Hydration, shrinkage, cracking, and mechanical properties of cementitious materials with lignocellulosic biomass wastes.

The disposal of lignocellulosic biomass wastes imposes a huge economic and environmental burden on this society. Recycling lignocellulosic biomass wastes and applying them to cementitious materials provides a sustainable and value-added way for both agriculture and concrete industries. To comprehensively identify the effect of lignocellulosic biomass wastes at different scales on cementitious materials, the hydration, shrinkage, cracking, and mechanical properties of cementitious materials with lignocellulosic biomass wastes were studied. Given the three different forms (powders, chips, and fibers) of lignocellulosic biomass wastes in this study, the research was implemented in three stages. In the first stage, hemp powders were collected through grinding the residual of hemp products and then chemically treated using saturated lime water to partially remove hemicellulose, lignin, and impurities. The effect of untreated and treated hemp powders on the hydration of cement paste was studied. It was found that partially replacing cement with untreated and treated hemp powders can delay cement hydration. Compared with untreated hemp powders, treated (washed or nonwashed) hemp powders showed a lower delay effect on cement hydration, distilled-water-washed treated hemp powders delayed less than nonwashed treated hemp powders, and coarse hemp powders exerted a lower delay effect on cement hydration than fine hemp powders. In the second stage, ground wood chips were lightly or highly torrefied and then used to partially replace sand in mortar. The effect of non-torrefied and torrefied ground wood chips on the mechanical properties of mortar was studied. Compared to the mortar containing non-torrefied ground wood chips, those containing highly or lightly torrefied ground wood chips were found to have higher flexural strength and compressive strength due to the enhanced bonding between the wood chips and paste matrix. Although all the tested mortars with ground wood chips have lower strength than the mortar without any wood chips, their toughness was found to be comparable or higher, indicating better energy absorption capacity. In the third stage, kenaf fibers were chemically treated using different inorganic chemicals. The characteristics of raw and chemically treated kenaf fibers were investigated through a series of tests. It was found that chemically treated kenaf fibers have lower hemicellulose and extractives, lower moisture sorption capacity, and higher tensile strength and crystallinity index. And then, alkaline treated and alkaline-hydrogen peroxide treated kenaf fibers, together with raw kenaf fibers, were selected to be used as reinforcements in cementitious materials. The effect of these three types of kenaf fibers on the autogenous shrinkage, drying shrinkage cracking, and flexural behavior of cementitious materials was studied. It was found that compared to raw kenaf fibers, these two treated kenaf fibers can lead to reduced shrinkage and cracking and also improved flexural strength and toughness. This research provides some guidance for the future application of lignocellulosic biomass at different scales to non-structural concrete elements (such as pavement and roof). Hemp powders can be used to partially replace cement, with a dosage limit of 10% by weight of cement. Wood chips can be used to partially replace sand, with a recommended replacement level of 10% by weight of sand for OW and HTW, and a recommended replacement level of 5% for LTW. Kenaf fibers can be used as reinforcement, with a recommended dosage of 0.5% by weight of cement (or 0.12-0.24% by volume of the composites)

Bond Properties of Magnesium Phosphate Cement-Based Engineered Cementitious Composite with Ordinary Concrete

A magnesium phosphate cement-based engineered cementitious composite (MPC-ECC) was developed using polyvinyl alcohol (PVA) fibers and fly ash. In this study, the bond behavior of MPC-ECC with ordinary concrete was evaluated through single and double shear bond strength tests. The effects of the water to solid mass ratio (W/S), the sand to binder mass ratio (S/B), the molar ratio of MgO to KH2PO4 (M/P), the fly ash content (F), the borax dosage (B), the volume fraction of PVA fibers (Vf), and curing age on the bond behavior of MPC-ECC with ordinary concrete were examined. The results showed that as the W/S increased, the single and double shear bond strengths were gradually reduced. As the S/B increased, the double shear bond strength increased; the single shear bond strength first decreased up to an S/B of 0.1 and then increased. With the increase of M/P, the single and double shear bond strengths increased. With the increase of F, the single shear bond strength first increased up to an F of 30% and then decreased; the double shear bond strength decreased. With the increase of B, the single and double shear bond strengths increased first and then decreased, and their strength reached its maximum at a B of 6%. The increase of Vf improved the single and double shear bond strengths. The research results can provide some technical guidance for repairing concrete structures with MPC-ECC

