Cement and Concrete Research(2022 - 2023)
Chemical synthesis and crystallographic data on iron doped cubic ye'elimite
Abir F.-Z.; El Hafiane Y.; Smith A.; Kondo Y.; Sakai Y.; Asaka T.; Fukuda K.; Mesnaoui M.; Abouliatim Y.; Nibou L.
Cement and Concrete Research, Elsevier Ltd., Vol.173, 2023, .
(https://doi.org/10.1016/j.cemconres.2023.107257)
Abstract
Pure powders of ye'elimite Ca4Al6-2xFe2xSO16 particles containing iron were synthesized by chemical route for the first time, the maximum of ye'elimite formed was obtained at 1250 ‹C for 1 h. The increase in iron content in the reaction system is accompanied by the increase on amount of the iron-stabilized cubic phase after calcination at sufficient temperature, at the expense of the orthorhombic phase until a concentration of x = 1.13 where only the cubic phase is detected. The presence of iron also causes the formation of ferritic phases. A protocol of elimination of the ferritic phases was proposed. This chemical treatment with sodium dithionite was applied to compositions containing a large majority of cubic ye'elimite and the isolation of cubic ye'elimite grains was successful. Thanks to very fine crystallographic analyses, the crystal structure of Ca4[(Al4.74Fe1.26)O12]SO4, a cubic ye'elimite doped only with Fe2O3, has been successfully determined for the first time. c 2023 Elsevier Ltd
On the long-term delayed strain of concrete structures
Aili A.; Torrenti J.M.; Sellin J.P.; Barthelemy J.F.; Vandamme M.
Cement and Concrete Research, Elsevier Ltd., Vol.165, 2023, .
(https://doi.org/10.1016/j.cemconres.2022.107086)
Abstract
Creep and shrinkage of concrete are essential for the safety assessment of large civil engineering structures. The present paper presents two different approaches to predicting the delayed strain considering a single material point to represent the structure. The first one is a decoupled approach, such as design codes, that splits the delayed strain into four components and predicts each of them as a function of several parameters such as concrete strength. In the second approach, delayed strain is modeled as the viscoelastic response of concrete to applied external loads and/or internal hygric stresses. The advantages and inconveniences of both methods are discussed. In the end, delayed strains of concrete are predicted using these approaches for two examples of real structures: a prestressed concrete bridge and a mock-up of a biaxially prestressed containment building. c 2022 Elsevier Ltd
A response to the discussion paper on gNumerical flow simulation of fresh concrete with viscous granular material model and smoothed particle hydrodynamicsh
Li Z.
Cement and Concrete Research, Elsevier Ltd., Vol.166, 2023, .
(https://doi.org/10.1016/j.cemconres.2023.107115)
Abstract
The parameter L0 with a unit length (=1.0 m) was omitted in our paper, and the unit of loading speed s1 and the expression of parameter c7 were not shown, which result in that the dimensions of shear strain and shear strain rate shown in Eq.(16) were misinterpreted. In this response paper, we added the L0 in the expressions of parameters c6 and q, and explained the unit of s1, as well as gave the expression for the c7. The addition of L0 do not change the simulation results and conclusions of our paper. c 2023 Elsevier Ltd
The practical application of a self-developed temperature stress testing machine in development of expansive concrete blended with calcium sulfoaluminate additives
Ou G.; Lin Z.; Kishi T.
Cement and Concrete Research, Elsevier Ltd., Vol.164, 2023, .
