Apparent Water Research Articles

Mechanical properties and flow characteristics of dolomite-based porous supports for catalysts using different pore-forming agents

Three kinds of pore-forming agents (corn flour, starch, and biochar) were selected to prepare dolomite-based porous ceramic catalyst carriers with good mechanical properties. Pore-forming agents occupy space within preformed agglomerates, such that after the pyrolysis and sintering have been completed there are spaces within the resulting ceramic material. Porous ceramic samples prepared with biochar exhibited high apparent porosity and water absorption. By contrast, the apparent porosity of the porous ceramic samples prepared with starch as the pore-forming agent was low. When the ratio of the dolomite to quartz sand in the ceramic aggregate was changed from 4:6 to 3:7, the change of the apparent porosity of the porous ceramic samples made with starch as a pore-forming agent was very small, with high bulk density and compressive strength. Compared with corn flour and biochar, starch was less suitable as a pore-forming agent for porous ceramics. The apparent porosity and water absorption of the porous ceramics prepared with biochar as a pore-forming agent decreased slightly. But its bulk density and thermal conductivity were increased. This is mainly attributable to the fact that biochar is lighter, but it performs well in terms of mechanical strength and thermal conductivity.

Influence of Thermal Treatment of Moroccan Red Clay on its Physicochemical and Mechanical Behavior

AbstractRed clay is considered to be of significant value to the economy in Morocco, particularly in the Safi region, because of its abundance. This raw material has long been known for its quality in the manufacture of clay materials, but its use was limited to traditional ceramics. The red clay raw material was the subject of the current study with the objective of opening new industrial applications that will give added value to the Safi red clay. The physicochemical, mineralogical, and thermal properties of the Moroccan red clay were determined by X-ray fluorescence (XRF), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) analysis, X-ray diffraction (XRD), oriented aggregate, and particle-size analyses, powder density by helium pycnometry, carbonate content using the Bernard method, differential thermal analysis (TG–DTA), and the BET surface area. The compacted dry powder particles were calcined at three sintering temperatures: 900, 1000, and 1100°C for 2 h. The effect of sintering temperature on ceramic properties, such as apparent porosity, water adsorption, bulk density, and mechanical strength, was examined. Dense ceramics with lower porosity and greater mechanical resistance (~300%) were produced by increasing the sintering temperature from 900 to 1100°C. The conclusion was that the evolution of physicochemical and thermal properties is related to mineralogical changes, which show that anorthite is the major phase at higher temperatures.

Penerapan Jaringan Distribusi Sistem District Meter Area (DMA) SPAM Semarang Barat dalam Optimalisasi Penurunan Kehilangan Air Ditinjau dari Aspek Teknis dan Finansial (Studi Kasus : Area Pelayanan Reservoir Manyaran 1)

Drinking water is one of basic human needs that is very important to improve the quality of human life and economic growth of a region. PDAM Tirta Moedal, Semarang City developed “SPAM Semarang Barat” 1,000 liters/sec to serve water demand in West Semarang, Ngaliyan and Tugu sub-districts. Water losses in PDAM Kota Semarang is still at 40.10%, indicating that water distribution is not optimal. DMA is a strategy in managing water loss, especially real water loss, by dividing an open water supply network into isolated zones with smaller water meter. In this study, a technical and financial study was conducted regarding the implementation of DMA in the SPAM Semarang Barat distribution specifically for the Manyaran 1 Reservoir service area . The real water loss is caused by visible or invisible leakage of distribution pipes (background leakage). The billed authorized consumption is estimated at 4,189,607 m3/year, the unbilled authorized consumption is 7,361 m3/year. Apparent water loss is estimated at 147,455 m3/year or about 2%, while real water loss is around 2,172,896 m3/year or about 34%. The Infrastructure Leakage Index or ILI for the Manyaran 1 Reservoir distribution is 49. It means that PDAM is wasting some resource, which caused losses. Epanet 2.0 shows that peak hours pressure is between 30 – 70 m, there is no pressure below 10 m. Velocity at peak hours is in the range of 0.1 – 1.0 m/s. The investment requirement for DMA development in the Manyaran 1 service area Rp. 18,786,292,828, - for development of services as much as 5,843 SR. District Meter Area in distribution system is estimated to reduce the leakage rate by up to 20%, so that the potential revenue will increase by Rp. 26,083,764,633,-. It means that DMA is one of ways to solve water leakage problem.

