Concretes with Calcined Clay and Calcined Shale: Workability, Mechanical, and Transport Properties

Abstract

This paper analyzed the eco-efficiency of concretes (water/cement ratio = 0.50; cement content=350 kg/m3, and slump = 7 cm) with blended cement containing 25% by weight calcined pozzolan obtained from a low-grade kaolin (HKC) and an illitic shale (HIC) compared with ordinary portland cement concrete (HPC). The fresh, mechanical, and transport properties of these concretes were evaluated, as were the concrete efficiency parameters and the global warming potential (GWP) measured as CO2 eq/m3 concrete. The results classify both blended concretes as acceptable for use in construction, whereas HIC performs better as fresh concrete and has a slightly higher resistance to chloride penetration, HKC performs better regarding to mechanical and water transport properties. The suitability of clay or shale depends on the availability and distance from the production center of the materials. The results obtained in this paper are useful for defining the suitable use of each calcined material and for optimizing the concrete mix design based on its advantages and properties.