Bound Water Content Research Articles

Preparation of geopolymer concrete with Bayer red mud and its reaction mechanism

Red mud (RM) is a hazardous waste product resulting from alumina production in the aluminum industry. In China, the alumina industry generates a significant amount of solid waste RM annually. The accumulation of RM not only occupies a large area of land but also leads to environmental pollution. Currently, Bayer red mud (BRM) constitutes the majority of the piled-up RM in China. Due to its high alkalinity and low activity, BRM cannot be directly used in the cement industry, and its comprehensive utilization is severely limited. Thus, finding a bulk, safe, and cost-effective utilization method is crucial in tackling the massive accumulation of BRM. This study primarily focuses on the reactivity and reaction mechanisms of BRM in cement-based and geopolymer material. Firstly, it was demonstrated through compressive strength, chemical bound water content, SEM microstructures, and flowability that BRM exhibits relatively low reactivity in cement-based material. Experimental investigations were conducted to study the impact of the BRM addition and curing methods on the mechanical properties of BRM based geopolymer materials. The dosage range of BRM under different conditions was given. Through SEM-EDS analysis, the influence of BRM with its high-temperature activation on the early hydration products in geopolymer material was investigated. The reaction mechanism of BRM in geopolymers was analyzed, and a reliable, affordable, and efficient way to use BRM on a large scale was developed.

A novel bound water occurrence model for tight sandstone

Understanding the occurrence state and microscopic distribution of bound water, as well as the factors governing bound water saturation and its impact on natural gas flow within nano-scaled pore networks, holds significant importance for reservoir evaluation, productivity prediction, and production. However, the complexity of pore structure poses a challenge in quantitatively characterizing these aspects, and currently, no effective method exists to achieve this characterization. This study takes the Bashijiqike tight sandstone of the Kuqa Depression of the Tarim Basin as an example; by integrating physical property test, XRD, microscopic observation with casting thin section and SEM, HPMI, NMR, and NMR-supervised gas-charging experiment, proposed a novel bound water occurrence model to depict the microscopic distribution of bound water in nano-scaled pore space. Furthermore, the impact of bound water on gas-flowing behaviors was thoroughly examined and the complex relationships between bound water saturation and reservoir macroscopic and microscopic parameters were explored. In addition, based on the grey relational analysis, the critical controlling factor on bound water saturation were screened out.The bound water in the pore space of tight sandstone comprises two components: capillary-bound water within small pores (<rcutoff) and restricted (by pore/throat < rcutoff) large pores, layered water-film within large pores (>rcutoff). The water-film within large pores is non-uniform, non-isothick, and low in content. During gas charing to reservoirs, the water-film thickness decreased gradually as the charging force increased,with a minimum thickness ranging from 0.10 to 3.72 nm. Water-film accounted for 1.75% to 22.96% of the total bound water content, with an average of 7.28%. In contrast to previous studies,we found that water-film had a negligible impact on the minimum pore/throat radius for gas charging, with only an increase of 0.7 nm. However, it significantly altered the physical characteristics, reducing gas permeability from 46.11% to 97.84%, with an average reduction of 78.37%. Furthermore, a water-film effectively eradicated the slip effect, leading to the prevalence of Darcy and diffusion flow as the primary mechanisms for gas seepage. At low pressure, diffusion flow prevails, whereas Darcy flow dominates at high pressure. I/S-mixed layer and illite exert the most significant influence on bound water saturation.

Experimental study on water transfer mechanism of quicklime modified centrifugal dewatering clay

