Response to a real world need
All the time, concrete structures surround you. We feel convenience and safe in the structures. We are using concrete very well, and will keep riding on it and its improved form. Our research focuses on innovating our technology for concrete structures, materials and construction. Research articles published by the group can be found in Scopus database
Rheology and construction performance
Mortar flow is usually measured using a drop table. We also measure minislump flow for high-fluidity mortar even though it is not regulated in a standard test method. The channel flow is a good alternative to sensitively estimate the Bingham parameters of a sample.
ASTM C1437 - Standard test method for flow of hydraulic cement mortar
Shin, T.Y., Kim, J.H., First step in modeling the flow table test to characterize the rheology of normally vibrated concrete, Cem. Concr. Res. 152: 106678, 2022, https://doi.org/10.1016/j.cemconres.2021.106678
Kim, J.H., Lee, J.H., Shin, T.Y., Yoon, J.Y., Rheological method for alpha test evaluation of developing superplasticizers’ performance: channel flow test, Adv. Mater. Sci. Eng., 4214086, 2017, https://doi.org/10.1155/2017/4214086
Slump and slump flow of concrete are requisitely measured. A rheological model easily converts the test results into the material properties: Bingham parameters, yield stress and plastic viscosity.
Roussel, N., Coussot, P., “Fifty-cent rheometer” for yield stress measurements: from slump to spreading flow, J. Rheol., 2005, https://doi.org/10.1122/1.1879041
T.Y. Shin, J.H. Kim, S.H. Han, Rheological properties considering the effect of aggregates on concrete slump flow, Mater. Struct. 50: 239, 2017, https://doi.org/10.1617/s11527-017-1104-9
T.Y. Shin, S.H. Han, J.H. Kim, Estimation of yield stress and plastic viscosity of concrete using the slump flow test, J. Korea Concr. Inst. 32: 165-171, 2020, https://doi.org/10.4334/JKCI.2020.32.2.165
A new direction toward carbon utilization in construction industry
Aqueous CO2 curing technology does not need a huge chamber supplying gaseous CO2 for the early carbonation to enhance the performance of cement-based materials. CO2 is dissolved in an alkaline solution beforehand, and then blast-furnace slag mortar can be cured in the CO2 solvent. The resultant carbonation in early age improves the strength of the mortar samples together with a high CO2 uptake. In addition, the technology is easily augmented on the existing carbon capture process.
Han, S. H., Jun, Y., and Kim, J. H. (2022), The use of alkaline CO2 solvent for the CO2 curing of blast-furnace slag mortar, Constr. Build. Mater. 342: 127977, 2022, https://doi.org/10.1016/j.conbuildmat.2022.127977
Sustainability and lightweight aggregates
Our interests in the lightweight aggregates originate from the recycling of industrial by-products. Artificial (coarse) lightweight aggregates is produced by sintering coal-combustion ash and dredged soil, and we also use bottom-ash lightweight sand as it is. Consuming the ashes for producing concrete contributes to the sustainability of construction industry. However, their porous properties make it hard to have a stable concrete mixture. An equilibrium on the capillary pressure and pore suction of surround pastes accounts for the water absoprtion of the porous lightweight aggregates in the fresh-state mix. A physical model is proposed to consistently evaluate that of bottom-ash lightweight sand or coarse lightweight aggregate.
Kim, J.H., Lee, J.H., Kim, Y.-H., Equilibrium of capillary and pore water pressure in lightweight aggregates concrete, Mech. Adv. Mater. Struct., 2021, https://doi.org/10.1080/15376494.2021.1949510
Kim, Y.-H., Park, C.B., Choi, B. I., Shin, T.Y., Jun, Y., Kim, J. H., Quantitative Measurement of Water Absorption of Coarse Lightweight Aggregates in Freshly-Mixed Concrete, Int. J. Concr. Struct. Mater. 14: 34, 2020, https://doi.org/10.1186/s40069-020-00408-x