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[Display omitted] • Purified C–S–H seeding and impurities from seeding suspensions were used. • The presence of impurities slightly compromises the later-age strength development. • New perspective to better understand the longer-term effects of C–S–H seeding materials. The application of C–S–H seeding offers great potential for improving the early age strength of cement. However, the fundamental understanding of longer-term effects of C–S–H seeding on the properties of cementitious materials is still limited, partly due to the complex composition of C–S–H seeding materials. This paper studied the effects of purified C–S–H seeding and impurities separated from synthesized C–S–H seeding suspensions on the hydration and strength of limestone calcined clay cement (LC3) over a period of 90 days. The results showed that compared to reference, the addition of purified C–S–H seeding leads to an average increment of 16.5% in the compressive strength of LC3 at the first 7 days and does not significantly affect the strength development afterwards, while the presence of impurities can cause a 5.7% decrease in compressive strength at 90 days. The reason for this later-age discrepancy was attributed to the lower degree of hydration of alite and less reaction of metakaolin in the system with impurities compared to the system without impurities. The findings offer a new perspective to better understand the longer-term effects of C–S–H seeding materials on the performance of cementitious materials. [ABSTRACT FROM AUTHOR]

For seismic control and isolation techniques, low yield point steels are among the most reliable and ideal energy-dissipating materials. Structures under earthquake conditions are usually subjected to cyclic loads with large strain amplitudes, where excellent low cycle fatigue and fracture performance under repeated loading is an essential requirement. In the study presented in this paper, comprehensive and systematic investigation was conducted on the low cycle fatigue properties and fracture behaviors of low yield point steels (LY100, LY160, and LY225). Axial steel coupons were tested under different constant strain amplitudes ranging from 0.5% to 6% with increments of 0.5%. Following introduction of the experimental details, observations and fatigue life are reported. Then, based on the experimental data, the cyclic hardening behavior and the cyclic stress-strain response are thoroughly analyzed. Finally, with the aim of predicting the low cycle fatigue life, the material parameters of the Coffin-Manson relationship and Kuroda model are determined and comparative analyses are performed. This paper may provide a valuable reference for engineering applications and further research into the low cycle fatigue performance of low yield point steels. [ABSTRACT FROM AUTHOR]

To improve the photocatalytic performance and utilization of TiO 2 particles in cementitious materials, this work investigated and differentiated the influences of cement substrate pore structure and TiO 2 particles loading level on photocatalytic degradation of gaseous benzene. It is noted that TiO 2 particles have different loading behaviors on various density cement substrates surface. Low density cement substrates are useful to disperse the loaded TiO 2 particles due to the loose network pores of needle like hydrates, while high density substrates can cause the agglomeration of loaded TiO 2 particles. The photocatalytic performance results reveal that sample with ca. 0.8 g/cm 3 design density has the highest photocatalytic performance. However, TiO 2 loading concentration can also affect its agglomeration degree, which shows that the loaded TiO 2 particles gradually form the agglomerates with the increase of loading concentrations. The photocatalytic performance for degradation of gaseous benzene increases as increasing TiO 2 loading amounts, and then become to steady, suggesting that the optimum TiO 2 loading concentration (1.0 g/L) can allow the best utilizations of TiO 2 particles on porous cement surface. [ABSTRACT FROM AUTHOR]