A Review on the Application of Nanocellulose in Cementitious Materials

The development of the concrete industry is always accompanied by some environmental issues such as global warming and energy consumption. Under this circumstance, the application of nanocellulose in cementitious materials is attracting more and more attention in recent years not only because of its renewability and sustainability but also because of its unique properties. To trace the research progress and provide some guidance for future research, the application of nanocellulose to cementitious materials is reviewed. Specifically, the effects of cellulose nanocrystal (CNC), cellulose nanofibril (CNF), bacterial cellulose (BC), and cellulose filament (CF) on the physical and fresh properties, hydration, mechanical properties, microstructure, rheology, shrinkage, and durability of cementitious materials are summarized. It can be seen that the type, dosage, and dispersion of nanocellulose, and even the cementitious matrix type can lead to different results. Moreover, in this review, some unexplored topics are highlighted and remain to be further studied. Lastly, the major challenge of nanocellulose dispersion, related to the effectiveness of nanocellulose in cementitious materials, is examined in detail

Evaluation of Electric Field Integral Voltage Measurement Method of Transmission Line Based on Error Transmission and Uncertainty Analysis

Electric field numerical integration algorithms can realize the non-contact measurement of transmission line voltage effectively. Although there are many electric field numerical integration algorithms, lack of a comprehensive comparison of accuracy and stability among various algorithms results in difficulties in evaluating the measurement results of various algorithms. Therefore, this paper presents the G-L (Gauss–Legendre) algorithm, the I-G-L (improved Gauss–Legendre) algorithm, and the I-G-C (improved Gauss–Chebyshev) algorithm and proposes a unified error propagation model of the derived algorithms to assess the accuracy of each integration method by considering multiple error sources. Moreover, evaluation criteria for the uncertainty of transmission line voltage measurement are proposed to analyze the stability and reliability of these algorithms. A simulation model and experiment platform were then constructed to conduct error propagation and uncertainty analyses. The results show that the G-L algorithm had the highest accuracy and stability in the scheme with five integral nodes, for which the simulation error was 0.603% and the relative uncertainty was 2.130%. The I-G-L algorithm was more applicable due to the smaller number of integral nodes required, yet the algorithm was less stable in achieving the same accuracy as the G-L algorithm. In addition, the I-G-C algorithm was relatively less accurate and stable in voltage measurement

Finger Citron Extract Ameliorates Glycolipid Metabolism and Inflammation by Regulating GLP-1 Secretion via TGR5 Receptors in Obese Rats

Finger citron (FC) is one of many traditional Chinese herbs that have been used to treat obesity. The aim of this study was to elucidate the pharmacological effects and mechanisms of FC on obese rats. Rats were fed with a high-fat diet as a model of obesity and treated with FC at three different dosages for 6 weeks. Pathology in liver tissue was observed. Glucose levels, lipids levels, and inflammatory indicators in serum were evaluated by enzyme‐linked immunosorbent assay. Furthermore, the expression of G protein-coupled receptor 5 (TGR5) pathway genes in rat colon tissue was detected by reverse transcription-polymerase chain reaction analysis (RT-PCR). Our result revealed that FC alleviates obesity by reducing body weight (BW) and waist circumference, managing inflammation and improving glycolipid metabolism, liver function, and liver lipid peroxidation in vivo. In addition, the mechanism of FC on obesity is possibly the stimulation of glucagon-like peptide-1 (GLP-1) secretion by activating the TGR5 pathway in intestinal endocrine cells. Our studies highlight the obesity reduction effects of FC and one of the mechanisms may be the activation of the TGR5 pathway in intestinal endocrine cells

Bonding Properties between Fly Ash/Slag-Based Engineering Geopolymer Composites and Concrete

