How Lightweight Aggregate & Concrete can Reduce Global Warming Potential and Increase Sustainability of Concrete, Part 2 of 2

Monday, November 4, 2024  11:00 AM - 1:00 PM, Grand BR Salon D

The session will cover the following:
- Case studies on the application of lightweight aggregate and concrete to reduce global warming potential (GWP).
- Experimental investigations of the durability and service life enhancement of lightweight aggregate concrete.
- Analytical service life modeling and prediction of lightweight aggregate concrete applications.
- Lifecycle assessment of the environmental footprints of lightweight aggregate and concrete.
- Contribution of lightweight aggregate and concrete to sustainable development of resilient infrastructure.
- Mitigating climate change using lightweight aggregate and concrete.

Case Study: Salesforce Tower Chicago

Presented By: Elliot Wilm
Affiliation: The Walsh Group
Description: Salesforce Tower Chicago is a 58-story, steel structure with structural lightweight concrete on steel deck floor systems. The final development on Chicago’s Wolf Point, Salesforce is also the tallest with an overall building height of 837 feet. The building comprises approximately 1,400,000 gross square feet, 10,000 tons of structural steel, and 52,000 cubic yards of concrete. Salesforce is the first building in the city to require and measure EPDs to quantify embodied carbon of concrete, steel, and other construction materials. This presentation will explain the process of documenting the 19% overall reduction in carbon emissions resulting from using structural lightweight concrete for the elevated floor slabs.

Effect of Internal Curing on Performance of Calcium Sulfoaluminate Cement Concrete

Presented By: Royce Floyd
Affiliation: The University of Oklahoma
Description: Calcium sulfoaluminate (CSA) cement is an alternative, hydraulic cement that can be formulated to produce rapid setting and shrinkage compensating concrete. Production of CSA cements requires less energy and releases less carbon dioxide compared to conventional portland cement. This cement also requires approximately twice as much water as conventional portland cement for proper hydration and careful curing is required to achieve proper performance, especially relative to expansion. Therefore, introduction of internal curing water from presoaked lightweight aggregate has the potential for positive effects on the performance of CSA cement concrete. This presentation describes an initial study that examined concrete made using three CSA cements and portland cement with three different amounts of internal curing water added to each mix design using presoaked lightweight aggregate. The effect of internal curing on performance was evaluated using measurements of compressive strength, permeability, and shrinkage. The introduction of internal curing resulted in increased compressive strength and a reduction in shrinkage for all CSA cements examined. The shrinkage compensating concrete made with expansive CSA cement exhibited the most improvement in performance from adding internal curing water. In addition to the initial study, ongoing work on behavior of internally cured shrinkage compensating concrete made with expansive CSA cement is also described.

Eco-Mechanical Analysis of Lightweight Cement-Based Composites

Presented By: Alessandro Fantilli
Affiliation: Polytechnic University of Turin
Description: Since an optimal compromise between structural and environmental requirements needs to be reached in building materials, to tailor a sustainable reinforcement of lightweight cement-based composites the so-called eco-mechanical approach can be adopted. Such a comparative analysis was performed on two plates used to retrofit the sidewalks of a famous bridge in Italy. In the first plate, made with expanded clay aggregates, the traditional steel bars were the reinforcement. Whereas only polymeric fibers reinforced the same lightweight concrete in the second plate. In all the cases, the reinforcements guaranteed strength and ductility, as required by code rules. However, the plates made with the fiber-reinforcement showed lower eco-mechanical performances than those reinforced with rebar.

Decarbonizing Concrete by Using Biochar as LWA

Presented By: Mahdi Mirabrishami
Affiliation: Pennsylvania State University
Description: Incorporating biochar, as a material with a high amount of sequestered CO2, in cementitious mixtures could be a promising approach to address the global concern of reducing the carbon footprint of concrete structures. This presentation will evaluate the application of biochar as LWA with internal curing capabilities in cement-based mixtures. This assessment will be done in terms of how compressive strength, autogenous shrinkage, and internal relative humidity (IRH) are affected in the presence of two types of biochar from different manufacturers. The above-mentioned effects will be studied at 2 different particle size distributions for both types of biochar to see how a better advantage of using biochar as LWA in concrete could be taken while reducing concrete's carbon footprint.

The GWP of IC Concrete Bridge Decks – Why Details Matter

Presented By: Jason Weiss
Affiliation: Oregon State University
Description: This presentation will discuss the global warming potential (GWP) of internally cured (IC) concrete bridge decks. The GWP of several bridges will be calculated. Details of the calculations will be presented to discuss why details matter. A case will be made for the tremendous benefits that GWP calculations can bring. However, the shortcomings of the current industry approaches will also be discussed as well as issues to look out for in specification development.