Due to a dynamic development of infrastructure, engineers around the world are looking for new materials and structural solutions, which could be more durable, cheaper in the life cycle management, and built quickly. One of prospective solutions for building small-span bridges can be precast lightweight concrete reinforced with glass fiber-reinforced polymer (GFRP) rebars. Thanks to prefabrication, it is possible to shorten the construction time. Using lightweight concrete affects structure weight as well as transportation costs. GFRP rebars can make the structure more durable and also cheaper in terms of life cycle management costs. The paper focuses on the fatigue performance of a real-scale arch (10.0 m (33 ft) long, 1.0 m (3.3 ft) wide, and 2.4 m (7.9 ft) high) made of lightweight concrete and GFRP rebars (LWC/GFRP) in comparison with an arch made of normal weight concrete and typical steel reinforcement (NWC/steel). The fatigue loads ranging from 12 to 120 kN (2.7 to 27 kip) were applied in a sinusoidal variable manner with a frequency of 1.5 Hz. This research revealed that the NWC/steel arch exhibited significantly better fatigue resistance when compared to the LWC/GFRP arch. Differences in the behavior of the NWC/steel and LWC/GFRP models under fatigue load were visible from the beginning of the research. The LWC/GFRP model was exposed to fatigue loads, resulting in gradual deterioration at an early stage. This degradation was evident through stiffness being progressively reduced, leading to increased displacements and strains as the number of load cycles increased. The model did not withstand the fatigue load and was destroyed after approximately 390 thousand load cycles, in contrast to the NWC/steel model, which withstood all 2 million load cycles without significant damages or the stiffness being decreased. However, the prefabricated lightweight concrete arches with composite reinforcement seem to be an interesting alternative of load-bearing elements in infrastructure construction.

A large number of bridges in the Netherlands have transversely post tensioned deck slabs cast in-situ between flanges of precast girders and were found to be critical in shear when evaluated by Eurocode 2. To investigate the bearing (punching shear) capacity of such bridges, a 1:2 scale bridge model was constructed in the laboratory and static tests were performed by varying the transverse prestressing level (TPL). A 3D solid, 1:2 scale model of the real bridge, similar to the experimental model, was developed in the finite element software DIANA and several nonlinear analyses were carried out. It was observed that the experimental and numerical ultimate load carrying capacity was much higher than predicted by the governing codes due to lack of consideration of compressive membrane action (CMA). In order to incorporate CMA in the Model Code 2010 (fib 2012) punching shear provisions for prestressed slabs, numerical and theoretical approaches were combined. As a result, sufficient factor of safety was observed when the real bridge design capacity was compared with the design wheel load of Eurocode 1. It was concluded that the existing bridges still had sufficient residual bearing capacity with no problems of serviceability and structural safety.

Glass fiber-reinforced polymer (GFRP) bars show promise as a non-corrosive reinforcement alternative for coastal marine applications. Designers are reluctant to use new material systems without guidance or case studies demonstrating successful implementation. For the case of precast concrete piles, the current practice is prestressing with carbon steel strands. In this paper, a seawall replacement project in South Florida allowed for the demonstration of the use of reinforced concrete (RC) piles using GFRP bars and spirals. The field performance of the GFRP-RC piling system was validated by collecting data during driving by means of a pile driving analyzer (PDA). The measured internal stresses in the pile were compared with code requirements and concrete compressive strength determined from laboratory tests. The structural design used for these GFRP-RC piles and field-collected data on pile resistance, stresses, and integrity is presented and discussed in this paper.

This paper investigates the use of glass fiber reinforced polymer (GFRP) bars to reinforce the jointed precast bridge deck slabs built integrally with steel I-girders. In addition to a cast-in-place slab, three full-size, GFRPreinforced, precast concrete slabs were erected to perform static and fatigue tests under a truck wheel load. Each slab had 200 mm (7.9 in) thickness, 2500 mm (98.4 in) width normal to traffic, and 3500 mm (137.8 in) length in the direction of traffic and was supported over a braced twin-steel girder system. The closure strip between connected precast slabs has a width of 125 mm (4.9 in) with a vertical shear key, filled with ultra-high-performance concrete (UHPC). Sand-coated GFRP bars in the precast slab project into the closure strip with a headed end to provide a 100 mm (3.9 in) embedment length. A static test and two fatigue tests were performed, namely: (i) accelerated variable amplitude cyclic loading and (ii) constant amplitude cyclic loading, followed by static loading to collapse. Test results demonstrated excellent fatigue performance of the developed closure strip details, with the ultimate load-carrying capacity of the slab far greater than the demand. While the failure in the cast-in-place slab was purely punching shear, the failure mode in the jointed precast slabs was punching shear failure with incomplete cone-shape peroration through the UHPC closure strip, combined with a major transverse flexural crack in the UHPC strip. This may be attributed to the fact that the UHPC joint diverted the load distribution pattern towards a flexural mode in the UHPC strip itself close to failure.

In this study, the behavior of a calcined mixed clay (CMC) exhibiting a particularly high metakaolin content (~51 %) in composite cements (substitution rates 0–50 wt. %) was studied. It was found that CMC much decreases workability and substantially increases the water demand due to its higher fineness as compared to OPC. Furthermore, the water demand of pure calcined clays was investigated, and the order as follows was established: meta muscovite ≫ meta illite ≫ metakaolin > meta montmorillonite. Additionally, the dispersing effectiveness of a series of precast-type PCEs selected from the groups of MPEG, HPEG, and IPEG polymers was tested in blended cements holding 0–50 wt. % of the CMC. According to this, the HPEG PCE disperses these composite cements best, followed by the IPEG and the MPEG PCEs. Generally, the presence of CMC prompts significantly higher PCE dosages (up to 800 % more for the 50:50 OPC/CC blend). Furthermore, it was found that in OPC/CMC blended cements slump retention is much more difficult to achieve than in OPC. As such, an industrial ready-mix type HPEG PCE or its combination with sodium gluconate failed to provide flowability retention times which are commonly required by the ready-mix industry. Our study concludes that while such low carbon calcined mixed clay blended cements offer significant ecological advantages, they demand higher superplasticizer dosages which negatively affects their cost-effectiveness and at the same time poses significant technical challenges, particularly in ready-mix concrete applications. It should be mentioned that the problems pointed out here will be less severe for CMCs of lower metakaolin content.