• The hydration and microstructure of ternary HFC blends incorporated a large amount of FA and LP were revealed. • The synergistic effects between FA and LP in ternary HFC blends exhibit improving flexural strengths, decreasing drying shrinkage and cumulative heat. • The adverse effects between FA and LP in ternary HFC blends mainly exhibits decreasing compressive strengths and increasing total porosity percentages. • The synergistic effects between FA and LP in ternary HFC blends are mainly occurred at a later age. This paper studied the mechanical properties, hydration process, and microstructure of ternary high-ferrite Portland cement (HFC) blends with replacement at levels up to 50 % with limestone powder (LP) and fly ash (FA). Two mechanisms, synergy and negative effects between LP and FA are observed in ternary HFC-LP-FA blends. The synergistic effects between LP and FA in ternary HFC blends mainly exhibit improving flexural strengths, improving compressive strengths before 28 days, decreasing drying shrinkage and cumulative heat, accelerating the crystal nucleation and growth process (NG), stabilizing the ettringite (AFt) phase, prolonging polymerization of alumino-silicate chains, and refining the pore size distribution, etc. However, the synergistic effect between LP and FA in ternary HFC blends cannot compensate for the dilution effect caused by a large amount of LP and FA replacement. The adverse effects between LP and FA in ternary HFC blends are emerged and mainly exhibited decreasing in compressive strengths after 28 days and increasing total porosity percentages. LP plays a predominant role at an early age (before 28 days) in HFC blends and increases the cumulative heat; Specifically the cumulative heat of LP25 (25 indicates percentage replacement of HFC) before 10 h is 2.2 J/g higher compared to HFC. In addition, a rapid increase of bound water is emerged from 3 days to 28 days, for instance the bound water content in LP25 increases by 55.9 % from 3 days to 28 days. It is attributed to the nucleation effect of LP providing more nucleation sites and accelerating NG process. LP in HFC blends leads to the formation of monocarbonate and AFt phase trends to stabilization. FA plays a predominant role at the later hydration age (from 28 days to 90 days) in HFC blends attributing its pozzolanic reaction. Furthermore, the synergistic effects between FA and LP in ternary HFC blends are mainly occurred at a later age. [ABSTRACT FROM AUTHOR]

This study investigated the strategy of using zeolite fly ash bead (ZFAB) as a carrier of TiO 2 photocatalyst to improve the photocatalytic efficiency and long-term performance of photocatalytic cementitious materials. Various photocatalytic cementitious specimens with different ZFAB/TiO 2 dosages were prepared by surface sprayed and intermixed methods. Their characteristics and photocatalytic effects were evaluated. It was found that ZFAB could improve the exposure degree of TiO 2 particles in cement matrix surface, and the exposure contents were dependent on ZFAB/TiO 2 incorporation methods and dosages. The photocatalytic results showed that all ZFAB/TiO 2 applied cementitious samples performed better photocatalytic effects and long-term performance than that of samples prepared with pure TiO 2 . Moreover, the photocatalytic effects increased with the increase of ZFAB/TiO 2 dosages, and ZFAB/TiO 2 surface-sprayed samples displayed better effects than that of ZFAB/TiO 2 inter-mixed samples. These results indicates that ZFAB is useful to enhance the photocatalytic efficiency of TiO 2 in cementitious materials, which could reduce the cover risks of cement hydrates on TiO 2 particles, and improve its dispersibility and exposure degree as well. Thus, the use of ZFAB could provide a potential method for high efficiency and long-term application of TiO 2 in construction field. [ABSTRACT FROM AUTHOR]

Highlights: [•] The hierarchical porous FMOC substrate with good light transmittance was prepared. [•] Through a facile method synthesized FMOC/TiO2 catalyst with desirable microstructure. [•] Hierarchical structure provided more active TiO2 sites and large catalysis areas. [•] Reaction rate of FMOC/T12 was estimated to be about 3.87 times higher than MOC/T12. [•] TiO2 exhibited an excellent re-use performance on surface of porous magnesium cement. [Copyright &y& Elsevier]

• Push-out tests on fourteen CFSSST specimens were carried out. • The effects of different factors on τ - S relationship were analysed and discussed. • Based on the experimental results, an empirical τ-S relationship was proposed. The application of stainless steel tubes in concrete-filled steel tube systems can significantly improve their corrosion resistance in comparison with those that employ carbon steel tubes. In this paper, a series of push-out tests were carried out to investigate the bond stress-slip behavior between stainless steel tubes and concrete. A total of 14 concrete-filled square stainless steel tube specimens were tested, covering two cross-sectional width-thickness ratios (B / t = 30 and 50), two concrete strength (f cu = 44 and 76 MPa), three rib stiffener types (ordinary, saw-shaped and perfobond leister) and two stainless steel grades (austenitic and duplex). The test results indicate that B / t , f cu and stainless steel grade have noticeable influences on the ultimate bond stress (τ u) in concrete-filled square stainless steel tube and the addition of rib stiffeners significantly improves the bond behavior. The bond mechanism at different stages of loading and the effect of various parameters on τ u are discussed. Based on the test results, an idealized bond stress-slip strain (τ - ε S) curve was proposed, where good agreement between the test and the proposed model has been achieved. [ABSTRACT FROM AUTHOR]

