Heating Tests Research Articles

Implementation and verification of a user‐defined element (UEL) for coupled thermal‐hydraulic‐mechanical‐chemical (THMC) processes in saturated geological media

AbstractEfficient and accurate modeling of the coupled thermal‐hydraulic‐mechanical‐chemical (THMC) processes in various rock formations is indispensable for designing energy geo‐structures such as underground repositories for high‐level nuclear wastes. This work focuses on developing and verifying an implicit finite element solver for generic coupled THMC problems in geological settings. Starting from the mass, momentum, and energy balance laws, a specialized set of governing equations and a thermoporoelastic constitutive model is derived. This system is then solved by an implicit finite element (FE) scheme. Specifically, the residuals and the Jacobians are scripted in a user‐defined element (UEL) subroutine which is then combined with the general‐purpose FE software Abaqus Standard to solve initial‐boundary value problems. Considering the complexity of the system, the UEL development follows a stepwise manner by first solving the coupled hydraulic‐mechanical (HM) and thermal‐hydraulic‐mechanical (THM) equations before moving on to the full THMC problem. Each implementation step consists of at least one verification test by comparing computed results with closed‐form analytical solutions to ensure that the various coupling effects are correctly realized. To demonstrate the robustness of the algorithm and to validate the UEL, a three‐dimensional case study is performed with reference to the in‐situ heating test of ATLAS at Belgium in 1980s. A hypothetical radionuclide leakage event is then simulated by activating the chemical‐concentration degree of freedom and prescribing a constant high concentration at the heater's surface. The model predicts a limited contaminated regime after six years considering both diffusion and advection effects on species transport.

To the characterization of nervous processes in people with different heat sensitivity

The aim of the study was to diagnose functional mobility and strength of nervous processes in people with different heat sensitivity.Materials and methods. For this study, 150 students aged 17-20 years were involved. The subjects were divided into two groups, according to the questionnaire "Levels of heat sensitivity" and heat test. Diagnosing functional mobility of nervous processes in the feedback mode was conducted using the computer program "Diagnost 1M". The strength of nervous processes was also studied, according to the quality of mental load, using the imposed rhythm mode and in the feedback mode. Results. According to the results of the examination, it was found that participants with lower heat sensitivity (group B) have a higher rate of nervous processes strength according to the criterion of the total number of presented and processed signals within five minutes. They also had an average level of functional mobility of nervous processes. Participants with higher heat sensitivity (group A) had a lower than average level of functional mobility. In addition, a correlation was found between the minimum reaction time to a stimulus and the level of heat sensitivity in people. Regarding the quality of mental load performance using the imposed rhythm mode, a higher than average level of test errors was found in group A, while in group B this indicator was within the average level.Conclusions. Persons with lower heat sensitivity have a higher level of strength of nervous processes and their functional mobility, which results in more successful coping with mental load in the mode of imposed rhythm, compared to participants with higher heat sensitivity. Therefore, in subjects with a higher level of heat sensitivity, compared to those with a lower level, impaired concentration and decreased mental performance occur earlier.

Halides-Enhanced Buried Interfaces for Stable and Extremely Low-Voltage-Deficit Perovskite Solar Cells.

The perovskite buried interfaces have demonstrated pivotal roles in determining both the efficiency and stability of perovskite solar cells (PSCs);however, challenges remain in understanding and managing the interfaces due to their non-exposed feature. Here, we proposed a versatile strategy of pre-grafted halides to strengthen the SnO2 -perovskite buried interface by precisely manipulating perovskite defects and carrier dynamics through alteration of halide electronegativity (χ), thereby resulting in both favorable perovskite crystallization and minimized interfacial carrier losses. Specifically, the implementation of fluoride with the highest χ induces the strongest binding affinity to uncoordinated SnO2 defects and perovskite cations, leading to retarded perovskite crystallization and high-quality perovskite films with reduced residual stress. These improved properties enable champion efficiencies of 24.2% (the control: 20.5%) and 22.1% (the control: 18.7%) in rigid and flexible devices with extremely low voltage deficit down to 386mV, all of which are among the highest reported values for PSCs with a similar device architecture. In addition, the resulting devices exhibit marked improvements in the device longevity under various stressors of humidity (>5000h), light (1000h), heat (180h), and bending test (10000times). This method provides an effective way to improve the quality of buried interfaces toward high-performance PSCs.

