Materials that restore capacity and extend service life.

We study high-performance cementitious composites, fiber reinforcement, composite strengthening, and timber repair systems. Experimental testing and computational modeling are used together to understand material behavior and translate it into practical repair and design guidance.

UHPC with steel and synthetic fibers

Summary of UHPC fiber mixtures, functional tests, material mechanisms, and performance findings
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Wang, J. and Kim, Y.J. · ACI Materials Journal, 117(5) (2020), 179–191.View paper ↗

This experimental study examines cost-effective, silica-based UHPC made with locally available constituents in plain, steel-fiber, collated-polypropylene-fiber, and monofilament-polypropylene-fiber mixtures. Tests evaluate drying shrinkage, early-age temperature and maturity, compressive strength, and rapid chloride penetration. The results show that fiber type and geometry affect shrinkage and strength development: the steel-fiber mixture achieved higher load-carrying capacity and better early-age strength gain than the synthetic-fiber mixtures, while all tested UHPC mixtures remained in the Very Low chloride-permeability category.

Repair and load rating of timber bridges

Field testing, finite-element modeling, and load rating of timber bridges repaired with steel beams
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Kim, Y.J., Wang, J., and Ji, Y. · Engineering Structures, 303 (2024), 117469.View paper ↗

Field testing and validated finite-element models are used to rate deteriorated timber bridges before and after repair with hollow steel sections. The study demonstrates how repair configuration and live-load placement affect capacity, providing a mechanics-based path for extending the service life of existing timber infrastructure.

Research Articles

  1. Kim, Y.J., Wang, J., and Ji, Y. (2024). Rating of constructed timber bridges repaired with steel beams. Engineering Structures, 303, 117469.

  2. Kim, Y.J., Wang, J., Jung, W.-T., Kang, J.-Y., and Park, J.-S. (2023). Failure-mode-dependent behavior of CFRP-prestressed concrete girders. ACI Structural Journal, 120(5).

  3. Kim, Y.J. and Wang, J. (2023). Stochastic modeling and design recommendations for bond of UHPC interfaced with steel and FRP reinforcing bars. Construction and Building Materials, 367, 130297.

  4. Wang, J. and Kim, Y.J. (2020). Functional characteristics of UHPC with various fibers. ACI Materials Journal, 117(5), 179–191.

  5. Kim, Y.J. and Wang, J. (2019). Development of UHPC with various silica admixtures. ACI Materials Journal, 116(2), 33–44.

Research overviewView all three directions →