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Kaeng Khoi, Thailand

Pimraksa K.,Chiang Mai University | Chindaprasirt P.,Khon Kaen University | Huanjit T.,Chiang Mai University | Tang C.,Siam Research and Innovation Co. | Sato T.,Tohoku University
Journal of Cleaner Production | Year: 2013

Bottom ash (BA) from Mae Moh lignite power plant was used to synthesize zeolite and zeolite-like materials. Low temperature synthesis (100-110 °C) was completed using SiO2 to Al2O3 with molar ratios of 2.94 and 2.92, respectively. Factors investigated that affect synthesis include particle size distribution, pretreatment of BA, concentration of alkali solution and liquid to solid ratio. The synthesized product qualities were characterized by mineralogical composition, morphology, specific surface area, pore size, pore volume and cation exchange capacity. Natrolite-K zeolite (NAT-K) was obtained with a solution of BA and 7 M KOH. Zeolite-like material (potassium aluminosilicate hydrate: KASH) was obtained using very fine BA and 9 M KOH solution. The NAT-K, KASH and BA powders were used to replace type I Portland cement at 0, 5,10,20 and 30% by weight to produce composite materials for heavy metal encapsulation. The compressive strength and bulk density of the NAT-K- or KASH-hybridized cement mortars were tested at 1, 7 and 28 days. The heavy metal encapsulation capacity was also tested using the 28-day cement mortar containing either 5 wt% NAT-K or KASH adsorbed with Cr, Ni and Cd ions. The results showed that 5 wt% of NAT-K could improve early strength of cement mortar and the 28-day specimens with 5-10 wt% of NAT-K replacement had compressive strength similar to that of the normal cement mortar. The NAT-K and KASH encapsulate Cr, Ni and Cd ions in the structures of cement mortar matrices more than 97%. © 2012 Elsevier Ltd. All rights reserved.

Thongsanitgarn P.,Chiang Mai University | Wongkeo W.,Chiang Mai University | Sinthupinyo S.,Siam Research and Innovation Co. | Chaipanich A.,Chiang Mai University
Advanced Materials Research | Year: 2012

In this study limestone powders with different particle sizes of 5, 10 and 20 μm were used to replace a part of Portland cement in different replacement levels to produce Portland-limestone cement pastes. The percentages of limestone replacement are 0, 5, 7.5, 10, 12.5, 15 and 20% by weight. The effect of fineness and the amount of limestone powders on compressive strength and setting time are investigated. It has been established that limestone replacement causes reduce the compressive strength due to the dilution effect, but it can reduce energy consumption and CO2 emission in cement manufacturing. The fineness of limestone powder used has influence on the observed compressive strength values. From the standard consistency results, it seems that limestone has no effect on water requirement compared to Portland cement. Moreover, the increase in level of fine particles would require much water. Both initial and final setting times were decreased with an increase in the amount of limestone. Furthermore, at the same level replacement, the cement pastes using 5 μm of limestone show lower setting time than those using 10 and 20 μm, respectively. © (2012) Trans Tech Publications, Switzerland.

Sisomphon K.,Technical University of Delft | Sisomphon K.,Siam Research and Innovation Co. | Copuroglu O.,Technical University of Delft | Koenders E.A.B.,Technical University of Delft
Construction and Building Materials | Year: 2013

This project studies the self-healing potential of strain hardening cementitious composites (SHCC) incorporating calcium-sulfoaluminate based expansive additive (CSA) and crystalline additive (CA). Four mixes, control mix (M1), 10%CSA mix (M2), 1.5%CA mix (M3) and 10%CSA + 1.5%CA mix (M4), were used in the investigation. Pre-cracked specimens were subjected to different exposure conditions; namely, tap water (EC1), regularly refreshed tap water (EC2), wet/dry cycles (EC3) and air exposure (EC4). The recovery of mechanical properties can be obtained, particularly for M2 and M4 mixes. The concentration of carbonate ions in exposed water plays an important role on self-healing process. Calcium carbonate formation on crack mouth is preferable in terms of water tightness; however, this formation decreases the recovery of mechanical properties. The results from chemical analysis showed that the healing products are composed of CaCO3, C-S-H and ettringite. The proportion of healing minerals depends on exposure condition and the type of cementitious materials used. © 2013 Elsevier Ltd. All rights reserved.

Jongvisuttisun P.,Siam Research and Innovation Co. | Kurtis K.E.,Georgia Institute of Technology
Cement and Concrete Composites | Year: 2015

The availability, relative consistency, and renewability of hardwood pulp fibers have prompted interest in their use in fiber-cement composites, in which they may be used for a variety of purposes. This study clarifies the ability of hardwood pulp to reinforce mortar, its capacity to provide internal curing, and its role as early-age crack-control reinforcement through a coordinated series of restrained shrinkage, free shrinkage, and mechanical testing on mortar samples. It finds that hardwood pulp improves the restrained shrinkage behavior of mortar at an early age. That is, 0.5% and 0.75% (by volume) hardwood pulp-reinforced mortars exhibited a lower rate of stress development and lengthened time-to-cracking by about 1.6 times and 2.3 times, respectively, compared to a companion crack-prone ordinary mortar. The initial crack width also decreased by 88% in 0.75% hardwood pulp-reinforced mortar samples, which suggested an application aimed at assisting self-healing in cement-based materials with an appropriate binder composition. Hardwood pulp successfully provided internal curing to crack-prone mortar and thus reduced autogenous shrinkage. This reduction in shrinkage, together with a combination of increased early tensile capacity, reduced stiffness, and improved post-cracking toughness were identified as the key contributions of hardwood pulp in the improved resistance of mortar to early-age cracking. © 2014 Elsevier Ltd. All rights reserved.

Wansom S.,National Metal and Materials Technology Center | Janjaturaphan S.,National Metal and Materials Technology Center | Sinthupinyo S.,Siam Research and Innovation Co.
Cement and Concrete Research | Year: 2010

Rice husk ash (RHA) has long been known to possess a pozzolanic property. The abundance of rice husk as agricultural waste makes RHA the most promising candidate to be used as a supplementary cementitious material (SCM) in many rice-exporting countries. The use of RHA as an SCM helps reduce the use and thus the production of cement that involves great energy consumption and CO 2 emission. To promote the use of RHA as an SCM, a method to assess its pozzolanic activity is needed for the process of optimizing the burning conditions and/or selecting RHA from uncontrolled burning of rice husk as biomass fuel. The present work aims to use impedance spectroscopy to characterize pozzolanic activity of RHAs prepared on a pilot scale. The method is based on the rate of the normalized conductivity change of the Ca(OH) 2 + RHA paste, d(σ/σ0)/dt, during the first 24 h of hydration. The measurement was found to be sensitive to the unburnt carbon content in the 6-8 wt.% range and the amorphous SiO2 content (regardless of the unburnt carbon content). When used to evaluate two separate groups of RHAs, each with comparable unburnt carbon contents, the method gives very high correlation coefficients to the strength activity index at 3, 7, and 28 days. However, the correlation coefficients fall significantly when RHAs with vast difference in the unburnt carbon contents are considered together. The method thus proves to be powerful for evaluation of the pozzolanic activity of RHAs with comparable carbon contents. © 2010 Elsevier Ltd. All rights reserved.

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