Hydration Temperature Research Articles

Reaction kinetics and properties of pumice-based geopolymer systems cured at room temperature

This research investigated the kinetics of pumice-based geopolymer systems and their physical and mechanical properties. The effect of the Na2SiO3/NaOH ratio of geopolymer systems on the rate of heat evolution and total heat of reaction were examined via isothermal calorimetry of geopolymer pastes prepared with Na2SiO3/NaOH ratios of 2.5, 3, and 3.5. Hardened pastes were also studied with thermo-gravimetric analysis to determine weight loss. In addition, the unit weights and compressive strengths of the pastes prepared using pumice were measured. Although the hydration process starts the earliest in pumice-based geopolymer pastes with a Na2SiO3/NaOH ratio of 2, they have the lowest total hydration temperature. Na2SiO3/NaOH ratio of 2.5 by mass, shows higher weight loss obtained from TGA results. The compressive strength of the paste sample, prepared with a Na2SiO3/NaOH ratio of 3.5 by mass, was the highest, with 36.30 MPa at 28d. Depending on the Na2SiO3/NaOH ratio, it is thought that as the amount of Na2SiO3 increases in the samples, silica gel formation increases in later ages.

Hydration Absorption and Thermal Effects of Outcrop Porous Sandstone Based on Intelligent Experimental and Infrared Thermography Techniques

Sandstones are enriched in deep energy reservoirs and also exist as outcrop rocks, where the pore characteristics of sandstone are influenced by hydration absorption and thermal effects. To study the influence of the initial temperature on the hydration absorption characteristics of outcrop porous sandstone in the Mogao Grottoes, China, an intelligent experimental device for rock hydration was used. The hydration absorption characteristics and temperature effects of sandstone were analyzed by using infrared thermography techniques to monitor the infrared radiation characteristics of the sandstone’s surface during hydration absorption. The experimental results show that the higher the initial temperature of the rock samples, the shorter the time it takes for the sandstone to absorb enough water to reach saturation. The temperature variation of sandstone with different initial temperatures was also determined; the variation in the hydration absorption of sandstone conforms to certain rules, which can be expressed by formulae containing certain parameters. The changing trend of hydration absorption in outcrop porous sandstone shows that the hydration absorption increases rapidly at first, and then the rate of increase slows down until the hydration absorption remains unchanged after saturation. The experimental technique and method provide feasible means and techniques to evaluate the hydration absorption and thermal effects of outcrop porous sandstone, for further detecting the weathering degree of rock grottoes and revealing the damage mechanisms.

Preparation of nanoliposomes containing the extracts of Eleocharis dulcis corm-peels and ascertaining their aphidicidal activity against Megoura crassicauda and Acyrthosiphon pisum

Nanotechnology can improve the stability, slow release, and effectiveness of botanical pesticides. Eleocharis dulcis peel extract (EDPE) was found to have a potent aphidicidal activity in our past study. In order to increase its properties, EDPE nanoliposomes was prepared and its aphidicidal activity was also tested. The optimal preparation process of EDPE nanoliposomes was determined by single-factor examination and Box-Behnken response surface test design as soybean lecithin: cholesterol: EDP extract mass ratio of was 5:4.1:1, medium PBS pH of 7.3, hydration temperature of 45 °C, and chloroform as the organic solvent; the encapsulation ratio of EDPE nanoliposomes prepared by using the optimal prescription was 90.67%. The scanning electron microscope and transmission electron microscopy results showed that the nanoliposomes were round or ova; and the particle size was 222.55 ± 2.59 nm; the polydispersity index was 0.11 ± 0.03; the zeta potential was − 4.78 ± 2.61 mV. The stability test showed that the EDPE nanoliposomes had good stability within 60 d. EDPE nanoliposomes showed potent aphidicidal activity, and the LC50 were 136.59 and 83.99 mg/L for 48 and 72 h against Megoura crassicauda, respectively; and 315.78 and 154.34 mg/L against Acyrthosiphon pisum, respectively, higher than that of matrine. In addition, compared to non-capsulated EDPE, EDPE nano-liposomes improved both aphidicidal activity and the effective period. It follows then that EDPE nanoliposomes have the potential to be developed into botanical aphicides.

