By Jason Straka
Reducing net carbon dioxide emissions in finished concrete is a critical endeavor for the industry. As portland cement production accounts for a measurable percentage of global man-made CO2 emissions, stakeholders are under a microscope to change the way they finish binders and develop new approaches that are more sustainable through the entire cycle of concrete production. From plant to jobsite, sustainable concrete is top of mind as practitioners seek new ways to lessen projects’ carbon footprint.
One solution is to combine Portland Limestone Cement (PLC), also known as Type IL cement, with the GCP Verifi in-transit concrete management system. Type IL is similar to standard Type I/II cement, but can contain 5-15 percent finely graded limestone. It performs like Type I/II binder with the additional benefits of reducing net CO2 emissions by approximately 10 percent and potentially improving concrete durability.
Type IL cement is widely approved as a 1:1 portland cement replacement and can be combined with other supplementary cementitious materials such as fly ash and slag. Due to supply chain issues and an increasing push to sustainable building practice, Type IL cement has become more popular than ever—even though the material has been accepted in standards and used to make concrete for over 50 years.
TYPE IL CHALLENGES
Type IL cement is typically more temperamental than Type I/II, requiring ready mixed producers to have tighter control over the amount of water added to the concrete and the number and speed of drum revolutions in transit. Because Type IL is sometimes ground finer, there can be an increase in water demand as well as a decrease in strength and set times. In order to sustain the desired performance of concrete containing Type IL cement a greater degree of control is required.
The Verifi in-transit concrete management system helps control the inconsistencies of concrete containing Type IL cement from the plant to the jobsite. The system is the first-ever technology to address inefficiencies in the concrete delivery process by actively managing mix properties from batch plant to jobsite. Verifi leverages data from 10 years of continuous research and development, from over 20 different truck types and hundreds of types of concrete to collect over 90 billion rheological data points. The system’s mixer truck-mounted sensors collect real-time data to monitor, measure and manage concrete properties while a load is in transit to the jobsite. The data is transmitted from on-board computers that communicate via the cloud every 15 seconds, making the data accessible on phones, tablets and laptops.
AUTOMATION = CONSISTENCY
One of the most difficult aspects of ready mixed production is attaining concrete consistently from load-to-load. The challenge is particularly vexing with Type IL cement, as minor changes in material properties, such as aggregate moistures, can have significantly more impact. Verifi technology helps producers realize greater consistency across loads and mix optimization. The system’s batch screen very quickly alerts producers to potential changes in materials going into the concrete on a load-to-load basis. It can then automatically increase the slump while the concrete is en route to the jobsite, adding water and/or admixtures as needed to deliver the order within spec.
The Verifi system provides data on fresh concrete throughout the delivery cycle that can be shared within the producer’s organization and across the supply chain to identify opportunities to improve quality and efficiency. The overall impact of the Verifi system is a smaller carbon footprint.
Jason Straka is a Product Manager with GCP Applied Technologies
When Type IL cement is paired with the Verifi in-transit concrete management system, the sustainability and performance benefits of a load of ready mixed are dramatically enhanced, GCP Applied Technologies notes. The system tempers the impacts of Type IL variability, adds to a producer’s efficiency, and helps reduce material waste.