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The adsorption behavior and dispersing capability of hyperbranched phosphated polycarboxylate superplasticizers (PCEs) containing phosphate monoester and phosphate diester were investigated. The hyperbranched structures were constructed using a special monomer dimethylaminoethyl methacrylate (DMAMEA) to create the branches during the polymerization. Meanwhile, the polymer architectures were tailored by varying the content of phosphate monoester and phosphate diester in the backbone via free radical solution polymerization. In contrast to comb-like PCE, hyperbranched PCEs presented a weaker dispersion capability at w/c = 0.29, but with a lower water-to-cement ratio (w/c), the hyperbranched PCEs exhibited a better dispersion capability than the comb-like PCEs. The dynamic light scattering (DLS) and transmission electron microscope (TEM) analysis showed that the adsorption layer of hyperbranched PCEs were thicker than that of comb-like PCEs. A thicker adsorption layer thickness generated thinner diffusion water layer thickness. The increase of the free water amount due to the thinner water diffusion layer is the key mechanism for improving the dispersibility and decreasing the viscosity of cement paste. [ABSTRACT FROM AUTHOR]

An attractive approach for the preparation of spirocyclic benzofuran–furocoumarins has been developed through iodine-catalyzed cascade annulation of 4-hydroxycoumarins with aurones. The reaction involves Michael addition, iodination, and intramolecular nucleophilic substitution in a one-step process, and offers an efficient method for easy access to a series of valuable spirocyclic benzofuran–furocoumarins in good yields (up to 99%) with excellent stereoselectivity. Moreover, this unprecedented protocol provides several advantages, including readily available materials, an environmentally benign catalyst, a broad substrate scope, and a simple procedure. [ABSTRACT FROM AUTHOR]

In recent years, with the rapid development of Internet technology, the integration of platform economy and e-commerce has become a popular business model. Two-sided platforms have a specific impact on sales, customer experience and transaction efficiency of both sides. In the current severe situation caused by the coronavirus pandemic, both the traditional unilateral market platform and the emerging two-sided market platform are in urgent need of a change in operation mode to reduce the marketing cost. Inspired by the cooperation between Meituan, a two-sided platform, and WeChat, a social media platform, this paper investigates the two-sided platform's scalable decisions on when to cooperate and how to optimize the pricing and investment decisions. We analyze how the two-sided platform makes decisions by considering the changes of network externalities from the cooperation with the social network platform. Compared with the scenario of non-cooperation, we derive the conditions under which platform cooperation can increase demands and increase platforms' profits, and analyze how cooperation affects the optimal pricing strategies. We find that the cooperation leads to a larger demand and a higher total profit, but might lead to higher registration prices for the platform users. Furthermore, we adopt the Nash bargaining framework and introduce platform bargaining power parameters to obtain the optimal cooperation and sharing strategy. Finally, we show how to adjust the investment strategy of the two-sided platform under platform cooperation. [ABSTRACT FROM AUTHOR]

This paper takes 30 provinces in China as the research subjects and constructs a real options model to explore the impact of carbon emissions trading market, energy storage subsidies, and their synergy on the optimal investment decision of household PV-ESS projects. The results show that a single factor has a catalytic effect on project investment, and both together have a better effect. And, project investment benefits are better in areas with abundant light resources and higher than average electricity prices. In addition, a sensitivity analysis is conducted on the initial investment cost, CO 2 price, and energy storage subsidies. The results show that immediate investment in all provincial projects can be achieved when the initial investment cost is reduced by 50%, or the CO 2 price is increased by about 33 times, indicating that the current environment is insufficient to attract investors. The results provide a reference framework for investment in household PV-ESS projects. • Use real options methods to assess investment decisions for household PV-ESS projects. • Explore the role of carbon trading market and energy storage subsidies on investment. • Research the impact of different regional power grids on investment value. [ABSTRACT FROM AUTHOR]

