• Journal of Microbiology and Biotechnology
• /
• v.27 no.7
• /
• pp.1331-1335
• /
• 2017

In this study, the feasibility of introducing calcite-forming bacteria into concrete pavements to improve their mechanical performance was investigated. Lysinibacillus sphaericus WJ-8, which was isolated in a previous study and is capable of exhibiting high urease activity and calcite production, was used. When analyzed via scanning electron microscopy (SEM) and X-ray diffraction, WJ-8 showed a significant amount of calcite precipitation. The compressive strength of cement mortar mixed with WJ-8 cells and nutrient medium (urea with calcium lactate) increased by 10% compared with that of the controls. Energy dispersive x-ray spectroscopy analyses confirmed that the increase in strength was due to the calcite formed by the WJ-8 cells.

• Structural Engineering and Mechanics
• /
• v.55 no.1
• /
• pp.137-160
• /
• 2015

The one-way (two-way) flexural strength of RCC prisms (circular slabs) reinforced with glass fiber textiles is addressed. To this end, alkaline-resistant glass fiber textiles with three surface weights were used in the composite, the matrix concrete was designed with zero/nonzero slump, and the textiles were used with/without an intermediate layer provided by epoxy resin and sand mortar. Prisms were tested under a four-point loading apparatus and circular slabs were placed on simple supports under a central load. Effects of the amount and geometry of reinforcement, matrix workability, and the intermediate layer on the ultimate load and deflection were investigated. Results revealed that, with a specific reinforcement amount, there is an optimum textile tex for each case, depending on the matrix mix design and the presence of intermediate layer. Similar results were obtained in one-way and two-way bending tests.

• International Journal of Highway Engineering
• /
• v.15 no.1
• /
• pp.47-56
• /
• 2013

PURPOSES: This study is to evaluate a ground water level effect on frost heaving in road pavements. METHODS: The effects of water table on frost heaving in pavement systems were evaluated from the mechanical analysis using FROST program. The input parameters and boundary conditions were determined by considering climates, pavement sections, and material properties specially subgrade soil types in Korea. RESULTS: When the water table located above the freezing depth, amount of frost heaving caused by freezing the water in pavement itself was big enough to damage in pavement system, although pavement system consists of fully non-frost-susceptible materials with sufficient thickness of anti-freezing layer. The amount of frost heaving was decreased rapidly with increasing the distance between the water table and freezing depth. CONCLUSIONS: It was concluded that there is no engineering problems related with frost heaving in practical sense when the distance between freezing depth and water table is over 1.5m for having subgrade soils less than 50% of #200 sieve passing to meet specification on quality control in Korea.

• Geomechanics and Engineering
• /
• v.32 no.5
• /
• pp.513-521
• /
• 2023

Temperature is one of the most critical elements that influence the rutting and fatigue resistance of flexible pavements. Particularly in extreme hot regions in Saudi Arabia, high temperature would significantly reduce the rutting resistance of flexible pavements leading to reduction of pavement service life. Due to the impacts of global warming, average temperature in Saudi Arabia is expected to further increase by about 4℃ by the end of the 21st century. The substantial increase in average temperature will elevate the expected pavement maintenance and rehabilitation cost. This paper analyzes the structural effects of temperature on pavement using layered elastic analysis based on finite element techniques. The research team calculated the potential loss of pavement service life due to the projected temperature increase and climate change. The paper also analyzed potential impact of using carbon waste in asphalt concrete to tackle the derogatory impacts of temperature rise.

• International conference on construction engineering and project management
• /
• 2009.05a
• /
• pp.1446-1452
• /
• 2009

This study is designed to examine the current status of the performance warranty systems for asphalt pavements implemented in Europe, USA, and Japan, and to review the feasibility and possibility of introducing this system into the Korean environment. For such objectives, the concept and necessity of performance warranty and the status of Korean contracting systems and overseas performance warranty systems were evaluated. In particular, the bidding systems, performance guarantee systems, and maintenance work inclusion status in the projects and warranty specifications of Europe, USA and Japan were comparatively evaluated. And methods of introducing the performance warranty system by utilizing defects liability system and design-build contracts of Korea were suggested.

• 한국도로학회:학술대회논문집
• /
• 2008.03a
• /
• pp.47-58
• /
• 2008

• 한국도로학회:학술대회논문집
• /
• 2008.03a
• /
• pp.15-29
• /
• 2008

• 한국도로학회:학술대회논문집
• /
• 2006.10a
• /
• pp.175-178
• /
• 2006

• 한국도로학회:학술대회논문집
• /
• 2002.10a
• /
• pp.119-124
• /
• 2002

• 한국도로학회:학술대회논문집
• /
• 2004.10a
• /
• pp.263-266
• /
• 2004