A systematic deliquescent additive selection approach for enhancement of reaction kinetics of thermochemical heat storage materials

A series of 16 salt mixtures consisting of potassium carbonate (K2CO3) as the base salt and a secondary salt hydrate in a 20 : 1 mol ratio of anhydrous K2CO3 to anhydrous additive were investigated as potential thermochemical heat storage (TCHS) composites. Those materials were evaluated based on their (de)hydration temperatures and reaction kinetics to find a suitable secondary salt mixture with enhanced phase change behaviour. The improved performance is expected to come from the enhancement of ionic mobility due to the deliquescence of the secondary salt. Based on the screening, we found that deliquescent and highly soluble salts are prone to reacting with K2CO3, forming new compounds that do not impact the behaviour of the base salt. Therefore, the most promising additives were salts that share a common ion with K2CO3 (KF, Cs2CO3) or salts that can react with K2CO3 forming a highly deliquescent salt (CsF, Cs2SO4). Based on the findings, we were able to design a selection procedure that can be applied to other salt hydrates considered for TCHS applications that suffer from poor kinetics and large reaction hysteresis.

Investigation on application of filling mining technology pass through abandoned roadway of reclaimed working face.

This paper aims to analyze the roof stability when the reclaimed working face passes through abandoned roadway. The mechanical model of main roof in abandoned roadway was established for the purpose of theoretical analyses. To ensure the stability of the abandoned roadway, the strength formula of backfill body was deduced. The optimum ratios among different compositions of the filling material were determined by experiment, while the viscosity, bleeding, hydration temperature and compressive strength of filling material were also studied. Test results indicated that the optimum ratio among coal ash, lime and compound activator is 80:15:5, and the ideal water cement ratio is 0.7:1. It was also found that no bleeding occurred, the rheological behavior of slurry presented shear thinning fluid and the hydration temperature of filling body was relatively stable which is mainly maintained at 40°C. The uniaxial compressive strength of filling material with 28 and 90 days curing were 3.35 and 6.62 MPa respectively. Under a confining pressure environment, the filling material presented an obviously plastic deformation. Field test showed that the filling rate was almost 100%, when working face passed through abandoned roadway, the surface of filled body was complete and no roof collapse was triggered. Therefore, a better bonding effect was proved for the filling body.

Bacterial Viability in Self-Healing Concrete: A Case Study of Non-Ureolytic Bacillus Species.

Cracking is an inevitable feature of concrete, typically leading to corrosion of the embedded steel reinforcement and massive deterioration because of the freezing-thawing cycles. Different means have been proposed to increase the serviceability performance of cracked concrete structures. This case study deals with bacteria encapsulated in cementitious materials to "heal" cracks. Such a biological self-healing system requires preserving the bacteria's viability in the cement matrix. Many embedded bacterial spores are damaged during concrete curing, drastically reducing efficiency. This study investigates the viability of commonly used non-ureolytic bacterial spores when immobilized in calcium alginate microcapsules within self-healing cementitious composites. Three Bacillus species were used in this study, i.e., B. pseudofirmus, B. cohnii, and B. halodurans. B. pseudofirmus demonstrated the best mineralization activity; a sufficient number of bacterial spores remained viable after the encapsulation. B. pseudofirmus and B. halodurans spores retained the highest viability after incorporating the microcapsules into the cement paste, while B. halodurans spores retained the highest viability in the mortar. Cracks with a width of about 0.13 mm were filled with bacterial calcium carbonate within 14 to 28 days, depending on the type of bacteria. Larger cracks were not healed entirely. B. pseudofirmus had the highest efficiency, with a healing coefficient of 0.497 after 56 days. This study also revealed the essential role of the cement hydration temperature on bacterial viability. Thus, further studies should optimize the content of bacteria and nutrients in the microcapsule structure.

