Addressing Embodied Carbon in Concrete – Why it Matters
Presented By: Larry Rowland
Affiliation: Heidelberg Materials
Description: This presentation will provide an overview of the carbon intensity of concrete and the role of cementitious binders in the embodied carbon in concrete products. It will review current best practices the industry is undertaking to achieve low carbon concrete mixtures. A discussion of the role of Life Cycle Assessments in accounting for carbon will be given along with guidance for optimizing carbon reduction strategies in concrete.
Development of Net-Zero Embodied Carbon Concrete Using Carbon- and Cellulose- Based Byproducts and Nanomaterials
Presented By: Panagiotis Danoglidis
Affiliation: University of Texas At Arlington
Description: The use of carbon- and cellulose- based waste biomass byproducts and nanomaterials presents a key technology for modifying the carbonation kinetic rates within the cementitious matrix, due to their unique CO2 uptake potential and porous/fibrillar morphology. This presentation demon-strates the development of sustainable, net-zero and negative concrete with high CO2 sequestra-tion capacity, resiliency and ductility by replacing ordinary Portland cement with biochar and waste cellulose fibers and reinforcing it with nanomaterials. This is a promising way for devel-oping eco-efficient and highly resilient concrete, with at least 2-3x higher CO2 capture and min-eralization ability and 100% increased pre-crack and post-crack tensile load bearing and strain energy absorption capacity over OPC concrete throughout the entire life cycle.
Minimizing Carbon Footprint in Cementitious Materials through the Integration of TiO2 Nanoparticles
Presented By: Carlos Moro
Affiliation: Texas State University
Description: This investigation aims to study the effect of nano-TiO2 addition on CO2 uptake of cement paste during CO2 curing. Cement paste mixtures with different percentages of nano-TiO2 (0%, 0.5%, 1%, 2%), and two different types of curing (normal curing (NC) at 23 ?C and 50% RH, and CO2 curing (CC) that includes a 12-h curing in a chamber with 20% of CO2) were studied. Compressive strength, X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), and an estimation of the net CO2 emissions were performed for each studied mixture and curing condition. All samples were tested at 48 h. Results showed that the optimum percentage of nano-TiO2 in terms of compressive strength is lower for CO2 curing samples than for NC samples. XRD and TGA results exhibited that the use of nano-TiO2 promotes the CO2 capture during the CO2 curing. Since nano-TiO2 reduces the size of CH, it increases the CH surface area. This may enhance the CH reactivity with the CO2, producing an increase in the CO2 uptake. Results also showed that not considering the effect of nano-TiO2 on compressive strength and promotion of CO2 capture would highly overestimate the net CO2 emissions of cementitious materials with nano-TiO2. It highlights the importance of selecting an adequate functional unit for the analysis.
Enhancing Strength and Reducing Porosity with C-S-H Seeds
Presented By: Nishant Garg
Affiliation: University of Illinois at Urbana-Champaign
Description: For low-carbon concrete mixtures, where high SCM contents (>40%) are employed, one of the primary challenges that need to be addressed is the low early-age strength. Without sufficient early-age strength, the construction schedule can be jeopardized. One approach to improve and potentially enhance early-age strength is that of nucleation seeding. Introduced in the late 2000s, C-S-H seeds have been known to accelerate and enhance hydration kinetics. Today, several commercial admixtures based on these C-S-H seeds are available in the market. In this talk, I will share our latest results with some of these commercially available C-S-H seeds – both from the lens of lab testing as well as field implementation. Finally, in addition, I will briefly touch upon newer lab-based, synthetic versions that can be potentially used as strength enhancers in the future.
Increasing Performance of Limestone Calcined Clay Cements (LC3) Using Graphene
Presented By: Cihang Huang
Affiliation: Purdue University - West Lafayette
Description: Limestone calcined clay cement (LC3) can reduce carbon emissions up to 50% compared with traditional ordinary Portland cement. While LC3 shows great promise in decoupling concrete production from embodied carbon emissions, durability and mechanical performance is hin-dered by inconsistent feedstock material composition and the lack of long-term data. Since its discovery in 2004, the carbon nano-material graphene has been thought of as a supermaterial due to its high tensile strength and electrical conductivity. Its inclusion in cementitious compo-sites has led to increases in compressive and flexural strength, which allows for reduced con-sumption of cement to achieve the same strength properties, lowering the embodied carbon emissions through the use of graphene. To that end, this work investigates how the addition of graphene to LC3 mortars and pastes affects hydration, strength, and durability properties, such as rapid chloride permeability and rapid chloride migration. It was found that the addition of 0.3% by weight of binder of graphene accelerates the hydration, increases the compressive strength, and decreases the permeability compared to a reference LC3 mix. These findings sug-gest that adding small amounts of graphene to LC3 composites could help overcome the issues presented by inconsistent feedstock material composition by improving the LC3 composite per-formance.