Due to the influence of natural factors and complex loads, the mechanical performance of ancient brick structures is deteriorating, and assessing the strength of bricks is crucial for structural safety. The sintered clay bricks of the Ming Dynasty Beijing city wall were scanned by computed tomography (CT), and the grey images of the microstructure and morphology inside the brick were obtained. The parameters including porosity, large porosity, average sphericity, graded sphericity porosity greater than 0.8 and fractal dimension have the largest correlation to the compressive strength of bricks. These parameters are used as input data and the compressive strength is used as output data, and then trained with the Back-Propagation (BP) neural network. The results show that the BP neural network model is more accurate than the traditional fitting model in assessing the compressive strength, which can provide the basis and reference for the rapid and non-destructive acquisition of the strength indexes of ancient green bricks. • Establishing BP neural network for ancient brick compression strength prediction. • Developing a pre-processing method for CT scanning data. • Quantifying the microscopic pore structure and morphology of ancient brick. • Determining pore parameters highly correlated with ancient brick compressive strength. [ABSTRACT FROM AUTHOR]

• Presoaked aluminosilicate porous agent has internal curing and pozzolanic effect. • Hydrates of pastes blended LWFA have excellent chloride binding capacity. • LWFA improves the properties of the interfacial transition zone of heat-cured mortars. Heat curing is a technology that has been widely used for concrete employed in urban infrastructures since it allows to achieve both high production efficiency and a high degree of control on the concrete performance. Nevertheless, some limitations in the light of degraded microstructures and low hydration degrees of cement at a later stage hinder the durability of it. In this paper, a type of lightweight fine aggregate (LWFA) that has a porous aluminosilicate structure was employed to address this issue. The substitution of LWFA for a portion of the conventional sand to provide internal curing (IC) and pozzolanic reaction for the heat-cured mortars was examined with respect to its influence on the chloride penetration resistance. Experimental measurements of chloride ions absorption and penetration depths are combined with extensive microstructural characterization such as BSE, XRD and TG analyses to determine the synergistic effect of LWFA impacted on heat-cured pastes and mortars. For heat-cured mortars employing 53% LWFA and 47% conventional sand as aggregates by volume, the coefficients of rapid chloride migration were estimated to be reduced by 20.2% and 41.4% at 28 d and 60 d, respectively. [ABSTRACT FROM AUTHOR]

• A novel carbonation-based photocatalytic material for capturing CO 2 has been prepared. • TSC shows excellent NO x degradation efficiency and durability after a 7200-minute test. • TSC offers a stable and eco-friendly solution for air purification in buildings and 'Carbon Neutrality'. Cement-based photocatalytic materials have attracted considerable attention for their potential in the degradation of air pollutants. However, there is a pressing need to enhance the environmental stability of surface photocatalyst loads and improve the low-carbon preparation of the loaded matrix. In this study, a novel TiO 2 -SiO 2 (TS) based CO 2 capture photocatalytic material (TSC) was prepared by compressing molding method. TSC exhibits excellent photocatalytic efficiency, as demonstrated by its performance in NO x degradation tests and rhodamine B degradation. Notably, the photocatalytic efficiency of TSC in removing NO and its nitrate selectivity did not decrease significantly after the 7200-minute scouring test, primarily due to the increased specific surface area and low Ti element leaching. These results suggest that the carbonation binding materials used in TSC shows great promise for photocatalytic building applications. Meanwhile, the carbonation process during curing enables the absorption of CO 2 , making it beneficial for achieving a "Carbon Neutral" approach. [ABSTRACT FROM AUTHOR]

• TiO 2 hydrosol of pH = 7.55 was optimized to prepare BMCWPM. • BMCWPM shows great degradation rate of toluene with the TiO 2 concentration of 5–20%. • BMCWPM has great photocatalytic cyclic durability. This study brings a novel magnesium oxychloride cement-based photocatalytic material. Basic magnesium chloride whisker (BMCW) was modified by nano-SiO 2 to improve the loading capacity of TiO 2 photocatalyst. Then, TiO 2 was supported in BMCW/SiO 2 to form the basic magnesium chloride whisker photocatalytic materials (BMCWPM). The effects of pH values and TiO 2 supporting concentrations on physio-chemical properties and photocatalytic performance were investigated in detail. As TiO 2 hydrosol pH value is about 7.55, the loaded BMCWPM has the best degradation efficiency on gaseous toluene. BMCWPM synthesized with 5 % TiO 2 supporting concentration shows the best photocatalytic efficiency of unit TiO 2 , also shows an excellent photocatalytic cyclic stability, the photocatalytic degradation efficiency and reaction rate of gaseous toluene are exceeding 55 % and 22.7*10−7 mol/m2 min, respectively. This study provides a kind of photocatalytic material with high efficiency and durability, which is expected to apply in wall decoration materials for air purification. [ABSTRACT FROM AUTHOR]

