ORCID Profile
0000-0002-0503-8353
Current Organisations
National Taipei University of Technology
,
University of New South Wales
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Publisher: MDPI AG
Date: 26-03-2021
DOI: 10.3390/SU13073708
Abstract: In this study, aggregates in asphalt concrete were partially replaced by basic oxygen furnace slag (BOFS) in proportions of 45 wt.%, 55 wt.%, and 75 wt.%. The thermal performances of the specimens are discussed based on the thermal conductivity, emissivity, and the indoor and outdoor temperature measurements. Consequently, 75 wt.% of the specimen’s aggregates were replaced by BOFS, which had a high emissivity of 0.86 across the sky window. In the indoor and outdoor tests, the temperature change was recorded to estimate the thermal performance of specimens. According to the quantitative calculation, when the substitution of BOFS was higher than 55 wt.%, the specimens had a better radiation cooling ability. Among these specimens, the specimen with the BOFS substitution of 75 wt.% absorbed the most heat inside the body, contributing to less heat remaining in the environment. Furthermore, because Newton’s cooling energy accounted for about 90% of the stored energy within 7 h, the heat dissipation after the seventh hour was primarily radiation cooling, corresponding to the emission across the urban boundary layer. As for the mechanical properties, the stability value, indirect tensile strength, and British pendulum number (BPN) were in line with the specifications under the proper BOFS substitution. In conclusion, BOFS has great applicability in pavements due to its thermal performance and mechanical properties. It not only achieves the goal of urban heat island mitigation by radiation cooling, but also reflects the concept of resource sustainability.
Publisher: MDPI AG
Date: 11-05-2020
DOI: 10.3390/MA13092203
Abstract: There are considerable resource reuse and environmental concerns regarding SiC sludge (SiCS) that results from cutting silicon ingots into wafers. In the current study, the effect of the Na2SiO3 solution/sodium hydroxide solution (NS/SS) mass ratio and SiCS amount on metakaolin geopolymers was found during geopolymerization system performance. The results indicate that while NS/SS ratio was relatively low, increasing the NaOH content resulted in a sufficient amount of OH− in the system to increase the solubility and hinder polycondensation, as indicated by the bulk density and setting-time results since the polycondensation was inhibited, the mechanical strength was reduced. This study demonstrated that a geopolymer can be formed from a substitution of 10% SiCS and with an NS/SS ratio of 1.6, and that this geopolymer is a feasible material.
Publisher: Elsevier BV
Date: 10-2019
Publisher: MDPI AG
Date: 18-02-2021
DOI: 10.3390/MA14040972
Abstract: The impact load, such as seismic and shock wave, sometimes causes severe damage to the reinforced concrete structures. This study utilized different lengths of chopped carbon fibers to develop a carbon-fiber-reinforced mortar (CFRM) and carbon-fiber-reinforced concrete (CFRC) with high impact and anti-shockwave resistance. The different lengths (6, 12, and 24 mm) of chopped carbon fibers were pneumatically dispersed and uniformly mixed into the cement with a 1% weight proportion. Then the CFRM and CFRC specimens were made for static and dynamic tests. The compressive and flexural strengths of the specimens were determined by using the standard ASTM C39/C 39M and ASTM C 293-02, respectively. Meanwhile, a free-fall impact test was done according to ACI 544.2R-89, which was used to test the impact resistances of the specimens under different impact energies. The CFRM and CFRC with a length of 6 mm exhibit maximum compressive strength. Both flexural and free-fall impact test results show that the 24 mm CFRM and CFRC enhances their maximum flexural strength and impact numbers more than the other lengths of CFRM, CFRC, and the benchmark specimens. After impact tests, the failure specimens were observed in a high-resolution optical microscope, to identify whether the failure mode is slippage or rupture of the carbon fiber. Finally, a blast wave explosion test was conducted to verify that the blast wave resistance of the 24 mm CFRC specimen was better than the 12 mm CFRC and benchmark specimens.
