“This is not your father’s concrete,” said NRMCC President Steve Lode. “We’ve invested heavily in the ability to deliver low-carbon concrete specifically tailored to the application it is being used for.
"That involves both programs like our Concrete Designer and Project Builder and the use of special high-density aggregates that allow us to less cement -- lowering carbon loads while delivering the high strength and high modulus of elasticity required in today’s demanding environment.”
Concrete Designer enables NRMCC’s technical experts to work with architects and engineers to refine ready-mix requirements. Project Builder lets customers produce a report showing the average, high, low, and median total embodied carbon for all of the concrete mixes in their projects. The program also allows users to analyze which concrete applications contribute the most embodied carbon to projects and to target carbon reductions.
Mix Design and Aggregates Part of Carbon Reduction Program
The focus on mix design and aggregate/admixture selection is part of NRMCC’s four-part carbon reduction program. The program also involves the use of special Type 1L Portland-Limestone cement, the conversion of NRMCC’s concrete mixer fleet from diesel fuel to renewable natural gas (RNG), and the ability to produce instant digital Environmental Product Declarations.
“At the same time that we see a demand from governments and environmental groups to reduce the carbon load of concrete, we’re also seeing a demand for special higher-strength concrete mixes. We’re totally committed to reducing the carbon load of our concrete while growing the market for structural, high-strength concrete We’re partnering with our customers to help them comply with the new laws and regulations and to reduce the overall carbon footprint of their projects,” Lode said.
“Getting NRMCC involved early on -- before the concrete is specified -- can help us come up with a mix that minimizes carbon impact and provides the necessary strength and modulus of elasticity while minimizing costs,” says Jim Little, NRMCC's Diretor of Technical Sales.
Special Aggregate Adds Strength While Using Less Cement
NRMCC can use special high-density aggregate sourced from the Orca Quarry -- a 130 million-ton glacial deposit on the northeast coast of Vancouver Island. The Orca aggregate is clean and dense, with natural surface texturing characteristics that help produce strong matrix bonding, The Orca aggregate results in a high-performance structural concrete with lower Portland cement and admixture requirements than the typical sand and gravel aggregates available locally in Southern California.
Sand and gravel aggregates typically yield concrete with a modulus of elasticity in the 3,800 ksi range at best. Orca aggregates can help push the modulus of elasticity up over 4,000 ksi and compressive strength above 10,000 psi. The aggregates can increase the value proposition of reinforced concrete by simplifying mix designs, lowering cement and admixture requirements, increasing resistance to deflection, and lowering embodied carbon.
Modulus of elasticity refers to a material’s ability to resist deformation. High-rise buildings are designed and constructed based on the calculated modulus of elasticity in order to comply with building drift limits. Building heights can trigger a requirement for notes on the structural plans specifying the modulus of elasticity for the concrete used in the seismic force-resisting system, including beams, columns, and shear walls.
“The advanced aggregates, Type 1-L cement, computer-aided mix design, computer-generated Environmental Product Declarations, and our fleet of Renewable Natural Gas mixers are all helping us deliver the best concrete mix, with the smallest carbon footprint -- at the best price to our customers,” Lode said.