A novel method for solving hydration heat release based on equivalent heat release theory

Current hydration heat release rate algorithms that consider the temperature history are based on the Arrhenius law and other hypothetical conditions. Nevertheless, reported research results have shown controversy regarding the values of Arrhenius law and other model parameters, potentially introducing errors in calculated results. Some studies have shown that adiabatic temperature rises at different placement temperatures can be expressed by a mathematical expression; thus, this study establishes a relational model for the hydration temperature rise rate of concrete structures under any temperature history. This study uses the hydration temperature rise rate of the adiabatic temperature rise test under equivalent conditions to directly obtain the hydration temperature rise rate for any temperature history. Except for special cases, the proposed algorithm does not rely on the Arrhenius law and other hypothetical conditions, thus avoiding errors caused by the associated assumptions. Additionally, this study utilizes an integration method to solve a problem in which a small calculation time step is required to guarantee the accuracy of the solution under the conventional finite element framework. Furthermore, an iterative algorithm is proposed to solve the problem in which the temperature at the end of the calculation time step must be used when the temperature history is considered. Examples show that the proposed method exhibits a high calculation precision and improves efficiency; and the maximum temperature difference between the calculated and measured values is only 0.085 °C.

Influence of seawater and sea sand on early-age performance and cracking sensitivity of concrete

Due to resource constraints, there has been a growing demand for alternative sources of water and sand in construction engineering. Recent advancements in technology, such as the use of fiber-reinforced polymers (FRP) reinforcement or impressed current cathodic protection-structural strengthening (ICCP-SS), have enabled the utilization of seawater and sea sand, garnering significant research attention. The study investigated various aspects of four types of early-age concrete based on the temperature stress testing machine (TSTM) method, including fresh properties, basic mechanical properties, hydration temperature history, restraint stress, autogenous shrinkage, creep, and cracking sensitivity. The results showed that seawater significantly increased the early tensile strength of concrete, while sea sand had the opposite effect. Compared with ordinary concrete, seawater and sea sand increased the early autogenous shrinkage of concrete, and the impact of seawater was more significant. For the early creep of concrete, seawater and sea sand reduced the maximum compressive creep of concrete, and the effect of sea sand was more remarkable. Seawater increased the tensile creep of concrete, while sea sand decreased the tensile creep of concrete. The comprehensive evaluation index indicates that seawater and sea sand have no significant effect on concrete's cracking sensitivity. This research may serve as a valuable reference for the use of seawater and sea sand in concrete.

Green Production of Biodiesel from High Acid Value Oil via Glycerol Esterification and Transesterification Catalyzed by Nano Hydrated Eggshell-Derived CaO

Biodiesel is a widely recognized and favored liquid biofuel, primarily attributed to its biodegradability and non-toxicity. However, the development of biodiesel is hindered by its high production costs. Here, we developed a method that combines glycerol esterification and transesterification reaction catalyzed using nano-hydrated CaO for the green production of biodiesel from high acid value oil. Waste eggshell was chosen as the calcium source to examine the effect of hydration temperature and duration. The catalysts were optimized using a synthesis process involving under calcination for 3 h at 875 °C, followed by hydration at 60 °C for 6 h and subsequent dehydration at 725 °C. The catalyst loading, alcohol-to-oil mass ratio, reaction temperature, and duration were optimized to 2.5 wt%, 35%, 60 °C, and 2 h, respectively. Under the optimized conditions, the yield of fatty acid methyl ester reached 94.44%. The catalyst was successfully reused eight cycles while maintaining a yield of fatty acid methyl ester at 80.52%. In addition, a comprehensive overview was summarized to compare the catalyst preparation methods, reaction conditions, biodiesel yield, and reusability in the production of biodiesel using eggshell-derived CaO.

