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Influence of Silane-based Impregnation Agent on the Permeability of Concretes
Baoju Liu,Jiali Qin,Minghua Sun 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.8
Three types of silane-based impregnation agent (short for SIA) are used to treat the concrete surface, and the influence of water/ binder (W/B) ratio, mineral admixtures, curing methods, the type and dosage of SIA on the capillary water absorption and electric flux of concretes is examined. Results show that the penetration depth of SIA increases with the increasing of the W/B ratio and SIA dosage, and is related to the type of SIA. Surface treatment by SIA can reduce capillary water absorption and electric flux of concretes, the W/B ratio and curing methods are no longer the main factor, the increasing of the SIA dosage can further improve the surface protection effect of concrete. Mineral admixtures improve the compactness of concretes, and the combined effects of surface treatment and admixtures can evidently enhance the impermeability of concrete. Different types of SIAs have different mechanisms of action on the surface treatment of concrete, and thus have different impacts on the permeability of concrete. The concrete treated by SIA2 with the effects of the penetration and the formation of surface film layer has lower permeability.
Liu, Baoju,Tan, Jinxia,Shi, Jinyan,Liang, Hui,Jiang, Junyi,Yang, Yuanxia Techno-Press 2021 Advances in concrete construction Vol.11 No.3
Due to economic and environmental benefits, increasing the substitution ratio of ordinary cement by industry by-products like fly ash (FA) is one of the best approaches to reduce the impact of the concrete industry on the environment. However, as the substitution rate of FA increases, it will have an adverse impact on the performance of cement-based materials, so the actual substitution rate of FA is limited to around 10-30%. Therefore, in order to increase the early-age strength of high replacement (30-70%) low-calcium ultrafine FA blended cement paste, sodium sulfate and calcium sulfate dihydrate were used to improve the reactivity of FA. The results show that sodium sulfate has a significant enhancement effect on the strength of the composite pastes in the early and late ages, while calcium sulfate dihydrate has only a slight effect in the late ages. The addition of sodium sulfate in the cement-FA blended system can enhance the gain rate of non-evaporation water, and can decrease the Ca(OH)2 content. In addition, when the sulfate chemical activators are added, the ettringite content increases, and the surface of the FA is dissolved and hydrated.
Effect of cement as mineral filler on the performance development of emulsified asphalt concrete
Liu, Baoju,Wu, Xiang,Shi, Jinyan,Wu, Xiaolong,Jiang, Junyi,Qin, Jiali Techno-Press 2020 Advances in concrete construction Vol.10 No.6
Cold-mixed asphalt mixture is a widely recommended asphalt pavement materials with potentially economic and environmental benefits. Due to the reduction of natural non-renewable mineral resources, powder minerals with similar properties are considered as new mineral fillers in asphalt mixtures. This study explored the feasibility of using cement to replace natural limestone powder (LP) in emulsified asphalt concrete modified by styrene-butadiene styrene copolymer. The experimental tests, including compressive strength, Marshall stability as well as moisture susceptibility test, were used to investigate the mechanical properties, the Marshall stability, flow value, as well as the moisture damage. In addition, the influence of material composition on the performance of asphalt concrete is explained by the microstructure evolution of the pore structure, the interface transition zone (ITZ), and the micromorphology. Due to mineralogical reactivity of cement, its replacement part of LP improved the mechanical properties, Marshall stability, but it will reduce the moisture susceptibility and flow value. This is because with the increase of the cement substitution rate, the pore structure of the asphalt concrete is refined, the width of ITZ becomes smaller, and the microstructure is more compact. In addition, asphalt concrete with a larger nominal particle size (AC-16) has relatively better performance.