• TiO 2 hydrosol of pH = 7.55 was optimized to prepare BMCWPM. • BMCWPM shows great degradation rate of toluene with the TiO 2 concentration of 5–20%. • BMCWPM has great photocatalytic cyclic durability. This study brings a novel magnesium oxychloride cement-based photocatalytic material. Basic magnesium chloride whisker (BMCW) was modified by nano-SiO 2 to improve the loading capacity of TiO 2 photocatalyst. Then, TiO 2 was supported in BMCW/SiO 2 to form the basic magnesium chloride whisker photocatalytic materials (BMCWPM). The effects of pH values and TiO 2 supporting concentrations on physio-chemical properties and photocatalytic performance were investigated in detail. As TiO 2 hydrosol pH value is about 7.55, the loaded BMCWPM has the best degradation efficiency on gaseous toluene. BMCWPM synthesized with 5 % TiO 2 supporting concentration shows the best photocatalytic efficiency of unit TiO 2 , also shows an excellent photocatalytic cyclic stability, the photocatalytic degradation efficiency and reaction rate of gaseous toluene are exceeding 55 % and 22.7*10−7 mol/m2 min, respectively. This study provides a kind of photocatalytic material with high efficiency and durability, which is expected to apply in wall decoration materials for air purification. [ABSTRACT FROM AUTHOR]

• Accelerated corrosion of the longitudinal reinforcement and stirrup was carried out by the electroosmosis-constant current-dry wet cycle method. • The effects of the corrosion degree, stirrup spacing and cover thickness parameters on the bond performance were analyzed by pull-out tests. • A modified bond-slip constitutive model that considers the corrosion of longitudinal bars and stirrups was proposed. The corrosion of longitudinal rebar and stirrups will cause serious degradation of the bond performance between steel bars and concrete. To investigate the impact of both longitudinal rebar and stirrup corrosion on the bond behavior, 35 reinforced concrete (RC) pull-out specimens were subjected to accelerated corrosion tests with electroosmosis/constant current/dry-wet cycling and pull-out tests. The influence laws of the degree of corrosion of the longitudinal reinforcement, degree of corrosion of the stirrups, cover thickness, stirrup spacing and longitudinal reinforcement diameter on the bond performance were also investigated. The bond behavior between corroded steel bars and concrete was analyzed from the aspects of corrosion form, failure mode and bond strength. Subsequently, based on the experimental data, a modified bond-slip constitutive model that considers the design parameters, stirrup corrosion and longitudinal rebar corrosion was built and verified. The modified bond-slip constitutive model was applied to the cohesive element to establish a finite element model of the corroded pull-out specimens, and additional parameters were analyzed. [ABSTRACT FROM AUTHOR]

In recent years, photocatalytic cement-based materials have demonstrated a positive impact on reducing air pollutants. However, challenges arise from the aggregation of photocatalysts and the intricate internal environment of cement-based materials, resulting in diminished photocatalytic efficiency. To address these issues, the TiO 2 @SiO 2 photocatalyst which reduced agglomeration and was easy to disperse was prepared by sol-gel method, and the TiO 2 @SiO 2 photocatalyst was added into γ-C 2 S carbonated cementitious material system by surface loading and blending to prepare the photocatalytic carbonation coating. In this paper, the TiO 2 @SiO 2 photocatalyst synthesized at solution pH 4.16 had the highest photocatalytic degradation efficiency of nitrogen oxides. The photocatalytic efficiency of the prepared carbonated coating was evaluated through the degradation efficiency of nitrogen oxide and rhodamine B. When the content of TiO 2 @SiO 2 was 7%, the photocatalytic carbonation coating had the highest photon removal efficiency for NO (0.17%), and the degradation rate for rhodamine B was 32.94% after 7 h illumination. The photocatalytic effect of the photocatalytic carbonated coating prepared with surface loaded TiO 2 @SiO 2 was better than that of the doped coating. When the surface loading was 1.5 g/m2, the photocatalytic efficiency of the coating on NO reached 0.81%, and the degradation rate of rhodamine B after 7 h illumination was 36.92%. This method introduced a novel concept for the future application of photocatalytic building materials, contributing to carbon sequestration and energy conservation efforts. • A novel photocatalytic carbonation coating has been prepared. • The novel coating had excellent photocatalytic degradation performance. • It provides a new idea for air purification and carbon reduction. [ABSTRACT FROM AUTHOR]

