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A new perspective on the hydration process of graphene oxide (GO)/cement composites is provided in this paper. The quantitative evaluation of GO on the hydration of four minerals and the di...

Temperature distribution in concrete is significant to the concrete structure’s macro properties and different factors affect the heat transfer in concrete, and therefore influence the temperature distribution. This work established a three-dimensional transient heat transfer model coupled with various environmental factors, using the finite element method for calculating the results and real-measured data for testing accuracy. In addition, a sensitivity evaluation of various factors was conducted. Due to various environmental factors, the results revealed that the prediction of temperature distribution in concrete by the three-dimensional model had great accuracy with an error of less than 4%. A particular hysteresis effect of temperature response in the concrete existed. Considering heat transfer in different spatial directions, the model can predict the temperature change of each spatial point instead of the spatial surface in different depths, proving the shortcomings of a one-dimensional heat transfer model. A greater solar radiation intensity caused a more significant temperature difference on the concrete surface: the surface temperature difference in July was twice as significant as that in December. Wind speed had a cooling effect on the concrete surface, and stronger wind speed accompanied with a stronger cooling effect made the surface temperature closer to the ambient temperature. Material properties had different effects on the temperature distribution of the surface part and internal part: the specific heat capacity determined the speed of the outer layer temperature change while the thermal conductivity determined the speed of the inner layer temperature change.

This work examines the influencing mechanism of light radiation on performances and structures of calcium silicate hydrates (C-S-H) through exposing synthetic C-S-H samples to high-power Xenon radiation. The compositions, chemical structures and nanomorphology of C-S-H were investigated using XRD, TG, 29Si NMR, Ca XANES, Si XANES and TEM. Xenon radiation reduces the chemically bound water content in C-S-H and the drying effect induced by Xenon radiation is more pronounced in C-S-H with lower Ca/Si ratio. Xenon radiation increases the polymerization of C-S-H and elongates the silicate chain by driving separated Si–O tetrahedron to connect with each other without changing its Ca/Si ratio. Furthermore, Xenon radiation reduces the coordination numbers of Ca–O and causes the self-organization of chemical structure at molecular and atomic scales. The existence of portlandite improves the resistance of C-S-H to compositional and structural changes induced by Xenon radiation. These findings pave the way for understanding aging mechanism of cement-based materials under the action of solar radiation.

The main bridge of Nanjing Jiangxinzhou Yangtze River Bridge is in the form of a cable-stayed bridge with three towers and two main spans, with a total length of 1796m and a main span of 600m. The towers and main beams are all composite structures, which is the first all-steel-concrete composite cable-stayed bridge in the world. The bridge originally develops the steel shell-concrete composite tower, investigates coarse aggregate reactive powder concrete (CA-RPC), and applies it to the main girder to form a lightweight and high-performance beam. Numerous technologies have been achieved in new materials, new structures, new processes, and many other aspects. The unique structural concept has significantly increased the factory manufacturing speed, which not only reduces the work and labour cost 25% but also reduces the amount and loss of materials during construction, which has made contributions to the development of cable-stayed bridges.

To improve the problem of collapsibility of loess, adding industrial materials such as cement is common engineering treatment, but this seriously damages the reclamation performance of soil. Calcium lignosulfonate (CLS) from paper plant waste fluids is a natural bio-based polymer with good application prospects as a soil improver. In this paper, the collapsibility and mechanical properties of CLS improved loess were investigated using a collapsibility test, gray correlation analysis, and an unconfined compressive strength test (UCS). In addition, the strengthening mechanism of CLS-improved loess was also explored based on scanning electron microscopy (SEM), microstructure parameters, and X-ray diffraction. The collapsibility coefficient decreased rapidly after CLS was admixed, and the single and double-oedometer methods showed the same change trend. The order of grey correlation degree of collapsibility on each index from large to small was: moisture content, pore ratio, dry density, and CLS content. The dosage of CLS greatly influenced the mechanical properties and collapsibility of stabilized loess. The optimum amount of CLS for Xi’an loess was 3%, at which the collapsibility coefficient was reduced by more than 95%, and the 28 d UCS increased by 180.01%. From the microstructure and mineral composition analysis perspective, CLS plays a role in filling pores and linking soil particles. After the protonation and ion exchange effect of CLS, the grain size and double electric layer thickness of mineral composition were reduced, and the structural compactness was increased. These research results are of great scientific significance for the ecological modification of soils.