Impact of calcium sulfoaluminate cement on printability and early strength development of a slag-based 3D printing cementitious material

Blast furnace cement (BFC) as a binder for 3D printing cement (3DPC) has potential to lower carbon-footprints, but its unstable workability and strength development hinder its application. In this article, blast furnace cement (BFC), a mixture of ordinary Portland cement (OPC) and ground granulated blast furnace slag (GGBFS) based binder was designed toward low-carbon 3DPC, and the impact of calcium sulfoaluminate cement (CSA) content on printability and early strength of printed materials was discussed. The researched components of the materials, GGBFS, OPC and CSA, were first designed based on the 24 h early strength development. Slugs test was utilized to investigate 3D printability, and adiabatic hydration temperature, compressive strength, X-ray diffraction, thermal gravimetric analysis, and solid Si-nuclear magnetic resonance were used to analyze the early strength development and hydration products. For 1 h of hydration, CSA played a significant role in the hydration, due to generation of rod-shape Aft, which resulted in increase of yield stress as indicated by the slugs test. For 24 h of hydration, when CSA is less than 20%, it is C-S-H gel provided the strength; when CSA content is more than 20%, AFt constructs the skeleton, and unhydrated material and AH3 fill in the voids of the skeleton, resulted in high early strength. Strength response surface results indicated that GGBFS, OPC and CSA mass ratio of 5:4:1 is the best in this research. The 3DP opening time is in the range of 20–40 min, and the compressive strength at 24 h reaches 14.43 MPa.

TEMPERATURE IMPACT ON THE HYDRATION AND SETTING MECHANISM OF C-S-H BONDING ON NANO-BIOMASS SILICA WITH POLY-CARBOXYLATE ETHER

<p>Pozzolanic material and a chemical admixture have been used in the current investigation; Nano Biomass Silica (NBS) and Poly-Carboxylate Ether (PCE). NBS produces 20% of the 590 million tonnes of paddy produced globally. Amorphous silica, a mineral component used in concrete, is present in sizable levels in these by-products (NBS). A binary and ternary of NBS with partial replacement of Ordinary Portland Cement (OPC) and the addition of PCE with varying dosage by weight of cement were used. This study's goal is to determine how they affect paste Setting time (ST) and Standard consistency (SC), and hydration temperature evaluation conducted in hot weather with various percentage at NBS from 6, 12 and 18% and PCE with varying dosage from 0.8, 0.9 and 1%. The chemical bond & structure of pozzolanic and chemical admixture in the FTIR were analysed. While PCE showed very little impact on consistency, higher w/b ratios with higher NBS levels were required for the maintenance of OPC-NBS paste consistency standards. The Initial setting time (IST) & Final setting time (FST) for binary OPC-NBS pastes significantly raise to 6% NBS, followed by a decrease at 12% and 18% NBS. However, for OPC-PCE pastes, the IST increased to 0.8%PCE followed by decrease at 0.9% and 1% PCE. In cement paste, PCE can be added as an additive, but the FST increases with an increase in the PCE percentage. At the same time, the mineral admixtures NBS can be used as a cement paste to decrease the FST and also reduce agricultural waste. NBS will effectively use silica ash as a microstructure filler as an additive in manufacturing to produce a certain form of cement with specific IST and FST, in particular for the sustainability of building materials and in hot weather.</p>

Effects of emulsified asphalt on the rheological behaviors of magnesium phosphate cement

The traditional method for repairing asphalt pavement relies on hot-mix asphalt. Owing to its high energy consumption, this method proves inadequate in meeting the growing demands of low-carbon and environmental protection. Further, the utilization of cold-patching material is limited due to its slow strength development and poor long-term durability. Therefore, in this study, an organic–inorganic composite system that is based on the addition of emulsified asphalt and magnesium phosphate cement (MPC-EA) for filling asphalt pavement cracks was developed. Since the rheological properties of the slurry play a crucial role in determining its suitability for injection into the area to be reinforced and the effectiveness of crack repair, the effect of EA content on rheological properties was investigated. Specifically, the rheological properties of the slurry were analyzed at 260 s, and the rise in hydration temperature during this period was monitored to better understand the hydration process. The addition of EA drastically influenced the shear thickening of the original MPC system, and the rheological parameters changed with an increase in the EA content (10%–40%). The rheological loss mechanism of the composite system was elucidated by studying the hydration temperature and rheological parameters of the MPC-EA composite system. Further, an early rheological model of the composite system was established to understand the interaction mechanism of the MPC-EA composite system, and a constitutive equation of MPC-EA that considers the influence of EA content was devised. This study provides valuable information that can facilitate the field application of novel repair materials for pavement crack repair.

