Lack and quality decrease of supplementary cementing materials (SCMs) such as fly ash and granulated blast-furnace slag is increasingly prominent in China. Thus, the use of coal gangue (CG) and coal gasification slag (CGS) as SCMs in concrete attracted more researcher’s attention. This paper investigated the mechanical strength, porosity, and durability of CG-and CGS-added concrete. Experimental results showed that the activity of the treated CG and CGS is better than that of ordinary mineral SCMs, indicating that CG and CGS concrete can satisfy the requirements of ordinary construction under reasonable processing technology. Both CG-added and CGS-added concrete illustrated better chloride penetration resistance. The aluminum element contained in CG and CGS causes the C3S hydration to generate ettringite which is an erosion product under sulfate erosion, and it will intensify the damage of sulfate erosion. After 125th freeze-thaw cycles, the CGS-added concrete has no obvious failure which indicates that CGS-added concrete has great capacity in the frost resistance.
In accordance with an orthogonal experiment design, a series of ACs for methylene blue (MB) removal had been prepared in the presence of small amounts of KOH in raw material combined with delicate acid washing after carbonization and before steam activation. ACs were characterized, and their adsorption capacities for MB were determined as well. It was found that it was feasible to regulate and optimize pore structure in coal-based ACs by tuning preparation conditions concisely and properly, and the MB adsorption capacities were linearly correlated with their specific surface areas. Based on statistic analysis, it was revealed that among the four process variables studied for the sorbent prepared in this work, the activation temperature was found to be the most significant one for the MB adsorption capacity, the next ones were the activation time, the flow rate of water vapor and the amount of KOH, and an optimized preparation condition was figured out.
Based on concrete carbonation test methods available and common carbonation test equipments, this article designed and developed a new concrete carbonation test equipment. The device consists of a gas storage tank and many independent small carbonation chambers. With a compact structure, the device is small, simple and practical. With its advantages of not only improving the CO2gas utilization, but also making full use of available space with the design of several smaller carbonation chambers, the device could carry out more carbonation tests without affecting their progresses. The device has a wide usage and promising future.
Porous carbon nitride microsphere with dimaters ranging from 2 to 6 micrometers were synthesized via chemical vapor deposition in this work. Electron microscope images of the composite show that they have multiwalled innerstructure, which was built by disorderly stacked g-C3N4 curved layers assembled from nitrogen bridges of pyramidal structure, making them porous surfaced. Their mechanical and optical properties were studied with nanoindenter and UV-VIS spectra. It shows that they have good mechanical properties and, compared to carbon nitride synthesized by solvent method, out carbon nitride composite showed relativly broader light absorption band between 400 nm and 600 nm. Also, its visible light degradation of methyl blue was studied, showing its potential as visible light photocatalytic for water purification.
CaSO3and CaO are main components in solid waste from flue gas semi-dry desulfurization process. A series of slag cements were prepared from cement clinker and blast furnace slag, in the process of which CaSO3 and CaO were added. The composition and macrostructure of the derived cements were studied in detail with the aid of XRD and SEM. Furthermore, the influence of amount of CaSO3and CaO on the mechanical properties and setting time for slag cement were evaluated, the mechanisms of which were also discussed. The results show that due to the formation of AFt and AFm in the hydration process, the CaSO3has an obvious setting retarding effect on the slag cement, and quality slag cement can be obtained when the amount of slag and CaSO3are 20% and 2%, respectively, the compressive strengths of which at 3, 7, 28 d are 30.8, 39.1, 53.7 MPa, and bending strengths at 3, 7, 28 d are 9.6, 10, 11.9MPa, respectively. Besides, CaO added which can play a role of alkali-activator for slag cement can not cause the soundness problem of slag cement.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.