This study investigates the water transfer mechanism of quicklime modified centrifugal dewatering clay. A small-scale centrifuge device was used to investigate the change of bound water content in modified clay under different laboratory test conditions including quicklime content and curing age, and analyze the water transfer mechanism in the process of quicklime treatment, and its impact on clay properties. The results show that the content of pore water decreased by 6.2% ∼ 16.9%, the content of bound water increased by 4.2% ∼ 12.9%, and the content of hydration water increased by 6.1% ∼ 14.1% due to hydration reaction caused by the quicklime. The increase of quicklime content facilitates the conversion of free water into bound water and hydration water in a relatively short time. The pozzolanic reaction occurs on the surface of the clay particles to absorb free water and convert it into bound water, while part of Ca (OH)2 crystals generated by hydration reaction adhere to the surface of clay particles, grow into needle-shape and fibrous structures, and absorb free pore water and convert it into hydration water. For field applications, the mixing percentage of quicklime is recommended to be below 9% by dry weight. From the cost perspective, 7-day curing age is recommended in the field. The essence of quicklime modification is to transform the free water with relatively low pF potential energy into the bound water and hydration water with relatively high pF potential energy. A schematic diagram of water transfer mechanism was also proposed in this study for quicklime modified clay and validated using the aforementioned experimental data.

New insight into the additives in preparation and reduction of shield slurry

In the preparation of the slurry in the slurry shield (SSS) and subsequent reduction of the waste slurry produced by the slurry shield (WSSS), the additives in SSS improve the quality of filtration cake on the excavation surface, but they may also remain in WSSS, which have a negative impact on the reduction efficiency of WSSS. Therefore, it is valuable to establish the relationship between SSS and WSSS with additives as a link. Given this, this paper prepared WSSS with different dosages of additives and studied the influence of residual additives on the reduction. The residual additives made the reduction efficiency of WSSS worse, and the specific resistance to filtration increased by one to two orders of magnitude. The residual additives change the content of bound water or reduce the available sites of the soil particles that can be adsorbed by flocculants, leading to worse reduction results. To reduce the difficulty of reduction, combining polymer and bentonite as additives are recommended to prepare SSS. Polyaluminium chloride (PAC) acts by reducing bound water content through the interaction with residual bentonite, simultaneously augmenting PAM flocculation, which is recommended for reducing WSSS. This paper provides a reference for selecting materials used to prepare SSS and the subsequent reduction of WSSS.

Enhancing data reliability in quantitative characterization of moisture distribution in sludge using DSC: Impact of sample attributes and test parameters

Exploring moisture distribution, especially bound water content, is vital for studying and applying sludge dewatering. The differential scanning calorimetry (DSC) method has been extensively utilized for the quantitative characterization of moisture distribution in sludge. However, this method has certain limitations, such as low reproducibility of results, leading to controversial parameter values in different papers and hindering result comparison. In this study, we investigated the influence of key sample attributes on measuring sludge bound water using the DSC method.The findings demonstrated that the moisture content and mass of sludge samples substantially influenced the reproducibility and stability of DSC test results. To ensure data reliability, the moisture content of the sludge sample should be minimized and kept below 84%, with the mass not exceeding 10 mg. Compared to the influence of sludge moisture content and sample mass, the heating rate (1⁓5 °C/min) minimally affected DSC test results. This study offers a comprehensive insight into how sample attributes and test parameters affect the quantitative characterization of bound water in sludge using the DSC method. Furthermore, practical strategies are presented to enhance the method's applicability in sludge bound water characterization.

Effect of direct electric curing on the mechanical properties, hydration process, and environmental benefits of cement-steel slag composite

Steel slag (SS) is a solid waste produced from the steelmaking process. The weak early hydration activity of steel slag limits its application in cementitious materials. This study attempts to improve the early-age performance of cement-SS composite by direct electric curing (DEC) to broaden the application of SS in cementitious materials. Specifically, The study involves continuous monitoring of performance changes of the specimens over time, with a particular focus on early-age characteristics. The change in strength and capillary water absorption of the hardened paste are evaluated. The pore size distribution and content are investigated by BET, and the effects of DEC on the hydration process of cement-SS composite are determined by XRD, TG, and BSE. The results demonstrate that DEC effectively improves the early-age strength of specimens. The 1d strength of the specimens increased by more than 50% at 50% steel slag dosage. Additionally, DEC effectively reduces the pore size. DEC does not change the type of hydration products of the paste but effectively accelerates the hydration process of the cement-SS composite. This accelerated reaction leads to a notable increase in calcium hydroxide and bound water content at an early age, consequently improving the degree of hydration reaction in steel slag. SEM-BSE analysis revealed changes in the atomic composition of the C-S-H gel near the SS, accompanied by blurred boundaries in the morphology of SS particles. Moreover, this study analyzes the economic and environmental benefits of using cement-steel slag composite with DEC. Considering the strength factor, the cost required to obtain a unit strength by DEC is only 55.88%-71.28% of that required with standard curing method. Simultaneously, carbon emission is reduced by 28.79%-44.16%. Thus, DEC is a sustainable and practical method for promoting the utilization of steel slag in cementitious materials, offering both economic and environmental benefits.