A microbial transglutaminase-induced cross-linked sodium caseinate (MSC) was used to stabilize zein nanoparticles, and the study was to investigate whether zein-MSC nanoparticles (zein-MSC NPs) can be used as an encapsulation carrier for resveratrol. A group of resveratrol-loaded zein-MSC nanoparticles (Res-zein-MSC NPs) with varying zein to Res mass ratios was first prepared. The particle sizes and zeta-potentials were in the ranges from 215.00 to 225.00 nm and from −29.00 to −31.00 mV. The encapsulation efficiency (EE) of Res was also influenced by the zein to Res mass ratio, and the encapsulated Res existed in an amorphous form. The major interactions between Res and zein-MSC NPs were hydrogen bonding and hydrophobic interaction. Furthermore, compared with free Res, the photo-stability and bioaccessibility of Res-zein-MSC NPs were significantly improved. The cellular studies also showed that Res-zein-MSC NPs exhibited lower cytotoxicity and desirable anti-inflammatory activity.

Underwater adhesives with intrinsically tough and stable performance are urgently needed for environmental and engineering applications. Marine organisms have inspired numerous studies on the design and development of wet adhesives. Here we report a facile yet powerful strategy that recapitulates the delivery process of mussel adhesion for the development of strong and durable hydrogel adhesives. With the hydrogel matrix serving as an interfacial binding site, while the nanocrystal fillers contribute to the strong cohesion, they demonstrate outstanding adhesion abilities to a wide range of wet surfaces including aluminum, ceramics, glass, polymers and wood. Moreover, in contrast to commercial products for underwater bonding, the hydrogel adhesives present continuous strength growth instead of degradation with time due to the hydration effects and intrinsic reinforcement capabilities of ye'elimite. By synergistically combining macroscopic scale architectures and molecular level interactions, this in situ formation strategy opens a new route to incorporate nanocrystals into a hydrogel matrix, leading to a universal bonding solution on diverse surfaces underwater.

Photovoltaic (PV) power generation technology is the main renewable energy utilization technology. However, dust deposition severely affects the PV power generation efficiency and decreases the production capacity of PV power plants. In this study, the factors affecting PV technology were divided into the following three types: occlusion, corrosion, and temperature rise. A dust-collecting PV model considering dust deposition and rainfall scouring was established; a PV performance index was proposed. By conducting experiments with different dust mass densities, it was found that the short-circuit current (SCC), open-circuit voltage (OCV), and PV output power of PV decreased with the increase in dust mass density. In the initial stage of dust deposition, dust exhibited the greatest effect on the performance of PV. In the later stage of dust deposition, the effect of dust deposition became stable. The initial 10 g/m2 dust decreased the PV output power by 34%. In addition, the conversion efficiency and fill factor (FF) decreased with the increase in dust mass density; both of them were exponential functions. When the dust mass density was low (less than 30 g/m2), the dust mass density increased by 10 g/m2, and the conversion efficiency decreased by an average of 3.4%. Finally, by conducting economic calculations, it was found that a PV power plant where dust has not removed for one year will cause 12% loss of power generation.

Synthesis of polyaryl ether (PAE), poly(salicylic acid)-co-poly[p-methylphenyl oxy poly(ethylene glycol) ether] by condensation polymerization and its properties in cement pastes are discussed. The...