高温超電導マグネットを用いたアルミ押出成形用400 kW級直流誘導加熱装置の開発

We have been conducting research and development of the DC induction heating device of aluminum billet using HTS magnets. In this R&D, following the development of main components such as the HTS magnet system, the heating control system and the mechanism for grasping and rotating the aluminum billet, the demonstration device for 400 kW-class billet heater was developed and the heating power of over 400 kW was demonstrated. In this study, as the final step of the R&D, we conducted a continuous repetitive heating test and evaluation of the electromagnetic and mechanical influence due to the heating operation on the HTS coil.

Accelerated aging of unencapsulated flexible GaInP/GaAs/InGaAs solar cells by means of damp heat and thermal cycling tests

The extended damp heat and thermal cycling tests were performed on unencapsulated flexible thin-film GaInP/GaAs/InGaAs solar cells to assess the long-term stability. The solar cells were subjected to 85 °C/85% damp heat test for more than 1000 h and 420 cycles of thermal cycling test between −60 °C and 75 °C, respectively. The performance attenuations of flexible solar cells were less than 2% in both cases, which were due to the slow decline of the open-circuit voltage with aging time. The slight decrease in open voltage was attributed to the increase in reverse saturation current due to the enhanced recombination, which was in good agreement with the calculation based on the two-diode model. The good performance of the unencapsulated flexible GaInP/GaAs/InGaAs solar cells in severe environment indicated the stable and reliable device fabrication art in the experiment.

Graphene NanoPlatelet-based coating as thermal protection from high-power radiative fluxes

A major disadvantage of polymer-based composite materials is their poor performance when exposed to relatively high heat flux. At temperatures typically above 300–400 °C, the organic matrix decomposes releasing heat, smoke, and toxic volatiles, jeopardising the composite mechanical performances. The heat flux resistance of composites can be improved by integrating protective coatings on their surface. In the present work, graphene nanoplatelet (GNP) films are employed as thermal barrier coatings (TBCs) to mitigate the thermal degradation of Carbon Fibres Reinforced Plastic (CFRP). The films were bonded onto the heat-exposed surface of CFRP laminates. Laser spot heating tests, with different laser power densities (25–150 kW/m2), were adopted to assess the effectiveness of the coating. The effect of the thickness of the protective layer has been tested too, by changing the number of layers (from 1 to 2 layers). From the results, a significant reduction in the temperatures and damages were observed. Moreover, the damage extension and residual mechanical performances of exposed samples have been assessed as a function of the power density and the protection level. A significant improvement of the post-heat flexural moduli and a significant reduction of the damaged areas have been obtained in laminates protected with high-loaded graphene nanoplatelet films.

Investigation of thermal energy storage system based on mining by-products for the recovery of Moroccan mining industrial waste heat

Implementing thermal energy storage system for energy intensive industrial processes such as mining industry is regarded as viable alternative to increase the energy efficiency by capturing waste heat, storing it, and then using it to produce power during night or for daily demand-supply matching. The present work aims at examining the integration of thermocline packed-bed system to recover waste heat for a Moroccan mining industry from numerical, technical and economic viewpoints. The storage single tank uses thermal oil as the heat transfer fluid, and the mining by-product (Porcellanite) issued from the same industry as storage material. An earlier developed and validated model is deployed to simulate the thermocline behavior of the storage tank and assess the performances of the investigated storage material. The mining by-product undergone extensive experimental characterization including chemical and structural composition, thermophysical properties, mechanical behavior, and durability testing, before and after thermal cycling. Porcellanite is predominantly composed of quartz with a porosity of around 0.31 and a bulk and skeletal densities of 1650 and 2420 kg/m3, respectively. Thermal cycling impacts positively its heat capacity by raising it from 0.4 J/g.K to 0.98 J/g.K resulting in a considerable increase of energy density. The thermal stability of the storage material was also demonstrated. Less than 2% of mass loss are reported after heating tests. These results revealed the suitability of the by-product for medium-temperature range. Furthermore, numerical outcomes demonstrate the great potential of the storage material to store and/or release energy with a charge efficiency of 87% and discharge efficiency of 88%. Finally, the proposed solution to recover waste heat (heat exchanger and thermal energy storage system) was economically evaluated for the Moroccan mining industrial process. Findings demonstrate an economic profitability of the proposed solution opening an important prospect for circular economy.