Mechanical properties, carbon footprint and cost of ultra-high performance concrete containing ground granulated blast furnace slag

This paper deals with the possibility of formulating low-carbon UHPC by replacing cement with ground granulated blast furnace slag (GGBS). Slags of two fineness levels (420 m2/kg (SL1) and 700 m2/kg (SL2), respectively) are incorporated as volume replacements for cement at 30% and 50%. The possibility of completely replacing silica fume (SF) with superfine slag (SL2) in UHPC is also investigated.The results show that reducing the SF allows for the production of UHPC with satisfactory mechanical properties. The incorporation of 30% of GGBS (SL1 or SL2) accelerates the hydration process due to the reduced SP content and the nucleation site effect, which improves long-term compressive strength. In the presence of a high level of ordinary slag (50% of SL1), the dilution effect dominates and a decrease in compressive strength can be observed at all ages. Due to the physical effect of superfine slag, 30% of SL2 yields a high 28-day compressive strength (151.2 vs. 136.5 MPa for the SL2-based reference mix) despite the absence of SF particles. The relatively low bound water content, as determined by thermogravimetric analysis (TGA), indicates the presence of a large amount of unreacted cement, which contributes to the improved mechanical performance of UHPC mixes. A 28-day splitting tensile strength greater than 7 MPa is measured across all UHPC produced, with a maximum value of 9.2 MPa for concrete containing 30% of SL2 and without SF. A 50% SL2 UHPC with a very low carbon dioxide index (approx. 4.15 kg/m3/MPa) and a compressive strength of 139 MPa, similar to the SF-based reference mix, have indeed been achieved. However, this mixture is found to be the most expensive (at 496 €/m3), due to the high cost of superfine slag, in comparison with cement.

Experimental study on mass transfer behavior and mechanism in nuclide-containing sandy soil under temperature gradient

The level of nuclear waste emergency disposal is an important factor restricting the rapid development of the nuclear energy industry under the trend of global energy revolution. To promote the effective application of artificial ground freezing (AGF) for the treatment of nuclear wastewater leakage, the mass transfer and migration mechanism of key nuclides (137Cs, 90Sr, and 129I) during unidirectional freezing of saturated silty sand were elucidated in this study. Temperature sensors and a nuclear magnetic resonance (NMR) were used to explore the internal temperature and moisture variation characteristics of nuclide-containing sandy soil during the freezing. Furthermore, using the designed device, a unidirectional freezing of different nuclide-containing sandy soils was performed to establish a relationship between the development characteristics of the freezing front and the mass transfer of nuclide. The results show that the T2 spectrum of nuclide-containing sandy soils has the most significant change from 0 °C to -1 °C, and the bound water content of I-containing sandy soil remains evident change when the temperature decreases below -1 °C. During unidirectional freezing, owing to the influence of the freezing front on nuclide migration, the resistivity curve exhibits a V-shaped jump, and the concentration peaks appear in turn along the freezing direction and show a stepwise increase. Nuclide mobility is closely related to the freezing rate of the corresponding location. With an increase in freezing thickness, the freezing rate decreases and the nuclide mobility increases. Owing to the combined influence of water-ice phase transition, concentration gradient and matrix suction in sandy soil, the concentration only increases within a small area at the face of the freezing front. The differences in migration behavior of nuclides in sandy soil driven by temperature gradient is mainly due to the different degrees of compression of nuclide ion on the diffusion double electric layer of soil particles, which results in different forms of unfrozen water within the sandy soils. The overall mobility of the three nuclides shows the following sequence: Cs>I>Sr. In the practical application of AGF, attention should be paid to the effects caused by the rapid migration of low-valence cationic nuclides and the retention of high valence cationic nuclides in the frozen wall.

