Seung-Yeon Han

Cellular Sprayed Concrete: A Very-Simple and Economic Method for Remixing an OPC into HPC at a Field

A very simple and economic method for remixing an ordinary Portland cement concrete (OPC) into a high performance concrete (HPC) at a job site was developed, which is called “Cellular sprayed concrete”. Cellular sprayed concrete is produced by incorporating a preformed foam and fine powders in a ready mixed concrete and is conveyed under pressure through a pneumatic hose or pipe and projected into place at high velocity, with simultaneous compaction. This paper describes on the concept of cellular sprayed concrete and a basic mechanical properties of a high performance concrete by incorporating a cellular and silica fume.

Effect of Hydrodemolition and Cutting Diameter of Pull-off Test on the Bond Strength of LMC Bridge Deck Pavement

Latex modified concrete (LMC) has many advantages against an ordinary Portland concrete. Hundreds of projects have been completed using LMC for overlay in Korea. A sound bond is an essential requirements of bridge deck pavements, and the bond property of a bonded overlay to its substrate concrete during the life-time is one of the most important performance requirements. This paper compare and evaluate the effect of the hydrodemolition and cutting diameter of the pull-off test into the bond strength of latex-modified concrete overlay by a series of experimental variables. The concrete surface preparation methods included hydrodemolition, cold milling and jack hammer. The core cutting diameters of pull-off test included four levels: 50, 75, 100 and 150 mm.

Construction Method and Durability Evaluation of Mock-up Test for Bobsleigh Track

This study examined the durability and method for making a mockup of bobsled tracks for constructing a bobsled stadium, which is a sport in the Winter Olympics. As bobsleigh games are very fast and dangerous, a safety design for players and a precise construction using highly efficient shotcrete is necessary. Moreover, a general molding construction is difficult because bobsleigh tracks are composed of various curves and slopes, and it is necessary to construct them using high-strength and high durability materials. The developed method for making a mockup and performing durability evaluation of bobsleigh tracks through this research will be applied in the construction of the 2018 Pyeongchang Winter Olympics Sliding centre and bobsleigh tracks using domestic techniques.

Dispersibility and Flexural Toughness Evaluation of Fiber Reinforcement Cellular Sprayed Concrete by added Foam

In this paper, dispersibility of steel fiber is improved mixing with form for material development of protection and blast resistant structure sprayed concrete. And it is developed a high toughness cellular sprayed concrete material using steel fiber. Oversupply form for dispersibility improvement of steel fiber is mostly fade away through sprayed, finally it is satisfied with the proper mixing ratio under 3 % ~ 6 %. This is considered for compressive strength and flexural toughness. Test results of compressive strength showed superior strength capability in 28, 56 days, also flexural strength and flexural toughness is great. Then oversupply form is enhanced for dispersibility of steel fiber and I think that it did not cause decreasing of strength. But analysis results of pore structure through image analysis failed for a great spacing factor and specific surface area. This is largely measured in spacing factor because air content have a grate evaporation effect for sprayed.

Durability Assessment for Crushed Sand Wet-mix Shotcrete Mixed with Mineral Admixtures

The purpose of this dissertation was to investigate the effect of mineral admixtures, such as fly ash, blast furnace slag powder, meta kaolin and silica fume, on the basic properties and durability of crushed sand shotcrete, selecting a series of shotcrete mixtures with a variable admixture. Compressive strength increased as the content of mineral admixtures increased, specially it was the most effective when using meta kaolin both at sample specimen and core after shotcreting. Rapid chloride ion permeability test and sulfuric acid resistance test showed that both durability increased as the substitute rate of mineral admixture increased. In air void analysis with image analysis, the targeted the spacing factor and specific surface were not satisfied because air-entrained agent was not used.