Phys.org  August 4, 2021 Researchers at the University of Delaware hypothesized that the microbial communities of concrete reflect those of the concrete components and that these communities change as the concrete ages. To show how microbial communities change over 2 years of outdoor weathering they used two sets of concrete cylinders, one prone to the concrete-degrading alkali-silica reaction (ASR) and the other having the risk of the ASR mitigated. After identifying and removing taxa that were likely laboratory or reagent contaminants, they found that precursor materials, particularly the large aggregate (gravel), were the probable source of ∼50 to 60% of […]