Papers by Keyword: Fly Ash (FA)

Abstract: Lightweight glass ceramic foams have been prepared from a mixture of solid wastes, namely 40 wt-% red mud and 60 wt-% fly ash. In this work, we illustrate the effects of variables in heat treatment process, including the sintering temperature and the holding time, on the quality of the foams. The reduction of sintering temperature as well as the holding time, was found to limit the coalescence and improve the apparent density and the compressive strength.

Abstract: This paper presents the mechanical properties of a lightweight geopolymer concrete synthesized by the alkali-activation of a fly ash source (FA) produced by mixing a paste of geopolymer with foam produced by using NCT Foam Generator. Two curing conditions are used, curing at room temperature and curing in an oven with a constant temperature which is 60 oC. Bulk density showed that fly ash-based geopolymer lightweight concrete is light with the density of 1225 kg/m³ - 1667 kg/m³ with an acceptable compressive strength of 17.60 MPa for the density of 1667 kg/m³.

Abstract: With the improvement of utilization technology of fly ash, the fly ash is gradually changing from waste to important resources. Therefore, the forecast of regional fly ash production and sales is becoming more and more important to power plant operation. This paper selects Beijing-Tianjin-Tangshan area, Zhangjiakou area, Southeastern Coastal area, Western area this four typical region of China, using the 2010-2013 quarter production and sales data of fly ash as the original data sequence in the four region to build a BP neural network model for network for 2014-2015 prediction analysis. From the prediction results we can conclude that prediction accuracy conforms to the required standard, indicating that the prediction model is valid.

Abstract: The purpose of this study is to evaluate the flexural behavior of hybrid high performance RC beams with web openings (Hy-HPRWO) that are constructed by using circle steel tube, hybrid fibers and Garnet, Fly-ash. One regular RC beam with openings (HPRC) and four Hy-HPRWO specimens were manufactured and tested under monotonic loading. It was evaluated by flexural experiment of Hy-HPRWO through comparison of failure mode, load-deflection curves, ductility and ultimate load (V_u). Test results showed that the ultimate load of the Hy-FPSC3 specimens were approximately 5.82% better than that of the HPRC, in addition their ductility behavior was 68.1% better than the HPRC.

Abstract: In this paper, the influence of water cement ratio, prewetting degree of lightweight aggregate, flyash content and air content on the internal relative humidity (IRH) and drying shrinkage of lightweight aggregate concrete (LAC) were studied using a relative humidity sensor and drying shrinkage apparatus. Results showed that the IRH of concrete decreased rapidly at early age and slowed down at late age, and prewetting lightweight aggregate could compensate the loss of IRH. The effect of compensation could be enhanced with the increasing of prewetting degree of lightweight aggregate, and the addition of flyash retarded the decrease of IRH at early age. The drying shrinkage of LAC increased quickly at early stage and it slowed down to the even after 60 days or longer age. Furthermore, the drying shrinkage of LAC increased with increasing of water cement ratio. The effect of air content on the drying shrinkage of LAC was limited at early stage. However, at the late stage it grew at different level with increasing of air content. By raising the prewetting degree of lightweight aggregate, mixing with proper dosage of flyash, the shrinkage rate of LAC can be reduced markedly. Key words: lightweight aggregate concrete, internal relative humidity, drying shrinkage, prewetting degree, flyash.

Abstract: Fly ash (FA) and granular blast-furnace slag (GBFS) are usual mineral admixtures to conventional concrete, and their contents substituted for Portland cement definitely affect development rate of strength of concrete. C30 and C60 concrete samples with FA and/or GBFS were prepared to study the influence of substitution content of the mineral admixtures on 3 d, 7 d and 28 d strength. The results reveal that the development rate of strength in period from 3 d to 7 d gets slow with increasing content of mineral admixtures except for concrete with only GBFS less than 20%. In the case of substituting FA as the only mineral admixture for part of cement, the development rate of strength of C30 concrete in period from 7 d to 28 d keeps roughly constant even that of C60 concrete increases. When substituting mineral admixtures in the presence of GBFS for cement within experimental range, the development rate of strength in period from 7 d to 28 d gets fast with increasing substitution content. The enhancing effect of combining FA and GBFS occurs in period from 7 d to 28 d for both C30 and C60 concretes (FA+GBFS≤40%), even occurs in period from 3 d to 7 d for C60 concrete. Based on 7 d strength and the development rate, 28 d strength of concrete can be predicted accurately.

Abstract: The influence of the content of matekaolin powder and fly ash in cement on controlling ASR was evaluated using Accelerated Mortar Bar Test (AMBT). Replacing cement with matekaolin powder to the extent of 5%,10%,15%,20%,25%,and with fly ash to the extent of 10%,20%,30%,35%,40%, 45% respectively. The result show that matekaolin powder and fly ash both can control Alkali-aggregate activity but to different degrees. Small amount of metakaolin powder exerts significant influence, whereas only when the proportion of fly ash is up to 35%, can it control ASR effectively. The effect and mechanism of the control of the extension of glass aggregate activity was studied by means of SEM analysis.

Abstract: Calcium oxide, as a modified material, is used in pyro-modification of fly ash and the modified fly ash is used to treat phosphorus-containing wastewater, and treatment effect of modified fly ash on phosphorus-containing wastewater in different modification conditions is studied . Results show that good effect is obtained when the mass ratio of fly ash and calcium oxide ratio is 1:1, the roasting temperature is 950 °C, roasting time is 4h, and phosphorus removal rate can up to 92%. SEM pictures of raw fly ash and modified fly ash showed that modified fly ash particles become rough and porous, with a larger surface area, so it has good adsorption properties. Key words: Fly ash; Pyro-modification; Phosphorus-containing wastewater; Adsorption

Abstract: The fly ash of non grade with low activity can not be directly used in the cement concrete. After a lot of tests, several kinds of fly ash grinding excitation materials were chosen to be ground together with fly ash of non-grade and low activity. The studies show that three kinds of fly ash grinding excitation materials A, B, C can not only decrease the water demand ratio but also increase the activity index of the polished ash as well. All other indexes meet the requirements of technical specification standards for fly ash gradeI. Based on the effect of excitation activity and economic benefits, the fly ash grinding material B was chosen as the main active materials for the power plant to make excitation ash,the fly ash composite materials can be widely used in cement concrete with high activity index and great benefits, and the problems for the application of the long-term piled fly ash can also be solved .

Abstract: In this study, composition for bottom ash and fly ash of MSWI was analyzed and zeolite was synthesized in order to expand its recycling on high quality and mass consumption. Analysis of ash its characteristics was performed by XRF, XRD, SEM, EDX, TG/DTA. Bottom/fly ash was fired for elimination of unburned carbon at 750°C/12 hr, crushed and synthesized to zeolite in 1, 2, 3, 4, 5 M NaOH solutions under 105°C/24hr by hydrothermal method. Calcite and calcium-silicate compound was mainly contained in bottom ash and CaCl₂∙4H₂O, Ca (OH)₂, NaCl, and calcite and KCl in fly ash. Especially amount of Cl was much contained in fly ash due to Korean food waste characteristics. Bottom ash could synthesize Zeolites in form of sodalite under 3~4 M NaOH and fly ash could synthesize Zeolite A under 1~2 M NaOH. In addition, zeolite synthesized with bottom ash had higher specific surface area and zeolite from fly ash had higher CEC value. Accordingly, ash from MSWI could be recycled for further valuable uses such as non-point pollutant control and/or soil amendment.