Effect of Gamma Irradiation on Shelf Life, Nutritional, and Glycemic Properties of Three Indian Brown Rice Varieties

Brown rice (whole grain, BR) has lower glycemic index (GI), is a healthy replacement for white rice (WR). However, BR has a short shelf life, is susceptible to pest infestation. Gamma irradiation is a safe approach to prevent the latter. This study examines effect of gamma irradiation on the physical, cooking, nutritional, shelf life and glycemic properties of three Indian parboiled BR. Parboiled BR of ADT-43, BPT-5204, and Swarna rice varieties were packed in polyester and polypropylene pouches (60 µ thickness) and subjected to gamma irradiation [750–820 Gy] (IR). Appropriate controls without irradiation (NIR) were maintained. Irradiation did not induce major changes in the physical and nutritional properties, except for resistant starch which significantly increased after irradiation in ADT-43 and BPT-5204. Irradiation reduced the cooking time, increased loss of solids in the cooking water and decreased apparent water uptake (particularly in BPT-5204). IR varieties exhibited longer shelf life (8–9 months) compared to 6 months shelf life of NIR varieties. The shelf stability of IR Swarna rice was superior in terms of delayed rancidity development compared to all other rice. All BR samples exhibited the ranking of ‘like moderately’ in the sensory acceptability tests at 6 months of storage and scores decreased subsequently. Irradiation did not affect GI [all showed medium GI, except a high GI for IR BPT 5204] and helped in shelf life extension of parboiled BR by preventing insect infestation.

Polyols and Polyurethane Foams Obtained from Mixture of Metasilicic Acid and Cellulose.

Hydroxyalkylation of the mixture of metasilicic acid and cellulose with glycidol and ethylene carbonate leads to a polyol suitable to obtain rigid polyurethane foams. The composition, structure, and physical properties of the polyol were studied in detail. The obtained foams have apparent density, water absorption, and polymerization shrinkage, as well as heat conduction coefficients similar to conventional, rigid polyurethane foams. The polyols and foams obtained from environmentally unobtrusive substrates are easily biodegradable. Additionally, the obtained foams have high thermal resistance and are self-extinguishing. Thermal exposure of the foams leads to an increase of the compressive strength of the material and further reduces their flammability, which renders them suitable for use as heat insulating materials.

Investigating the Effect of Different Parameters on Physical Properties of Metakaolin-Based Geopolymers

Recently, geopolymers have received widespread attention due to their ability to completely replace ordinary cement with better efficiency, lower cost, and less damage to the climatic environment. This paper aimed to prepare MK-based geopolymer cement at ambient temperature with different alkaline activators and processing parameters. XRD, PSA, DTA-TGA, SEM, and other techniques have characterized the prepared samples. ANOVA test was employed to identify the main effect of the processing parameters. Results showed that the incorporation of potassium ions has a negative effect on the physical properties of GP, in which the presence of such ions tends to decrease the density of GP. Furthermore, the apparent porosity and water absorption were increased. For Na and K, Na-activated GP, it was also concluded that the density of GP increases by increasing Si/Al ratios. Despite the Na-based GP processes having a larger density in compared to the K, Na-based ones. The results also suggested a strong effect of the WMK ratio on physical properties, in which decreasing this ratio is necessary to achieve GP with better properties. The findings also revealed that a one-minute mixing period was sufficient for producing a homogeneous and dense GP paste.

A comprehensive comparison of facial skin hydration based on capacitance and conductance measurements in Chinese women.