(https://doi.org/10.1016/j.cemconres.2022.107045)
Abstract
Early-age cracking of concrete is a complex problem related to temperature, restraint and curing conditions. Cracking sensitivity is hard to evaluate quantitatively and the use of expansive additives to mitigate cracking remains empirical in-situ. This study developed a Temperature Stress Testing Machine (TSTM) to evaluate early-age properties of concretes under varied engineering conditions. The general design of TSTM and the mathematical derivation of its working principle are provided. With the developed TSTM, early-age properties (free deformation, restrained stress, elastic modulus and early-age creep effect) of Calcium Sulfoaluminate (CSA) expansive concrete are tested comprehensively. Experimental results indicate that under high temperature condition, CSA concrete is not effective to compensate shrinkage, while the combination of CSA and lightweight aggregate resolves the problem. It offers us valuable insights on potential application of TSTM into mix design of crack-resistant concretes under complex engineering conditions. c 2022 Elsevier Ltd
A comprehensive review of C-S-H empirical and computational models, their applications, and practical aspects
Duque-Redondo E.; Bonnaud P.A.; Manzano H.
Cement and Concrete Research, Elsevier Ltd., Vol.156, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106784)
Abstract
The C-S-H gel is an elusive material. Its variable composition and disordered nature complicate a complete characterization of its atomic structure, and the elaboration of models is key to understanding it. This work aims to review those proposed models, dividing them into empirical and computational models. After a brief description of related crystalline calcium silicate hydrates, empirical C-S-H models based on interpretation of experimental data are presented. Then, we focus on the historic development of atomistic models to study the C-S-H, until the current state of the art. We describe current computational C-S-H models built from the empirical models and computer simulations. We review common applications of these computational models: the aluminum incorporation, the elastic and mechanical properties, the diffusion of water and ions in nanopores, and C-S-H/organic composites. Finally, we discuss some practical aspects of the computational models and their interpretation, as well as possible future directions. c 2022 The Authors
Solidification and stabilization of strontium and chloride ions in thermally treated calcium aluminate cement modified with or without sodium polyphosphate
Irisawa K.; Namiki M.; Taniguchi T.; Garcia-Lodeiro I.; Kinoshita H.
Cement and Concrete Research, Elsevier Ltd., Vol.156, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106758)
Abstract
Cementation of aqueous radioactive waste contaminated with a significant 90Sr is challenging due to the potential radiolysis of water contents. Utilization of calcium aluminate cement (CAC) modified with sodium polyphosphate (CAP) is interesting as its water content can be reduced by thermal treatment. The present study investigated solidification and stabilization of Sr2+ and Cl? ions in CAC and CAP with or without thermal treatment. A leaching test showed a superior Sr2+ ion stabilization in CAP: apparent diffusion coefficient of Sr2+ was smaller than in the CAC by 5 orders of magnitude. CAC cured at 20 ‹C had the best stabilization for Cl? ions among the samples tested. Friedel's salt formed in CAC may have contributed to the immobilization of Cl? ions. The stabilization of Cl? ions by CAP was significantly improved by the thermal treatment likely because of the improvement in the microstructure previously reported. c 2022 Elsevier Ltd
Effect of magnesium silicate hydrate (M-S-H) formation on the local atomic arrangements and mechanical properties of calcium silicate hydrate (C-S-H): In situ X-ray scattering study
Kim G.; Im S.; Jee H.; Suh H.; Cho S.; Kanematsu M.; Morooka S.; Koyama T.; Nishio Y.; Machida A.; Kim J.; Bae S.
Cement and Concrete Research, Elsevier Ltd., Vol.159, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106869)
Abstract
This study explored the effect of M-S-H formation on the local atomic arrangements and mechanical properties of C-S-H. The elastic moduli of the samples were calculated using shifted atomic distances (r) and d-spacings (d) acquired by applying an external load on the pastes during X-ray scattering experiments. The experimental results indicated that the crystal structure of C-S-H remained intact with MgCl2 addition. At the highest Mg/Si ratio (Ca/Si = 0.6, Mg/Si = 0.2), change in the dominant phase occurred from C-S-H to M-S-H because the low pH environment hindered the formation of C-S-H and facilitated the formation of M-S-H. The elastic modulus decreased with increasing Mg/Si ratio up to 0.1 owing to both C-S-H destabilization and low M-S-H content in the samples. Conversely, the elastic modulus increased in the paste synthesized with the highest Mg/Si ratio because considerable M-S-H had formed, which exhibited a higher elastic modulus than C-S-H. c 2022 Elsevier Ltd
Surface area development of Portland cement paste during hydration: Direct comparison with 1H NMR relaxometry and water vapor/nitrogen sorption
Kurihara R.; Maruyama I.