Reactive transport models of the geochemical interactions at the iron/bentonite interface in laboratory corrosion tests

Carbon steel and compacted bentonite have been proposed as candidate materials for the overpack and buffer, respectively, of the multi-barrier system of a geological high-level radioactive waste repository. Carbon steel corrosion may impair bentonite properties. The interactions of corrosion products and bentonite are analyzed with laboratory corrosion tests. Here coupled thermo-hydro-chemical-mechanical (THCM) models of two types of heating and hydration tests performed on compacted bentonite in contact with Fe powder are presented to study the iron-bentonite interactions at representative repository conditions. Tests on small cells (SC) were performed under unsaturated non-isothermal conditions in 25 mm long columns containing 21 mm of bentonite and 4 mm of Fe powder. Tests on medium-size cells (FB) were performed under unsaturated non-isothermal conditions in 99.8 mm long columns containing 86.8 mm of bentonite and 13 mm of Fe powder. Model results for the SC tests showed that magnetite and Fe(OH)2(s) were the main corrosion products which compete for Fe2+ precipitation. Computed corrosion products precipitate mainly in the Fe powder, penetrate a few mm into the bentonite and reproduce the measured iron weight data. Model results of the FB tests showed that magnetite precipitates throughout the Fe powder interface and reproduce the main trends of the corrosion products. Model results of these corrosion tests will be of great relevance for the performance assessment of engineered barriers of radioactive waste repositories.

Modelling Self-Heating and Self-Ignition Processes during Biomass Storage

A mathematical model was developed to predict the self-heating and self-ignition processes of relatively dry biomass during storage, considering in detail the effects of moisture exchange behaviour, low-temperature oxidation reaction and associated heat and mass transfer. Basket heating tests on fir pellets and powder at temperatures of 180–200 °C were conducted to observe the heating process and determine the kinetics of low-temperature chemical oxidation for model validation. As a result, it was demonstrated that the developed model could reasonably represent the self-heating and spontaneous combustion processes of biomass storage. Furthermore, the numerical study and model sensitivity analysis revealed that reasonably describing the low-temperature oxidation and associated heat and mass transfer process with reliable estimations of kinetic and thermophysical parameters of the biomass material is necessary for predicting the self-ignition, considering the effect of water exchange behaviour is essential to predict the self-heating process even for relatively dry biomass, such as pellets, with the moisture content up to 15–20%.

Thermal and Photo‐Degradation Study of α‐FAPbI3‐Based Perovskite Using In Situ X‐Ray Diffraction

AbstractHybrid halide perovskite has established its credibility as high performance thin film photovoltaic technology. Perovskite based on formamidinium cation is at the core composition to top performances and stability. Herein, a depth study based on temperature‐controlled in situ X‐ray diffraction focusing on the photo‐active formamidinium lead iodide (α‐FAPbI3) is reported. In particular, the thermal stability of the latter and the degradation pathways under different experimental conditions are clarified. Based on this in situ technique, the lattice thermal expansion coefficient is reported that provides relevant information on possible mechanical stress created upon temperature cycling or damp heat test. The results support that α‐FAPbI3 degradation is substantially accelerated when temperature is combined to illumination and when it is interfaced with the extraction layers. In addition, by contrast to in darkness for which α‐FAPbI3 degrades directly into PbI2, the existence of a temperature gap under illumination involving an intermediate step with a non‐crystalline phase resulting from the perovskite degradation and contributing to the formation of PbI2 by‐product is revealed.

Silica and kaolin reinforced aluminum matrix composite for heat storage

Abstract This study used aluminum scraps to produce a secondary aluminum metal matrix for heat storage analyses. Silica and kaolin reinforced aluminum metal matrix composites were successfully produced via stir casting. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed for phase and microstructure characterization. XRD revealed alumina (corundum), aluminum and kyanite phases while SEM indicated pores in the composites. Density, average specific heat (from 30 to 200°C), thermal conductivity, and hardness tests were carried out. Total heat energy stored per kg, from 30 to 200°C, was obtained. The inclusion of 7.5 and 15 wt% kaolin increased the specific heat of the matrix from 474.3 to 564.57 J·kg−1·°C−1 and 474.3 to 679.03 J·kg−1·°C−1, respectively. Likewise, adding 7.5 and 15 wt% silica sand increased the thermal conductivity of the matrix from 154.99 to 175.62 W·m−1·°C−1 and 154.99 W·m−1·°C−1 to 181.38 W·m−1·°C−1, respectively. The addition of 7.5 wt% silica sand and 7.5 and 15 wt% kaolin increased the hardness value of the matrix from 72.11 to 73.11 HB, 72.11 to 81.38 HB, and 72.11 to 82 HB, respectively. Hardness of the composites reinforced with kaolin is higher than that of the composites reinforced with silica sand. This is attributed to the higher molecular weight of kaolin. Significant increase in specific heat and thermal conductivity was achieved.