The aim of this study was to compare the data of conductance and capacitance measurements of facial skin hydration and to evaluate and discuss the advantages and disadvantages of the different approaches. We measured skin capacitance (Corneometer® CM 825) and skin conductance (Skicon-200EX®) on 30 pre-defined facial sites of 125 Chinese women, resulting in 3750 readings per device. The data were analysed and compared, and continuous colour maps were generated on a 3D avatar for capacitance, conductance, relative difference (Δ%) and correlation (R-value) by interpolating between the individual readings and converting the values to colours. This visualization allows a better interpretation of the results. The complexity of facial skin hydration is revealed by this approach. The similarities and discrepancies in the facial hydration maps are clearly apparent. Due to the superiority of the Skicon in measuring high hydration levels, differences in skin hydration were evident on the forehead compared with the Corneometer maps, which may be related to the more superficial measurement of the Skicon within the stratum corneum. Conversely, a greater understanding of the complexity of facial skin hydration in the nasolabial fold was obvious when using the Corneometer. The best congruence between the instruments was found at two specific but separated facial areas, one around the inner eye region and the other one on a line between the nasolabial sulcus and the oblique, lateral jaw. Interestingly, the data were not normally distributed for both instruments and they had opposite skews. All facial clusters were statistically different from each other (p< 0.001), except the cheek and jaw for the Skicon. Larger than expected percentage coefficients of variance were found for the Corneometer on some facial sites that might be explainable by differences in stratum corneum physiology and biochemistry. Corneometer values of 48 AU and Skicon values of 132 μS were taken as the cutoff for normally hydrated facial skin. Both devices have their advantages and disadvantages suggesting that bio-instrumental measurement of skin hydration is actually more complicated than commonly thought and that the different facial zones and the use of multiple instrumentation have not been adequately considered.

Relative lake level reconstructions for glacial Lake Agassiz spanning the Herman to Campbell levels

Lake Agassiz was the largest North American pro-glacial lake during the last deglacial period, and the routing of the overflow is hypothesized to have affected thermohaline circulation and in turn, global climate. Here an existing glacial isostatic adjustment model is applied to Campbell beach strandline data to synthesize and correlate published radiocarbon- and OSL-dated lake level indicators in an effort to produce relative lake-level curves and a drainage history. The curves highlight where the water level history of Lake Agassiz is well understood, and where additional work is necessary. Many OSL-dated strandlines between 14.5 and 13.2 ka record meltwater routing through a southern outlet to the Gulf of Mexico during this time, and that lake levels fell due to sill incision and glacial isostatic adjustment (GIA). Oxygen isotope records from marine sediments tracking continental runoff, plus deglacial isochrones, suggest eastern outlets to the Atlantic Ocean opened at around 13.2 ka, near the onset of the Younger Dryas (YD) stadial, but the evidence within the basin is scant. At some point during the YD, Lake Agassiz overflow shifted to a northwestern outlet into the Arctic Ocean, and the reconstructed lake levels track lake-level rise driven by uplift of the northwestern outlet, which eventually transferred water to the southern outlet to create the Campbell level of Lake Agassiz. The apparent shallow water depth (∼4 m) of overflow at the southern outlet relative to earlier phases suggests multiple active outlets at this time (northwestern, southern, and perhaps eastern). Oxygen isotope records from the Gulf of Mexico indicate overflow via the southern outlet occurred in two brief phases, likely explained by an oscillating ice margin that regulated overflow. Considerable work remains to assess the timing of deglaciation to understand when Lake Agassiz first drained east and north. Lacking are details of eastern drainage and any dated stratigraphic record of likely lake level fluctuations during the Younger Dryas.

Oxidation of Cysteine by Electrogenerated Hexacyanoferrate(III) in Microliter Droplets.

Chemical reactivity in droplets is often assumed to mimic reactivity in bulk, continuous water. Here, we study the catalytic oxidation of cysteine by electrogenerated hexacyanoferrate(III) in microliter droplets. These droplets are adsorbed onto glassy carbon macroelectrodes and placed into an immiscible 1,2-dichloroethane phase. We combined cyclic voltammetry, optical microscopy, and finite element simulations to quantify the apparent bimolecular rate constant, kc,app, in microdroplets and bulk water. Statistical analyses reveal that the apparent bimolecular rate constant (kc,app) values formicrodroplets are larger than those in the continuous phase. Reactant adsorption to the droplet boundary has previously been implicated as the cause of such rate accelerations. Finite element modeling of this system suggests that molecular adsorption to the liquid|liquid interface cannot alone account for our observations, implicating kinetics of the bimolecular reaction either at the boundary or throughout the microliter volume. Our results indicate that cysteine oxidation by electrogenerated hexacyanoferrate(III) can be accelerated within a microenvironment, which may have profound implications on understanding biological processes within a cell.