This study introduces a new regional feed-in tariff (FIT) pricing mechanism for solar photovoltaic (PV) energy in China, informed by real option (RO) theory and incorporating the increasing significance of tradable green certificate (TGC) policy revenues. The mechanism aims to balance government and consumer burdens with investor benefits. By factoring in additional income from green certificate sales, the study calculates the internal rate of return (IRR) to fall between 8 and 16% and uses a Monte Carlo simulation to determine optimal FITs for 30 Chinese provinces. These optimal FITs are then compared with current FITs, which are categorized by three types of solar resource regions, revealing that many current FITs are set within an inappropriate range and require adjustment. Additionally, the study observes minor differences in provincial FITs within six regional power grids, suggesting that setting FIT guide prices at the regional grid level is more practical than by solar resource regions. A sensitivity analysis examines the impact of green certificate prices, carbon prices, and technological advancements on the FIT for solar PV, comparing scenarios in a realistic environment versus a more favorable one. The results indicate that in a better environment—with higher TGC and carbon prices and encouraged corporate innovation—the FIT for solar PV is closer to the cost of coal-fired electricity, thus promoting grid parity. The study advocates for adjustments to the FIT mechanism, higher TGC and carbon prices, and the encouragement of innovation to enhance the competitiveness of solar PV energy in China's energy market. [ABSTRACT FROM AUTHOR]

In this study, polydimethylsiloxane (PDMS) was applied for overall hydrophobic modification of alkali-activated slag (AAS) mortars aiming to reduce its high water sorptivity. The effects of the amount and viscosity of PDMS on the water absorption characteristics and mechanical properties of AAS mortars were investigated. Meanwhile, MIP, the surface contact angle of AAS mortars and SEM-EDS, Inverse gas chromatography (IGC), FT-IR, XRD of hardened AAS pastes were performed for analyzing the modification mechanisms. The results indicated that the water sorptivity of PDMS-modified AAS mortar decreased by 90 %, and the contact angle of the inner surface increased from 14° to 128° when the dosage of PDMS reached 8 % (by weight of binder). The main modification mechanisms of PDMS in AAS system can be summarized as: Firstly, the formation of hydrophobic coatings on the surface due to the cross-linking reaction between C-S-H gel and PDMS reduces the surface energy and the hydrophilicity of hardened AAS pastes, achieving chemical modification; Secondly, the hierarchical structures formed by micro papillary increases the surface roughness, thus enhancing the hydrophobic effect further through physical modification. Moreover, the coarsening of capillary pores also reduces the capillary force during water absorption process. Meanwhile, the addition of PMDS maintains comparable strength development of AAS mortars, which is beneficial for the practical application. • PDMS-modified AAS mortars converted from hydrophilic to hydrophobic porous materials. • A 90 % reduction of water sorptivity of mortars was achieved by addition of PDMS. • The hardened PDMS-modified AAS pastes possessed lotus-leaf-like microstructure formed by micro papillary. • The PDMS-modified mortar exhibited stable strength development. [ABSTRACT FROM AUTHOR]

Distributed photovoltaics (PV) play a key role in the energy transition. We construct an investment value and timing assessment model based on the real options method to improve scientific decision-making in distributed PV investing in an uncertain environment. The model is applied to analyze projects in the East China Power Grid region under multiple self-consumption ratio scenarios. The results show that investing in distributed PV projects is beneficial, but there are differences in the optimal investment timing under different self-consumption ratios. Investors can defer investment for as early as one year to obtain optimal investment value. • Propose the distributed PV investment decision model based on the real option method. • Consider the uncertainty of initial investment cost and the on-grid price. • Investigate the impact of distributed PV power generation self-consumption ratio. • Investigate the impact of carbon trading on investment value and investment timing. [ABSTRACT FROM AUTHOR]

The electrochemical tests commonly used for evaluating reinforcement corrosion in Portland cement-based concrete may not be appropriate for testing alkali-activated slag (AAS) concrete due to its different pore structure and pore solution composition. In this article, corrosion behaviour of the steel bars in 12 AAS concrete mixes with different alkali concentration and modulus of sodium silicate solution was monitored by using gravimetric mass loss measurement. The results obtained from other electrochemical tests were compared to the gravimetric mass loss to determine their suitability for assessing the corrosion of steel in AAS concrete. It was found that only 7.8–28% of the mass loss was accounted for by the macrocell current for AAS concretes, indicating that this type of test underestimates the corrosion of the steel in AAS concrete. The steel bars in the AAS concretes gave a much higher negative half-cell potential value, presumably due to the influence of sulfides. In summary, it has been established that the criteria for assessing the onset and progress of corrosion of steel in Portland cement concrete are not suitable for the same purpose in the range of AAS concretes studied. [ABSTRACT FROM AUTHOR]