Publisher: MDPI AG
Date: 10-10-2021
DOI: 10.3390/MA14205940
Abstract: This study explores the practicability of using drill cutting (DC) as raw material to fabricate building bricks through the high-temperature sintering method and low-temperature geopolymeric setting (LTGS) process. Drilling mud can be recycled and reutilized after certain treatment procedures and is considered as a non-hazardous waste. However, the treatment process is time-consuming and not cost-effective. For the sintering method, low porosity and high mechanical strength bricks can be sintered at temperatures above 800 °C and meet CNS standards. For the low-temperature geopolymeric setting process, sodium silicate was selected as an activating agent for geopolymerization of drill cutting. Several process parameters, such as Si2O/Na2O modulus of alkali solution and low-temperature geopolymeric setting temperature, were investigated. The physical and mechanical properties of the fabricated brick were evaluated. According to the test results, 72.4 MPa compressive strength building bricks with low porosity (13.9%) and water absorption (6.0%) can be fabricated with 2.0 Si2O/Na2O alkali solution at 500 °C. The drill cutting brick fabricated not only meets the CNS 382.R2002 common brick standard, but also solve its disposal problem.
Publisher: MDPI AG
Date: 18-06-2020
DOI: 10.3390/SU12125002
Abstract: The basic oxygen furnace slag is a major waste by-product generated from steel-producing plants. It possesses excellent characteristics and can be used as a natural aggregate. Chemically, the basic oxygen furnace slag encloses free CaO and free MgO, which is the main reason for the expansion crisis since these free oxides of alkaline earth metals react with water to form their hydroxide yields. The objective of the present research study is to stabilize the basic oxygen furnace slag by using innovative geopolymer technology, as their matrix contains a vast quantity of free silicon, which can react with free CaO and free MgO to form stable silicate compounds resulting in the prevention of the basic oxygen furnace slag expansion predicament. Lab-scale and ready-mixed plant pilot-scale experimental findings revealed that the compressive strength of fine basic oxygen furnace slag-based geopolymer mortar can achieve a compressive strength of 30–40 MPa after 28 days, and increased compressive strength, as well as the expansion, can be controlled less than 0.5% after ASTM C151 autoclave testing. Several pilot-scale cubic meters basic oxygen furnace slag-based geopolymer concrete blocks were developed in a ready-mixed plant. The compressive strength and autoclave expansion test results demonstrated that geopolymer technology does not merely stabilize the basic oxygen furnace slag production issue totally, but also turns the slags into value-added products.
Publisher: Wiley
Date: 24-05-2021
DOI: 10.1002/EP.13682
Abstract: This study used silicon carbide sludge (SCS) and waste glass fiber (WGF) to prepare SCS/WGF porous (SWP) eco‐fireproof materials by a hydrogen peroxide foaming agent. The results showed that the compressive strength of s les that were cured for 1 day and had an SCS replacement level of 10% and added amounts of WGF of 0.5% and 2.0% were 0.32 and 0.46 MPa, respectively. Additionally, it was observed that the stress–strain curves were relatively extended. WGF could improve the geopolymeric matrix of the composites in terms of formation and/or redistribution of cracks by bridging cracks and perforations within the matrix. When the added amounts of WGF were 0.5% and 2.0%, the reverse‐side temperatures of the s les were 238 and 262°C, respectively, which showed that adding an appropriate amount of WGF could effectively reduce the reverse‐side temperature of SWP eco‐fireproof materials. The results displayed the beneficial influence of SCS and WGF in improving bulking density, compressive strength, and flexural strength and in reducing porosity and thermal conductivity. Therefore, the results showed that SWP eco‐fireproof materials reinforced using SCS and WGF have potential as building materials.