An Investigation on the Synthesis of Alkali Activated Materials from Thermally Modified Clays

The sustainability and economic competitiveness of alkali activation technology greatly depends on expanding the raw materials database with locally available resources. Therefore, a notable trend has been witnessed toward the exploitation of common clays as alternatives to well-established solid aluminosilicate precursors due to their availability and wide geographical distribution. However, common clays are complex and dedicated research is needed to tailor synthesis procedures and mix designs for different clay resources. This paper describes the outcomes of a study conducted to investigate the influence of several synthesis parameters (solid-to-liquid ratio, NaOH molarity, Si availability, and curing conditions) on the properties of alkali activated binders produced from different thermally modified clays. Optimal synthesis conditions for benchmark metakaolin systems have been identified and binders were produced with progressive dosages of metakaolin replacement by common local clays. Fundamental physical and mechanical properties such as apparent density, open porosity, water absorption, and compressive strength were examined at different curing ages, and X-ray diffraction (XRD) was used to provide complementary mineralogical insights. By combining the effects of the parameters studied, mortar specimens were produced with the developed binders, reaching compressive strength values exceeding 28.2 ± 0.1 MPa, a bulk density as low as 1.78 ± 0.0 g/cm3, and open porosity and water absorption values lower than 15% and 8%, respectively. These properties are comparable to those of conventional hydraulic products, which presents them as interesting candidates for construction. Ultimately, this work aims to contribute with valuable insights toward the valorization of a large group of unexploited clay precursors by demonstrating the feasibility of producing technologically competitive alkali activated materials with little or no use of the prime precursors, thus adding to the extant knowledge and contributing to future scientific and industrial developments in this field.

Combining 14CDOC and 81Kr with hydrochemical data to identify recharge processes in the South German Molasse Basin

• Combination of 14 C DOC and 81 Kr provides new insight of recharge dynamics in the UJA. • Groundwater dating with 14 C DOC and 81 Kr proves to be useful for deep aquifers. • Groundwater dating revealed high spatial heterogeneity in groundwater ages. • The main recharge area of the UJA may be located at the southern border of the SGMB. • Glaciations may be the driving force for groundwater recharge. To face the challenges of ongoing climate change, renewable energy sources are needed to reduce CO 2 emissions to the atmosphere. The South German Molasse Basin (SGMB) contains an important geothermal aquifer in Germany; however, an enhanced understanding of the flow regime at the basin scale remains a fundamental limiting factor in assessing a long-term and sustainable strategy for using this green energy source. Here we report 14 C DOC and 81 Kr groundwater dating results together with hydrochemical data, stable water isotopes, noble gases and out-diffusion experiments that indicate that the thermal groundwater consists of at least two groundwater sources: a formerly unknown young groundwater component with apparent water ages between 9,800 and 18,700 a and an old groundwater component, which shows an apparent water age of up to approximately 300 ka. The results of the out-diffusion experiments with core material from the Upper Jurassic aquifer (UJA) suggest that diffusion processes between rock-matrix water and more mobile fracture water represent a controlling mechanism for groundwater flow and the observed extended apparent groundwater ages within the UJA. The observed elevated 14 C DOC activities and the high spatial heterogeneity in groundwater ages close to the southern margin of the SGMB were interpreted as a recharge zone of the system. The combination of the 14 C DOC and 81 Kr methods shows the potential as a powerful groundwater dating tool for deep aquifers.