Cardiometabolic Effects of DOCA-Salt in Mice Depend on Ambient Temperature.

Mice prefer warmer environments than humans. For this reason, behavioral and physiological thermoregulatory responses are engaged by mice in response to a standard room temperature of 22 to 24 °C. Autonomic mechanisms mediating thermoregulatory responses overlap with mechanisms activated in hypertension, and, therefore, we hypothesized that housing at thermoneutral temperatures (TNs; 30 °C) would modify the cardiometabolic effects of deoxycorticosterone acetate (DOCA)-salt in mice. The effects of DOCA-salt treatment upon ingestive behaviors, energy expenditure, blood pressure, heart rate (HR), and core temperature were assessed in C57BL/6J mice housed at room temperature or TN. Housing at TN reduced food intake, energy expenditure, blood pressure, and HR and attenuated HR responses to acute autonomic blockade by chlorisondamine. At room temperature, DOCA-salt caused expected increases in fluid intake, sodium retention in osmotically inactive pools, blood pressure, core temperature, and also caused expected decreases in fat-free mass, total body water, and HR. At TN, the effects of DOCA-salt upon fluid intake, fat gains, hydration, and core temperature were exaggerated, but effects on energy expenditure and HR were blunted. Effects of DOCA-salt upon blood pressure were similar for 3 weeks and exaggerated by TN housing in the fourth week. Ambient temperature robustly influences behavioral and physiological functions in mice, including metabolic and cardiovascular phenotype development in response to DOCA-salt treatment. Studying cardiometabolic responses of mice at optimal ambient temperatures promises to improve the translational relevance of rodent models.

Multi-scale modeling and simulation of bidirectional coupled moisture and heat transfer in concrete

The change of humidity and temperature field of concrete is closely related to its long-term time-varying performance of shrinkage and creep. Therefore, accurate prediction of temperature and humidity in concrete plays an important role in studying the service performance of concrete structures. In the study, the mechanism of coupled moisture and heat (M&H) transfer in concrete is systematically analyzed from three scales: micro-nano scale, mesoscale, and macroscale; meanwhile, a multi-scale theoretical model of coupled M&H transfer in concrete is established. In addition, a novel simulation method of bidirectional coupled of M&H is proposed and the corresponding ABAQUS subroutine is compiled. Based on the existing experiments, the concrete temperature and humidity data for 180 days were further monitored, which verified the feasibility of the proposed method. Finally, the prediction results of M&H transfer are analyzed and compared in three cases: uncoupling, unidirectional coupling, and bidirectional coupling. For the temperature prediction, the early hydration temperature rise is underestimated under the uncoupled model and the unidirectional coupled model that only considering the influence of temperature on humidity, and the prediction error of unidirectional coupled model that only considering the influence of humidity on temperature is relatively small. For the humidity prediction, both uncoupled and unidirectional coupled models underestimate the water consumption, and the closer to the surface of the concrete, the greater the error. Through experiments and numerical simulation analysis, it is suggested that the bidirectional coupled effect should be considered in the analysis of wet-heat field of concrete. This study provides a new way for the modeling and simulation of coupled M&H of concrete, and lays the foundation for the long-term performance research of infrastructure.

