Aim of research
The aim was to determine the influence of more intensive, two-stage mixing processes on the early hydration and microstructure formation of differently composed, ressource-efficient Portland-composite cements and composite cements and also on the strength development and durability of concrete. Systematically, it was determined to what extent the cement performance can be improved by more intensive, two-stage mixing and the combination of limestone and blast furnace slag or fly ash or calcined clay.
Methods
The hydration and microstructure formation of suspensions and mortars produced in intensive mixers or suspension mixers at different energy inputs were determined by heat flow calorimetry, X-ray diffraction analysis, differential scanning calorimetry and electron microscopy as well as ultrasonic transmission measurements, compressive strength testing and porosity measurements. The results were verified on fresh concretes and hardened concretes, produced in industry-oriented, two-stage mixing processes on a pilot plant scale, by means of consistency, compressive strength and durability investigations.
Benefits for small and medium-sized companies (SME)
The results can be used in particular by SMEs in the cement and concrete industry to expand the portfolio of clinker-efficient cements with reduced specific CO₂ emissions and high-performance concretes and especially to evaluate corresponding mixing systems. The results provide insights into ressource-efficient standard cements, which are currently still used in a subordinate way, and help the concrete industry to better assess their performance using intensive mixing systems. This strengthens the competitiveness of SMEs in the decarbonisation of concrete construction.
