Portion Of Fly Ash Research Articles

Cyclic loading effects on the heat-generation performance of carbon nanotube-embedded cement composites

Abstract This study investigates the heat-generation stability of carbon nanotube (CNT)/cement composites after exposing to cyclic loading conditions. The specimens were fabricated with varying CNT contents and levels of fly ash replacement. Results showed that increasing CNT content reduced electrical resistivity, while the impact on the electrical characteristics was found to be insubstantial, even though a considerable portion of fly ash was replaced. In addition, the electrical resistivity of the specimens after exposed to cyclic loading increased. Electrical heating tests revealed both negative and positive temperature coefficient effects depending on the applied voltages. Higher CNT contents improved the heat-generation capability, but the heating capability decreased after exposed to the cyclic loadings which is deduced from the damage of CNT networks during cyclic loadings. In this regard, the authors concluded that the heat-generation stability can be significantly affected by the applied loadings. Thus, the future research will be conducted to improve the heat-generation stability of the cement-based electrical heating systems as exposed to artificial deteriorations.

Influence of Steam Curing Method on the Performance of Concrete Containing a Large Portion of Mineral Admixtures

A comparison was made between the impact of raising the thermostatic temperature and the impact of prolonging the thermostatic time on the performance of steam-cured concrete containing a large portion of fly ash (FA) or ground granulated blast furnace slag (GGBS) by analysing the form removal strength, chemically combined water content, reaction degree, strength development, chloride permeability, and volume stability. For the materials and test conditions reported in this study, raising the thermostatic temperature is more favourable for concrete containing FA, as indicated by the significantly higher form removal strength and the higher growth of reaction degree of FA compared with prolonging the thermostatic time. With an increase in the thermostatic temperature, the hydration degree of a binder containing FA or GGBS initially increases and subsequently decreases. Although concrete containing FA can obtain satisfactory form removal strength with steam curing at 80°C, the late strength development of concrete containing FA is slow for the same curing conditions. The effect of the late performance of resistance to chloride ion permeability improved by FA is better than the effect improved by GGBS. The risk of destroying the structure of concrete containing a large portion of FA or GGBS due to delayed ettringite formation (DEF) is minimal when specimens were steam-cured at 80°C.

Properties of Materials from Activated Fly Ash from Fluidized Burning

This paper describes basic properties of materials composed of fly ash produced during fluid burning. This material is based on alkali-activated fly ash which contains a portion of fly ash produced during fluid burning. Firstly the physical and chemical properties was described for each type of fly ash and fly ash mixture. The new materials composed of fly ash mixture and fly ash may have the similar mechanical and physical properties. The work focused on findingan appropriate technological procedure, the optimum composition of mixtures. Long-term stability was simulated by means of accelerated aging of these materials.

Properties of Materials from Activated Fly Ash from Fluidized Burning

This article deals with the basic properties of materials based on alkali-activated fly ash which contains a portion of fly ash produced during fluid burning. The primary task of our research was characterization of physical and chemical properties of each type of fly ash and fly ash mixture. The new materials composed of fly ash mixture and fly ash may have the similar mechanical and physical properties. The work focused on findingan appropriate technological procedure, the optimum composition of mixtures. Long-term stability was simulated by means of accelerated aging of these materials.

Use of ternary blend of Portland cement and two pozzolans to improve durability of high-strength concrete

This paper presents the use of ternary blend of Portland cement with two pozzolans in producing high-strength concrete. Portland Cement Type I (CT) was partially replaced with ground Bagasse Ash (BA), ground rice husk-bark ash (RB) and Fly Ash (FA) at the dosage levels of 20% and 40% by weight of binder. In addition to a single material replacement, a blend of equal weight portions of RB and FA; and BA and FA were used. Compressive strength, porosity, chloride penetration, corrosion resistance and modulus of elasticity of concretes were determined. Test results reveal that the resistance to chloride penetration of concrete improves substantially with partial replacement of CT with a blend of equal weight portion of FA and RB; or FA and BA and the improvement increases with an increase in the replacement level. The corrosion resistances of FARB and FABA concretes were better than the CT concrete or concrete with one pozzolan. The ternary blend is attractive as FA reduces the amount of the SP needed to maintain the workability and the enhanced resistance to chloride penetration is also obtained from the synergic effect between the two pozzolans.

인공경량골재의 탄산화 반응에 따른 물성향상에 관한 연구

The mechanical property enhancement was studied using fly ash produced from fluidized bed type boiler in power plant, which contains a lot of Ca component being used to carbonate for fixation in the lightweight aggregates made of cement and some portion of fly ash as a cement substitution under the supercritical condition. Specimens having various fly ash substitution rates and curing periods were carbonated under the supercritical condition at . The weight change rate, carbonation rate by TG/DTA analysis, 1% Phenolphthalein test, specific gravity and mechanical compression strength test were performed to observe the mechanical property enhancement of the cemented materials after carbonation under the supercritical condition and to make sure those could be classified as lightweight aggregates having specific gravity under 2.0.