated temperature range, the initial conditions before the drying of the samples cured at 5 and 23 °C strongly affected the final phase composition.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"7 ","pages":"Article 100020"},"PeriodicalIF":0.0,"publicationDate":"2022-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549221000177/pdfft?md5=885f048af5f9094f1c7de99b39557b2c&pid=1-s2.0-S2666549221000177-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91599659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat capacity, isothermal compressibility, isosteric heat of adsorption and thermal expansion of water confined in C-S-H","authors":"Tulio Honorio,&nbsp;Fatima Masara,&nbsp;Farid Benboudjema","doi":"10.1016/j.cement.2021.100015","DOIUrl":"10.1016/j.cement.2021.100015","url":null,"abstract":"<div><p>Nanoconfinement is known to affect the property of fluids. The changes in some thermo-mechanical properties of water confined in C-S-H are still to be quantified. Here, we perform molecular simulations to obtain the adsorption isotherms in C-S-H as a function of the pore size (spanning interlayer up to large gel pores). Then, fluctuations formula in the grand canonical ensemble are used to compute the isothermal compressibility (and its reciprocal, the bulk modulus), the heat capacity, the coefficient of thermal expansion and thermal pressure, and the isosteric heat of adsorption of confined water as a function of the (nano)pore size. All these properties exhibit a pore size dependence, retrieving the bulk values for basal spacing above 2 nm. To understand why property changes with confinement, we compute structural descriptors including the radial distribution function, apparent density, hydrogen bonds counting, and excess pair entropy of water as a function of the confinement. These descriptors reveal significant structural changes in confined water. The heat capacity shows a good linear correlation with the apparent density, entropy, and hydrogen bond number. The values of water property as a function of the basal spacing are a valuable input for multiscale modeling of cement-based materials.</p></div>","PeriodicalId":100225,"journal":{"name":"CEMENT","volume":"6 ","pages":"Article 100015"},"PeriodicalIF":0.0,"publicationDate":"2021-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2666549221000128/pdfft?md5=d7b2b1b5e7c8af1fc25eac2c34175f40&pid=1-s2.0-S2666549221000128-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78827932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}