Participants in some of New York City’s largest concrete construction projects are now trying to determine the potential impact of the Feb. 17 conviction of the city’s main concrete testing firm and its owner for filing false test reports. A state supreme court jury in Manhattan rules that Testwell Laboratories and its owner, V. Reddy Kancharla, were guilty of the flawed fillings related to concrete strength on more than 100 projects that used the firm’s services. They included the Freedom Tower at Ground Zero and the Second Avenue subway. The jury has yet to rule on other charges against Kancharla, including one count of enterprise corruption, the most serious, which could bring a maximum sentence of 25 years. But jurors acquitted a Testwell steel inspector of all charges and has yet to rule on charges against a company vice president. “They were the go-to people,” says one city building-contractor executive.