Construction and demolition waste in cement matrices as sinkholes of atmospheric pollution: Effect of the 2022 airborne dust in the Iberian Peninsula.

The coincidence of a study on different ecocements to environmental exposition in Madrid (Spain) with the airborne dust from the Sahara desert in the same location, during the year 2022, facilitated the knowledge of the ecocement permeability to different sources of contamination. In general, mortars with a siliceous composition are more compact and less permeable to environmental particles compared to those with a calcareous composition. Binary mortars with glass have an intermediate response to pollutants and the most favorable for the incidence of contamination are ternary sulfoaluminate cements.

Physical and Mechanical Behavior of New Ternary and Hybrid Eco-Cements Made from Construction and Demolition Waste.

Construction and demolition waste (CDW) currently constitutes a waste stream with growing potential use as a secondary raw material in the manufacture of eco-cements that offer smaller carbon footprints and less clinker content than conventional cements. This study analyzes the physical and mechanical properties of two different cement types, ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement, and the synergy between them. These cements are manufactured with different types of CDW (fine fractions of concrete, glass and gypsum) and are intended for new technological applications in the construction sector.

Durability of Construction and Demolition Waste-Bearing Ternary Eco-Cements.

In recent years, the development of ternary cements has become a priority research line for obtaining cements with a lower carbon footprint, with the goal to contribute to achieve climate neutrality by 2050. This study compared ordinary Portland cement (OPC) durability to the performance of ternary cements bearing OPC plus 7% of a 2:1 binary blend of either calcareous (Hc) or siliceous (Hs) concrete waste fines and shatterproof glass. Durability was measured further to the existing legislation for testing concrete water absorption, effective porosity, pressurized water absorption and resistance to chlorides and CO.

Simulation of the Attrition of Recycled Concrete Aggregates during Concrete Mixing.

Concrete mixing can lead to mechanical degradation of aggregates, particularly when dealing with recycled concrete aggregates. In this work, the attrition of such materials during mixing is studied by means of experiments and simulations. The effect of the presence of fines, water addition, flow configuration of the mixer (co- or counter-current) and impeller frequency is discussed.

Behaviour and Properties of Eco-Cement Pastes Elaborated with Recycled Concrete Powder from Construction and Demolition Wastes.

This work analyses the influence of fine concrete fractions (<5 mm) of different natures -calcareous (HcG) and siliceous (HsT)-obtained from construction and demolition waste (C&DW) on the behaviour of blended cement pastes with partial replacements between 5 and 10%. The two C&DW fractions were characterised by different instrumental techniques. Subsequently, their lime-fixing capacity and the physico-mechanical properties of the blended cement pastes were analysed.