• This paper investigates the effect of glass-ceramic aggregates on mortar properties. • Dissolved ions from glass-ceramics improve ITZ performance. • Addition of glass-ceramics significantly improves chlorine and abrasion resistance. This study aimed to improve the durability of concrete in the marine environment through the utilization of waste glass-ceramics as aggregates. The investigation focused on their effects on the mechanical strength, chloride attack resistance, and abrasion resistance of high-ferrite Portland cement mortar (HFCM). Inductively coupled plasma, X-ray diffraction, scanning electron microscopy-backscattered electronic, and microhardness techniques analyzed the impacts of glass-ceramics on the interfacial transition zone's (ITZ) composition, structure, and strength. Results demonstrated that glass–ceramic fine aggregates possessed low alkali activity, posing no potential risk of alkali silicate reaction. The partial substitution of natural sand with glass-ceramics improved HFCM's mechanical strength and resistance to chloride attack and abrasion. The dissolution of trace amounts of Si4+ and Al3+ from the glass-ceramics contributed to the hydration reaction and facilitated the development of a compact and robust ITZ. Overall, HFCM with glass-ceramics effectively resisted the harsh marine environment, specifically against chloride ion erosion and wave erosion. [ABSTRACT FROM AUTHOR]

Graphical abstract A dynamic adsorption–migration-photocatalysis-desorption occur on MOC surface for HCHO degradation. The phase 5 in MOC materials adsorb pollutant gas, HCHO molecules migrated to active sites in the catalyst along nano-needle via concentration gradients. HCHO was degraded under visible light by Ag/AgBr nanoparticles. After photocatalysis, HCHO molecules were converted into CO 2 and H 2 O. Highlights • AgBr nanoparticles were deposited on MOC substrate by spraying AgBr nanoparticle suspension with the size of 200 nm. • The nanosized needle-like structure of Phase 5 favored adsorption and photocatalytic reaction. • The Ag/AgBr/MOC composites prepared in daylight achieved the best performance in formaldehyde removal. • In the bottle-like artwork test, formaldehyde (50 ppm) could be degraded completely within two days. Abstract As a promising decorating material, magnesium oxychloride (MOC) cement was characterized with a three-dimensional network composed mainly by phase 5 with needle-like structure. AgBr nanoparticle with 200 nm particle size was deposited on magnesium oxychloride cement substrate. The metallic silver nanoparticles were produced from AgBr particle with the irradiation. Thus the composite was prepared containing metallic silver, AgBr and MOC cement. The final products showed high performance for HCHO degradation. The content of magnesium oxychloride cement had an impact on degradation efficiency. The sample with the molar ratio of H 2 O/MgO 14 showed higher degradation efficiency than other groups. A bottle-like artwork was fabricated based on the prepared composites and tested for HCHO degradation under room temperature and daylight. HCHO with an initial concentration of 50 ppm can be degraded completely within two days. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Superhydrophobic Magnesium Oxychloride Cement was fabricated. • The water contact angle increases with the increase of surface roughness ratio. • A modified Wenzel equation was proposed based on the fractal calculation. • Superhydrophobic MOC surface also can achieve self-cleaning. Abstract The poor water-resistance mechanism of magnesium oxychloride cement (MOC) is well understood in the past decades due to cations and anions in the hydration products. It is difficult to achieve the hydrophobic property on this kind of inorganic material surface. In the present work, MOC with a superhydrophobic surface was fabricated by the nanocasting technique using sandpaper as the template. The water contact angle on the superhydrophobic MOC surface reached up to ∼142°. The fractal dimensions of the MOC surface with different roughness ratios were calculated by box-counting method. The results suggest that the water contact angle increases with the increase of surface roughness ratio. A modified Wenzel equation was proposed and verified with experimental data to predict the hydrophobicity of MOC surface. The contact angle hysteresis on the superhydrophobic MOC surface was found to be less than 5° due to the nano-rods microstructure of phase 5. Based on the results, it was concluded that the dual-level fractal structure in micro- and nano-scales, e.g. micro papilla and nano-forest, contributed to the superhydrophobic behavior of the MOC composed of hydrophilic substances. In addition, self-cleaning was achieved on the superhydrophobic MOC surface. [ABSTRACT FROM AUTHOR]