Cement and Concrete Research, Elsevier Ltd., Vol.157, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106805)
Abstract
The specific surface areas of sealed-cured hardened cement pastes (HCP) were evaluated during the hydration process using three types of Portland cement and with two different water-to-cement ratios. The BET surface area was measured by water vapor/nitrogen sorption and directly compared with that obtained by the fast exchange model measured by 1H NMR relaxometry. The results confirmed that the total surface area evaluated by 1H NMR was consistently 2?2.5 times larger than the water vapor BET surface area for different HCPs. This difference is attributed to the local stacking of C-S-H layers: the surface between adjacent stacked layers is not measurable by water vapor due to the nature of the pre-treatment, while 1H NMR is able to measure the entire interlayer surface. The nitrogen surface area is better able to include the majority of the HCP gel pore surface by 1H NMR for white and high-early-strength Portland cement. c 2022 The Authors
Revisiting Tennis-Jennings method to quantify low-density/high-density calcium silicate hydrates in Portland cement pastes
Kurihara R.; Maruyama I.
Cement and Concrete Research, Elsevier Ltd., Vol.156, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106786)
Abstract
The Tennis-Jennings quantification method was revisited for characterizing low-density (LD) and high-density (HD) calcium silicate hydrates (C-S-H). Parameterized Portland cement pastes were prepared with different Blaine values of ordinary Portland cement and different types of cement using two water-to-cement (W/C) ratios (0.40 and 0.55). The hydration processes in these samples were examined using nitrogen sorption measurements and X-ray diffraction (Rietveld) analyses. The densities of LD and HD C-S-H were determined to be 1.19 and 1.79 (g/cm3 of dried C-S-H), respectively. Variation of the mass ratio of the LD C-S-H to the total C-S-H with hydration depended on the fineness of the original cement powder within the same Portland cement and the type of cement, especially at the later hydration for higher W/C ratios. For cement pastes with lower W/C ratios, the type of cement did not have a significant effect on the LD C-S-H precipitation at later hydration. c 2022 Elsevier Ltd
40 years of PCE superplasticizers - History, current state-of-the-art and an outlook
Lei L.; Hirata T.; Plank J.
Cement and Concrete Research, Elsevier Ltd., Vol.157, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106826)
Abstract
2021 marks the 40th year since polycarboxylate superplasticizers (PCEs) have been invented by Nippon Shokubai company in Japan. This invention clearly represents a major breakthrough and milestone in modern concrete technology. In this review article, at first Dr. Hirata ? the main inventor of PCE superplasticizers ? reports on the history behind their invention and market entry. Thereafter, recent developments and innovations in PCE technology are presented. As of today, the market offers a wide range of chemically different PCE products, among them HPEG and IPEG PCEs have occupied the largest market share because of their superior cost-effectiveness. At this moment, novel types of PCEs including EPEG and GPEG PCEs are being introduced, thus enriching the family of vinyl ether (VPEG) superplasticizers. In spite of the huge success of PCEs, also challenges in specific applications such as their sensitivity towards clay contaminants or the viscous (gstickyh) flow behavior of concrete mixed at low w/c ratios became obvious and will be addressed. Furthermore, as the concrete industry currently undergoes a fundamental transition to low-carbon binders in order to reduce anthropogenic CO2 emission, PCE superplasticizers suitable for such low or zero clinker binders including calcined clay blended cements or alkali activated slags are being sought and the current state-of-the-art in this field will be discussed. Finally, the future perspectives of PCE technology in a dramatically changing industry are assessed and the pivotal role of PCEs in this mega transition faced by the construction industry will be pointed out. c 2022 Elsevier Ltd
A response to the discussion paper on grheological behaviors and model of fresh concrete in vibrated stateh
Li Z.
Cement and Concrete Research, Elsevier Ltd., Vol.152, 2022, .
