Dowels effectiveness investigation between ultra high performance fiber reinforced concrete and reinforced concrete

In the present study, the performance of Reinforced Concrete (RC) beams which were strengthened with Ultra High Performance Fiber Reinforced Concrete (UHPFRC) and dowels at the interface was investigated. RC beams with a length of 2.2 m strengthened with UHPFRC layers at the tensile side. Before the application of the layers, the interface between RC and UHPFRC was roughened. During the testing, the interface slips between UHPFRC and RC were recorded using Linear Variable Differential Transformers (LVDTs). The beams were tested under four-point flexural test. The results of the present study indicated that the dowels at the interface reduce the slips at the interface, delay the formation of cracks and result in higher load carrying capacity

Ultra-high-performance fiber-reinforced concrete under cyclic loading

Ultra-high-performance fiber-reinforced concrete (UHPFRC) is a novel cementitious material with enhanced strength in tension and compression, and significantly high energy absorption in the postcracking region. The application of UHPFRC for the earthquake strengthening of existing structures could considerably improve the performance of existing structures due to its superior properties. There are published studies where the direct tensile and the flexural behaviors of UHPFRC have been investigated and the superior tensile strength and post-crack energy absorption have been highlighted. However, there are not any published studies on the performance of UHPFRC under cyclic loading. In this paper, the results of an extensive experimental program on UHPFRC under direct tensile cyclic loading are presented and a constitutive model for the response of UHPFRC under cyclic loading is proposed. The accuracy of the proposed model is validated using experimental results from various loading histories and for different percentages of fibers, and the reliability of the proposed model is highlighted

Dowels effectiveness investigation between ultra high performance fiber reinforced concrete and reinforced concrete

In the present study, the performance of Reinforced Concrete (RC) beams which were strengthened with Ultra High Performance Fiber Reinforced Concrete (UHPFRC) and dowels at the interface was investigated. RC beams with a length of 2.2 m strengthened with UHPFRC layers at the tensile side. Before the application of the layers, the interface between RC and UHPFRC was roughened. During the testing, the interface slips between UHPFRC and RC were recorded using Linear Variable Differential Transformers (LVDTs). The beams were tested under four-point flexural test. The results of the present study indicated that the dowels at the interface reduce the slips at the interface, delay the formation of cracks and result in higher load carrying capacity

Strengthening of existing reinforced concrete beams using ultra high performance fibre reinforced concrete

The addition of reinforced concrete layers and jackets for the earthquake strengthening of existing beams and columns is one of the most commonly used techniques in earthquake prone areas

A novel corrosion resistant repair technique for existing reinforced concrete (RC) elements using polyvinyl alcohol fibre reinforced geopolymer concrete (PVAFRGC)

Strain hardening fibre reinforced geopolymer concrete, which utilises waste material rather than primary mineral products and is suitable for cast-in-place applications, shows considerable potential as a resistant, more environmentally friendly, concrete repair material. This study assesses the corrosion protection performance of polyvinyl alcohol fibre reinforced geopolymer concrete as a repair material. The applicability of polyvinyl alcohol fibre reinforced geopolymer concrete as a repair material for preventing steel corrosion was investigated using specimens that simulated surface coating repair. Large scale beam repair was conducted using beams where part of the concrete cover at various depths (12.5% and 25% of the total beam depth) was replaced by polyvinyl alcohol fibre reinforced geopolymer concrete. Accelerated corrosion tests were performed using an induced current technique by applying a nominal 300 mA/cm2 constant anodic current for approximately 90 days. Results from flexural strength tests showed significant improvements in the structural performance of the reinforced concrete beams repaired with polyvinyl alcohol fibre reinforced geopolymer concrete following accelerated corrosion. The results can be summarised as follows: surface coating with polyvinyl alcohol fibre reinforced geopolymer concrete significantly reduced corrosion damage in terms of mass loss, crack distributions and structural performance, while differences in surface coating thickness also considerably affected the corrosion resistance of the repaired beams