This paper presents pedagogical techniques used to teach fresh and hardened properties of concrete. Fresh properties of concrete include the evaluation of slump, unit weight, and air content. The hardened properties of concrete include compressive and tensile strengths. Students typically have little to no prior experience working with concrete. Since concrete structures date back to Ancient Rome, many students assume concrete is a basic material that has not changed in centuries, and they do not view concrete as an engineered material. Therefore, their understanding of how concrete is an engineered material and its use is essential. This paper focuses on how both fresh and hardened concrete properties are taught in the classroom to best introduce students to concrete as an engineered material. The pedagogical methods focus on engaging students using experiential education through hands-on laboratory activities, projects, and game-based learning activities. Examples of the pedagogical approaches are presented herein, and they are supported by lessons learned by the authors based on their experience implementing these methods in the classroom. two environmental conditions, sustained elevated temperatures (ST) and freeze-thaw (FT) cycles. The concrete cylinders were wrapped with a single layer of GFRP and CFRP wrap. GFRP wraps improved concrete strength by up to 30% and ductility in excess of 600% for ambient condition specimens, while the enhancements in strength and ductility under the same conditions by CFRP wraps were about 70% and 700%, respectively. The strength enhancements were reduced severely for specimens tested under ST protocol beyond the glass transition temperature (Tg) with a minor reduction in ductility enhancement. On the other hand, freeze-thaw conditioning showed minimal effect on strength and ductility enhancements provided by the FRP wraps. The current and past findings were then used to suggest environmental reduction factors for the design of FRP wraps. A comparison of these factors with ACI 440.2R-17 showed that environmental factors suggested by the ACI code were not applicable at temperatures beyond Tg.

Concrete continues to be the most widely used material in the world, second only to water. Concrete is used in most civil infrastructure systems, but it often remains inadequately understood by the profession. For civil engineers to adapt to a world requiring ever-increasing efficiency, durability, and sustainability, and in which novel material formulations and products are introduced monthly, engineers must be able to make decisions as to the acceptability of these materials, and their effect on the performance of civil infrastructure. Essential to that ability is students’ understanding of the basics of cement hydration and its relationship to property development in the fresh and hardened concrete state. Towards that goal, this paper presents the basics of cement hydration, resources for learning more about the subject, and approaches to transferring knowledge to undergraduate-level students, through both lecture- and lab-based activities. Topics addressed include prioritization of topics for undergraduate civil engineering students to learn with regards to cement hydration processes, approaches to effective teaching of these topics including active learning in the classroom and laboratory, as well as knowledge exchange strategies, assessment techniques, and lessons learned from past experiences teaching these topics.

This research investigates the High Performance Concrete (HPC) jacketing method to strengthen reinforced circular concrete piers/columns. Four different types of HPC jackets such as Self-Consolidating Concrete (SCC), Engineered Cementitious Composites (ECC) and two types of Ultra-High Performance Concrete (UHPC) with three jacket thicknesses of 25 mm, 38 mm and 51 mm, with same reinforcement configuration were used to strengthen reinforced SCC core piers and analyze behavior. Thirteen pier specimens were tested to failure under concentric axial load applied through the SCC core. Test results indicated performance enhancement of piers strengthened with UHPC and ECC jackets, which not only prevented brittle failure but also improved the ductility and energy absorbing capacity by achieving a superior ultimate axial load capacity increase by more than 90% with a jacket thickness of 33% of the core diameter. Existing Code and analytical equations with reduction factors can be used for predicting axial load capacity of the strengthened piers/columns but choice of equations should be based on types of jacket concrete to ensure safe design.

Recently, a new generation of concrete sandwich panels (CSPs) comprising ultra-high performance concrete (UHPC) wythes and glass fiber reinforced polymer (GFRP) as reinforcement and shear connectors was developed and evaluated experimentally. In this study, a non-linear finite element model is presented to study the detailed behavior of these panels under bending. The model included detailed features such as a constitutive material law that considers the post-crack stiffening of UHPC, failure of GFRP material, wythe-to-insulation contact and slipping, and stability failure. Compared with eight previously tested panels, the model predictions of ultimate load, general load-deflection behavior, and failure modes matched those from experiments. The composite degree of each panel, a key design parameter frequently used in characterizing the structural and thermal efficiencies of CSPs, was determined from the ultimate load of the tested panel and that of two additional numerically-based non and fully composite ones and ranged between 3 to 34%. The structural performance of the GFRP connector was deemed satisfactory for the range of composite degrees proposed for the panels. The validated model will be deployed in a large parametric analysis studying different material and geometric variables and assisting in developing a design tool to estimate the strength and composite degree of UHPC CSPs with GFRP reinforcement.

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.