Effect of High-Voltage Electric Field on Thawing Kinetics and Quality Characteristics of Frozen Beef

This study investigated the impact of high-voltage electric field (HVEF) thawing technology on the thawing rate, water retention characteristics, microstructure, and nutritional composition of thawed beef. Compared with the control group, in which thawing occurred under natural conditions, the experimental group, in which beef was thawed under HVEF (12 kV, 16 kV, 20 kV, 24 kV, 28 kV), showed a significantly shorter thawing time, and the higher the voltage was, the faster the thawing rate. The total loss rate of thawed beef reached its minimum value of (54.2 ± 0.62) % at 28 kV, and the water retention of the experimental group was significantly better than that of the control group (p &lt; 0.05). Therefore, it can be concluded that HVEF thawing enhances the water retention ability of beef. In a color comparison, it was evident that the color of the beef thawed by HVEF was significantly better than that of the control group. The results of scanning electron microscopy (SEM) indicated that thawing beef by HVEF can reduce the damage to the myofibril structure. Low-field nuclear magnetic resonance (LF-NMR) showed that beef thawed by HVEF had a significantly increased bound water content. According to the determination of malondialdehyde content, beef thawed by HVEF had a reduced degree of lipid oxidation; the content at 16 kV was 2.4 mg/kg, and the degree of lipid oxidation was the lowest. Fourier transform infrared (FTIR) spectroscopy analysis revealed that the absorption peak positions of the beef samples did not show significant changes under different conditions. However, the absorption peak intensity in the experimental group was generally higher than that in the control group. Examination of the protein secondary structure via infrared spectroscopy revealed that, compared with the control group, HVEF thawing transformed the proteins from an ordered structure to a disordered structure. The increase in disordered structure reduced the fiber gap of the sample and improved the water retention of the beef. The above experimental results indicate that HVEF thawing can improve the water-holding capacity of the sample and reduce the thawing damage to the quality of the sample.

Evolution mechanism of the low-carbon MgO-based alkali-activated system under different heat-treatment conditions

Magnesium silicate hydrate (M-S-H) gel is the main product of MgO-based alkali-activated system (MAAS). The molecular structure and phase changes of M-S-H gel at different temperatures were characterised. The results showed that the initial MgO:SiO2 affected the Mg:Si ratio and the binding water content of M-S-H gel. With the decrease of Mg:Si ratio, the proportion of structural water in the gel decreases. Compared with structured water, the change of free water can more accurately characterise the content of M-S-H gel in the system. Below 600°C, the molecular structure and phase composition are relatively stable. When the temperature reached 1000°C, M-S-H gel transfers from amorphous phase to crystallized phase. The study characterised the evolution of MASS under different heat treatment conditions.

The Chemical Compatibility of Sand–Attapulgite Cut-Off Walls for Landfills

Soil–bentonite cut-off walls have been widely used to control landfill pollution but they do not have good chemical compatibility with landfill leachate. Attapulgite can be substituted for bentonite in landfill cut-off walls. However, little is known about the chemical compatibility of attapulgite cut-off walls and leachate. This study experimentally investigated the chemical compatibility of attapulgite cut-off wall specimens with organic and inorganic contaminants and found that a sand–attapulgite cut-off wall has good chemical compatibility with organic contaminants. A CaCl2 solution was used to represent inorganic contaminants, and chemical oxygen demand (COD) was used as an indicator of organic content. The hydraulic conductivity of the cut-off wall initially decreased and then increased to become approximately constant as Ca2+ concentration increased. Changes in COD concentration were divided into a decreasing stage (0–10,000 mg/L) and a constant stage (10,000–40,000 mg/L). The increase or decrease in hydraulic conductivity was by no more than one order of magnitude. The increase in the hydraulic conductivity of the sand–attapulgite cut-off wall is explained in terms of bound water content and pore structure. An increase in Ca2+ concentration decreased the bound water content of the cut-off wall while the CaCl2 solution increased macropore and mesopore volume and decreased small pore volume in the sand–attapulgite cut-off wall. The purpose of this study was to elucidate the chemical compatibility of a sand–attapulgite cut-off wall with organic and inorganic contaminants and to increase the understanding of the interactions between the cut-off wall and the contaminants. The results of this research are informative for improving the application, design, and construction of sand–attapulgite cut-off walls.

