Practicality of clinker‐efficient binders with calcined clays in durable concretes

Abstract

Concretes made with clinker‐efficient binders incorporating calcined clays are the most promising option for future low‐carbon concretes. In this context, the selection of binder components and the adjustment of concrete using available calcined clays present the greatest challenge for practical application. This paper focuses on the pathway from the clay pit to the concrete plant: clay selection and reactivity – properties in mortar – design of concrete and durability. The Panoramabar at the Landesgartenschau in Neustadt an der Weinstraße is the first construction project in Germany to use concrete with a binder containing 55 wt.‐% clinker (including sulfate carrier), 30 wt.‐% calcined clay and 15 wt.‐% limestone powder. This concrete complies with strength class C30/37 and exposure classes XC4, XF1, XS2, XD2 and WF. With respect to practical application, workability, pumpability and heat development are also discussed. The developed concrete is substantially below commonly published benchmark values for conventional concretes with similar technical properties. This favorable result is attributable in particular to the use of calcined clay, which allows for a reduced clinker factor and thereby lowers the climate impact of the binder system.