• Ca(OH) 2 reduced the efflorescence extent of alkali-activated slag(AAS) mortar. • The mitigation mechanism of Ca(OH) 2 on the efflorescence of AAS mortar was analyzed. • Ca(OH) 2 decreased the permeability and ion leaching capacity of AAS. • The mechanical properties of AAS mortar were enhanced by addition of Ca(OH) 2. Due to the high alkali concentration, weak binding of Na+ and relatively open microstructure, the efflorescence of alkali-activated slag (AAS) cement is a critical barrier limiting its widespread application. To reduce the efflorescence, Ca(OH) 2 was added as a Ca-rich precursor into the binder with the dosage of 3, 6 and 9 wt% by slag. The efflorescence of AAS mortars was identified by visual inspection and mass weighing of efflorescence products formed on the surfaces of the mortar. Capillary porosity, water absorption rate, Na+ leaching test, XRD and TG analysis were also carried out to explain the change of microstructure and hydration products caused by the incorporation of Ca(OH) 2. The results revealed that the addition of Ca(OH) 2 significantly reduced the coverage areas and the amount of efflorescence products. However, visual inspection results were not consistent with that of mass weighing of efflorescence products, ion leaching, etc. If the impact of efflorescence on microstructure should be considered, visual inspection is not suitable. It can be concluded that the addition of Ca(OH) 2 can mitigate the efflorescence by following reasons: firstly, the capillary porosity decreased from 16.86% to 15.22% and the water absorption rate decreased from 0.0366 mm/s1/2 to 0.0179 mm/s1/2 by adding 9% Ca(OH) 2 , which means that the migration pathway of the Na+ and water within the mortar was decreased. Secondly, the leaching results indicated that fewer Na+ leached from the Ca(OH) 2 -added samples, either from powder leaching or block leaching, which means that the addition of Ca(OH) 2 may enhance the binding of Na+ by hydration products through increasing the C-A-S-H gel content. [ABSTRACT FROM AUTHOR]

[Display omitted] • The cohesion interactions mainly determine plastic viscosity of AAS pastes. • The greater attractions between particles is the reason for its higher viscosity. • The friction interactions mainly determine the yield stress of AAS pastes. The workability and pumping performance of alkali-activated slag (AAS) concrete are affected by its rheological properties, which are related to the interactions between slag particles in the pastes. The rheological properties of AAS paste with different equivalent sodium oxide (Na 2 O eq) dosage activated by sodium hydroxide (NaOH) and sodium silicate (waterglass) with different SiO 2 /Na 2 O molar ratios were investigated in this study. The rheological mechanism was studied from the cohesion and friction interactions by calculations from parameters such as the Zeta potential of particles in the pastes, surface energy, hydrogen bond, and friction coefficient of the alkaline activators. The results indicated that the yield stress of AAS pastes was lower than that of the paste made with slag and water, whereas the plastic viscosity was higher. The yield stress of AAS pastes was mainly determined by the friction interactions between particles. The plastic viscosity was mainly affected by attractive interactions, including van de Waals interactions and Lewis acid-base interactions. The electrostatic repulsion interactions were felt at a very short distance because the AAS pastes were systems with the high ionic strength, which means that the electric double layer were severely compressed, therefore, the attractive interactions were predominant. Taken together, these results suggest that the improvement of plastic viscosity of AAS pastes should be achieved by changing the attractive interactions. [ABSTRACT FROM AUTHOR]

