Eco-efficient concrete prepared with ternary slag cements

The cement and concrete industries have an urgent need to reduce their carbon emissions. Current reduction strategies are both insufficient and unsustainable. An emerging strategy is to prepare concrete with a reduced quantity of water and reactive materials in what is known as high filler - low water cement and concrete. This thesis aims to develop a better understanding of said cements and concretes with respect to their hydration and microstructural development, rheology, and mixing behaviour. Cements are prepared with blends of limestone filler, ground granulated blast furnace slag, and Portland cement.This experimental work uncovers a variety of performance advantages when varying the physical characteristics of the limestone filler at high replacement rates. Increasing the limestone fineness accelerates the hydration of both the OPC and GGBS as measured via isothermal calorimetry. This acceleration leads to a significant increase in early strength as measured by proxy via ultrasonic pulse velocity measurements. The ternary blends demonstrate denser mircrostructures than blends of OPC and limestone with time.Next, ternary cement pastes were examined via rotational rheometry where a primary concern is viscosity and shear-thickening behaviour. When modifying only the physical characteristics of the limestone filler, significant differences could be observed with respect to shear thickening behaviour of the low-water ternary cement pastes. These differences were further explored via X-ray tomography, amongst other techniques.Pastes were further examined with respect to mixability via mixing energy curves. Selected physical and chemical parameters were modified to evaluate the ability of the components to facilitate the distribution of water and modify mixing behaviour. The results suggest that the mixability of a cement paste is governed by the same variables governing the rate of capillary rise through powder beds: liquid viscosity, liquid surface tension, contact angle between the solid particles and the liquid, and the geometry of the voids between solid particles.Finally, concrete was prepared with reactive material contents of 150 kg/m3 and lower. The concrete had fresh and hardened state properties suitable for a large fraction of the ready-mix concrete industry. A binder intensity of less than 2.5 kg m-3 MPa-1 was achieved, much lower than what is typically produced at industrial scale, with a much lower CO2 footprint.