1. Nanostructured calcium silicate hydrate seeds accelerate concrete hardening: a combined assessment of benefits and risks.
- Author
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Bräu M, Ma-Hock L, Hesse C, Nicoleau L, Strauss V, Treumann S, Wiench K, Landsiedel R, and Wohlleben W
- Subjects
- Administration, Inhalation, Air Pollutants, Occupational chemistry, Animals, Bronchoalveolar Lavage Fluid chemistry, Calcium Compounds administration & dosage, Calcium Compounds chemistry, Construction Materials analysis, Dose-Response Relationship, Drug, Germany, Humans, Larynx immunology, Larynx pathology, Lung immunology, Lung pathology, Macrophages, Alveolar drug effects, Macrophages, Alveolar immunology, Macrophages, Alveolar pathology, Male, Materials Testing, Metaplasia, Nanostructures administration & dosage, Nanostructures chemistry, Nanostructures ultrastructure, Particle Size, Rats, Rats, Wistar, Risk Assessment, Silicates administration & dosage, Silicates chemistry, Air Pollutants, Occupational toxicity, Calcium Compounds toxicity, Construction Materials toxicity, Larynx drug effects, Lung drug effects, Nanostructures toxicity, Silicates toxicity
- Abstract
Nanotechnology creates new possibilities to control and improve material properties for civil infrastructure. Special focus in this area is put on Portland cement and gypsum. Together their annual production is by far larger than for any other material worldwide. Nanomodification of these materials can be done during the few hours between dissolution and hardening, especially by nucleation of the re-crystallization with suitable colloids. Here we report first results in homogeneous seeding of the precipitation of calcium silicate hydrates within a real Portland cement composition. The occupational safety during the production phase and during mixing of concrete paste is addressed in detail by in vivo testing. We perform 5-day inhalation with 21-day recovery in rats and analyze organ-specific toxicity and 71 endpoints from bronchoalveolar lavage (BALF) and blood. In BALF parameters, no test-related changes were observed, indicating the generally low toxicity of the test material. Some mild lesions were observed in larynx level. In the lungs, all animals of the 50 mg/m³ concentration group revealed a minimal to mild increase in alveolar macrophages, which recovered back to control level.
- Published
- 2012
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