Performance of waste based alkaline mortars submitted to accelerated carbon dioxide curing

- Fly ash is generated in high amount and have a very low reuse rate.
- Waste based mixtures have enough compressive strength for masonry blocks.
- Calcium hydroxide and sodium concentration of 8 M leads to optimum compressive strength.
- Significant correlations between the flexural strength and the compressive strength were noticed.
- Increasing the sodium hydroxide molarity increased the stiffness of the mixtures.

Carbon dioxide sequestration is crucial for targets limiting global warming could be achieved. This paper discloses results of an investigation concerning the performance of fly ash/waste glass alkaline-based mortars with two additives and recycled aggregates exposed to accelerated carbon dioxide curing. Mechanical properties as well as water absorption, drying shrinkage and carbon sequestration potential were studied on it. The results show that the mixtures with calcium hydroxide and sodium hydroxide concentration of 8 M leads to the highest compressive strength (10 MPa) which is high enough for the production of masonry blocks. Significant correlations between the flexural strength and the compressive strength were noticed. The mixtures show a low water absorption by immersion (9%) as well as by capillary (1.4 kg/m2 H0.5). The results of the modulus of elasticity show that increasing the sodium hydroxide molarity increased the stiffness of the mixtures. The results of drying shrinkage are in line with the results of the capillary water absorption and of the elastic modulus. A maximum CO2 sequestration (164 kgCO2eq/m3) is noticed for the mixture with a sodium concentration of 8 M based on the additive calcium hydroxide.