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The production of concrete for construction purposes is a major source of anthropogenic CO2 emissions. One promising avenue towards a more sustainable construction industry is to make use of naturally occurring mineral-microbe interactions, such as microbial-induced carbonate precipitation (MICP), to produce solid materials. In this paper, we present a new process where calcium carbonate in the form of powdered limestone is transformed to a binder material (termed BioZEment) through microbial dissolution and recrystallization. For the dissolution step, a suitable bacterial strain, closely related to Bacillus pumilus, was isolated from soil near a limestone quarry. We show that this strain produces organic acids from glucose, inducing the dissolution of calcium carbonate in an aqueous slurry of powdered limestone. In the second step, the dissolved limestone solution is used as the calcium source for MICP in sand packed syringe moulds. The amounts of acid produced and calcium carbonate dissolved are shown to depend on the amount of available oxygen as well as the degree of mixing. Precipitation is induced through the pH increase caused by the hydrolysis of urea, mediated by the enzyme urease, which is produced in situ by the bacterium Sporosarcina pasteurii DSM33. The degree of successful consolidation of sand by BioZEment was found to depend on both the amount of urea and the amount of glucose available in the dissolution reaction. [ABSTRACT FROM AUTHOR]

Biodegradable poly(butylene succinate)/organo-montmorillonite nanocomposites were prepared at different organo-montmorillonite loadings, using maleic anhydride-grafted poly(butylene succinate) as compatibilizer. Poly(butylene succinate) nanocomposites were exposed to outdoor natural weathering for 180 days. Weight loss and decrease in mechanical properties after weathering revealed the degradation of poly(butylene succinate). Natural weathering caused photo-oxidation on poly(butylene succinate), leading to the formation of degraded products, as manifested in Fourier transform infrared spectroscopy. Gel permeation chromatography showed a significant reduction in molecular weight after weathering. It was noted that poly(butylene succinate) nanocomposite exhibited lower degradability as compared to neat poly(butylene succinate), due to the enhanced barrier properties after the addition of organo-montmorillonite. However, the incorporation of maleic anhydride-grafted poly(butylene succinate) increased the degradability. Degree of crystallinity of poly(butylene succinate) reduced after weathering, as shown in differential scanning calorimetry. Scanning electron microscopy analysis revealed fungal and bacterial colonization on the sample surface. In addition, the isolation and identification of bacterial strain were also performed. [ABSTRACT FROM PUBLISHER]