Bang Khen, Thailand

Phranakhon Rajabhat University

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Bang Khen, Thailand
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Makul N.,Phranakhon Rajabhat University | Rattanadecho P.,Thammasat University | Pichaicherd A.,Thammasat University
Cement and Concrete Composites | Year: 2017

Microwave (MW)-accelerated curing has emerged as an innovative and popular curing method for concrete materials. This paper reports the results of a study to model the horn antenna used for the MW irradiation of a workpiece with a mobile MW-accelerated concrete curing unit, based on a coupled thermal and electromagnetic analysis. The mathematical models were useful for evaluating the heat generation within a horn antenna and as a basis for constructing a mobile MW-accelerated curing unit with an operating frequency of 2.45 GHz and a MW power level of 800 W. Further, the early-age compressive strength development and volume stability of MW-cured concrete were investigated in terms of its shrinkage and compared to the properties of autoclave-cured concrete. The design results showed that under the concept of the allowable maximum temperature for the concrete workpiece, which was controlled to less than 80 °C, a horn antenna that was 216.70 mm wide, 333.68 mm long, and 273.0 mm high produced a uniform thermal distribution in a concrete workpiece. Moreover, experimental investigations showed that the application period for curing using a mobile MW-curing unit was considerably shorter than that in autoclave curing methods. The appropriate delay time (time after concrete mixing) was 30 min, and MW irradiation for 45 min could improve the maximum 8-h early-age compressive strength of MW-cured concrete, whereas an application time of 15 min produced the 28-day compressive strength. When a concrete workpiece was cured at high temperature using MW energy for more than 15 min at a temperature greater than 80 °C, the effect was a continuous increase in the early-age compressive strength, which was greater than that achieved by autoclave curing. In terms of volumetric stability, MW-curing for 30 and 45 min increased the ultimate shrinkage to a greater extent than that by autoclave curing and vice versa in the case of a MW application time of 15 min. © 2017 Elsevier Ltd


Sua-iam G.,Bangkok University | Makul N.,Phranakhon Rajabhat University
Journal of Cleaner Production | Year: 2017

In this article, we considered the properties of self-consolidating concrete (SCC) into which both high-volume fly ash waste (FA) and high-volume recycled alumina waste (AW) were incorporated. FA was used as a cement substitution at 40% and 60%, and AW was used as a substitute for fine aggregate at 25%, 50%, 75%, and 100 %wt. The SCC blends were designed with the intention of creating a controlled flowing slump. In this study, the workability and mechanical properties of the blends were investigated by utilizing slump flow, J-ring flow behavior, blocking flow evaluation, V-funnel, compressive strength, and ultrasonic pulse velocity (UPV) estimations. The findings show that, compared with SCC without AW, the SCC blends that included AW required increased doses of superplasticizer and produced denser fresh concrete. With the increased cement content and altered FA content, the percentage of superplasticizer required and thickness of the fresh SCC decreased. When AW was incorporated at between 25% and 75%, its rheological and mechanical benefits became significant enough that including it in SCC became practical. Eventually, it is possible to manufacture SCC economically by using high volumes of FA and AW and even make it possible to develop green and environmentally friendly SCC. © 2017 Elsevier Ltd


Rattanadecho P.,Rangsit University | Makul N.,Phranakhon Rajabhat University
Drying Technology | Year: 2016

Offering advantages of energy-saving rapid drying rates, short processing times, deep penetration of the microwave energy, instantaneous and precise electronic control, and clean heating processes, microwave-assisted drying (MWD) has become a popular method that is currently used for many materials and processes. This article presents a systematic and comprehensive review of experimental and theoretical studies regarding the kinetic mechanisms of MWD. Factors affecting, methods for measuring, and applications of the dielectric property are discussed. From the experimental perspective, laboratory- and commercial-scale MWD systems are elaborated, including the equipment used and the stability, safety, and regulation of MWD systems. Theoretical investigations of thermal and nonthermal equilibrium models and moving-load computational models are discussed. Finally, some future trends in the research and development of MWD systems are suggested. © 2016, Copyright © Taylor & Francis Group, LLC.