Ultrahigh-strength concrete (UHSC) is a promising material for engineering applications, owing to the rapid increase of compressive strength at early ages. In this study, the creep behaviour of UHSC with an ultralow water/binder ratio (= 0·16) under loading at early ages was investigated. The influence factors of loading age (1, 2, 3 and 7 d), normal coarse aggregate and steel fibre content (0, 1 and 2%) were taken into consideration. Experiment results showed that the addition of coarse aggregates and ultrafine steel fibres were obviously effective in decreasing the creep deformation of UHSC but that the specific creep of UHSC with 2% steel fibres was higher than that of UHSC with 1% steel fibres. Specimens loaded at earlier ages had higher creep. At a microscopic level, it could be seen that the creep of UHSC was influenced by hydration products and concrete internal defects. From a macroscopic perspective, it could be seen that this was the result of a combination of strength and elastic modulus development factors. By introducing a coordination factor for the development of strength and elastic modulus, a modified creep model was proposed to predict the creep of UHSC.

Autogenous shrinkage of cementitious materials is a key factor leading to early-age cracking of concrete. Based on the micromechanics, the underlying multiscale framework and capillary pressure theory, a multiscale model of autogenous shrinkage is presented for cementitious materials with a homogenization method. By comparing the predictive values from models with the experimental data in the literature, the HYMOSTRUC relative humidity model and Shimomura and Maekawa pore size distribution model are recommended for use in the proposed autogenous shrinkage multiscale model. Combined with the HYMOSTRUC chemical shrinkage model, the simulated results of the autogenous shrinkage multiscale model proposed in this paper match well with the experimental data in the literature and the predictive capability is successfully validated.

Studies on building carbon emissions focus mainly on the materialization phase of life cycle, as carbon emissions in this stage is intensive and high. This paper proposes a simplified model to calculate embodied carbon emissions in building design stage by conducting a process-based inventory analysis of carbon emissions from materials used in 129 residential buildings, 41 office buildings, and 21 commercial buildings during materialization phase. The results indicate that average carbon emissions per unit area from building materials used in residential buildings, office buildings, and commercial buildings are 514.66 kgCO2e/m2, 533.69 kgCO2e/m2 and 494.19 kgCO2e/m2, respectively. Besides, ten kinds of building materials (namely, steel, commercial concrete, wall building materials, mortar, copper core cables, architectural ceramics, PVC pipes, thermal insulation materials, doors and windows, and water paint) constitute 99% of total carbon emissions in all three types of buildings. These materials are major carbon emissions sources in materialization phase. Thus, embodied carbon emissions can be significantly reduced by limiting the amount of these materials in architectural design as well as by using environmental friendly materials.

Accurate determination of the thermal conductivity of building material is key to calculating its heating/cooling loads and energy consumption. The thermal conductivity of building material is not only related to the pore structure characteristics but also the internal static moisture distribution and moisture transfer characteristics, and the mechanisms of both differ in how they affect the internal heat transfer performance. This paper analyzed the influential quantitative relations between the static moisture distribution and moisture transfer with respect to the thermal conductivity of building materials in different hygrothermal environments. The analysis is based on the additional thermal conductivity calculation method derived from static moisture distribution and moisture transfer proposed by us. The results show that the static moisture distribution has a notable influence on the thermal conductivity under the heating conditions in winter, whereas the influence of moisture transfer is negligible. Nonetheless, the influence of both factors on the thermal conductivity should be considered during air-conditioning in summer. The comprehensive correction rate of the thermal conductivity of building materials in typically hot and humid areas in China are determined, and the influence of the thermal conductivity of moist building materials on the heat transfer coefficient of enclosure structures is analyzed.

The adsorption of polycarboxylate (PCE) superplasticizer is the key step in the dispersing of cement particles, which is closely associated with problems in practice (e.g. compatibility). The adsor...