(https://doi.org/10.1016/j.cemconres.2021.106653)
Abstract
The meanings and dimensions of notations Nca, Nc and c3were not clearly described in our published paper, and the approximation and the split representation of logarithmic function caused Eq. (11) to be not easily understood. In this response paper, the author first explained the dimensions of Nca, Nc and c3, and the derivation process of Eq. (11). Then, parameter L0 with unit length was added to the related equations, the suitability and necessity of approximating Eq. (10) to get Eq. (11) and the influence of this approximation were also explained. c 2021 Elsevier Ltd
Surface area changes in C3S paste during the first drying analyzed by 1H NMR relaxometry
Maruyama I.; Fujimaki T.; Kurihara R.; Igarashi G.; Ohkubo T.
Cement and Concrete Research, Elsevier Ltd., Vol.156, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106762)
Abstract
The drying process of pure C3S paste with a water to binder ratio of 0.55 under different relative humidity conditions was monitored using proton nuclear magnetic resonance relaxometry. The desorption isotherm of the interlayer water was obtained experimentally. The relationship between the interlayer water content and T2 value of the interlayer water defines the surface relaxation time, which provides quantitative data regarding the adsorbed water. According to the fast exchange model, the surface area at the sealed condition was 630 m2/g-calcium silicate hydrate (C-S-H), and it decreased during drying, which was associated with an increase in chemically bound water. The ratio of the decrease in the interlayer surface area to the increase in chemically bound water was 5400 m2/g. Based on this value, the total surface area of C-S-H was calculated to 830 to 921 m2/g-C-S-H. c 2022 Elsevier Ltd
Effect of fineness of cement on drying shrinkage
Maruyama I.; Sugimoto H.; Umeki S.; Kurihara R.
Cement and Concrete Research, Elsevier Ltd., Vol.161, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106961)
Abstract
The effect of fineness of cement on drying shrinkage was investigated. Three cement paste samples with different fineness values were prepared from the same clinker. The changes in length and mass, and water vapor sorption of the dried cement pastes after 3, 7, 28, and 91 d of curing were obtained. The relationships between drying shrinkage and the degree of hydration were not identical under the different cement fineness values. Therefore, there exists another mechanism behind the increase in drying shrinkage, apart from the faster degree of hydration. It was found that drying shrinkage is well predicted by the index SH2O,v ~ B, where B denotes the Blaine value of cement, and SH2O,v represents the water vapor sorption surface area. Hence, it was deduced that C?S?H undergoes an anisotropic volume change under drying and a greater shrinkage in the circumferential direction of the original cement grains. c 2022 Elsevier Ltd
Emulsification of low viscosity oil in alkali-activated materials
Reeb C.; Davy C.A.; Pierlot C.; Bertin M.; Cantarel V.; Lambertin D.
Cement and Concrete Research, Elsevier Ltd., Vol.162, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106963)
Abstract
This research aims to understand the mechanisms enhancing the fixation of low viscosity mineral oils, including tailings, in reactive inorganic matrices, by emulsification. To this purpose, significant amounts of a model low viscosity pure mineral oil (20%vol) are immobilized in alkali-activated materials (AAM), either based on metakaolin or blast furnace slag. In such case, Portland cement-based matrices are not adequate (emulsification delicate to manage and excessive setting retardation). Various surfactants are used to ease the oil emulsion. Visual observation and rheology evidence two distinct groups of surfactants. One contributes to structuring the oil/AAM fresh mix, with greater viscosity than without surfactant; the other includes non-structuring surfactants, without change in viscosity. Each group depends on the AAM considered. Whatever the AAM and the surfactant, the oil droplet size decreases significantly, without consistent correlation with the interfacial tension between oil/activating solution (AS). Interfacial tension alone does not explain the reduction in oil droplet size. Characterization of diluted ternary suspensions (solid particles ? oil ? AS) relates the structuring effect to interactions between oil and solid particles, through the surfactant polar head groups and non-polar hydrocarbon tails. A detailed mechanism explaining the oil stabilization and the mix structuring is discussed. c 2022 Elsevier Ltd
On the significance of interfacial chemistry on the strength of fly ash-cement composites
Shishehbor M.; Sakaniwa D.; Stefaniuk D.; Krakowiak K.J.; Abdolhosseini Qomi M.J.