Makul N.,Phranakhon Rajabhat University | Rattanadecho P.,Rangsit University | Agrawal D.K.,Pennsylvania State University
Renewable and Sustainable Energy Reviews | Year: 2014

Microwave heating is a highly efficient technique for various thermal processes. Advantages of microwave heating compared to conventional processing methods include energy-saving rapid heating rates and short processing times, deep penetration of the microwave energy (which allows heat to be generated efficiently without directly contacting the work-piece), instantaneous and precise electronic control, clean heating processes, and no generation of secondary waste. Microwave energy processes for heating, drying, and curing have been developed for numerous laboratory-scale investigations and, in some cases, have been commercialized. Microwave energy use should theoretically be advantageous in the processing of cement and concrete materials (e.g., hydraulic Portland cement, aggregate, and water). These materials exhibit excellent dielectric properties and, therefore, should be able to absorb microwave energy very efficiently and instantaneously convert it into heat. This paper provides a comprehensive review of the use of microwave energy to process cement and concrete materials, as well as a critical evaluation of currently utilized microwave heating mechanisms and high-performance microwave systems. The current status of microwave applications and future research and development trends are also discussed, including such thermal processing methods as the high-temperature sintering of cement materials, the accelerated curing of precast concrete products, as well as the drilling and cleaning of decontaminated concrete surfaces by the built-up internal pressure. The results of this review indicate that microwave heating is directly associated with dielectric loss by the cement and concrete. Microwave processing can be used to improve clinkering and to reduce the clinkering temperature by about 100 °C. Considerations when constructing mathematical models of microwave heating for cement and concrete should include the influences of heat and mass transfer during microwave curing on the temperature difference in the concrete, the degree of uniformity of the internal structure, and the ultimate performance of the product. Future studies of microwave energy in cement and concrete applications might include investigations of adaptive (time-dependent) dielectric properties, coupling chemical reactions in the presence of microwave energy, the design and construction of suitable microwave systems, and the prediction of related phenomena (e.g., thermal runaway, as a highly regulated safety issue). © 2014 Elsevier Ltd.


Ahmed I.,University of Maryland University College | Jangsawang W.,University of Maryland University College | Jangsawang W.,Phranakhon Rajabhat University | Gupta A.K.,University of Maryland University College
Applied Energy | Year: 2012

Mangrove is a biomass material that grows in wetland sea waters and is often used to produce charcoal due to its unique characteristics of long and sustained burning and negligible residue. High temperature pyrolysis has been conducted for mangrove biomass in a laboratory scale semi-batch reactor. The effect of reactor temperature on syngas yield and syngas characteristics has been investigated. Reactor temperature was varied from 600 to 900 °C in 100 °C intervals. The increase in reactor temperature resulted in increased syngas yield, hydrogen yield and energy yield. Evolutionary behavior of the syngas characteristics has also been investigated. The increase in reactor temperature increased the peak value of syngas flow rate, hydrogen flow rate and output power. The increase in reactor temperature decreased the time duration of pyrolysis. Cumulative yield of syngas, hydrogen and energy was calculated based on the time dependent relationship. Higher reactor temperatures shortened the time duration required for 99% release of syngas, hydrogen and energy. For example, time duration required for 99% yield of hydrogen was approximately 73. min at 600 °C and only about 26. min at 900 °C. Required time duration for 99% yield of energy was ∼62. min at 600 °C and ∼15. min at 900 °C. The gasification of the same material at 900 °C has been carried out to determine the role of gasifying agent on the fate of material and resulting syngas properties. The results showed gasification yielded more syngas, hydrogen and energy than that obtained from pyrolysis. © 2011 Elsevier Ltd.


Sua-Iam G.,Phranakhon Rajabhat University | Makul N.,Phranakhon Rajabhat University
Journal of Cleaner Production | Year: 2013

Bagasse ash is an abundantly available combustion by-product in the sugarcane industry. We examined the effect of adding limestone powder to self-compacting concrete mixtures in which large amounts of bagasse ash were employed as a fine aggregate replacement. A Type 1 Portland cement content of 550 kg/m3 was maintained in all of the mixtures. The fine aggregate was replaced with 10, 20, 40, 60, 80, or 100% bagasse ash and limestone powder by volume. Mixtures were designed to yield a slump flow diameter of 70 ± 2.5 cm. The workability (slump flow, T50cm slump flow time, V-funnel flow time, and J-ring flow) and hardened properties (ultrasonic pulse velocity and compressive strength) of each mixture were measured, and blocking assessments were performed. The volumetric percentage replacement of 20% limestone powder in fine aggregate incorporating 20% bagasse ash effectively enhanced the workability and hardened properties of self-compacting concrete.