Publisher: Elsevier BV
Date: 08-2017
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 05-2020
Publisher: MDPI AG
Date: 13-02-2022
DOI: 10.3390/SU14042134
Abstract: Sustainability is a central value in the United Nations’ 17 sustainable development goals (SDGs), which include no poverty, zero hunger, good health and well-being, quality education, gender equality, clean water and sanitation, affordable and clean energy, decent work and economic growth, industry innovation and infrastructure, reduced inequalities, sustainable cities and communities, responsible consumption and production, climate action, life below water, and life on land [...]
Publisher: Wiley
Date: 24-07-2020
DOI: 10.1002/EP.13431
Publisher: MDPI AG
Date: 07-09-2020
DOI: 10.3390/SU12187333
Abstract: The recycling of SiC sludge material is crucial for resource reutilization and environmental protection. In the current study, the effect of the mass ratio between the Na2SiO3 and sodium hydroxide (NaOH) solutions (NS/SS ratio) and the effect of SiC sludge on metakaolin geopolymers was comprehensively investigated to determine the underlying performance of the geopolymerization system. During thermal evolution, the second exothermic peak of 1.6NS10SCS (NS/SS ratio: 1.6, 10% SiC sludge) showed a heat evolution value of 990.6 W/g, which was the highest among other geopolymers. Additionally, the 1.6NS10SCS s le after 28 days of curing showed the highest flexural strength (6.42 MPa), compared to that of the others, and the DTA/TG (differential thermal analysis/thermogravimetry) results showed that the weight loss percentage increased to 14.62% from 400 to 750 °C. For the 29Si nuclear magnetic resonance deconvolution, 1.6NS10SCS exhibited high fractions of Q4(3Al) (33.63%), Q4(2Al) (23.92%), and Q4(1Al) (9.70%). Thus, the geopolymer with the optimal SiC-sludge replacement level and NS/SS ratio contained more macropores and geopolymer gels, which benefit structural development. The experimental results indicated that SiC-sludge can potentially serve as a partial replacement for metakaolin and exhibited favorable mechanic characteristics.
Publisher: MDPI AG
Date: 18-08-2022
Abstract: Geopolymer (GP) has been considered a potential material to replace ordinary Portland cement (OPC) because of its excellent mechanical properties and environmentally friendly process. However, the promotion of GP is limited due to the large shrinkage and the different operating procedures compared to cement. This study aims to reduce the shrinkage of ground granulated blast furnace slag (GGBFS) based GP by the hydration expansion properties of activated magnesium oxide (MgO). The slurry of GP was blended from GGBFS, MgO, and activator and the compositions of the activator are sodium hydroxide (NaOH), sodium silicate (Na2SiO3), and alumina silicate(NaAlO2). Herein, the GGFBS and MgO were a binder and a shrinkage compensation agent of GP, respectively. After unmolding, the GP specimens were cured under four types of environments and the lengths of the specimens were measured at different time intervals to understand the length change ratio of GP. In this study, two groups of GP specimens were made by fixing the activator to binder (A/B) ratio and the fluidity. The test results show that adding MgO will reduce the shrinkage of GP as A/B ratio was fixed. However, fixing the fluidity exhibited the opposite results. The X-ray diffraction (XRD) was used to check the Mg(OH)2 that occurred due to the MgO hydration under four curing conditions. Three statistical and machine learning methods were used to analyze the length change of GP based on the test data. The testing and analysis results show that the influence of curing environments is more significant for improving the shrinkage of GP than additive MgO.