The deterioration of reinforced concrete structures caused by chloride‐induced corrosion is a major threat to their service life. Previous studies show that defects in the steel–concrete interface have a significant impact on the corrosion process of steel bars. Study on the chloride permeability of steel–concrete interface is very important for revealing the mechanism. In this article, we devised a new experimental method named chloride penetration depth test which was used to evaluate the chloride permeability along the steel–concrete interface. Two types of fresh concretes, normal concrete (NC) and lightweight aggregate concrete (LWAC) with obviously different stability, were designed to obtain specimens of various defect sizes in the steel–concrete interface. The results show that the chloride penetration depth measured with the new method increased with the defect size in the steel–concrete interface determined by backscattered electron (BSE) imaging and nanoindentation technology, indicating that the chloride permeability of steel–concrete interface could be identified by the method we proposed. [ABSTRACT FROM AUTHOR]

• Passivity of mild steel embedded in MKPC-CSA blended paste were investigated. • CSA addition significantly influences the degree of passivity. • Passivity increases with increased CSA addition and 30% CSA addition leads to a much higher passivity. • 30 % CSA addition benefits the precipitation of phosphate ions and formation of Fe2+ oxide in passive film. This study did a pioneer work focused on the passivation of mild steel embedded in magnesium potassium phosphate cement (MKPC)-calcium sulphoaluminate cement (CSA) blended paste via electrochemical measurements and materials characterization techniques. Results showed that 30 % CSA addition in MKPC leads to a passivity of mild steel much higher than that in Portland cement (PC) paste. The passivity of mild steel increased with an increase in CSA content in MKPC paste due to an increase in pH and phosphate concentration in pore solution. The formation of iron phosphate and Fe2+ oxide in passive film of MKPC-30 %CSA contributes to its highest passivity. [ABSTRACT FROM AUTHOR]

This study examines the potential of using calcium‐rich precursors to improve the strength of alkali‐activated slag (AAS) cement at low temperature. To achieve this target, the effect of calcium‐rich precursors on the early strength development of AAS mortars cured at 5°C was assessed. The strength development was investigated along with its internal temperature, microstructure and reaction products. It is found that the calcium‐rich precursors can improve the early strength of AAS around 35% and the group with Portland cement clinker gave the highest strength. Calcium oxide can also increase the compressive strength of AAS cement, but its effectiveness is not as good as the sample with clinker. Adding calcium sulfoaluminate can increase the early strength, while no significant contribution to 28‐day strength could be found. The results highlight that compressive strength of modified AAS mortar can reach 15 MPa at 6 h and 20 MPa at 24 h at 5°C, suggesting that this binder could be a valuable alternative for low temperature construction. [ABSTRACT FROM AUTHOR]

Ground granulated blast-furnace slag (GGBS) is widely used as supplementary cementitious material of interest for adjusting the performance of concrete. Unlike standard commercial products, characteristics of GGBS from different iron manufacturers vary significantly and assessment of its reactivity, especially at an early age, is not well-established despite numerous parameters specified in current standard systems. Three GGBSs with different setting features during the alkali-activated process were dissolved in either deionised (DI) water or NaOH solution in this study. To illustrate the fundamental processes of reaction kinetic, the dissolved ion concentrations, glassy structural changes, and chemically bound water were measured using ICP-OES, FTIR, and TG respectively. Meanwhile, thermodynamic calculations were carried out to estimate the precipitation of C–S–H gels, which is directly linked with setting behaviours. The results clearly show the differences in the dissolution of the three GGBSs, which could be used to indicate the activity of GGBS. The GGBS with higher activity (i.e. faster setting during alkali activation) tends to dissolve evenly in DI water, whilst those with lower activity show that the silicate groups with lower polymerisation dissolved faster. The chemically bound water determined by TG analysis and the effective saturation index (ESI) are promising parameters for reflecting the activity of GGBS during dissolution in the alkali media. Although this study demonstrated the dissolution rate of higher polymerised silicate groups in GGBS should be the root for the differences in its activity, more structural information on the glassy phase and the interactions of alkali with the surface of GGBS still require further understanding. It is speculated that the ratio of Al[IV]/Al[V] plays an important role in the activity of GGBS. This finding may shape a certain basic understanding of how GGBSs dissolve in neutral and high pH solutions and highlight a re-evaluation of assumptions in thermodynamic simulation under different conditions. [ABSTRACT FROM AUTHOR]

