Resources

An important step in the drive to meet carbon reduction goals in the concrete industry is American Concrete Institute’s (ACI) uniquely positioned Center, NEU: An ACI Center of Excellence for Carbon Neutral Concrete. With the purpose of driving research, education, awareness, and global adoption of the use of carbon-neutral concrete materials and technologies in the built environment, NEU envisions a concrete industry in which all have access to technologies and the knowledge needed to produce and place carbon-neutral concrete and concrete products

The concrete industry is working to reduce its carbon footprint, but despite the amount of work already accomplished, there is still much to do. In a significant step to help meet carbon reduction goals, the American Concrete Institute (ACI) has established a uniquely positioned center, NEU: An ACI Center of Excellence for Carbon Neutral Concrete.

The article discusses testing of a system designed to achieve overall carbon negativity. The system comprises a concrete slab supporting a wall constructed using concrete masonry units (CMUs). The concrete slab was made of alkali-activated cement containing algae-derived carbon-storing, biogenic limestone. The CMUs contain biomineralizing microalgae and a proprietary hydrogel binder as cement replacement.

This article summarizes the results of a study on the shrinkage behavior of an ordinary portland cement (OPC), a portland-limestone cement (PLC), and a PLC-Slag cement. The results show that the OPC, PLC, and PLC-Slag systems have similar early-age shrinkage, stress development, and cracking behavior, despite the higher fineness of the PLC. Eliminating the largest cement particles during the grinding/separation process used in the production of the PLC allows PLC mixtures to have pore size distributions that are similar to those for OPC mixtures.

This article presents results of testing of concrete pavements constructed from mixtures with portland limestone cement (PLC) and portland cement (PC), manufactured from the same clinker in the same plant. Performance of these pavements after 3 to 4 years’ service in aggressive climates in Canada was evaluated and compared. Discussed test results include compressive strength, depth of carbonation, chloride permeability, and apparent chloride diffusion.

This article, the third in a series on portland limestone cement (PLC), reports on the mechanisms that allow PLC mixtures to maintain the same levels of durability performance as portland cement (PC) mixtures. It discusses results of alkali-silica reactivity, sulfate resistance, freezing-and-thawing, scale resistance, and carbonation testing. PC and PLC used in presented studies came from the same mill circuit. The target limestone content of the PLC was 12%, the limestone was interground with the cement clinker, and the fineness of the PLC was increased to achieve the same 28-day (mortar) strength as the PC.

This article serves as an introduction to a series of articles on portland limestone cement (PLC) to be published in this and upcoming issues of Concrete International. Key points include PLC’s role in concrete construction and some of the associated benefits. The article also refers readers to several recent studies comparing PLC and portland cement.

This article reports on the mechanisms that allow portland limestone cement (PLC) mixtures to maintain the same levels of strength as portland cement (PC) mixtures. Mechanisms discussed include the filler effect, increased cement paste volume, heterogeneous nucleation, faster kinetics of hydration, and production of calcium carboaluminates. The performance of two PLCs produced on two different milling circuits are compared against a control PC produced on one of the same circuits.