Novel multi-helical coil heat exchanger-based small-scale organic Rankine cycle: A detailed heat transfer analysis

This paper discusses a prototype of the ORC, which is developed utilizing a novel multi-coil evaporator and condenser for the waste heat source with a temperature below 100 °C. R123 acts as a working fluid for the ORC. The thermal performance of a multi-helical coil is evaluated experimentally and compared to the single-helical coil heat exchanger available in the literature.The performance of a novel multi-coil heat exchanger depicts that when the Reynolds Number varies from 60000 to 120000, the heat transfer coefficient varies from 1560 W/(m2K) to 2900 W/(m2K) for a single coil heat exchanger and 3014 W/(m2K) to 4531 W/(m2K) for multi helical coil evaporator. The Nusselt Number varies from 300 to 570 for single-coil heat exchangers and 715 to 1076 for multi-helical coil heat exchangers. The results show that the expander's power output is around 2.14 kW and proportional to the evaporator temperature and pressure increase. The high condensing temperature decreases the expander power output. The main contribution of the present work is developing a small ORC system with novel multi-helical coil heat exchangers and testing them on a lab scale for the most probable application to fulfill the electricity requirement in remote areas in the future.

Interface heat transfer for hydronic heating: heating tests of concrete blocks and numerical simulations

ABSTRACT A comprehensive understanding of the heat transfer mechanism of hydronically-heated structures is crucial to predicting their heating performance. However, few studies considered the heat transfer at the interface of heating pipe and host material. In this paper, heat transfer at two critical interfaces for hydronically-heated concrete structures, e.g. pipe-concrete interface and concrete-air interface, has been tested and analyzed. Two concrete blocks, one with an embedded cross-linked polyethylene (PEX) pipe and one with an attached PEX pipe, were fabricated to represent heated bridge decks for the heat transfer study. The two blocks were tested inside a freezer box in a series of heating response tests at varied room and fluid temperatures. Measured temperatures at different depths were used to find the convection heat transfer coefficient and the thermal contact conductance between the concrete and PEX pipe through equations developed via finite difference method (FDM). Finite element models (FEM) of the two blocks were developed to verify the thermal contact values derived from a 1-D thermal resistance model. A comprehensive analysis of the temperature response of the models was performed, especially at the two interfaces, and the FEM models were able to predict the lab measurements accurately. The obtained contact heat transfer coefficient and the FEM models can be used for all hydronically-heated structures.

Skin microvascular reactivity in patients with diabetic retinopathy.

Early detection of microangiopathic complications of diabetes mellitus (DM) is necessary to analyze the patient's condition and prevent disease progression. The study was aimed to investigate the relationship between the presence of retinopathy and decreased reactivity of the microcirculatory bed in patients with diabetes. The study involved 130 subjects: healthy volunteers (n=48), DM patients without retinopathy (n=53) and with retinopathy (n=29). Skin microvascular reactivity was assessed on the forearm using laser Doppler flowmetry with a local heating test combined with occlusion. The slope of local thermal hyperemia curve (Slope-120) and other parameters of microvascular reactivity showed difference in pairwise comparisons between the groups. Slope-120 had the highest sensitivity (0.759) and specificity (0.717) in detection of diabetic retinopathy. The decrease of Slope-120 was associated with retinopathy (odds ratio (OR) - 8.3 (2.9-24.1), p<0.001), even after adjusting for other factors (OR - 11.0 (1.6-77.2), p=0.016). Thus, assessment of skin microvascular reactivity may be a useful test for detecting signs of microangiopathic complications and for screening patients in risk group. Decreased microvascular reactivity has been shown to be prospective as an independent indicator of retinopathy in type 1 DM.

Minimizing buried interfacial defects for efficient inverted perovskite solar cells.

