Characteristics Of The Interfacial Bonding Between Normal Concrete Substrate And Ultra High Performance Fiber Concrete Repair Material / Bassam A.O Tayeh
As a rule of thumb, the interfacial bonding between old concrete structures with a newly overlay repair material is one of the most important factors for structural functionality and safety as well as durability performance. In order to acquire an enhanced resistance against penetration of harmful substances, a good and effective bonding is necessary at the concrete interfaces. The objective of this study was to examine experimentally the mechanical properties and permeability characteristics short term and long term of the interface performance between normal concrete (NC) substrate which represented old concrete structures and an overlay of ultra high-performance fibre concrete (UHPFC) as a repair material. The mechanical interfacial bond characteristics were assessed using the slant shear, splitting tensile, pull-off and flexural tests to quantify the influence of the differently roughened substrate surfaces and to assess the effect of different substrate moisture conditions. On the other hand, the permeability characteristics were evaluated by means of the rapid chloride permeability, gas and water permeability and ~ porosity tests. Five types of surface textures were used: as cast (AC) (without surface preparation), sandblasted (SB), wire brushed (WB), with drilled holes (DH), and with grooves (GR). The roughness of the substrate surfaces was quantified using an optical three-dimensional surface metrology device (Alicona Infinite Focus). The microstructure of the interfacial transition zone was also studied using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS). The short and long-term results showed that the newly overlay UHPFC achieved high bond strength and bonds efficiently with the NC substrates. The pull-off test and flexural test results revealed that all failures occurred in the substrate, regardless of the substrate surface roughness. Majority of failures in the splitting tensile and slant shear test also occurred in the substrate. The composite UHPFC I NC substrate having a sandblasted surface behaved closely as a monolithic structure under splitting and slant shear tests. A very good correlation, mostly R2 > 80% was obtained between the substrate roughness parameters and the results of the splitting cylinder tensile and slant shear tests. The permeability tests proved that the interfacial bonding was very good and efficient which significantly improved the impermeability of the composites. SEMIEDS proved that the use of UHPFC as repair material chemically, physically, and mechanically improved the repaired interfacial transition zone to become stronger and denser, as well as more uniform, and durable.
Characteristics Of The Interfacial Bonding Between Normal Concrete Substrate And Ultra High Performance Fiber Concrete Repair Material / Bassam A.O Tayeh
Characteristics Of The Interfacial Bonding Between Normal Concrete Substrate And Ultra High Performance Fiber Concrete Repair Material