Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Influence of calcined clay morphology on flow in blended cementitious systems
Abstract Retaining workability in blended cementitious systems containing calcined clays remains challenging. Here, the influence of calcined clay morphology on both fresh and hardened properties of blended cementitious materials is evaluated through flow and strength testing, comparing the performance of halloysite nanotubes, agglomerated halloysite spherical particles (obtained through spray drying), and conventional metakaolin sheets. In addition, calorimetry and quantification of portlandite content assess the influence of clay morphology on pozzolanic reactivity. All tests were performed at 10 % cement replacement by mass and benchmarked against ordinary portland cement (OPC) and OPC diluted with 10 % quartz. Calcined halloysite spheres were found to increase mortar flow by 30–75 %, produce a similar heat evolution profile, and moderately increase strength (up to 8 %) by 56 days, compared to 100 % OPC. This is achieved without a notable change in pozzolanic reactivity compared to halloysite nanotubes, beyond 7 days. Each of these performance metrics is equivalent to or an improvement over metakaolin sheets, demonstrating that the spherical morphology obtained through spray drying produces a calcined clay with advantages, particularly in workability.
Highlights Spray drying forms a spherical morphology from halloysite clay nanotubes Spherical 1:1 clays increase the flow of mortars, relative to those containing clays with nanotube or sheet morphology Calcined halloysite, regardless of morphology, exhibit pozzolanic reactivity similar to metakaolin Spherical clay decreases performance in comparison to nanotube clay, but performs similarly to sheet morphology Spray drying offers a new approach to tailoring performance of cementitious materials containing calcined clays
Influence of calcined clay morphology on flow in blended cementitious systems
Abstract Retaining workability in blended cementitious systems containing calcined clays remains challenging. Here, the influence of calcined clay morphology on both fresh and hardened properties of blended cementitious materials is evaluated through flow and strength testing, comparing the performance of halloysite nanotubes, agglomerated halloysite spherical particles (obtained through spray drying), and conventional metakaolin sheets. In addition, calorimetry and quantification of portlandite content assess the influence of clay morphology on pozzolanic reactivity. All tests were performed at 10 % cement replacement by mass and benchmarked against ordinary portland cement (OPC) and OPC diluted with 10 % quartz. Calcined halloysite spheres were found to increase mortar flow by 30–75 %, produce a similar heat evolution profile, and moderately increase strength (up to 8 %) by 56 days, compared to 100 % OPC. This is achieved without a notable change in pozzolanic reactivity compared to halloysite nanotubes, beyond 7 days. Each of these performance metrics is equivalent to or an improvement over metakaolin sheets, demonstrating that the spherical morphology obtained through spray drying produces a calcined clay with advantages, particularly in workability.
Highlights Spray drying forms a spherical morphology from halloysite clay nanotubes Spherical 1:1 clays increase the flow of mortars, relative to those containing clays with nanotube or sheet morphology Calcined halloysite, regardless of morphology, exhibit pozzolanic reactivity similar to metakaolin Spherical clay decreases performance in comparison to nanotube clay, but performs similarly to sheet morphology Spray drying offers a new approach to tailoring performance of cementitious materials containing calcined clays
Influence of calcined clay morphology on flow in blended cementitious systems
Benkeser, Daniel (Autor:in) / Hernandez, Kimberly (Autor:in) / Lolli, Francesca (Autor:in) / Kurtis, Kimberly (Autor:in)
26.07.2022
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Efficiency of Calcined Clay in Cementitious Systems
| British Library Conference Proceedings | 2013