Characteristics and atmospheric processes of water-soluble ions in PM2.5 and PM10 over an industrial city in the National Capital Region (NCR) of India

This study investigates water-soluble inorganic ions (WSIIs), their potential formation mechanism, particle bound water content and acidity (pH) in ambient aerosols in Ghaziabad, an industrial city located downwind of Delhi, the Indian National Capital. 24-hour integrated PM2.5 and PM10 samples were collected using collocated samplers at two receptor locations every third day throughout the year. The samples were collected on Nylon filter substrates (preceded by a denuder upstream for capturing acidic gases) and Teflon filter substrates for WSII and mass measurements, respectively. Further, on-site meteorological parameters were recorded at both locations. The annual average PM concentrations observed were: PM2.5: 144 ± 81 μgm−3 (Site A), 163 ± 95 μgm−3 (Site B); and PM10: 245 ± 116 μgm−3 (Site A), 279 ± 152 μgm−3 (Site B). On average, SO42−, NO3−, Cl− and NH4+ contributed to ∼90% to PM2.5WSII mass and ∼82% to PM10WSII mass, which in turn made up ∼35% of PM2.5 mass and ∼23% of the PM10 mass across both sites. SO42− concentration was found to be highest followed by NO3−, NH4+ and Cl− for both PM fractions. Mann-Whitney U test revealed that both sites were similar with respect to WSII mass indicating city's airshed average concentration with respect to the major ions. The highest WSII contribution to the total PM was found in winter season (37–40% for PM2.5 and 27–31% for PM10) followed by monsoon (36–38% for PM2.5 and 18–21% for PM10), post-monsoon (28–34% for PM2.5 and 21–23% for PM10) and pre-monsoon (21–27% for PM2.5 and 15% for PM10). High contribution during winter was because of higher emissions of precursor gases in combination with moderate relative humidity (36–59%) and minimal precipitation (average ∼0.2 mm). Sulphur Oxidation Ratio and Nitrogen Oxidation Ratio indicated high photochemical oxidation with a greater extent of SO42− formation compared to NO3−. Although high concentrations of NH3 gas were observed, there was insufficient NH4+ ions for neutralizing counter ions with Ammonium Neutralization Ratio values of 0.76±0.14 for PM2.5 and 0.62±0.14 for PM10. Finally, aerosol liquid water content (ALWC) and acidity were estimated using a thermodynamic equilibrium model, ISORROPIA-II. It was found that PM2.5 pH varied from 2.9 to 6.2 (avg. 4.4±0.8) and the PM2.5 mass doubled at RH ∼90% because of the high particle bound water. Consequently, a reduction in SO2 would result in instantaneous cuts of SO42−, PM2.5, and ALWC.

Non-Electroneutrality Generated by Bacteriorhodopsin-Incorporated Membranes Enhances the Conductivity of a Gelatin Memory Device.

We have previously demonstrated the potential of gelatin films as a memory device, offering a novel approach for writing, reading, and erasing through the manipulation of gelatin structure and bound water content. Here, we discovered that incorporating a bacteriorhodopsin (BR)-lipid membrane into the gelatin devices can further increase the electron conductivity of the polypeptide-bound water network and the ON/OFF ratio of the device by two folds. Our photocurrent measurements show that the BR incorporated in the membrane sandwiched in a gelatin device can generate a net proton flow from the counter side to the deposited side of the membrane. This leads to the establishment of non-electroneutrality on the gelatin films adjacent to the BR-incorporated membrane. Our Raman spectroscopy results show that BR proton pumping in the ON state gelatin device increases the bound water presence and promotes polypeptide unwinding compared to devices without BR. These findings suggest that the non-electroneutrality induced by BR proton pumping can increase the extent of polypeptide unwinding within the gelatin matrix, consequently trapping more bound water within the gelatin-bound water network. The resulting rise in hydrogen bonds could expand electron transfer routes, thereby enhancing the electron conductivity of the memory device in the ON state.