Recycling of waste magnesia refractory brick powder in preparing magnesium phosphate cement mortar: Hydration activity, mechanical properties and long-term performance

Waste magnesia refractory bricks (MRBs) that remain from industrial production are landfilled in large quantities or recovered to prepare recycled bricks with low added value. In consideration of the significant level of magnesia in waste bricks, this work proposes to extract and recover magnesia from spent bricks for manufacturing magnesium phosphate cement mortar (MPCM). The essential attributes of recycled magnesia (RM) and its influence on the workability, hydration temperature rise, mechanical properties, phase evolution, long-term performance and microstructure of MPCM were analyzed. The results reveal that RM significantly prolongs the setting time and reduces the overall hydration heat release, which is beneficial to the application in large-scale engineering. The compressive strength of MPCM prepared by RM (MPCMRM) initially grew and then decrease with the increase of magnesia to phosphate ratio (M/P ratio). The optimal performance was observed at M/P = 4, and the compressive strength cured for 3 h and 28 d were 39.1 MPa and 68.5 MPa respectively. While the mechanical properties of MPCMRM were marginally inferior to those of dead-burned magnesia (DM), it was found to satisfy the early and long-term strength requirements of engineering repair materials. In addition, MPCMRM did not generate new mineral phases, and the crystal morphology of hydration products (struvite) was worse than that of mortar prepared by DM. MPCMRM also exhibits excellent water resistance and volume stability due to the crystal characteristics of low-activity RM. It seems that RM can completely replace DM to prepare MPCM and achieve satisfactory performance, which not only reduces the cost of repair materials, but also provides a fresh approach for the recycling of waste MRBs.

An injectable bioactive poly(γ-glutamic acid) modified magnesium phosphate bone cement for bone regeneration.

As potential alternatives for calcium phosphate bone cements, magnesium phosphate bone cements (MPC) have attracted considerable attention in recent years. However, their several defects, such as rapid setting times, highly hydration temperature and alkaline pH due to the part of the unreacted phosphate, restricted their applications in human body. With aim to overcome these defects, a novel polypeptite poly(γ-glutamic acid) (γ-PGA) modified MPC were developed. Effect of γ-PGA content on the injectability, anti-washout ability, setting times, hydration temperature, mechanical compressive strength, in vitro bioactivity and degradation were investigated. Moreover, in vitro cyto-compatibility was evaluated using MC3T3-E1 cells by CCK-8 and Live/Dead staining. All these results indicated that the 10%PGA-MPC with an improved handling performances, low hydration temperature, high mechanical compressive strength, and good cyto-compatibility hold a great potential for bone repair and regeneration.

Finite element modeling of early-age temperature development of in-situ concrete under variable ambient temperatures

The early-age temperature rises in in-situ concrete, caused by the exothermic hydration of cement, poses a significant risk of thermal cracking in concrete structures. This issue is particularly critical in large-scale structures, where thermal cracking can lead to serious structural integrity issues. Therefore, the accurate prediction of the concrete hydration temperature development is paramount for predicting and mitigating early thermal cracking in concrete. However, one of the main challenges in predicting in-situ concrete temperatures is the significant effect of variable ambient temperature on cement hydration rates and concrete heat dissipation. To address this challenge, this paper presents a finite element modeling (FEM) approach that accurately predicts the early-age temperature development of in-situ concrete by adequately considering the effect of variable ambient temperatures. The model integrates the heat of hydration of the cement, the impact of ambient temperature variations, and the heat transfer through the concrete and insulation mould. The cement hydration rate under real-life ambient temperatures is simulated using an Arrhenius-based method, which mathematically adjusts the isothermal calorimetry curves to reflect the actual conditions. Additionally, the study investigates the inhibitory effect of Ground Granulated Blast-furnace Slag (GGBS) on the early hydration temperature of concrete, with experimental tests and FEM simulations conducted on concrete mixes where up to 70% of the cement was replaced with GGBS. The validity of the FEM model was confirmed through comparison with concrete semi-adiabatic tests, demonstrating that the model provides accurate predictions of the temperature development of in-situ concrete. Importantly, the results indicate that the adjusted isothermal calorimetry curves successfully capture the ambient temperature effect on the cement hydration rate. The results provide valuable insights for the design of concrete structures, particularly in preventing early-age thermal cracking.

Optimization of a Luteolin-Loaded TPGS/Poloxamer 407 Nanomicelle: The Effects of Copolymers, Hydration Temperature and Duration, and Freezing Temperature on Encapsulation Efficiency, Particle Size, and Solubility.