Controlling the perovskite morphology and defects at the buried perovskite-substrate interface is challenging for inverted perovskite solar cells. In this work, we report an amphiphilic molecular hole transporter, (2-(4-(bis(4-methoxyphenyl)amino)phenyl)-1-cyanovinyl)phosphonic acid, that features a multifunctional cyanovinyl phosphonic acid group and forms a superwetting underlayer for perovskite deposition, which enables high-quality perovskite films with minimized defects at the buried interface. The resulting perovskite film has a photoluminescence quantum yield of 17% and a Shockley-Read-Hall lifetime of nearly 7 microseconds and achieved a certified power conversion efficiency (PCE) of 25.4% with an open-circuit voltage of 1.21 volts and a fill factor of 84.7%. In addition, 1-square centimeter cells and 10-square centimeter minimodules show PCEs of 23.4 and 22.0%, respectively. Encapsulated modules exhibited high stability under both operational and damp heat test conditions.

Corrosion effects in bifacial crystalline silicon PV modules; interactions between metallization and encapsulation

This study addresses the influence of different encapsulation materials on performance losses in bifacial PV modules after extended damp heat testing. The widely used ethylene vinyl acetate (EVA) is compared to polyolefin elastomers (POE) and thermoplastic polyolefins (TPO). We show that modules based on n-type bifacial solar cells (tunnel oxide passivated contact, TOPCON) are more prone to degradation than p-type (Passivated emitter rear cell, PERC) based laminates. More specifically, the front side metallization of these n-type cells corrodes under extended damp heat testing, yielding a decreased fill factor in the I–V characteristics and the appearance of dark spots and dark areas in electroluminescence imaging. The newer generation of encapsulant materials (POE and TPO), slowly replacing EVA in the modules commercialized today, demonstrate an improved protection of the metallization. Apart from the nature of the encapsulant, the cell type and the presence or absence of glass cover plates are also shown to influence the metal grid corrosion. To better understand the mechanisms at play, post-mortem analysis was carried out on small sized degraded PV laminates, by drilling out circular samples (“coring”) that could be analyzed in depth. The analyses revealed a weakened bond between the metallization and the silicon emitter, ultimately causing metal grid delamination. The proposed mechanism behind this delamination starts with the degradation of lead glass, which is part of the cell metallization grid and contains lead oxide (PbO). This compound is susceptible to dissolution in acidic environment.

Strengthening mechanism of granulated blast-furnace slag on the uniaxial compressive strength of modified magnesium slag-based cemented backfilling material

The hydrating active mineral in the modified magnesium slag-based (MMS-based) backfilling material is mainly β-phase dicalcium silicate characterized with slow speed of hydration and low early strength. This disadvantage restricts the application of modified magnesium slag (MMS) as cementitious material in backfilling mining to some extent. In this work, the strengthening mechanism of granulated blast-furnace slag (GBFS) on the uniaxial compressive strength (UCS) of MMS-based cemented backfilling material has been investigated systematically. The hydration heat tests reveal that the duration of induction and acceleration periods are gradually shortened and the appearance time of the second exothermic peaks are obviously advanced as the proportion of GBFS increases. The total normalized hydration heat releases of MMS-based pastes containing 0, 1%, 2%, 3% and 4% (solid-mass proportion) GBFS at 120 h are 15.76, 16.02, 18.40, 22.31, and 25.54 J/g, respectively. Compared with the blank control group, the hydration heat release of MMS-based paste at 120 h increased by 62% with addition of 4% (solid-mass proportion) GBFS. In addition, the TG-DTG tests shown that the final mass-losses of MMS-based cemented backfilling materials tend to increase with the increase of the amount of GBFS. The 3- and 7-days UCSs of MMS-based backfilling mortars tend to increase dramatically with the increase of proportion of GBFS. A small amount of GBFS (1 wt%) can significantly improve the 28- and 56-days UCSs of the MMS-based mortars. Compared with the blank control group, the UCSs of MMS-based mortars cured 3, 7, 28, and 56 days increased by 74.2%, 94.6%, 38.0%, and 24.1% respectively with addition of 5% (solid-mass proportion) GBFS. The SEM, XRD, FTIR, and TG-DTG tests show that the MMS-based mortars containing GBFS generated more hydration products, yielded more compact microstructures, and consumed CH more quickly compared with that of blank control group. Compared with fly ash (FA), GBFS dissolves faster in alkaline media (leaching reactive Al and Si early), and releases much more hydration heat and Ca2+ ions during the process of pozzolanic reaction. The above three factors strengthen the UCS of MMS-based mortar. The results of this study can provide theoretical guidance for the raw material ratio design and field application of MMS-based cemented backfilling paste.