Concrete infrastructure repair remains a formidable challenge. The application of engineering geopolymer composites (EGCs) as a repair material in the field of rapid structural repair can ensure the safety of structural facilities and prolong their service life. However, the interfacial bonding performance of existing concrete with EGCs is still unclear. The purpose of this paper is to explore a kind of EGC with good mechanical properties, and to evaluate the bonding performance of EGCs with existing concrete using a tensile bonding test and single shear bonding test. At the same time, X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were adopted to study the microstructure. The results showed that the bond strength increased with the increase in interface roughness. For polyvinyl alcohol (PVA)-fiber-reinforced EGCs, the bond strength increased with the increase in FA content (0–40%). However, with the change of FA content (20–60%), the bond strength of polyethylene (PE) fiber-reinforced EGCs have little change. The bond strength of PVA-fiber-reinforced EGCs increased with the increase in water–binder ratio (0.30–0.34), while that of PE-fiber-reinforced EGCs decreased. The bond–slip model of EGCs with existing concrete was established based on the test results. XRD studies showed that when the FA content was 20–40%, the content of C-S-H gels was high and the reaction was sufficient. SEM studies showed that when the FA content was 20%, the PE fiber–matrix bonding was weakened to a certain extent, so the ductility of EGC was improved. Besides, with the increase in the water–binder ratio (0.30–0.34), the reaction products of the PE-fiber-reinforced EGC matrix gradually decreased

Development and design of ultra-high ductile magnesium phosphate cement-based composite using fly ash and silica fume

Magnesium phosphate cement (MPC) is one of the most promising binders to partially replace Portland cement to reduce carbon emissions. This study attempted to develop and design an ultra-high ductile MPC-based composite (UHDMC) using fly ash (FA) and silica fume (SF). Firstly, the macro-mechanical analysis of the UHDMC indicated that both the ultimate tensile stress and the ultimate tensile strain improved greatly when the additions of FA and SF replacing MPC were 30% and 20%, respectively. Compared to the addition of SF, the addition of FA resulted in a lower ultimate tensile stress but a higher ultimate tensile strain of UHDMC. Secondly, the micro-mechanical properties of the UHDMC were examined, and the stress-based and energy-based pseudo strain hardening indices (PSHσ and PSHJ, respectively) were calculated. It was found that both PSHσ and PSHJ of the UHDMC increased as the addition of SF or FA contents replacing MPC increased. Compared to the addition of SF, the addition of FA resulted in a similar PSHσ but a higher PSHJ. A quantitative relationship between pseudo strain hardening indices and ultimate tensile strain was established to guide the design of UHDMC with a desired ultimate tensile strain. It was found that PSHσ and PSHJ should reach above 2.2 and 26.7 concurrently for the UHDMC with ultimate tensile strains up to and above 3%. Lastly, the microanalysis was conducted to reveal the influence mechanism of FA and SF on the UHDMC. This study provides some technical guidance on the development and optimal design of UHDMC

Development and Efficacy Evaluation of a Novel Nano-Emulsion Adjuvant for a Foot-and-Mouth Disease Virus-like Particles Vaccine Based on Squalane

The successful development of foot-and-mouth disease virus-like particles (FMD-VLPs) has opened a new direction for researching a novel subunit vaccine for foot-and-mouth disease (FMD). Therefore, it is urgent to develop an adjuvant that is highly effective and safe to facilitate a better immune response to be pair with the FMD-VLP vaccine. In this research, we prepared a new nano-emulsion adjuvant based on squalane (SNA) containing CpG using the pseudo-ternary phase diagram method and the phase transformation method. The SNA consisted of Span85, Tween60, squalane, polyethene glycol-400 (PEG400) and CpG aqueous solution. The average particle diameter of the SNA was about 95 nm, and it exhibited good resistance to centrifugation, thermal stability, and biocompatibility. Then, SNA was emulsified as an adjuvant to prepare foot-and-mouth disease virus-like particles vaccine, BALB/c mice and guinea pigs were immunized, and we evaluated the immunization effect. The immunization results in mice showed that the SNA-VLPs vaccine significantly increased specific antibody levels in mice within 4 weeks, including higher levels of IgG1 and IgG2a. In addition, it increased the levels of IFN-γ and IL-1β in the immune serum of mice. Meanwhile, guinea pig-specific and neutralizing antibodies were considerably increased within 4 weeks when SNA was used as an adjuvant, thereby facilitating the proliferation of splenic lymphocytes. More importantly, in guinea pigs immunized with one dose of SNA-VLPs, challenged with FMDV 28 days after immunization, the protection rate can reach 83.3%, which is as high as in the ISA-206 control group. In conclusion, the novel squalane nano-emulsion adjuvant is an effective adjuvant for the FMD-VLPs vaccine, indicating a promising adjuvant for the future development of a novel FMD-VLPs vaccine