The Xayaburi Hydroelectric Power Project located in the Lao People’s Democratic Republic (Lao PDR) has been made of more than 4 million cubic meters of concrete and its construction site is located in the area of limited sources of raw materials of concrete-mixed sand, that is, the volume of sand in the Mekong River in the construction site is inadequate, let alone the fact that the sand’s physical property is rather fine than the required standard of sand to be used for concrete mixture. For these reasons, it is necessary to use limestone for production as crushed sand to be mixed with certain portions of the river sand for concrete production. Upon mixture of such two types of sand, the fineness modulus would be obtained in accordance with the requirements of concrete-mixed sand, and the quality concrete can be produced as required. However, the sand so produced from crushing would have fine aggregate or dust of smaller than 75 microns in size which must not exceed 3 percent of the requirements; while the crushed sand so produced would have dust particles averaging 10 - 13 percent. The method to reduce dust in crushed sand was to wash it before using, which needed water and electricity, with residue from such process. To enable such a large-sized construction project to minimize the environmental impact and use resources for the maximum benefits, further studies and testing of crushed sand were conducted, and it was found that dust or fine aggregate to be washed off could be used for concrete mixture without any impact on quality, through various methods, testing, and seeking approval for use from a supervising engineer based on the Deming Cycle (PDCA) until the approval was granted for use of such crushed sand without having the washing process, and the quality control was still required from the origin of materials, namely, rock mine, until the concrete production, to ensure that the concrete work met quality and had properties as required, in respect of the property of fresh concrete during placing of concrete and the property of setting of concrete, and that the raw materials could be produced as required according to the construction plan.
As a result of use of the crushed sand, the Company was of the view that such information would be useful to the engineering profession in Thailand on use of crushed sand in concrete, therefore, an article regarding “The Use of Limestone Powder in Concrete of the Xayaburi Hydroelectric Power Project” was proposed to the Thailand Concrete Association and the “TCA Concrete Practice Award : Silver Medal for 2016” was then granted. In addition, the ARE-QP Award was granted from the Asian Network for Quality (ANQ) in the ANQ Congress 2017, Kathmandu, Nepal, from the article’s subject “Continuous Improvement on Concrete Quality for Xayaburi Hydropower Project” and the ASEAN Outstanding Engineering Achievement Award for Successful Design, Completion and Commissioning from AFEO (ASEAN Federation of Engineering Organizations), an award recognizing excellence in engineering and contributions to national development.