Luteolin is a flavonoid compound that has been widely studied for its various anti-cancer properties and sensitization to multidrug-resistant cells. However, the limited solubility and bioavailability of Lut hindered its potential clinical use. Theoretically, the combination of this compound with vitamin E TPGS and poloxamer 407 can produce a synergistic effect to enhance tumor apoptosis and P-glycoprotein inhibition. This study aimed to develop and optimize vitamin E TPGS/Poloxamer 407 micelles loaded with luteolin through investigating certain factors that can affect the encapsulation efficiency and particle size of the micelle. A micelle was prepared using the film hydration method, and the micellar solution was lyophilized. The cake formed was analyzed. The factors investigated include the concentrations of the surfactants, ratio of vitamin E TPGS/Poloxamer 407, temperature of the hydrating solution, duration of hydration, and freezing temperature before lyophilization. The effects of these factors on the encapsulation efficiency and particle size of the micelle were also studied. The encapsulation efficiency was measured using a UV-Vis spectrophotometer, while particle size was measured using dynamic light scattering. The optimized micelle was found to have 90% encapsulation efficiency with a particle size of less than 40 nm, which was achieved using a 10% concentration of surfactants at a vitamin E TPGS/Poloxamer 407 ratio of 3:1. The optimized temperature for hydrating the micellar film was 40 °C, the optimized mixing time was 1 h, and the optimized freezing temperature was -80 °C. The solubility of the luteolin-loaded micelles increased 459-fold compared to pure Lut in water. The critical micelle concentration of the vitamin E TPGS/Poloxamer 407 micelle was 0.001 mg/mL, and the release study showed that luteolin-loaded micelles exhibited sustained release behavior. The release of luteolin from a micelle was found to be higher in pH 6.8 compared to pH 7.4, which signified that luteolin could be accumulated more in a tumor microenvironment compared to blood. This study demonstrated that several factors need to be considered when developing such nanoparticles in order to obtain a well-optimized micelle.

Strength and Microstructure Assessment of Partially Replaced Ordinary Portland Cement and Calcium Sulfoaluminate Cement with Pozzolans and Spent Coffee Grounds.

Supplementary cementitious materials are considered a viable and affordable way to reduce CO2 emissions from the cement industry's perspective since they can partially or nearly entirely replace ordinary Portland cement (OPC). This study compared the impact of adding spent coffee grounds (SCGs), fly ash (FA), and volcanic ash (VA) to two types of cement: OPC and calcium sulfoaluminate cement (CSA). Cement samples were characterized using compressive strength measurements (up to 210 days of curing), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray diffraction (XRD), attenuated total reflection infrared spectroscopy, and hydration temperature measurements. In all the studied systems, the presence of SCGs reduced compressive strength and delayed the hydration process. CSA composite cement containing 3.5% SCGs, 30% FA, and 30% VA showed compressive strength values of 20.4 MPa and 20.3 MPa, respectively, meeting the minimum requirement for non-structural applications. Additionally, the results indicate a formation of cementitious gel, calcium silicate hydrate (C-S-H) in the OPC-based composite cements, and calcium alumino-silicate hydrate (C-A-S-H) as well as ettringite in the CSA-based composite cements.

High-Volume Recycled Waste Glass Powder Cement-Based Materials: Role of Glass Powder Granularity

The use of recycled waste glass powder (RWGP) as a partial substitute for cement in cement-based materials offers a promising solution for reducing environmental impact and promoting sustainable waste management practices. An experimental study was conducted on a reference material made with Portland-limestone cement CEMII/A-LL42.5R and three other materials containing 50 wt% RWGP with different mean diameters, d50: 16, 18, and 25 µm. The main objective was to analyze the role of RWGP granularity in the short- and medium-term properties of the cement-based materials. The results showed that coarser RWGP granularity led to an increase in fluidity and Portlandite content, while water demand and mechanical properties decreased. However, the range of RWGP granularities tested did not significantly affect the initial setting time, fresh and dry density, hydration temperature, and water porosity. These findings suggest that the choice of RWGP granularity should depend on the desired properties of the cement-based material.