Antibacterial Properties and Cytotoxicity of 100% Waste Derived Alkali Activated Materials: Slags and Stone Wool-Based Binders

Abstract

In this study we compare the leaching behavior and the antibacterial and cytotoxic properties of 100% slag or stone wool derived alkali activated materials. The antibacterial activity was measured as the inhibiting capacity against two Gram-negative bacterial strains, Escherichia coli and Pseudomonas aeruginosa and one Gram-positive bacterial strain: Enterococcus faecalis. The cytotoxicity properties were tested on mouse embryonic fibroblast NIH-3T3 cell-line. It was proved that the high quality of the 3D aluminosilicate network of the consolidated materials obtained from powders of CaO or MgO-rich slags or stone wool, opportunely activated with NaO and/or Na-silicate, was capable of stabilizing heavy metal cations. The concentrations of leachate heavy cations were lower than the European law limit when tested in water. The effect of additives in the composites, basal fibers or nanocellulose, did not reduce the chemical stability and slightly influenced the compressive strength. Weight loss in water increased by 20% with basalt fibers addition, while it remained almost constant when nanocellulose was added. All the consolidated materials, cement-like in appearance, exhibited limited antibacterial properties (viability from 50 to 80% depending on the bacterial colony and the amount of sample) and absence of cytotoxicity, envisaging good acceptance from part of the final consumer and zero ecological impact. CaO-rich formulations can replace ordinary Portland cement (showing bacterial viability at 100%) with a certain capability for preventing the reproduction of the E. coli and S. aureus bacteria with health and environmental protection results.

Investigation of Durability Properties for Lightweight Structural Concrete with Hemp Shives Instead of Aggregate

“…It is well known that lime concrete has slightly higher values of water sorption coefficients. An increase in pH negatively affects bacterial viability, particularly Gram-negative bacteria E. coli [40,41]. The above observation was confirmed in our studies (Figure 7a).…”

Use of Organic Dyes to Color the Metakaolin‐Based Geopolymer: A Physico‐Chemical Characterization

“…Ionic conductivity and pH measurements were performed on the eluate solutions used for dyeing adsorption after sample removals, whereas the integrity and weight loss tests were carried out according to the protocols reported elsewhere in Dal Poggetto et al [7][8][9][10] Finally, FTIR spectra were recorded employing a Prestige 21 Shimadzu (Japan) instrument equipped with a deuterated triglycine sulfate (with potassium bromide windows detector). The spectra were recorded in the 400-4000 cm −1 region, with a resolution of 2 cm −1 (60 scans).…”

Why geopolymers and alkali‐activated materials are key components of a sustainable world: A perspective contribution

“…In the medical field, geopolymers have been proposed for controlled‐release drug delivery (for e.g., opioids 127 or the COVID‐19 drug niclosamide 128 . The antibacterial properties of different types of geopolymers have been also investigated, including discussion in relation to their potential cytotoxicity to mammal cells 129–132 . Porous aluminosilicate geopolymers have been investigated to remove cytotoxic agents from biological environments, specifically focusing on macroporous and mesoporous geopolymers 133 and their effect on their inhibiting capacity against Gram‐negative bacterial strains ( Escherichia coli ) and Gram‐positive bacterial strain ( Staphylococcus aureus ).…”