Abstract

In conventional design of concrete structural elements, the same concrete mix is used throughout a given element. This can lead to regions of unutilised material and a conservative coverage of non-controlling material properties. Efforts to produce metrics that describe the efficiency of constituent materials in concrete demonstrate that better use of normal concrete mixes can be exploited. However, the predominant focus of design methods towards achieving a minimum compressive strength makes multi-criteria optimisation of the non-controlling properties difficult to target. Varying the concrete mix design within an element to achieve spatially variable structural and durability demands presents an opportunity to reduce the total cement content used within a concrete element and thereby reduce associated economic and environmental costs. The factors which may affect the compatibility between casting layers of different concrete mixes are being explored experimentally to understand the boundaries within which deterioration mechanisms are not unintentionally proliferated.