Publisher: Wiley
Date: 26-03-2018
Publisher: MDPI AG
Date: 07-2020
DOI: 10.3390/APP10134577
Abstract: Lost-wax casting, also called precision casting, is the process of casting a duplicate metal sculpture cast an original sculpture. The ceramic shell mould used in lost-wax casting usually consists of several layers formed with fine zircon and granular mullite particles using silica gel as a binder. However, it is a complicated and time-consuming process. Large amounts of waste moulds that need to be disposed and recycled become an environmental concern. In this study, waste shell sand from the recycled mould and calcium carbonate/metakaolin were used as raw materials to prepare geopolymer slurry and coating. The influence of mixing ratio and the SiO2/K2O modulus of the alkali solution on the setting time and green/fired strength were evaluated. Ceramic shells with one to four layers of geopolymer slurry and waste sand sprinkling were fabricated and tested for their permeability and green/fired strength. It was found that geopolymer shells had higher green/fired strength and better permeability than the original zircon/mullite shell. For foundry practice, metal casts were fabricated using recycled ceramic shell moulds with one to four layers of geopolymer coating. All cast results have their dimensions all within tolerance limitation and up to 13 h can be saved for the preparation of shell moulds.
Publisher: MDPI AG
Date: 26-08-2020
Abstract: The key objective of this study was to develop marble-based geopolymer concrete and examine the viability of its application as a sustainable structural material for the construction industry. The results of the research demonstrated that marble-based geopolymer concrete can be developed, and its physical/mechanical properties were shown to have a very good performance. According to various experimental tests and a large-scale ready-mixed plant test, it was found that the marble-based geopolymer concrete displayed a good workability and was not easily influenced by temperature changes. The results showed that marble-based geopolymer concrete has an excellent potential for further engineering development in the future.
Publisher: Mineralogical Society of America
Date: 09-2022
DOI: 10.2138/AM-2021-7765
Abstract: In this paper, high-pressure data from a synchrotron X-ray diffraction study on a lillianite (Pb3Bi2S6) single crystal up to ~21 GPa are presented. A phase transition from lillianite (space group Bbmm, LP lillianite) to the high-pressure form β-Pb3Bi2S6 (space group Pbnm, HP lillianite) was confirmed and bracketed between 4.90 and 4.92 GPa. The transition is reversible but of first-order with a hysteresis of ~2.8 GPa. It showed weak effects of pseudo-merohedral twinning that disappeared upon decompression, testifying to a full recovery of the single crystal of lillianite. This makes lillianite an interesting shape-memory material. With a bulk modulus K4.9 = 78(3) GPa and K′ = 5.1(4), β-Pb3Bi2S6 is markedly less compressible than lillianite [K0 = 44(2) GPa, K′ = 7(1)]. Compressional anisotropy increases markedly in β-Pb3Bi2S6 with compressibility along the b axis [M0b = 130(6) GPa and Mb′ = 19(3) in lillianite, M4.9b = 145(4) GPa and Mb′ = 16.0(7) in β-Pb3Bi2S6] significantly larger than that along the other two axes [M0a = 118(5) GPa, Ma′ = 21(3), M0c = 139(12) GPa, and Mc′ = 31(10) in lillianite, M4.9a = 242(12) GPa, Ma′ = 8(1), M4.9c = 242(5) GPa, and Mc′ = 29(1) in β-Pb3Bi2S6]. The behavior of lillianite at high pressure is an interesting case study in relation to non-quenchable ultrahigh-pressure phases likely occurring in the inner Earth, like post-perovskite MgSiO3, the oxide homologue N = 1 of the lillianite series. The β-Pb3Bi2S6 structure, on the other hand, is the N = 3 homologue of the meneghinite series to which the higher-pressure modification of the post-perovskite structure also belongs (homologue N = 1). This makes the two forms of Pb3Bi2S6 potential equivalents of high- and ultrahigh-pressure Mg silicates that could occur both in the deep earth and in other rocky extrasolar planetary bodies.