The addition of coarse aggregate in ultra-high performance concrete offers several benefits, including the reduction of self-shrinkage, cost reduction, and increased modulus of elasticity. However, it also affects the dispersion space of steel fibers, resulting in a combined effect that both enhances and limits their respective advantages. An image method was used to describe the dispersion of steel fibers and coarse aggregate in the specimens along their length, width and height directions, respectively. The impact of dispersion of steel fibers and coarse aggregate on bending performance was investigated by four-point bending tests using various surfaces as the bottom tensile zone. Furthermore, the damage occurrence mode and crack development process are discussed using micro-morphology and cross-sectional graphs. The results show that the combined effect of steel fibers and coarse aggregate is not conducive to dispersion in the length direction but prevents settling due to gravity during vibration. Differences in bending properties among various surfaces in the bottom tension zone was significant, but the synergy between steel fibers and coarse aggregate reduced these differences by 1.5–2.4 times. Steel fibers in ultra-high performance concrete containing coarse aggregate act as crack arrestors, resulting in ductile damage. Cracks develop partly through the coarse aggregate and partly along the interface transition zone, indicating that the addition of coarse aggregate does not compromise flexural strength. • Dispersion variability was observed in the length, width, and height directions, influenced by the combined effect. • The combined effect mitigated the settling of steel fibers in ultra-high performance concrete. • The coarse aggregate has a limited effect on the flexural strength but diminishes post-peak performance. • The dispersion of steel fibers is the primary factor influencing post-peak performance. • The combined effect reduced the variation in bending parameters for different surfaces acting as the bottom tension zone. [ABSTRACT FROM AUTHOR]

To investigate the damage fractal and energy dissipation of dolomite marble under blasting load, Dahongshan Copper Mine was selected as the test object and one-dimensional SHPB impact tests with different strain rates were carried out. The dynamic compressive strength, damage morphology, fractal fragmentation, and energy dissipation of the rock were analyzed. The results showed that the absorbed energy per unit volume and the crushing energy per unit mass of dolomite marble are closely related to the dynamic compressive strength. The fractal dimension D of dolomite marble increases with increasing strain rate, and the smaller the average block size of the rock, the degree of crushing deepens. In addition, as the incident energy increases, the crushing energy of the rock also increases, and the energy dissipation intensifies. Finally, after comparative analysis, the reasonable strain rate range is 68.14–77.61 s−1, and the reasonable specific energy absorption value range is 0.65–0.98 J/cm3. The fractal pattern of rock deformation and damage can be reasonably explained from the perspective of energy dissipation. [ABSTRACT FROM AUTHOR]

• Effect of Na 2 CrO 4 on the hydration kinetics of blast furnace slag were studied. • The Na 2 CrO 4 showed a strong alkaline activating on the blast furnace slag. • The compressive strength could be significantly improved by adding Na 2 CrO 4. • The main reaction products were C-(A)-S-H and CrO 4 -U phase. • A large number of alkalis was released during the reaction between slag and Na 2 CrO 4. Blast furnace slag (BFS) is a potential candidate for the immobilization of chromium-bearing wastes. This paper investigated the effect of soluble hexavalent chromium (Na 2 CrO 4) on the early hydration behavior of BFS by means of isothermal calorimetry, X-ray diffraction (XRD), thermogravimetry (TG), scanning electron microscopy (SEM) and pH measurement of pore solution. Meanwhile, the compressive strength of BFS pastes in the presence of different dosage of chromate was tested for the structural study. The primary aim was to verify the alkaline activation of Na 2 CrO 4 on the BFS. It was found that the BFS in water had scarcely hydrated in the first 7 days, whereas the addition of Na 2 CrO 4 greatly accelerated the hydration of BFS and promoted the hardening. Increasing the Na 2 CrO 4 dosage could significantly improve the compressive strength, which was sufficient to meet the requirement for immobilization of wastes. The hydration products of BFS in Na 2 CrO 4 solutions were mainly C-(A)-S-H and CrO 4 -U phase. The CrO 4 -U phase played a key role in Cr(VI) binding due to its layered structure. During the formation of CrO 4 -U phase, a large number of alkalis was released, which largely increased the pH of pore solution, thus greatly promoting the BFS hydration. The results indicated that the Na 2 CrO 4 had a strong alkaline activation on blast furnace slag. [ABSTRACT FROM AUTHOR]