REAL WATER SAVINGS OF SIMULATED IRRIGATION METHODS AND FARM MANAGEMENTS IN SUGARCANE: CASE STUDY IN MALANG REGENCY

Water scarcity problem in East Java threatens Indonesia's sugarcane production. Various water conservation techniques are carried out to reduce water use and achieve optimal production. This study aimed to analyze the real water savings of various irrigation methods and farm managements commonly used by farmers to respond to water drought and increase crop production in Malang Regency. AquaCrop modeling software and REWAS tools were used to simulate sugarcane production under various conditions and calculate real water savings from each scenario. The results showed that irrigation methods were able to increase crop yields compared to rainfed farming. Good farm managements were also able to produce yields two times higher compared to minimum managements. Without good managements, irrigation did not show higher water productivity than rainfed agriculture. By changing the irrigation method from furrow irrigation to drip irrigation, it was only able to achieve real water savings up to 14% compared to the apparent water savings which is up to 84%. The above results do not intend to prevent drip irrigations and good farm managements use, instead to emphasize the importance of proper calculations on real water savings at the basin level in terms of water scarcity. Future study is required to acquiring a better knowledge of real water savings in sugarcane through field experiments.

Thiolated 2-Methyl-β-Cyclodextrin as a Mucoadhesive Excipient for Poorly Soluble Drugs: Synthesis and Characterization.

Thiolated cyclodextrins are structurally simple mucoadhesive macromolecules, which are able to host drugs and increase their apparent water solubility, as well as interact with the mucus layer prolonging drug residence time on the site of absorption. The aim of this study was to synthesize through green microwave-assisted process a freely soluble thiolated 2-methyl-β-cyclodextrin (MβCD-SH). Its inclusion complex properties with dexamethasone (Dex), a poor water soluble drug, and mucoadhesive characteristics were also determined. The product was deeply characterized through NMR spectroscopy (2D COSY, 2D HSQC, 1D/2D TOCSY, and 1D ROESY), showing a thiolation degree of 67%, a selective thiolation on the C6 residues and a monomeric structure. The association constant of MβCD and MβCD-SH with Dex resulted in 2514.3 ± 32.3 M−1 and 2147.0 ± 69.3 M−1, respectively, indicating that both CDs were able to host the drug. Microrheological analysis of mucin in the presence of MBCD-SH showed an increase of complex viscosity, G′ and G″, due to disulphide bond formation. The cytotoxicity screening on fibroblast BALB/3T3 clone A31 cells indicated an IC50 of 27.7 mg/mL and 30.0 mg/mL, for MβCD and MβCD-SH, respectively. Finally, MβCD-SH was able to self-assemble in water into nanometric structures, both in the presence and absence of the complexed drug.

Radium isotope assessment of submarine groundwater discharge and associated nutrient inputs in Eastern Liaodong Bay, China

The accurate assessment of submarine groundwater discharge (SGD) and associated nutrient fluxes plays a significant role in water resources management and ecological environment protection in the coastal area. Currently, Liaodong Bay has become one of the most polluted marine areas in China. However, the nutrient fluxes carried by the SGD and its environmental effects have not yet been thoroughly reported in eastern Liaodong Bay, China. In this study, the distribution of 224Ra/223Ra activity ratio and its influencing factors under the geochemical conditions were explored. The activity of radium was affected by the water type and the geochemical factors. The radium isotopes in seawater were positively correlated with the ratios of Mg2+/Na+ and Ca2+/Na+ but negatively correlated with salinity and SO42−. The average apparent water age was evaluated to be 13.0 days. Furthermore, based on the radium mass balance model, the total average SGD flux was calculated to be 1.31 × 108 m3 day–1. The nutrient fluxes carried by the SGD were 7.16 × 107, 1.01 × 106, 1.61 × 107, 0.92 × 106, and 5.41 × 107 mol day−1 for DIN, DIP, NH4+, NO2−, and NO3−, respectively. The nutrient inputs through the SGD have an average DIN : DIP ratio of 70, which was able to seriously affect the ecological environment. The SGD-derived nutrient fluxes were higher than the local river input, which demonstrated that the SGD was a major source of nutrients affecting regional marine ecosystems.

