RILEM Technical Committee 282 CCL will co-sponsor. This RILEM committee “Calcined Clays as Supplementary Cementitious Materials” formed in 2018 and working toward developing standards for use of calcined clays in concrete.
This session will address both fundamentals of pozzolan activation through calcination, considering relatively pure and impure natural sources, and practical use of these materials in concrete construction. The intended audience includes engineers, contractors, researchers, and students interested in alternative sources of pozzolans.
Session 1 will cover the fundamentals of pozzolan calcination, including effects of composition and processing, on structure and performance.
Session 2 will address practical use of calcined pozzolans at an industrial scale.
(1) Report up-to-date information on industrial production of natural pozzolans, including calcined clays;
(2) Explain the influence of calcined pozzolans on fresh concrete properties;
(3) Identify the influence of calcined pozzolans on hardened concrete properties, including their influence on durability;
(4) Review construction and performance of concrete structures produced using calcined pozzolans.
This session has been approved by AIA and ICC for 2 PDHs (0.2 CEUs). Please note: You must attend the live session for the entire duration to receive credit. On-demand sessions do not qualify for PDH/CEU credit.
Industrial Experience with Production and Use of Calcined Clay-Limestone Cement
Presented By: Jesper Damtoft
Affiliation: Cementir Holding
Description: Calcined clay-limestone cement has been produced and marketed in Denmark since January 2021 under the brand name FUTURECEMTM. The presentation describes the development and documentation of the new cement type including acceptance into the Danish concrete standard. Examples of use in constructions and implications for the sustainability of concrete constructions will be given.
Implementation of LC3 in the Field
Presented By: Karen Scrivener
Affiliation: Ecole Polytechnique Fdrale De Lausanne
Description: In this presentation we will discuss the steps needed to implement LC3 (limestone calcined clay cement) in the field, from the identification of suitable clay, through optimization of calcination and the cement formulation. Finally, we will look at some performance results with respect to both strength and durability.
Using Metakaolin for Enhancing Durability and Mitigating Alkali-Silica Reaction (ASR) in Concrete
Presented By: Frank Ong
Affiliation: Master Builders Solutions US
Description: Some of today’s concrete structures can be more complex than ever. In addition, concrete mixtures need to be designed to meet specific durability requirements based on the structure’s expected environmental exposure conditions. This can be challenging with some local concrete-making materials. A case in point might be alkali–silica reactivity (ASR) that can be a major concrete durability concern for a project. Current solutions to address ASR may not always be applicable, economical, or sustainable. Transporting quality, non-reactive aggregates long distances to a project in lieu of using locally available reactive aggregates might address the ASR concern but will not be ideal in terms of economics. Other ASR mitigating options such as fly ash may be limited in availability and lithium-based chemical admixtures can sometimes face supply chain challenges. This presentation will provide information and test data on the use of metakaolin in concrete, another alternative for mitigating ASR. Metakaolin can also help meet other durability, sustainability, and performance requirements. The practical application of metakaolin use in concrete in two unique, and demanding projects will be shared.
Viability of Mixed-Mineral Calcined Clay for U.S. Market
Presented By: Nicholas Fowler
Affiliation: University of South Florida
Description: For the past several decades, metakaolin has become the dominant form of calcined clay for use in concrete in North America. While calcined clay produced from waste and lower purity materials than typically used for metakaolin production have been used as a supplementary cementitious material in concrete for over 90 years, it’s use fell out of favor for a while, but is now entering a renaissance worldwide. Especially when combined with fine limestone powder, it has the potential to improve durability, reduce carbon footprint, and reduce cost. One potential strategy to implement this material in North America called CCIL is to add calcined clay (CC) blended a small amount of gypsum at the batch plant with a Type IL cement added separately. This approach would flexibility to the plant by allowing for custom blends of the material to achieve a given property. The carbonation, chloride diffusion, and sulfate attack durability properties of an industrially produced calcined clay made from lower purity clay and used in conjunction with different cement types made with varying levels of limestone powder will be presented. The durability properties of cementitious systems made with waste and clays procured from the U.S. southeast will also be discussed. Finally, recommendations for use of durable concrete made with calcined clay will be given.
Predicting the Rheology of Limestone Calcined Clay Cement (LC3)
Presented By: Ogulcan Canbek
Affiliation: Georgia Institute of Technology
Description: Predictions of LC3 workability are important for field placements. It is understood that the rheological properties of LC3 are dominated by the composition and amount of calcined clay used. However, we lack an understanding on how other factors – including limestone particle size and gypsum addition rate - influence the rheology of LC3 incorporating different calcined clay contents. In this research, rheology of LC3 was related to hydration kinetics and microstructural evolution, obtained by isothermal calorimetry and in-situ XRD, respectively. The results suggest that rheology of LC3 formulations can be predicted by parametrized hydration kinetics, with an interaction term related to the LC3 composition.
Physical Properties and Durability Performance of a Canadian Calcined Clay
Presented By: R Doug Hooton
Affiliation: University of Toronto
Description: Calcined kaolin (MK) from a commercial source in Saskatchewan, Canada was evaluated. Air-entrained concretes were cast at w/cm 0.40 at 10, 15 and 20% mass replacement of cement, and at 15% replacement at w/cm 0f 0.50. In addition, a ternary mixture with 15% MK and 20% slag was included. Setting times were only slightly impacted but with 15 and 20% MK, strengths were improved over control mixtures at 1, 3, 7, 28, 56, and 120 days of age. Drying shrinkages of MK mixtures were lower than the control. ASTM C1202 coulomb values of MK mixtures were much lower than controls while 28-day ASTM C1556 bulk chloride diffusion values were lower by a factor of 3. In terms of mitigation of alkali-silica reaction, 10% was insufficient but concrete mixtures with 15% MK, 20% MK and the ternary MK-slag binder had expansions of less than 0.04% at 2 years in ASTM C1293. Sulfate resistance assessed using sodium sulfate solutions in ASTM C1012 was excellent, but when exposed to magnesium sulfate, there was considerable, progressive mass loss in spite of meeting the expansion limits. The only test where MK mixtures showed inferior performance was in de-icer salt scaling. However, the surfaces of the scaling slabs may have been adversely affected by steel trowel finishing—a practice that is no longer included in the CSA version of the salt scaling test.