MARBLEHEAD – Aggregate Industries NE of Saugus, the firm which has admitted supplying substandard concrete to the Big Dig, has received a $1.4 million contract to supply concrete and asphalt to Marblehead for the next three years.The selectmen’s unanimous vote to approve the contract last week raised some eyebrows in the audience.Local resident Carol Collins reminded the board that the multi-million-dollar concrete supplier has agreed to pay a $42 million civil settlement and $8 million in criminal fines.The settlement was announced July 28 by the U.S. Attorney. Aggregate pleaded guilty to conspiracy to defraud the federal government for supplying 5,700 truckloads of substandard concrete to the Big Dig.Collins asked how the contract would be monitored.Selectman William Woodfin said the type of concrete the town is using is verified as appropriate under the contract.Selectmen Chairman Harry Christensen said the town has a process for monitoring the quality of the concrete it receives.