Volatile organic compounds (VOCs) emitted from decorative building materials are the main source of indoor air pollution, which endangers human health. Source control is the most direct method to reduce the amount of harmful substances emitted from a material. In view of the excellent adsorption performance and effective fixation of the adsorbent on VOC molecules, small amounts of adsorbents can be blended into the raw materials used in the production of building materials, which results in the manufacture of modified building materials with low VOC emissions. According to the type and ratio of additional adsorbents, the VOC emission characteristics of the modified building materials vary. Based on the analysis of the multi-component and multi-scale mass transfer mechanism, a prediction system for the VOC emission characteristics of modified building materials was proposed. Four types of adsorbents, namely, wood-based activated carbon (WAC), shell activated carbon (SAC), coconut shell activated carbon (CSAC), and potassium permanganate impregnated alumina (PIA) were used to manufacture the modified medium density fiberboards. Moreover, pore structure characterization tests and environmental chamber tests were conducted to verify the accuracy of the theoretical prediction system. The results revealed that an absorbent with a high partition coefficient has a more significant source suppression effect. The proposed VOC emission characteristic prediction system for modified building materials can optimize the type and ratio of adsorbents for engineering applications and therefore, provide a basis for the selection of effective VOC source control strategies.

Sulfonate graphene nanosheet (SGN), as a new chemical admixture obtained by sulfonation of graphene, has been used to investigate the effects on tricalcium silicate (C3S – Conventional cement chemistry notation is often used in this article to specify the composition of solid phase, whereby C = CaO, S = SiO2, F = Fe2O3 and H = H2O) hydration. Results show that SGN can prolong the dissolution period and induction period during C3S hydration owing to its adsorption behavior. In situ X-ray diffraction analysis demonstrated that the crystal growth on 001 planes of Calcium hydroxide (CH) will be enforced by addition of SGN, which is probably by the following steps: 1) Ca2+ released by C3S more likely diffused to the surface of SGN prior to nucleation of CH; 2) the nanosheets provide a template for aligned growth of the CH especially on the 001 planes. Meanwhile, scanning electron microscope photos directly show that the growth of CH is layer by layer on the 001 plane when SGN was added. Hopefully, the mechanism of C3S hydration cooperating with SGN proposed in this paper can make a guidance for the application of SGN in cement based materials.

In this paper, nine new diffuse fraction and eight new diffuse coefficient models were developed by introducing precipitation as one of the model parameters. Concurrently, thirty-four existing diffuse fraction and eleven existing diffuse coefficient models were reviewed. The existing and proposed models were compared to assess their applicability in different climate zones in China. According to the best models and climate zones, general models were established. Overall, introducing precipitation could effectively improving the underestimation problems of daily diffuse solar radiation; for diffuse fraction models, precipitation had stronger correlation with diffuse radiation than relative humidity in humid areas and weaker correlation in arid areas. For diffuse coefficient models, the models incorporating precipitation could obtain better accuracy than temperature and relative humidity in all climate zones under similar meteorological parameters. Therefore, precipitation should be preferentially adopted, followed by temperature and relative humidity. The general models developed in this paper performed well in estimating the daily diffuse solar radiation. The average coefficient of determination, root mean square error and mean absolute bias error of diffuse fraction general models were 0.82, 1.44 MJm−2 d−1 and 1.04 MJm−2 d−1, respectively; while the corresponding values of diffuse coefficient general models were 0.69, 1.98 MJm−2 d−1 and 1.54 MJm−2 d−1, respectively. The general models could represent the daily diffuse solar radiation estimation of stations without diffuse solar radiation records.

Buildings on tropical islands in the South China Sea are facing an overheating challenge. High-water-absorbency unglazed porous ceramic (UPC) materials could counteract heat gain by evaporation. Salty humid air and seawater in the marine environment lead to evaporative cooling differences from inland conditions. This research replicated a salty humid atmosphere with a stable concentration similar to the actual environment in a dynamic hot-humid climate wind tunnel (DHWT). The influence of salt in gas-liquid media on evaporative cooling is discussed. The results showed that the salt concentration of humid air in the wind tunnel can be controlled by adjusting the atomization rate and the concentration of the atomized liquid. Humid air and liquid with salt reduced the evaporation rate of the UPC tiles. The influence of salty humid air was generally less than that of seawater. In 6 mg/m3 salty air, the total evaporative cooling effect decreased by 2.63% and 40.44% when saturated with fresh water and a 3.5% sodium chloride solution, respectively, relative to saturation with fresh water and evaporation in humid air without salt. In conclusion, sea salt in humid air and in the liquid phase reduced but did not eliminate the evaporative cooling effect of UPC materials. Seawater source utilization showed a significant benefit in cooling and water conservation aspects in coastal areas.