In this study, cementitious materials (here defined as a high-performance cement paste produced by mixing Type 1 Portland cement with an effective amount of water) were manufactured in accelerated conditions using microwave-assisted low-pressure processing (i.e., accelerated curing). Based on the concept that the hydration reaction of cementitious materials comprises three main periods - a dormant period, an acceleration period, and a deceleration period - process parameters were determined for the most effective period (acceleration) for producing paste via microwave processing. The time-dependent dielectric characteristics of the cementitious paste and the water-cement ratio by mass influenced the temperature, i.e., caused it to increase, and the properties of the microwave-cured paste. The results show that the use of microwave-assisted low-pressure processing improved the paste's mechanical properties. Specifically, microwave energy can accelerate compressive strength development 15 min after the completion of microwave-assisted low-pressure curing. With a delay time of 60 min, microwave energy can process the paste almost a day faster than water curing, which is the standard method for curing paste. The use of microwave energy, therefore, can significantly reduce the required energy and production time in the manufacture of high-performance paste. © 2015 Elsevier Ltd. All rights reserved.


Sua-Iam G.,Phranakhon Rajabhat University | Makul N.,Phranakhon Rajabhat University
Journal of Cleaner Production | Year: 2014

This paper describes a study undertaken to explore the use of a high volume of lignite coal fly ash (FA) as a replacement for Type I Portland cement (OPC) and a high volume of rice husk ash (RHA) as a replacement for fine aggregate in the production of self-consolidating concrete (SCC). OPC was partially replaced with 0%, 20%, 40%, and 60% FA by volume, and fine aggregate was replaced with 0%, 25%, 50%, 75%, and 100% RHA by volume. Mixtures were designed based on a slump flow diameter of 70 ± 2.5 cm. The workability properties (i.e. slump flow, T50 cm slump flow time, V-funnel flow time, and J-ring flow) and hardened properties (i.e. compressive strength and ultrasonic pulse velocity) of SCC were determined, and a blocking assessment was performed. Increasing the FA or RHA content beyond a certain level reduced the compressive strength and increased the water requirement of the SCC mixture. However, up to 60% FA could be used to produce SCC with a compressive strength of 40-50 MPa. In addition, RHA could comprise up to 25% of the SCC, which is an acceptable value of compressive strength according to the Building Code Requirements. Moreover, partial replacement of OPC by FA and fine aggregate by RHA can result in substantial cost savings and alleviate environmental problems. © 2014 Elsevier Ltd. All rights reserved.


Sua-Iam G.,Phranakhon Rajabhat University | Makul N.,Phranakhon Rajabhat University
Construction and Building Materials | Year: 2013

Alumina is a common by-product of industrial grit blasting operations. While alumina itself is relatively harmless, the grit blasting waste is regarded as hazardous when contaminated with heavy metals. The concrete industry has initiated the use of solid waste additives in order to address environmental problems. We studied the feasibility of using alumina waste (AW) as a partial replacement for the fine aggregate in self-compacting concrete (SCC). The mixtures were designed to produce a controlled slump flow diameter. The fine aggregate was replaced with up to 100% AW by weight. The rheological and mechanical properties of the SCC mixtures were evaluated based on slump flow, J-ring flow, blocking assessment, V-funnel, air content, compressive strength, and ultrasonic pulse velocity measurements. The filling and passing ability of the fresh concrete decreased in proportion to the alumina content. Mixtures containing up to 75% AW possessed average compressive strengths of 20.9 MPa at 3 days and 45.9 MPa at 28 days. © 2013 Elsevier Ltd. All rights reserved.


Sua-Iam G.,Phranakhon Rajabhat University | Makul N.,Phranakhon Rajabhat University
Construction and Building Materials | Year: 2013

Self-compacting concrete (SCC) is a relatively recent development in the construction industry. It flows under its own weight while remaining homogeneous in composition. We examined the feasibility of using limestone powder (LS) as a modifying agent in self-compacting concrete in which a portion of the fine aggregate was replaced with untreated rice husk ash (RHA). The mixtures were designed to produce a controlled slump flow. The Portland cement content was 550 kg/m3 for all of the mixtures. The fine aggregate was replaced with up to 100% RHA and LS by volume. The T50 slump flow, J-ring flow, blocking assessment, V-funnel, air density, and compressive strength of the SCC mixtures were tested. The fresh properties of the RHA-containing mixtures were improved in mixtures containing less than 60 vol.% RHA. SCCs containing LS exhibited superior hardened properties, and the fresh and hardened properties of SCCs made using RHA were substantially improved when combined with LS. Limestone powder has the potential to improve self-compacting concrete mixtures in which untreated RHA is used as a partial fine aggregate replacement. © 2012 Elsevier Ltd. All rights reserved.

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