Highlights • Pore structure of HFPC concrete is obviously optimized by addition of SF. • MK contributes to form more aluminate hydrates enhancing binding capacity of chloride. • The elevated temperature is detrimental to resistance of chloride penetration. Abstract As a typical kind of sulphate resistance Portland cement (SRPC), high-ferrite Portland cement (HFPC) has drawn extensive interesting, and is expected to be used in marine environment, but the low chloride resistance is a primary issue and requires to be notably enhanced. This study therefore has investigated the effects of the curing temperature and supplementary cementitious materials (SCMs) on chloride migration in HFPC precast concrete. The results show that two representative SCMs, namely, silica fume (SF) and metakaolin (MK), could significantly improve the resistance of steam cured HFPC concrete to chloride permeation. The improving mechanism of SF is based on optimization of the pore structure to retard migration of chloride, while MK is based on promotion of the chloride binding capacity. This study could give an insight into a new type of precast concrete with excellent sulphate and chloride resistance in marine environment. [ABSTRACT FROM AUTHOR]

• Q phase enhanced the strength and water resistance of FGD gypsum products. • Primary hydrates of FGD gypsum-Q phase system included AFt, AFm, and gibbsite. • Total porosity of FGD gypsum was reduced by Q phase hydraulic hydrates. Flue gas desulfurization gypsum-quaternary phase (FGD gypsum-Q phase) system is investigated to enhance the mechanical and water resistance performance of gypsum specimens. FGD gypsum specimens were prepared with 5–15% content of Q phase at the standard consistency fluidity. Setting time, compressive strength, and water resistance of gypsum specimens were discussed. The results indicated that gypsum specimens with 10% Q phase cured at 7 d had the highest softening coefficient of 0.689 and water absorption of 20.42%, of which, dry compressive strength could reach to18.95 MPa and wet compressive strength could reach 13.06 MPa. The structural properties of gypsum specimens were detected by XRD, TG, SEM, 27Al NMR, and LF-NMR. The hydration heat of FGD gypsum-Q phase system was measured to characterize hydration. These results suggested that Q phase extended the heat release time of the system, and increased the total hydration heat, while hydrates could refine the pore structure, in which the primary hydrates included calcium sulfate dihydrate, ettringite, monosulfoaluminate, and gibbsite. It is concluded that Q phase could improve the compressive strength and water resistance of FGD gypsum specimens, which contributes to the application of FGD gypsum and Q phase. [ABSTRACT FROM AUTHOR]

• A novel ternary alkali-activated cement. • A new type of alkali activator which could control the release rate of alkali and delivery of alkali in situ. • Alkali is encapsulated within the alkali-doped carboxylate glass. • The water-saturated SAP works in cement as water supplier and internal curing agent. In this paper, we introduce a novel approach for the targeted delivery of concentrated alkali required for activation of aluminosilicate-based cements, which avoids exposure to caustic solutions on site. The solid alkali, encapsulated within a water-soluble glass (alkali-doped carboxylate glass) is dry blended with mineral admixtures (ground granulated blast slag and fly ash) and water saturated superabsorbent polymers (SAP, being the only source of mix water in this study). The solubility of alkali-doped carboxylate glasses (ACG) was characterized. The hydration of ground granulated blast slag (GGBS) and fly ash (FA) with different curing times were monitored by SEM, XRD, FT-IR and solid-state MAS NMR, which showed the co-existence of calcium aluminum silicate hydrate (C-A-S-H) gel and sodium aluminosilicate hydrate (N-A-S-H) gel in the hydration products. The mechanical properties of AAC were tested, and the compressive strength of AAC (using ACG as alkali activator, water saturated SAP as water source) reached over 40 MPa after curing for 28 days. [ABSTRACT FROM AUTHOR]

