Sessions & Events

 

All sessions and events take place in Central Daylight Time (CDT).
All events take place at the Hyatt Regency New Orleans.

On-demand sessions will be available for viewing in the convention platform/event app under "On-Demand Content" within 24-48 hours of the session premiere. Please note, on-demand sessions are not available for CEU credit. *Denotes on-demand content.


Open Topic Session, Part 2 of 2

Tuesday, March 26, 2024  4:00 PM - 6:00 PM, Strand 11B

The purpose of this session is to offer authors/speakers an open forum for presentation of recent technical information that does not fit into other sessions scheduled for this convention. Any aspect of structural analysis or design, concrete materials science, or construction, manufacturing, use, and maintenance and health monitoring of concrete structures and products can be presented.

Learning Objectives:
(1) Examine the use of epoxy-coated reinforcing bars in UHPC;
(2) Discuss advanced 4D X-ray CT to analyze coal combustion ashes.
(3) Develop insights into the use of nano materials for accelerating CO2 uptake and strengthening ITZ;
(4) Review 3D concrete printing and enhancing thermal efficiency using phase change materials.

This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.


Bond Behavior of Epoxy-Coated Reinforcing Bars in Non-Proprietary UHPC

Presented By: SANJEEB THAPA
Affiliation: University of Kansas
Description: Non-proprietary ultra-high-performance concrete (UHPC) mixtures were developed for use in closure strips between precast members on reinforced concrete bridges. The mixtures contained ODOT approved Type I portland cement, slag cement, silica fume, graded fine aggregate, two high-range water-reducers (HRWRs), one of which incorporated a viscosity modifying admixture, and 2% by volume of 0.5-in. steel fibers. Several HRWRs of each type were included in the evaluations. Mixtures were evaluated based on flow, fiber distribution, flexural properties, compressive strength, and effect on bond strength using a modified pullout test and the ASTM A944 beam-end test for No. 5 uncoated, ASTM A755 epoxy-coated, and ASTM A1124 textured-epoxy-coated reinforcing bars. The UHPC mixture with the best properties was used to cast a closure strip between two precast sections to determine the splice strength of No. 4, No. 5, and No. 8 uncoated, epoxy-coated, and textured-epoxy-coated reinforcing bars with minimum clear covers ranging from 1.00 to 2.63 in. The results of the splice test were used to develop design recommendations. The study showed that UHPC can be made using ODOT approved materials. The splice strength of reinforcing bars in UHPC is two times the value in conventional concrete. The negative effects of epoxy coating on bond strength are lower in UHPC than in conventional concrete. ASTM A1124 textured epoxy-coated bars have the same bond strength as uncoated bars.


Strengthening the ITZ Interactions of Metakaolin-OPC Concrete using Monodispersed Carbon-based Nanomaterials

Presented By: Rohitashva Singh
Affiliation: University of Texas Arlington
Description: While compressive strength of concrete can be enhanced by using metakaolin (MK), such approach results in a relatively brittle material with limited tensile strain capacity. This study presents the multiscale mechanisms to improve the modulus of elasticity and strain energy absorption capability of the Interfacial Transition Zone (ITZ) in MK-cement concrete using low concentrations of monodispersed carbon nanotubes (CNTs) and nanofibers (CNFs). Nanoscale imaging and mechanical property mapping at the Interfacial Transition Zone (ITZ) between the nanomodified MK-OPC matrix and aggregates (Figure 1) showed that the local nanostructure and morphology of ITZ was modified, resulting in an impressive increase in the modulus of elasticity (+20.7%) and toughness (+23%). Results of the three-point bending test on notched beam specimens indicated a 1.5x higher tensile load-carrying and strain energy absorption capacity of the CNT reinforced MK-cement concrete compared to the reference MK-cement concrete at the pre-peak/elastic and post-crack stages of deformation.


