Trade Journals for the Concrete Industry

Ultra-high performance concretes were optimised for the application of two layered concrete paving slabs. One is based on ordinary Portland cement, the other is based on alkali-activated material. The basic mixes reach compressive strength values defining them as ultra-high performance concretes. The efflorescence potential is reduced and the resistance against physico-chemical impact is increased compared to standard face concretes due to the very low capillary porosity. Both face concretes were adjusted in rheological properties for the use in a hermetic press and the chemical compositions were developed to reduce efflorescence. The abrasion resistance, freeze-thaw resistance and microstructural aspects were tested for both mentioned mixes. Further improvements could be found by intentional carbonation, which was tested under controlled conditions in a CO2-reactor.