Improving capillary water absorption of high-volume fly ash mortar by curing temperature and limestone addition

The effects of curing temperature (20°C, 40°C and 60°C) and the addition of limestone powder (LP) (6% and 12%) on the capillary water absorption (CWA) of high-volume fly ash (HVFA) cement mortar were investigated. X-ray diffraction analysis and tests for chemically bound water content (CBWC), compressive strength and porosity were also conducted. It was found that, for a fly ash (FA) content exceeding 30%, the CWA increased significantly. When the FA content was 50%, the curing temperature was raised to 40°C or the LP content was 12%, the CBWC increased greatly. Increasing the curing temperature or adding LP increased the compressive strength and decreased the porosity of the HVFA cement mortar. Prediction of the water penetration depth in the HVFA cement mortar was consistent with the CWA results. The results of this work indicate that an increase in curing temperature or the addition of LP could be an efficient way of improving the CWA performance of HVFA cement mortar.

Hydrocolloids-aided control of oil penetration and distribution in deep-fried breaded fish nuggets

To investigate the effect of hydrocolloids on oil penetration and distribution in fried batter-breaded fish nuggets (BBFNs), sodium carboxymethyl cellulose (CMC-Na), guar gum (GG), and xanthan gum (XG) were individually blended (0.2 or 0.3%, w/w) into the mixture (1:1, w/w) of wheat gluten (WG) and wheat starch (WS) to form batters. The moisture absorption capacity of XG was found to be the highest, followed by CMC-Na, GG, WG, and WS. Hydrocolloids increased the batter viscosity, shear modulus, WS gelatinization and WG denaturation temperatures, BBFNs pick-up, thermogravimetry temperature, and the bound water content in crust. This trend was opposite with enthalpy change (ΔH) during starch gelatinization and protein denaturation, both of which lessened pores and cracks, leading to an inhibition of oil penetration into fried BBFNs. Of the three hydrocolloids, XG exhibited the greatest effect, followed by CMC-Na and GG. Therefore, XG was suitable for reducing fat content of fried BBFNs. Overall, the hydrophilic and thickening capabilities of the three studied hydrocolloids and their interactions with WS and WG altered the batter characteristics and reinforced the thermal stability of the crust, thereby reducing oil penetration and distribution in deep-fried BBFNs. This work will not only provide new ideas to clarify oil penetration based on hydrocolloids for fried BBFNs, but also provide scientific instructions for the large-scale production of low-fat fried batter-breaded foods.

Microwave-Induced Behavior and Digestive Properties of the Lotus Seed Starch-Chlorogenic Acid Complex.

The effect of chlorogenic acid (CA) on the dielectric response of lotus seed starch (LS) after microwave treatment, the behavior and digestive characteristics of the resulting starch/chlorogenic acid complex (LS-CA) at different degrees of gelatinization and the inhibition of α-amylase by chlorogenic acid were investigated. The variation in dielectric loss factor, ε″, and dielectric loss tangent, tanδε, of the microwave thermal conversion indicated that LS-CA had a more efficient microwave-energy-to-thermal-energy conversion efficiency than LS. This gelatinized LS-CA to a greater extent at any given temperature between 65 and 85 °C than LS, and it accelerated the degradation of the starch crystalline structure. The greater disruption of the crystal structure decreased the bound water content and increased the thermal stability of LS-CA compared to LS. The simulated in vitro digestion found that the presence of the LS-CA complex improved the slow-digestion property of lotus seed starch by increasing its content of resistant and slowly digested starch. In addition, the release of chlorogenic acid during α-amylase hydrolysis further slowed starch digestion by inhibiting α-amylase activity. These findings provide a foundation for understanding the correlation between the complex behavior and digestive properties of naturally polyphenol-rich, starch-based foods, such as LS, under microwave treatment, which will facilitate the development of starch-based foods with tailored digestion rates, lower final degrees of hydrolysis and glycemic indices.

