performance. Such flexibility is needed, since going “the last mile” in energy optimization can require inventive solutions. “The closer you get to achieving a truly net zero project, the more carefully you have to look at all the material inputs involved. This is where it makes sense to do comprehensive calculations, starting early in the design phase, comparing a variety of materials and looking at the full range of life-cycle considerations,” said Larry Rowland, Sustainability Market Manager, Heidelberg Materials North America. Many organizations are, in fact, casting a wider net to improve their sustainability outcomes and targeting areas of their value chain where the most improvement can be made. By most estimates traditional cement manufacturing is responsible for about 7 percent of all man-made CO2 emissions. This means the concrete, which is so vital to practically any project, can represent a significant percentage of the embodied carbon in a finished building. Therefore, improving a project’s sustainability by addressing the CO2 contributions of cement and concrete can be a good place to begin.
industry has already seen extensive adoption of portland limestone cement, in which some of the clinker in ordinary portland cement is replaced with ground limestone, a change that significantly reduces the embodied CO2 of the cement. Concrete producers are also improving sustainability by using supplemental cementitious materials such as slag, fly ash, and other materials, often in combination with portland limestone cement. A carbon-reduction approach that will be critical to decarbonize cement manufacturing over the longer-term is carbon capture, utilization, and storage (CCUS). “CCUS helps owners and designers reduce their reliance on carbon offsets by using cement that has a substantial reduction of embodied carbon in the first place,” said Cariaga. The CCUS project currently planned for Heidelberg Materials North America in Edmonton, Canada, is expected to result in the world’s first full-scale implementation of CCUS at a cement plant. “When operational, cement produced at the Edmonton facility will be net zero carbon,” said Cariaga. “This is important to concrete producers, allowing them to potentially achieve net zero concrete. Moreover, the net zero cement from Edmonton CCUS could potentially enable owners–private and public–across North America to achieve substantial reduction of embodied carbon in their projects.” Another important shift is the adoption of digital solutions throughout the cement supply chain. Digital transformation in the ready mixed concrete industry is moving quickly, and the trend is certain to continue since artificial intelligence (AI) is making its way into everyday workstreams. AI and other cloud-based tools help optimize carbon by providing greater transparency than ever before. The tools enhance inventory and mix management, trucking logistics, fleet optimization, and more. “Pairing this with real-time concrete strength from Giatec SmartRock® equips our contractors to make informed decisions. We give them eyes on their concrete as it’s arriving and inside their concrete as it cures. The vision will be to give real time insight into our product that will provide opportunity/transparency into the embodied carbon and performance characteristics of the concrete matrix which will provide many new enhanced values to our customers,” said Erica Flukinger, Digital Director, Heidelberg Materials North America. Cement and Concrete: Their Role in a Building’s Life Cycle Life-cycle assessment is another way to support performance-based outcomes. “An important area that isn’t being accounted for is embodied carbon related to maintenance needs. The sooner we can begin data collection on this category of carbon emissions, the better, because as the saying goes, ‘what gets measured gets managed,” said Cariaga. Life cycle cost analyses (LCCAs) are useful for capturing all costs associated with a building project—not only its construction, but its cost to operate and even its eventual disposal or recycling use. LCCAs capture the efficiencies associated with longevity of a
Assessing Cement- and Concrete-Related Carbon
Environmental Product Declarations (EPDs), which are third-party- verified against industry benchmarks, represent one tool making carbon intensity measurements easier. EPDs for cement and concrete compare the embodied carbon impacts of different mixes and materials, allowing owners and designers to measure the environmental impact. EPDs have been instrumental in bringing material suppliers on board earlier than ever before. Nevertheless, EPDs are mostly helpful in assessing carbon generated during raw materials sourcing, product manufacturing and construction—the traditional parameters for measurement. Working with suppliers’ representatives on project-specific designs allows the team to take carbon calculations to the next level, identifying carbon inputs up through turnkey and building operations. “The opportunity is for the team to build on the transparency that’s being achieved by using the EPD. EPDs open the door for the supplier to be engaged early in the design of a project. By working together— and by acknowledging that all the traditional concerns such as schedule and constructability are still critical—we can provide market driven solutions to meet an owner’s sustainability goals,” said Rowland. For example, by working together, materials suppliers and structural engineers can identify ways to reduce the total amount of concrete in a structure. The use of high-performance concrete can reduce floor thicknesses and/or lessen the volume of concrete required for columns, for example, thereby lowering the carbon intensity of individual building elements. Since the volume of concrete is closely tied to slab depth, it is a big driver of embodied carbon, achieving a one- or two- inch reduction by using a high-performance material. This can be the case even if the high-performance material is, itself, of higher carbon intensity than an ordinary mix. Carbon-Reducing Formulations, Manufacturing Processes and Digital Transformation Cement manufacturers are also working hard to lower the carbon emissions associated with cement production. The construction
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September 2023 csengineermag.com
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