In this study, the interaction between the major phase of cement clinker, C3S, and GO was explored to investigate its effect on the microstructures of G3S/GO composites at different GO dosages in a range of 0–0.05 wt%. The compressive strength of C3S/GO composites was tested and their microstructural developments were analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TG), nitrogen adsorption and 29Si solid-state nuclear magnetic resonance (NMR) techniques. The results show that the addition of GO can improve the compressive strength of C3S/GO paste up to 32.5% at 1 day. In addition, the incorporation of GO provided an increasing number of nucleation sites to form denser microstructure and refined the pore structure by reducing the total porosity and increasing the gel pores. In particular, the hydration degree was increased by approximately 20% at the age of 7 days when the GO dosage was in the range of 0.03–0.05 wt% as evidenced by TG and NMR results. The ratio of Q2/Q1 in C-S-H gel decreased slightly with the increased GO content, which was further corresponding to the decreased mean chain length of C-S-H gel. Therefore, the introduction of GO exerts a positive effect on the hydration of C3S, which provides essential supports to the hydration mechanism of GO in Portland cement matrix.

It is necessary to improve indoor air quality while meeting the indoor thermal demand of buildings during winter. The transpired solar collector (TSC) is a solar energy integration technology in buildings, which usually consists of a heat collecting plate with infiltration holes, an air layer, an insulation wall, air outlet and other appurtenances. It not only provides preheated fresh air for the indoor environment, but also reduces the cold wind infiltration heat load in winter. In this paper, the heat transfer process of each component of the transpired solar collectors was analyzed comprehensively. Findings on, the heat collection efficiency, heat exchange efficiency indexes and optimized parameters of the transpired solar collectors are presented. Moreover, an integrated and detailed performance test platform for the transpired solar collectors heating characteristics and optimization parameters was developed. Additionally, a comprehensive and multi-condition experimental study was carried out. One important finding is that the non-uniform distribution of infiltration holes at the top and bottom of the transpired solar collectors significantly influence on the preheating effect of fresh air and the overall efficiency of the system. Moreover, an increase in the uniformity of the infiltration holes, increase the heat collection efficiency and heat exchange efficiency by 25% and 10% respectively. Furthermore, the heat collection gain per unit of heat collecting plate area increased by about 34.7 W, and the outlet temperature could be improved by about 15 °C. These findings provide a critical design reference for the high-performance application of the transpired solar collectors in buildings.

The profiles of soluble and insoluble phenolic compounds in 11 commercial red sorghums (B11, B12, B13, B14, J124, J127, J138, J140, J142, J152, and J158) were investigated using ultraperformance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) analysis. A total of 48 phenolic compounds including 35 phenolic acids and their derivatives, 12 flavonoids, and 1 proanthocyanidin were identified, and 8 phenolic compounds were reported for the first time in sorghums. Four major 3-deoxyanthocyanidins were also quantified, with their soluble forms accounting for 99.75-99.87% of the total contents. Pearson's correlation analyses indicated that 3-deoxyanthocyanidins significantly contributed to the antioxidant capacities of the red sorghums and that 5-methoxy-luteolinidin showed the strongest correlation. Besides, the soluble phenolic fraction of B13 dose-dependently inhibited the proliferation of Caco-2 cells and the secretion of IL-1β and NO in RAW264.7 macrophages, which might be attributed to its relatively high total phenolic (TPC), flavonoid (TFC), and proanthocyanidin content (TPAC) values and radical scavenging capacities.

High-performance concrete easily generates early-age cracks due to its sharp and large temperature and relative humidity (RH) changes. The temperature and RH with and without axial compress...

To analyze the extent of fire risk in historic Chinese wooden structure buildings, the fire load characteristics of a historic temple in Beijing were studied. In this paper, thermogravimetric and c...