Somnuk Tangtermsirikul

CO2 capture using fly ash from coal fired power plant and applications of CO2-captured fly ash as a mineral admixture for concrete.

The utilization of fly ash as a solid sorbent material for CO2 capture via surface adsorption and carbonation reaction was evaluated as an economically feasible CO2 reduction technique. The results show that fly ash from a coal fired power plant can capture CO2 up to 304.7 μmol/g fly ash, consisting of 2.9 and 301.8 μmol/g fly ash via adsorption and carbonation, respectively. The CO2 adsorption conditions (temperature, pressure, and moisture) can affect CO2 capture performance of fly ash. The carbonation of CO2 with free CaO in fly ashes was evaluated and the results indicated that the reaction consumed most of free CaO in fly ash. The fly ashes after CO2 capture were further used for application as a mineral admixture for concrete. Properties such as water requirement, compressive strength, autoclave expansion, and carbonation depth of mortar and paste specimens using fly ash before and after CO2 capture were tested and compared with material standards. The results show that the expansion of mortar specimens using fly ash after CO2 capture was greatly reduced due to the reduction of free CaO content in the fly ash compared to the expansion of specimens using fresh fly ash. There were no significant differences in the water requirement and compressive strength of specimens using fly ash, before and after CO2 capture process. The results from this study can lead to an alternative CO2 capture technique with doubtless utilization of fly ash after CO2 capture as a mineral admixture for concrete.

Damage analysis of an RC column subjected to long-term transient elevated temperature

Damage in a reinforced concrete column subjected to long-term elevated temperature (approximately 150°C) was studied by conducting detail inspection as well as finite element analysis. The damage information was collected through visual inspection, non-destructive tests, coring, and chemical analysis. Inspection results illustrated more damage level in the portion exposed to high temperature. Chemical analysis as well as cracking patterns indicated that the damage was not the same as the damage caused by fire attack and was not caused by chloride penetration, carbonation or sulphate attack. The mechanism of the damage was clarified by using finite element analysis with a condition of sudden drop of surface temperature. It was found from the analysis that cracking can be induced on the surface of the column due to temperature gradient if there is a substantial surface temperature drop.

Forensic engineering techniques to analyze bombing events

Bombing at Erawan Shrine, Bangkok, Thailand on August 17, 2015 caused a massive damage to both lives and properties killing 20, injuring around 130, damaging vehicles, and other structures in the vicinity. This paper aims to estimate the TNT equivalent charge weight used for this bombing incident using Finite Element Analysis. Only the damage from blast pressure is considered in this paper. Analysis results are compared with onsite damage data obtained from online media. It is shown that an equivalent explosive of 3 kg of TNT bare charge could have been used for the bombing. To provide more insight, possible sizes of the explosive casing, type and weight of cased explosive are estimated. Based on evidences obtained from online media, the length of the pipe is assumed to be 25 cm. Two examples of TNT and C4 pipe bombs with diameter 3, 4 and 5 inch are investigated. The first example of TNT pipe bomb, a 4 or 5 inch pipe bomb could cause the damage in the same level as that observed from the incident. The second example of C4 pipe bomb, a 4 inch pipe bomb is the possible size which could have been used for bombing. The authors further investigate the damage to people resulted from blast pressure. Blast pressure at various distance is calculated using CONWEP code. It is found that the lethal zone is approximately 2 m. A person who stands between 2 m and 3.45 m from the explosion might suffer from lung damage whereas people in the range of 3.45 m to 8.5 m from the explosion might get eardrum rupture. Finally, importance of researches on this matter in order to minimize the risk and improve safety of the community is emphasized.

Mix Proportioning and Properties of Roller-Compacted Concrete Pavement Using Lignite Fly Ash

This paper explains the development of a roller-compacted concrete for constructing or renovating concrete pavement (RCCP), using lignite fly ash in Thailand. A method for proportioning the lignite fly ash RCCP based on the ratio between paste volume and void content of total aggregate is proposed. It was found from the tests conducted by varying fly ash replacement ratio, water to total binder ratio, and paste content that the range which gives rise to the optimum strength and density of the RCCP were in between 1.02 and 1.05 for the tested materials.