International Concrete Abstracts Portal

Teaching concrete pavement design presents unique challenges and opportunities for new civil engineering faculty. This paper outlines best pedagogical practices for teaching slab-on-grade, highway, and airport concrete pavements to senior undergraduate or graduate students. Grounded in constructivist learning theory, the proposed approach emphasizes active learning strategies, including problem-based projects, worked examples, and engagement with real design standards, to deepen student understanding. We discuss syllabus structure, key course content (pavement types, joint design, drainage, overlays, durability), and alignment with ABET accreditation outcomes for civil engineering programs. Literature on engineering education and design pedagogy is reviewed to support active, student-centered learning. Finally, a detailed course design and suggested teaching methods are presented. These highlight the free resources (e.g., CP Tech Center manuals, ACI guides) that new instructors can leverage. Results from prior implementations indicate improved student engagement, conceptual understanding, and attainment of learning outcomes.

The transverse joint detail on a concrete pavement project called for smooth dowel bars. Due to unavailability of such bars, the general contractor directed the concrete contractor to use greased deformed reinforcing bars instead. Will the greased deformed bars work as an equivalent to smooth dowels in contraction joints?

We analyzed pervious concrete with regard to its acoustic absorption behavior. For this purpose, we cast a pervious concrete test series using different coarse aggregates varying in shape (crushed vs. rounded) or size (2-5 mm (0.08-0.20 in.)), to 8-11 mm (0.31-0.43 in.)). All test series were compacted in a gyratory compactor with variable intensities to reach an aimed total porosity of 25.0, 22.5, and 20.0 % by vol. and thus to evaluate the effect of the amount of the porosity beside the effects of aggregate shape and geometry on the acoustic absorption. Furthermore, we quantified the effect of the pervious concrete layer height on its acoustic absorption by a stepwise alternate cutting and measuring of the specimens at layer heights from 100 mm (3.94 in.) to 40 mm (1.74 in.). We used the first maximum of the absorption coefficient, its frequency, and the sound wave propagation speed in the porous material to evaluate the acoustic absorption. In general, a higher porosity, bigger grain size, the use of rounded aggregates, and higher cylinder height increases the acoustic absorption. A characteristic pore structure factor was found, which allows a prediction of the frequency in dependence of the cylinder height.

The milling of road pavements produces a granular material (called recycled asphalt pavement, RAP) whose size and distribution are suitable for its use as aggregate in concrete. The use of RAP as aggregate in concrete would have a twofold beneficial effect: reducing the amount of wasted asphalt and limiting the consumption of natural aggregates. In view of an assessment of the actual environmental benefits of concrete made with RAP aggregate, a thorough evaluation of its performance needs to be carried out, both on the short term (e.g., workability, shrinkage) and on the long term (e.g., resistance to aggressive environment and protection of embedded reinforcement from corrosion). Structural and mechanical properties (e.g., compressive strength, modulus of elasticity) also need to be assessed. This note presents the preliminary results of laboratory tests aimed at the characterization of RAP as aggregate to produce concrete. The characterization included analyses of size distribution by sieving, assessment of fine, chloride content, ESEM observations and XRD analyses, moisture content, and water absorption. Tests were performed on batches of RAP coming from different production plants to assess the variability and also, for comparison, on natural limestone aggregate. Results show a particle size distribution with a good replicability within the same site; all particle size fractions seem to be covered and the maximum diameter is around 21-22 mm. Regarding the microstructure of the aggregates, this is practically the same as for natural aggregates, except for the bituminous coating. The chloride content was negligible. Water absorption is higher compared to values of natural aggregates, probably because of surface dust layers and various impurities, which soak more water.

The use of recycled aggregates allows for reducing the environmental impact of concrete materials, by reducing the amount of waste and limiting the consumption of natural resources. Recycled asphalt pavement (RAP) is a granular material that comes from the milling of road pavements whose size and distribution make it suitable as aggregate for concrete. The environmental benefits of the replacement of natural aggregate with RAP need to be assessed with a better understanding of the long-term behavior of RAP concrete, considering the evolution of its performance in time and its ability to guarantee an adequate service life when exposed in operating conditions. This note presents the preliminary results of research on the effect of RAP on concrete properties. The addition of RAP aggregate affects concrete properties in a fresh and hardened state. Some parameters showed clear trends with the percentage of RAP, however, also other factors (e.g. w/c ratio and curing time) seem to play a role. Compressive strength and dynamic modulus of elasticity of RAP concrete were always lower compared to reference concrete, while the electrical resistivity did not show a clear trend. Further investigations will be carried out to clarify the role of RAP aggregate.