Changes in the quality and protein structure of steamed bread under different quick‐frozen temperatures

AbstractBackground and ObjectivesThe quick‐frozen temperature may affect the quality of frozen food. The aim of this research was to investigate the effects of different quick‐frozen temperatures on the quality and protein structure of steamed bread.FindingsWith the decrease of quick‐frozen temperature, the water holding capacity and glutenin macropolymer content of frozen steamed bread increased, and the protein network structure in the steamed bread system was less damaged. A significant decrease of β‐sheet and random coils was found, from 48.6% to 39.4% and 24.1% to 21.9%, respectively. The significant decrease of A23 content and the melting enthalpy indicated that the frozen water content decreased and the bound water content in steamed bread increased. Steamed bread had higher springiness and cohesiveness at −32°C and −36°C.ConclusionsThe quality of steamed breads was better when quick‐frozen temperatures were at −32°C and −36°C. Therefore, from the perspective of more energy saving and environmental protection, steamed bread can be rapidly frozen at −32°C.Significance and NoveltyDifferent quick‐frozen temperatures have different effects on each index of steamed bread, which provides a certain theoretical basis for the quick‐frozen process of steamed bread.

Effect of Rehydration on Properties of Cement-Fly Ash System

In this article, the effects of rehydration on the performance of cement-fly ash systems were investigated by conducting rehydration tests of cement-fly ash systems under low water-binder ratio conditions, testing the chemically bound water content, expansion rate, and strength of specimens at different rehydration ages, combined with the alkalinity of pore solution, pore structure and micromorphology. The results show that the lower the water-binder ratio is, the higher the water content of the rehydration combination in the early stage is, but the lower it is in the later stage. The higher the fly ash content is, the lower the rehydration degree of the system will be. An alkaline environment is more effective in enhancing rehydration. The expansion rate of the specimen increases with the decrease of the water-binder ratio. The strength of the specimens with the water-binder ratio of 0.18 showed an alternating trend of increasing and decreasing with the increase of rehydration age, indicating that rehydration is a simultaneous process of repair and damage.

Effects of tamarind seed polysaccharides on physicochemical characteristics of frozen dough: structure-function relationship.

Recently, frozen dough has become more popular because of its ability to be quickly transformed into freshly baked foods. During the storage and transport process, frozen dough can suffer some degree of damage caused by ice crystallization and recrystallization. Adding polysaccharides to frozen dough is a good way to solve this problem. Tamarind seed polysaccharide (TSP) has excellent ice crystal steady ability and has also been widely used in frozen foods. However, there is no study on the use of TSP in frozen dough. TSP can stabilize the bound water content, inhibit the freezable water content, and increase elasticity. However, the dough with different structures of TSP added was less firm after 30 days of freezing compared to the dough without TSP, and the porosity and stomatal density of the prepared steamed bread gradually decreased. The addition of TSP reduced gluten deterioration during the freezing process, thus decreasing the collapse and uneven porosity of the steamed bread. The results could provide new insights into the structure of TSP and its effect on the quality characteristics of frozen dough. © 2023 Society of Chemical Industry.

Effect of popping and milling on physical, chemical, structural, thermal properties and angle of repose of amaranth seed (Amaranthus cruentus L.) and finger millet (Eleusine coracana L. Gaertn) from Udhagamandalam

The study was conducted to examine the effect of popping and milling on selected properties of amaranth and finger millet from Udhagamandalam. The amaranth and finger millet are cleaned, popped at high temperature for short time in an open pan method, and pulverised using a mixer at the laboratory. Water activity had decreased as the heat processing had reduced the bound water content 0.53 to 0.23. Alcoholic acidity had elevated levels in popped and pulverised grains in comparison to native grains. Grains showed a major change in surface area and porosity in the range of 0.12 to 1.20 m2/g and 3.20 to 4.54 Å. The intensity of the colour had shown higher in amaranth samples and lower on finger millet upon processing in the range of 44-74 L*, 4-7 a* and 2.8-11.6 b*. Crystallinity had shifted from A-shaped curves to a single V curve during processing. The native material underwent various treatments and decreased apparent and compact bulk density in comparison to native grains significantly from 0.82 to 0.14 and 0.69 to 0.35 in amaranth and finger millet respectively. The processing has improved overall physio-chemical properties.