Publisher: MDPI AG
Date: 28-07-2020
DOI: 10.3390/APP10155204
Abstract: Intact rock-like specimens and specimens that include a single planar joint or triangular sawteeth joint at various angles are prepared for split Hopkinson pressure bar (SHPB) testing at loading rates of 303.1–5233.6 GPa/s. Only results that are associated with an error (eε) of less than 20.0% are utilized in subsequent analyses. The effects of the loading rate and angle of the load applied to various joint patterns on the failure type and dynamic peak stresses/strength of the specimens are investigated. Experimental results demonstrate that failure of each specimen can be classified into the following four types, Type A: integrated with or without tiny flake-off, Type B: slide failure, Type C: fracture failure, and Type D: crushing failure. The results of statistical analysis of variance (ANOVA) indicate that the loading rate, the angles of the base plane (β), and the asperity (α) of the sawteeth joint of the specimen all affect its dynamic peak stress when fracture failure occurs. The loading rate and β are important when the slide failure occurs, and the loading rate is the sole factor that significantly influences its dynamic peak stress when the specimen is crushed to failure. The dynamic peak stress of the specimen increases with the loading rate, while the rate of increase gradually decreases. The β and α of a jointed specimen affect the location of stress concentration during loading, further influencing the dynamic peak stress of such a specimen under slide and fracture failure. When the loading rate is high and the specimen is crushed to failure, the influences of β and α disappear, and the increase of loading rate reduces the efficiency of raising the dynamic peak stress.
Publisher: Elsevier BV
Date: 10-2022
Publisher: MDPI AG
Date: 12-05-2020
DOI: 10.3390/SU12103967
Abstract: Basic oxygen furnace slag (BOFs) is difficult to reutilize because it contains excessive free lime, and thus causes serious expansion. For this reason, how to reuse BOF slag has turned out to be an imperative issue in order to meet the concept of a circular economy. The key intention of this research work is to develop a new way to reutilize BOF slag, which due to its high emissivity in the 8–13 µm wavelength range, can be used as a sustainable, passive radiative cooling material. Passive radiative cooling, without the consumption of any energy, achieves the cooling of a surface by reflecting the sunlight and radiating the heat throughout the outer space (not absorbed by the atmosphere). BOF slag is used as a radiative cooling material in geopolymeric coating. This coating possesses an emissivity of 0.95 within the range of 8–13 µm and also has high conductivity, but its gray appearance absorbs too much heat. Therefore, by improving the situation through a double-layer structure, a temperature drop of 5.9 °C was reached compared to non-coated concrete under simulated sunlight, simultaneously with a low heating rate and high cooling rate. Besides, the binding strength between the geopolymeric coating and Portland cement concrete is comparable to two commercial organic paints. It is highly probable that the utilization of BOF slag in geopolymeric coating is energy saving and also feasible for passive radiative cooling applications. Hence, it can greatly decrease indoor temperature and improve the comfort of people living in buildings.
Publisher: MDPI AG
Date: 24-12-2021
DOI: 10.3390/SU14010164
Abstract: Many studies have shown that paint with reflective heat can effectively reduce the temperature of the building envelope and reduce the future energy consumption of the building. This study inspired the next-generation inorganic geopolymer material (IGM) color paint without volatile matter, which could be applied on concrete surfaces to reduce energy consumption in warm seasons. In this study, a total of five insulating IGM paints, white, red, green, blue, and yellow, were applied to a 50 cm × 50 cm × 12 cm concrete slab top surface. The highest average light reflectance of all the paints was 87.5% of white IGM paint, which was higher than plain concrete (36.4%). The heat flux and surface temperature were examined in the laboratory, and those test results were verified outdoor. The results showed that the IGM paints could effectively reduce the surface temperature and heat flux of the upper and lower surfaces of concrete slabs, and the white colored IGM paint was the best performer among all five colors, whereas the heat storage coefficient (Sf) of red, white, yellow, blue, and green IGM painted concrete slabs were 0.57, 0.53, 3.62, 2.95, and 1.91 W·m−2·K−1, respectively, lower than plain concrete (24.40 W·m−2·K−1). This coefficient was presented to externalize the thermal admittance. The overall measurement results showed that the concrete slab with colored IGM paints had better heat insulation ability than the plain concrete slab, especially in white IGM paint.
Location: Taiwan, Province of China
No related grants have been discovered for Ta-Wui Cheng.