Improvements in Sustainable Concrete Properties for Expanding its Utilization in Civil Construction Projects
Presented By: Lateef Assi
Affiliation: Terracon
Description: The development of sustainable construction materials has been the focus of research efforts worldwide in recent years. Concrete is a major construction material; hence, finding alternatives to ordinary Portland cement is of extreme importance due to the high levels of carbon dioxide emissions associated with its manufacturing process. Geopolymer concrete has demonstrated promising mechanical and microstructural properties in comparison with conventional concrete; however, there are many limitations including but not limited to the need for external heat, activating solutions, variability found in fly ash sources and properties, and controlling initial and final setting times. The presentation will show that a significant improvement in 28-day compressive strength was achieved when the activating solution was changed. The need for external heat was eliminated and initial and final compressive strength was improved when partial Portland cement replacement was used. Initial and final setting time was extended and controlled when (3-6%) sucrose replacement of fly ash was included in the mixture. Several mechanical and durability properties were improved when two fly ash sources were utilized. In addition, the mechanical and durability properties were enhanced when different particle size distribution was used in the mixtures. These improvements will diversify sustainable concrete applications. Hence, it will increase its market share in concrete industries.
Reducing Embodied Carbon in Ready-Mix and Dry Cast Concrete Using Carbonated Calcium Silicate Cement
Presented By: David Smith
Affiliation: Solidia Technologies Inc.
Description: An essential strategy for reducing the global warming potential of concrete relies on replacement of portland cement with supplementary cementitious materials (SCMs) with lower embodied carbon. In addition to reducing concrete’s carbon intensity, SCMs add strength, improve durability, and lower costs. However, the challenges to SCM replacement of portland cement include material availability, quality control, and construction efficiency, specifically control of water demand (workability) without compromising strength and durability of cured concrete. This presentation is about engineering an SCM from carbonating calcium silicate cement conforming to ASTM C1905 Standard Specification for Cements that Require Carbonation. Cements conforming to C1905 can be made and carbonated at the cement plant using flue gas, then processed into an SCM that can replace 35% or more of the portland cement in ready-mix concrete. As with other SCMs, cement clinker reductions are delivered via blended cements that conform to ASTM C595 or C1157. This presentation provides a brief view of a comprehensive SCM evaluation program according to guidelines in C1709 including test pavements in harsh environments for over three years, as well as estimated GWP reductions and recent projects. In addition, cements that conform to C1905 can be used directly as a binder in the manufacture and carbonation curing of dry cast and some precast concrete products. Curing generally requires less than 24 hours rather than 28 days to meet ASTM product standard specifications for strength and durability while reducing embodied carbon by over 40%. The presentation introduces a new, state-of-the art manufacturing plant that incorporates rapid carbonation curing as a pioneer for future dry cast concrete product manufacturing.
Global Real-World Applications of Ye’elimite Containing Cements
Presented By: Eric Bescher
Affiliation: University of California, Los Angeles
Description: CSA-containing cements are a focus of committee 242. They have been of interest since the work by Klein on shrinkage-compensation in the 60s, and Ost’s work on rapid-setting cement. They now attract interest for their low GWP. There are several manufacturers of CSA-containing clinkers in the world, producing various types of binders. While the binders were first developed in the US, China took an early lead in the large-scale production of the materials. Since then, several manufacturers have sold and marketed the material worldwide, This presentation will review specifications, mineralogy, and real-world applications of the binders worldwide.
Magnesium Oxide as a Co-Alkaline Activator in Alkali-Activated Cement Used in Experimental Construction Products
Presented By: Mark Shand
Affiliation: Premier Magnesia,LLC
Description: Magnesium oxychloride, magnesium oxysulfate, and magnesium phosphate cement have been utilized for many years. More recent research and applications have focused on reactive magnesia cement (RMC), the incorporation of magnesium oxide into Portland cement concrete, and the carbonation of magnesium oxide to form magnesium carbonate cement. this presentation will concentrate on recent work that has been conducted on the use of magnesium oxide as a co-alkaline activator in alkali-activated cement and the experimental construction products made with it.
Carbonated Concrete: Real-World Applications, Real-World Benefits
Presented By: Yuri Mytko
Affiliation: Carbicrete Inc
Description: CarbiCrete’s technology replaces cement with steel slag, a steel-making by-product, and cures them with carbon dioxide, avoiding the GHG emissions associated with cement production, while permanently sequestering CO2 within the concrete through mineralization. Over a 36-month period, CarbiCrete ran a pilot project to optimize its patented process to produce cement-free, carbonated CMUs in an operational environment at scale. The project involved installing CarbiCrete’s curing system at an existing concrete plant, operated by hardscape manufacturer Patio Drummond, and ratcheting up production to commercial scale. In September of 2023, the CarbiCrete-enabled CMUs became available for sale and the CMUs have now been used in a number of construction projects. The focus of this talk will be the performance of these CMUs in real-world applications, and the environmental benefits associated with them.
Calcium Aluminates – Then and Now
Presented By: Charles Alt
Affiliation: Imerys
Description: Calcium aluminate cements began production in France in 1908 to answer a seawater durability need in the portland cement concrete industry. Since then, the evolution of usage has stretched across many industries and brought us now to modern low clinker concretes requiring a boost of strength at 24h through the use of ettringite. This presentation will attempt to touch on many of the properties found with Calcium Aluminates when used alone or in combination with other cementitious materials.
Magnesium Phosphate Concrete for Improved Chemical Resistance of Airfield Pavements
Presented By: Dylan Scott
Affiliation: Mississippi State University
Description: Magnesium Phosphate Concrete (MPC) represents a potential alternative to portland cement concretes (PCC) for key aspects of airfield pavement design. As a consequence of their maintenance and design, aircraft operations expose airfield pavements to petroleum and oil lubricants (POL) and high surface temperatures, resulting in deterioration of the paste, aggregate exposure, scaling, and ultimately the creation of foreign object debris (FOD). Traditionally, MPCs are used strictly as a small-scale repair material for its rapid setting and high early strength gain. However, other properties of MPC due to its reaction products and lower pH make the material more resistant to chemical attack from POL exposure. This work looks to summarize a now decade long effort to design, develop, characterize, and produce MPCs for airfield applications. Which, culminated in the construction of full-scale replacements of deteriorated parking apron slabs for tilt-rotor aircraft. Additionally, 2.5 years of performance evaluations will be provided along with ongoing efforts to provide guidance towards the development of MPC systems.
Applications of Sulfoaluminate Cements at CTS
Presented By: Julio Paniagua
Affiliation: CTS Cement Manufacturing
Description: Sulfoaluminate cements have been in use in the United States since the sixties. First as shrinkage-compensating cements and later as rapid-setting cements. CTS has been a leader in this field and has, over the years, developed a wide range of products and applications based on ye’elimite, from rapid-strength pavement to performance-engineered products. Concrete pavement infrastructure built in California during the 1960s-1970s required major rehabilitation by the 1990s. Ye’elimite-based cements pioneered this concept at Caltrans. Since then, CSA cement has been used across California and in many states for rapid highway pavement reconstruction, on the basis of performance specifications.
Examples of CSA uses include applications such as bridge hinge reconstruction, overlays, bridge deck repairs, link slabs, approach slabs, seismic retrofits, airfield pavements (gates aprons, taxiways, and runways) and well over 20 performance-engineered products from low-permeability concrete to UHPC, RSLMC and others.