Facile fabrication of durable and flexible superhydrophobic surface with polydimethylsiloxane and silica nanoparticle coating on a polyethylene terephthalate film by hot-roll lamination

Practical applications of superhydrophobic surfaces have been limited by several disadvantages such as complex fabrication processes, high modification cost, and low mechanical durability. In this study, we present a facile and low-cost fabrication method to make flexible superhydrophobic films by a hot-roll lamination process. The film consists of a hydrophobic polydimethylsiloxane (PDMS) and hydrophobic silica nanoparticle (SNP) composite coating layer on a polyethylene terephthalate (PET) film. The coated film displayed excellent superhydrophobic properties with an apparent water droplet contact angle of 176.3° and a sliding angle of 2.4°. The surface morphology, roughness, and cross-section chemical composition of the coated films were investigated by field emission scanning electron microscopy and confocal laser scanning microscopy. The mechanical durability of the coated films was evaluated using several tests such as scratching with sandpaper, repeated bending deformation, and adhesion tape tests. The fabricated superhydrophobic films still showed superhydrophobic behavior after 20 tape tests. In addition, the fabricated superhydrophobic films exhibited strong mechanical durability, which preserved their very high contact angle >160° and very small sliding angle <10° after a 350 cm abrasion test with 240 grit sandpaper and a pressure of 1.2 kPa. Also, the coated sample exhibited very stable superhydrophobicity after 100 bending cycles due to the elasticity of PDMS. The chemical stability of flexible PDMS/SNP coated PET films was also investigated in acidic, neutral, and alkaline solutions and showed excellent chemical stability in acidic and neutral media in contrast to the alkaline medium. The obtained results demonstrated the outstanding robustness of the fabricated flexible superhydrophobic films that are promising for self-cleaning and water droplet bouncing performance. • Superhydrophobic surfaces were fabricated by a facile method without toxic chemicals. • The durability of the superhydrophobic films was demonstrated by abrasion and tape tests. • The fabricated films exhibited good flexibility in bending tests. • The self-cleaning property of the fabricated coated surfaces was also observed.

PHYSICOCHEMICAL CHARACTERIZATION OF FERMENTED BOKASHI COMPOST PRODUCED ON FARM IN SOUTHERN BRAZIL

Bokashi is fermented organic compost capable of improving the physical, chemical, and biological conditions of the soils. The compost action in the agricultural production system is influenced by its preparation, resulting in products with different physicochemical characteristics. The study aimed to characterize bokashi produced on-farm and compare it with commercial products. The produced composts in southern Brazil were obtained through efficient microorganisms (EM), collected in an area of permanent preservation, and kefir. Two commercial composts were used for comparison (Plantae FertTM and Bokashi Sementes BrasilTM). Physical characteristics related to apparent specific gravity, water content, and water retention capacity and chemical characteristics related to nutrient contents, pH, and electrical conductivity were analyzed. For the physical characteristics, the mean and standard deviation were determined. The data from chemical parameters were submitted to the analysis of variance, and the means were compared by the Tukey test with 5% significance. Bokashi produced on-farm and commercial Bokashi showed similar physical characteristics. Commercial bokashi composts showed higher contents of nutrients than the composts produced on-farm. The analyzed composts showed adequate physicochemical parameters, with no factors limiting their use in agriculture.

Preparation of non-sintered sewage sludge based ceramsite by alkali-thermal activation and hydration mechanism

The recycling of sewage sludge (SS) and fly ash (FA) is significant for the disposal of increasing solid waste. In this study, SS and FA were used as raw materials, and sodium hydroxide (NaOH) and calcium oxide (CaO) were used as alkali activators to prepare non-sintered ceramsite under room temperature curing, and the optimal preparation conditions for the ceramsite were determined through single-factor experiments. Alkaline-thermal activation (ATA) was used to enhance the activity of SS and FA, and the results showed that the activities of SS and FA after ATA were largely improved, and composite activation by CaO and NaOH is more effective than that by either CaO or NaOH. The formed abundant sodium silicate hydrate (N-A-S-H) gels and few hydrated calcium silicate (C-A-S-H)/hydrated silicate (C–S–H) gels can bind well with the particles inside the ceramsite to form the denser structure. In addition, the cylindrical compressive strength of the ceramsite can reach 7.43 MPa, while the apparent density, bulk density, and water absorption are 2603 kg/m3, 852 kg/m3, and 8.37%, respectively under the conditions that the ratio of SS to FA is 8: 2, 9 wt% NaOH and 6 wt% CaO and 600 °C thermal activation, which can meet the standard of ceramsite (GB/T 17431.1–2010). This study provides an effective way for the utilization of SS and FA.