In this work, photocatalytic cement was prepared by loading Bi 2 WO 6 microspheres with Portland cement. 3D hierarchical Bi 2 WO 6 microspheres were synthesized by self-assembly of 2D nanosheets and nanoplates firstly. Interestingly, Backscattered Electron (BSE) images showed Bi 2 WO 6 hierarchical structure remained unchanged on the surface of hydration cement. The nanoplate and nanosheets which fell off from the Bi 2 WO 6 microspheres distributed evenly on the surface of the hydration products. As to the inner structure of Bi 2 WO 6 /cement, a porous structure was observed and Bi 2 WO 6 particles were located evenly in the pores. This result was in favor of enhancing photocatalytic performance and gas adsorption. The 15 wt% Bi 2 WO 6 /cement showed the highest photocatalytic activity, which can degrade the HCHO completely within 80 min under visible light. XRD and hydration heat results showed that Bi 2 WO 6 hardly influences the hydration process. However, when the Bi 2 WO 6 dosage was increased to beyond 15%, the hydration process was deterred and hydration heat decreased, which may influence the durability of the cement matrix. [ABSTRACT FROM AUTHOR]

Photocatalytic cementitious material (PCM) was prepared by porous magnesium oxychloride cement (PMOC) and TiO 2 photocatalyst. Influences of PMOC substrate surface microstructure on TiO 2 loading and photocatalytic performance had been investigated. The results revealed that loading effect mostly depends on PMOC substrate surface microstructure which could be controlled by its curing age. Appropriate interlaced microstructure enhanced TiO 2 dispersity, loaded mass and adsorption capability. PCM-14d specimen (14-day curing before TiO 2 loading) had the best photocatalytic performance, which could completely purify toluene (200 ppm) within 80 min. Practical simulation experiment indicated that PCM-14d specimen was 1.3 times better than nickel foam based photocatalytic material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Organosilane-fly ash hybrid was prepared. • A strong network is formed through PVP and hybrid crosslinking. • The compressive strength of polymer-modified cementitious material was enhanced. • The homogeneous distribution of FA by agitation helps disperse the polymer evenly. • The micro-mechanical properties of cement mortar were greatly enhanced. Low compressive strength has always been a problem for polymer-modified cementitious materials. In this paper, a crosslinking network that makes use of organosilane-fly ash (FA) hybrid and polyvinylpyrrolidone (PVP) was exploited to improve the compressive strength of polymer-modified cementitious materials. Two kinds of polymers and five different organosilanes with different functional groups were investigated. The best improvement was realized when aminosilane (–NH 2) or mercaptosilane (–SH) was used. The mechanism of the enhanced compressive strength was investigated extensively. A strong network is formed through the chemical connection between polymer, FA, organosilane, and calcium-silicate-hydrate (C-S-H). The cement paste has significantly enhanced micro-mechanical properties according to the nanoindentation testing results and the pore structure shows obvious improvement in the mercury intrusion porosimetry results. The presented strategy can thus effectively increase the compressive strength of polymer-modified cementitious materials without adverse effects. [ABSTRACT FROM AUTHOR]

• Three representative photocatalytic cement mortars were prepared. • TiO 2 supported on aggregate is a promising application way in mortar. • TiO 2 supported aggregates dispersed sample has high photocatalytic durability. The application of titanium dioxide (TiO 2) photocatalyst in concrete is considered a promising method to effective remove nitrogen oxide (NOx) pollutants. However, the influences of application ways on photocatalytic efficiency and catalyst durability should be concerned in detail for its large-scale application. This paper compared the photocatalytic NOx degradation efficiency and durability of conventional TiO 2 powder dispersed in cement mortar (TPC), TiO 2 supported aggregates mounted on cement mortar surface (TAS) and TiO 2 supported aggregates dispersed in cement mortar (TAD), with considering different environmental factors effects such as gas flow rate, NO initial concentration and relative humidity. The photocatalytic efficiency results show that the NOx removal efficiency of TAS is about 1.5 and 1.1 times higher than that of TPC and TAD, respectively, corresponding to the utilization efficiency of TiO 2 photocatalysts in TAS is ca. 10 and 16 times higher than in TPC and TAD, respectively. The surface abrasion test suggests that TAS has relatively low photocatalytic efficiency compared with TAD after polishing the sample surface by more than 2 mm, which depends on the mounted thickness of TiO 2 supported aggregates. The findings in this work can provide the basis for the application ways of TiO 2 supported aggregates in concrete by considering its photocatalytic efficiency, economic efficiency and catalytic durability. [ABSTRACT FROM AUTHOR]