Bifunctional hole-shuttle molecule for improved interfacial energy level alignment and defect passivation in perovskite solar cells

Perovskite solar cells have reached a power conversion efficiency over 25%, and the engineering of the interface between the perovskite and hole transport layer (HTL) has been crucial to achieve high performance. Here we design a bifunctional molecule CBz-PAI with carbazole-triphenylamine and phenylammonium iodide units to passivate defects at the perovskite/HTL interface. Owing to a favourable energy level alignment with the perovskite, the CBz-PAI acts as a hole shuttle between the perovskite layer and the HTL. This minimizes the difference between the quasi-Fermi level splitting of the perovskite, or ‘internal’ Voc, and the external device Voc, thus reducing voltage losses. As a result, solar cells incorporating CBz-PAI reach a stabilized power conversion efficiency of 24.7% and maintain 92.3% of the initial efficiency after 1,000 h under damp heat test (85 °C and 85% relative humidity) and 94.6% after 1,100 h under maximum power point-tracking conditions.

Deformation Mechanisms of Magnesium Silicate Hydrate Cement with a Shrinkage-Reducing Admixture under Different Curing Conditions

Magnesium silicate hydrate (M-S-H) cement, a type of green building material, has poor volume stability (i.e., large shrinkage deformation), which limits its application. As a new type of admixture, the behavior of a shrinkage-reducing admixture (SRA) in M-S-H cement has not been studied. Therefore, in this research, the effect of SRA on the shrinkage properties of the M-S-H cement system was evaluated. The mechanism of SRA was investigated by surface tension measurement, hydration heat testing, thermogravimetric analysis, and pore structure analysis. Experimental results indicate that SRA can reduce the shrinkage of the M-S-H mortar, and the optimal effect is exerted when the dosage is 3.0%, drying shrinkage decreases by 22.6%, and autogenous shrinkage decreases by 60% on day 28. However, it may also adversely affect strength development. The presence of SRA in M-S-H cement can reduce pore solution surface tension, delay hydration, and maintain relative humidity within the slurry, which can be maintained at 82.0% on day 28. It can also increase pore size and porosity. The inhibitory effect of SRA on the shrinkage of M-S-H mortar is valuable for its future practical applications.

Properties and microstructure of total tailings cemented paste backfill material containing mining and metallurgical solid waste

Introduction: In order to improve the utilization efficiency of industrial waste discharged in the process of iron and steel metallurgy, a kind of material that can replace cement for mine filling is sought. In the test, steel slag (SS) and vanadium-titanium slag (VTS) were used as the primary raw materials to prepare cementing agents (CA). Then, combine it with vanadium-titanium iron ore tailings (VTIOTs) to make mine cemented paste backfill material (CPBM).Methods: The composition, properties and hydration mechanism of CPBM are studied through various tests, in-cluding mechanical property test, hydration heat test, X-ray diffraction (XRD), scanning electronic mi-croscopy (SEM), and fourier transform-infrared spectroscopy (FT-IR).Results: The results show that when the following conditions are met, the slump is 216 mm, and the 28-day flexural strength and compressive strength of CPBM reach 4.25 and 9.41 MPa, respectively, which meets the requirements of Chinese National Standard GB/T 39489-2020 Technical specification for the total tailings paste backfill: the mass percentage SS: VTS: phosphogypsum (PG): dicyandiamide waste slag (DWS) = 31:59:6:4; the content of compound phosphoric acid (CPA) accounts for 4% of the dry material; the cement sand ratio of CPBM is 1:4; the paste mass concentration (PMC) is 80%; and the content of water reducing agent (WRA) is 0.18%.Discussion: Mechanism studies show that the hydration product of the CA is mainly ettringite (AFt) and C-S-H gel. The addition of CPA promotes the hydration of active minerals in SS and VTS. The existence of PG pro-motes the formation of AFt, and the formation of AFt further promotes the fracture of [AlO4]5− and [SiO4]4− along the bridge oxygen in VTS and SS.