Cement and Concrete Research, Elsevier Ltd., Vol.151, 2022, .
(https://doi.org/10.1016/j.cemconres.2021.106619)
Abstract
Despite the large number of studies on supplementary cementitious materials, the underlying physicochemical interfacial processes that govern their strength remain obscure. To address this knowledge gap, this paper strives to establish a relation between the chemical composition of fly ash (FA) at the molecular level and the macroscopic compressive strength in cement hydrates-FA composites. We develop a multiscale modeling framework that links the fundamental physicochemical attributes of calcium silicate hydrate (C-S-H)-FA interfaces across molecular (~1 nm), mesoscopic (~100 nm), and microscopic (~10 ƒÊm) length scales. We observe that FA's chemical composition affects the interfacial properties across all scales. FAs with higher network-modifier cation concentration show stronger molecular and mesoscale interfacial properties and statistically significant higher macroscopic compressive strength. This is particularly interesting for Class F FA, where early-age reactivity is negligible. c 2021 Elsevier Ltd
Mechanism understanding of alkali-silica reaction in alkali-activated materials system
Wang W.; Noguchi T.; Maruyama I.
Cement and Concrete Research, Elsevier Ltd., Vol.156, 2022, .
(https://doi.org/10.1016/j.cemconres.2022.106768)
Abstract
To provide a better understanding of the mechanism of alkali-silica reaction (ASR) in alkali-activated materials (AAMs) system, in this work, the ASR behavior of alkali-activated slag (AAS)/fly ash (AAFA) mortars were investigated, and compared with ordinary Portland cement (OPC) mortars. It is found that although the AAS mortar bars experience the shrinkage first, the onset of ASR-induced expansion of AAS mortar bars is earlier than OPC mortar bars. In AAMs system, the reactive silica from aggregates is evidently dissolved and participated in the early-age alkali-activation, and thereby leads to the reduction of reactive silica for ASR. The Ca/Si ratio of amorphous ASR products in AAS mortars was lower, while Al/Si and Na/K ratios were higher than that of OPC mortars. Based on the obtained experimental evidences, a conceptual model was proposed to interpret and compare the ASR behavior in OPC, AAS and AAFA systems. c 2022 Elsevier Ltd
Numerical approach to pipe flow of fresh concrete based on MPS method
Xu Z.; Li Z.; Jiang F.
Cement and Concrete Research, Elsevier Ltd., Vol.152, 2022, .
(https://doi.org/10.1016/j.cemconres.2021.106679)
Abstract
As a fundamental study of concrete pumping, this study developed a numerical method to simulate the flow and segregation of fresh concrete in pipes, based on the improved MPS (Moving Particle Semi-implicit) that has complete implicit algorithm, hereafter called I-MPS. The slip layer (LL) near the pipe inner wall was treated by the macroscopic approach, which estimates the slip resistance and the volumetric flow rate of LL from the apparent slip velocity of LL. Two constituent models were used to describe fresh concrete, called single-phase & mono-particle (SPMP) model and double-phase & multi-particle (DPMP) model, respectively. In the former, fresh concrete is considered as a single-phase granular fluid, but in the latter, fresh concrete is regarded as two-phase granular fluid with different particle shapes and sizes of coarse aggregate and matrix mortar. By comparing the numerical and theoretical pumping pressures of three concretes having slump from 13 cm to 21 cm, it was found that by using the macroscopic approach of LL and either of the constituent models, the numerical approach can predict properly the pumping pressure and velocity profile of fresh concrete in pipes. Moreover, if using the DPMP model, the segregation behavior of coarse aggregate particles during the pipe flow can also be simulated. c 2021 Elsevier Ltd