Alkali-activated slag (AAS) has attracted huge attention worldwide for its low CO 2 emission. However, the high water sorptivity of AAS is an obstacle before its practical application, while conventional methods can hardly solve this issue. In this study, the water sorptivity of AAS was decreased using a novel admixture, and the admixture shows a little effect on compressive strength at long ages. In order to clarify causes for its working mechanisms, the reaction process, reaction products and pore structure were investigated. The results suggest that sodium stearate (NaSt) plays an instrumental role in reaction process of AAS. Primarily, Na+ can provide a high alkaline environment, which is conducive for the dissolving of slag and increases compressive strength at the long term. Secondly, C 17 H 35 COO− can dramatically limit the movability of ions in the liquid phase due to its long molecular chain and thus, regulates precipitation of coagulation structure, improving the of ordering structure of C(N)-A-S-H and promoting formation of hydrotalcite-like phases (LDHs), from which the pore structure is upgraded by coarsening the pore diameters at the level of harmless and less harmful pores and decreases the pore connectivity. [ABSTRACT FROM AUTHOR]

• The rheological properties of AAS pastes have been improved by low surface free energy mineral admixtures. • The surface free energy properties of low surface free energy mineral admixtures have been determined by IGC method. • The interparticle forces were calculated to reveal the mechanism for rheological improvement. This study investigates the effect of low surface free energy mineral admixtures (CaF 2 -dominated fluorite (FL) and fluorine-containing lithium slag (LS)) on the rheological behavior of alkali-activated slag (AAS) pastes. The fluidity, rheological behavior, surface charge properties and surface free energy properties were tested. The interparticle forces based on extended Derjaguin-Landau-Verwey-Overbeek (EDLVO) theory were calculated to understand the mechanism for the rheological behavior improvement. The results revealed that both FL and LS could improve the fluidity and decrease the yield stress and plastic viscosity of AAS pastes. Furthermore, the attraction is manifested by the sum of electrostatic, van der Waals, and Lewis acid-base forces, and this value decreases with increasing LF or LS content, implying that the particle dispersion in AAS pastes is improved. Furthermore, observing flocculent structures captured by the metallographic microscope proves the better dispersion of AAS pastes after adding FL and LS. Moreover, incorporating LS or FL decreases the flexural and compressive strengths of AAS mortars. [ABSTRACT FROM AUTHOR]

• Adding 0.5 wt% calcium stearate can reduce 25% of the autogenous shrinkage of AAS; • The use of stearates can significantly reduce the internal capillary pressure of AAS; • The dynamic elastic modulus of AAS will reduce by 20% after adding stearates; • Elastic deformation only accounts for 10% of the total autogenous shrinkage of AAS. The autogenous shrinkage of the stearates-modified alkali-activated slag (AAS) mortar was investigated in this study. The experimental results suggested that the maximum reduction (25 %) of autogenous shrinkage of AAS can be achieved by adding 0.5 wt% calcium stearate, while potassium stearate and sodium stearate seem less effective in decreasing shrinkage. According to the results obtained, the mechanisms of shrinkage mitigation are mainly associated with the retardation of hydration, the coarsening of pore structure, and the increased contact angle. It is estimated that the capillary pressure of pores was reduced by 30 % ∼ 60 % when stearates were used. However, the elastic modulus of AAS was reduced by 20 % due to the bubble-stabilizing effect of stearates, especially at higher dosages, which would partially offset its decreasing effects on autogenous shrinkage. It is also found that the traditional physical model could be used to predict the autogenous shrinkage of plain and modified AAS samples, provided the effect of both elastic and creep parts is considered. [ABSTRACT FROM AUTHOR]