Accelerating CO2 Uptake in Cement Pastes through Nano-TiO2 Modification

Presented By: Marina Lopez-Arias
Affiliation: Purdue University - West Lafayette
Description: Our study explores the effect of the nanomodification of cement pastes on CO2 uptake rate. Samples of 0.5 w/b were exposed to three initial CO2 concentrations during eight 1-hour cycles. Results showed that nano-TiO2 addition enhances the CO2 uptake rate of cement pastes, enabling the capture of more CO2 with lower CO2 concentrations, increasing efficiency. Also, the use of nanoparticles reduces porosity, which should decrease the diffusion of CO2, implying a lower carbonation rate. However, data revealed that nanomodified samples absorb CO2 faster while the porosity is decreased. 3D X-ray tests suggest that the nanomodification increases the pore surface area while reducing the overall porosity.


3D Concrete Printing of Flat Arch Slab

Presented By: Haider Himairi
Affiliation:
Description: Construction automation such as 3D Concrete Printing (3DCP) is developing as a technique to expedite building with better quality control and sustainability. However, 3DCP faces challenges to print certain structural elements such as slabs. Aspects of the historical flat arch slab (FAS) system, consisting of extruded structural clay tiles supported by steel beams, may have potential to address this need. Inspired by the FAS system, this research explores the use of modern 3DCP in horizontal flat arch slab systems. Finite element modeling (FEM) is used to optimize section geometry and study the effect of parameters including different restraint conditions.


Experimental Investigation of Fracture Toughness in Coal Combustion Ash Concrete Using 4D X-ray CT

Presented By: Soniya Tiwari
Affiliation: Duke University
Description: Chemical compositions of coal combustion ash (CCA) samples obtained from power plants throughout the United States were previously determined. Many of these materials do not qualify as class C and class F fly ash which limits the potential to repurpose this abundant waste material. In the present study, the CCA samples are used to replace 0, 20, and 40 % of portland cement in cement paste specimens. The rectangular specimens are cured for up to 28 days and tested using a Deben 5 kN loadcell three-point bending apparatus. During the experiments, the loadcell is placed inside an X-ray computed tomography (CT) scanner to capture the crack development during loading (Figure 1). The results from the flexural strength tests will be used to calculate fracture toughness and to correlate mechanical behavior to the chemical compositions to further the understanding of CCA waste valorization for structural applications in the built environment.


Enhancing Thermal Efficiency in Building Materials: A Comprehensive Study of Phase Change Materials Integration and Performance

Presented By: Muhammed Bayram
Affiliation: Texas State University San Marcos
Description: The pressing need for energy-efficient building solutions has fueled research into innovative technologies, with a particular focus on thermal energy storage. Phase change materials (PCM) have emerged as a promising avenue, offering the potential to mitigate temperature fluctuations, reduce energy consumption, and enhance thermal comfort in buildings. This study synthesizes findings from diverse experimental work exploring the incorporation of PCM into various building materials to address this imperative. The combined study investigates PCM integration in architectural elements, encompassing cementitious composites, glass fiber reinforced gypsum composites and 3D printed polymer structures. In pursuit of comprehensive insights, a multi-scale approach is adopted, incorporating physical, mechanical, chemical, microstructural, thermal, light transmittance, and solar thermoregulation tests. Various types of PCM, including microencapsulated and shape stabilized PCM with diverse supporting materials have been selected to cater to specific material applications. The studies present a nuanced understanding of how these PCM-infused materials affect mechanical strength, thermal conductivity, latent heat values, and thermoregulatory properties. This comprehensive study explores the transformative potential of PCM across various building materials, emphasizing their role as key players in the development of energy-efficient and sustainable solutions. The incorporation of PCM in building materials showcases notable solar thermoregulation properties, ensuring a stable and comfortable indoor temperature. The results suggest that the PCM-incorporating materials developed in this study can be considered as environmentally friendly building materials, contributing to both thermoregulation and energy conservation in the construction industry.

Upper Level Sponsors

ACI Northern California and Western Nevada Chapter
Baker
Conseal
Euclid Chemical
FullForce Solutions
Master Builders
Natural Resources Research Institute - University of Minnesota
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