Introduction: The ENV model proposed by TRIZ secured light transmission by replacing the existing costly transparent optical fibers with lowcost transparent materials with improved constructability, and improved the production method by changing the existing laborintensive method of laying thousands or tens of thousands of optical fibers into a labor-saving system capable of mass production, which involves the use of a large external multi-porous mold. Results and Conclusion: The application of plastic based bar against optical fiber showed that the light transmitting ability was almost equal as well as the convenience of making light transmitting concrete. Additionally, the difficulties coming from heavy weight of trial product for material preparation, transportation, and processing process were tried to solve by applying lightweight aggregate and light foaming agent while maintaining minimum compressive strength.

There has been an increasing amount of waste concrete generated in recent years, which has made recycling more important. Waste concrete is generally recycled as recycled aggregates, and many studies have been conducted to seek ways to improve their quality. Such quality improvement processes has led to the generation of byproducts such as waste concrete powder, which needs to be recycled efficiently based on further research. Accordingly, this study was conducted with the aim to use waste concrete powder (WCP) to substitute silica powder in the manufacturing of the extrusion concrete panels in cases where high SiO₂ content is not a requirement. The results of this study showed a negative correlation between flexural strength and silica powder-WCP substitution ratio. For example, 50% substitution resulted in a product that satisfied the required flexural strength over 14 MPa as stipulated by the Korean Industrials Standards, and it gave rise to properties such as specific gravity, absorption ratio, length change, thermal conductivity, and fire-resistance that were similar to those of plain specimens. Based on these results, it was deemed that it would be possible to use WCP as an alternative material in place of siliceous fillers in cases where high-purity is not required.

Below-grade structures such as parking lots, underground subway tunnels, and basements are growing in scale and reaching deeper below-ground levels. In this type of environment, they become subject to higher water pressure. The concrete material of the structures is exposed to wet conditions for longer periods of time, which makes the proper adhesion of waterproofing membranes difficult. Joint movements from increased structural settlement, thermal expansion/shrinkage, and physical loads from external sources (e.g., vehicles) make securing durable waterproofing challenging. While ASTM Guides, Korean Codes, and BS Practice Codes on below-grade waterproofing stress the importance of manufacturer specification for quality control, ensuring high quality waterproofing for the ever-changing scale of construction remains a challenge. This study proposes a new evaluation method and criteria which allow for the selection of waterproofing membranes based on specific performance attributes and workmanship. It subjects six different waterproofing membrane systems (installed on dry and wet surface conditioned mortar slab specimens with an artificial joint to different cyclic movement widths) to 300 cycles in water to demonstrate that inadequate material properties and workmanship are key causes for leakages.

This study analyzed the correlation between the load transfer properties and the overall toughness in the flexural behavior of steel fiber-reinforced concrete after concrete matrix cracking. Beam specimens with identical aspect ratios were made with three different types of steel fiber, each of which had different properties, and were used for the flexural test. The load displacement graph from the test was divided into sections by behavioral properties, and the regression model by mix was analyzed to extract the correlation between the load transfer section (concrete-fiber) and the overall toughness. The analysis results showed three types of load displacement curve based on the fiber type and fiber content, and confirmed that the load reduction section towards fiber after concrete cracking and the slope and area of the load reascension section had a huge impact on the overall toughness. The regression model of the whole toughness (T_b) was then acquired by proposing the resulting correlation as the load transfer factor (LTF).