[Display omitted] • The role of CGS on the workability of cement paste with and without PCE was investigated. • The decrease of interparticle force leads to the improvement of fluidity when added CGS. • The aggregation of PCE in pore solution leads to its efficiency decrease in the cement pastes blended with CGS. Coal gasification slag (CGS) is the main by-product of coal gasification technology, and the utilization of CGS as mineral admixture is environmentally sound. In this paper, the effect and mechanisms of CGS on the workability (i.e., fluidity and rheological behaviors) of ordinary Portland cement (OPC) paste with and without polycarboxylate superplasticizer (PCE) were studied. The zeta potential and surface free energies of OPC and CGS were tested to calculate the electrostatic force and Van der Waals force variations due to the addition of CGS particles. The results revealed that CGS mainly decreases the van der Waals attraction force between binder particles, enhancing the fluidity and reducing cement pastes' yield stress and plastic viscosity. When blended with PCE, the dissolution of CGS mainly increased the ionic concentrations of Si(OH) x (4-x), which promoted the aggregation of PCE and decreased its adsorption, thus decreasing the fluidity and increasing the rheological parameters. [ABSTRACT FROM AUTHOR]

Increasing attention is concentrated on the alkali-activated slag (AAS) as an alternative binder owing to its low environmental impact and high mechanical strength, whereas the carbonation resistance of AAS can be quite problematic. In this work, calcined Mg/Al layered double hydroxide (CLDH) was synthesized and used to improve the carbonation resistance of AAS mortars activated by NaOH. The effect of CLDH on the carbonation depth, mechanical strength, and microstructure before and after carbonation was investigated. The results show that CLDH reconstructed the lamellar structure and formed a hydrotalcite-like phase because of its memory effect. The hydrotalcite-like phase acted as a buffer system to absorb CO 2 intruding into the AAS mortars from the atmosphere, which retarded the decalcification of C-(A)-S-H. Meanwhile, the porosity decreased and the mortars become denser by the addition of CLDH, which prevented the diffusion of CO 2 into the mortars. The compressive strength of AAS mortars was enhanced by the carbonation regardless of CLDH addition. Calcite and vaterite were the main carbonation products. The addition of CLDH did not significantly change the polymorphs of carbonates but mitigated their production. • The effect of CLDHs on the carbonation depth of AAS mortars is studied. • The effects of CLDHs on the phase composition and microstructure of AAS are discussed. • The CO 3 2− is absorbed by the process of CLDHs recrystallized to LDHs. • The porosity of AAS mortars is significantly reduced by adding CLDHs. • Adding CLDHs effectively reduces the susceptibility of AAS mortars to carbonation. [ABSTRACT FROM AUTHOR]

• Proper use of LS can increase fluidity and prolong setting time without losing strength. • LS can affect reaction products of AAS and its function depends on mix proportions. • Variations of pore structure of modified AAS cement relies on the dosage of LS. • Around 30% hydration degree of LS was achieved at 28 d for AAS with 40% LS. This study aims at discussing physical and chemical influence of limestone powder (LS) on the AAS system. General properties, including fluidity, setting time, drying shrinkage, and mechanical strength of AAS pastes/mortars, were examined. Pore structure change and phase assemblages of LS-AAS composites were studied. The results showed that the addition of 50 wt% LS increased the fluidity and setting time of AAS pastes, but reduced the total drying shrinkage of AAS mortars. Meanwhile, around 30% reduction in mechanical properties were found at the same replacement ratio. The pore structure was refined in the pastes with LS replacement<25 wt%, but was coarsened in the sample with 40 wt% LS. Limited new phase was formed in the sodium silicate activated slag samples, which was believed to depend on the modulus of the activator. Around 30% hydration degree of LS was achieved in 40 wt% LS-replaced AAS pastes hydrated for 7 ~ 28 d as determined by TG-DSC analysis. The main drawbacks of AAS, fluidity, setting time, and drying shrinkage, are improved by using high-volume LS, so use of high-volume LS in AAS system can be an option for the purpose of environmental protection. [ABSTRACT FROM AUTHOR]