Effects of Carbon Chain Length of Acrylate Monomer on Sizing Properties of Locust Bean Gum-g-P (AA-co-Acrylate)

In order to impart good application properties to locust bean gum size for all-polyester yarn, a series of acrylate monomers including methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and common hydrophilic monomer–acrylic acid were grafted onto molecular chains of native locust bean gum to obtain locust bean gum- g-P(AA-co-acrylate) products with similar grafting ratios through Fenton’s reagent, respectively. The effects of carbon chain length of the series of acrylates on sizing properties of the grafted locust bean gum for polyester warp were studied. It was found that by grafting acrylates onto the molecular chains of locust bean gum the sizing properties of the locust bean gum were improved markedly. Under the condition of similar grafting ratios, locust bean gum- g-poly(AA-co-methyl acrylate) showed the highest apparent viscosity, water solubility, film strength, wettability, and adhesion to polyester fiber in all the grafted locust bean gum prepared. Meanwhile, locust bean gum- g-poly(AA-co-butyl acrylate) and locust bean gum- g-poly(AA-co-2-ethylhexyl acrylate) had the highest wear resistance and elongation of sizing film, respectively. The modified locust bean gum grafted with acrylate monomers with different carbon chain lengths was able to meet various requirements in the sizing process for polyester yarn.

Characterization of sustainable mortar containing high-quality recycled manufactured sand crushed from recycled coarse aggregate

The current utilization of low-quality recycled fine aggregate sourced from concrete waste acting as river sand replacement cannot achieve the preparation required for high-quality recycled mortar, due to abundant existence of hardened old mortar in recycled fine aggregate. In this work, an innovative and viable approach is proposed to crush recycled coarse aggregate into recycled manufactured sand, which has high-quality properties similar to the manufactured sand crushed from natural stone, for preparing high-quality recycled mortar with high strength and good durability. The results showed that recycled manufactured sand constituted by large proportion of natural stone particles and small proportion of old mortar, owned higher apparent density and lower water absorption than recycled fine aggregate. Incorporating recycled fine aggregate increased the drying shrinkage and decreased the mechanical strength; however, the substitution of natural river sand by recycled manufactured sand in mortar decreased the drying shrinkage as a result of its irregular shape and coarse surface, meanwhile, first increased and then declined the mechanical strength following the increase of the replacing percentage, amongst which the mortar containing 50% recycled manufactured sand showed the best mechanical strength. The tested mortars with recycled manufactured sand showed a general increment in the water and chloride ingress yet exhibited the water absorption and chloride ingress much lower than the mortar with recycled fine aggregate. Particularly, decreasing the content of hardened old mortar in recycled manufactured sand further improved the properties of recycled mortar.

Improvement of recycled aggregate properties through a combined method of mechanical grinding and microbial-induced carbonate precipitation

Due to the shortage of natural aggregates, recycled aggregates are gaining great attention in civil engineering. However, recycled aggregates have lower apparent density and higher water absorption and crushing index as compared to natural aggregates. To enhance the properties of recycled mixed aggregates (RMAs), three different treatment routes were adopted in this work: mechanical grinding, microbial-induced carbonate precipitation (MICP), and a combined method of mechanical grinding and MICP. The apparent density, water absorption, and crushing index of RMAs were examined before and after each treatment, and the slump, apparent density, and compressive strength of recycled concretes (RCs) with treated and untreated RMAs were then investigated. In addition, the micro-mechanism of property improvement due to these treatments was analyzed by scanning electron microscopy (SEM). Experimental results revealed that the combined method, in comparison to the other two methods used separately, led to higher apparent density and lower water absorption and crushing index of RMAs. Moreover, RCs treated with the combined method exhibited greater slump, higher apparent density, and superior compressive strength than untreated RCs. Furtherly, compared with commonly used RA treatment methods presented in recent publications, the proposed combined method shows better influence on compressive strength of RCs.