Who: Akbota Aitbayeva
When: Friday, November 22nd, 10:00am
Where: PKI 350 (Omaha) or Zoom
Zoom: https://unl.zoom.us/j/94326501940
Title:
DEVELOPMENT AND EVALUATION OF THIXOTROPIC UHPC OVERLAY MIXTURES: WORKABILITY, RHEOLOGY, AND CONSTRUCTABILITY FOR BRIDGE APPLICATIONS
Abstract:
Ultra-high-performance concrete (UHPC) is known for its exceptional strength and durability but faces challenges in bridge deck overlays due to surface slope constraints. UHPC overlays require a thixotropic material that maintains workability, stability on slopes, and responsiveness to vibration. This study addresses the lack of suitable testing methods by evaluating UHPC overlay rheology and workability using existing and newly developed tests: the Patting Response (PR) test and the Vibration-Slope Stability (VSS) test. Seven UHPC mixtures were analyzed, varying binder content, water-to-binder ratio, fiber content, and admixture dosages. Correlations between static and dynamic flow tests and VSS were examined, enabling practical flow ranges and rheological parameter guidelines for field applications. A lab-scale sloped slab validated constructability, confirming that the proposed tests effectively assess flowability, vibration response, and slope stability. Recommended criteria for static and dynamic flows provide actionable guidelines for UHPC overlay applications.