On-site workers at Cemex, which provides cement and concrete products to local contractors, put out a small fire in its heating tank Monday morning before firefighters arrived.Vancouver Fire Capt. Kevin Murray said the fire was reported at 9:13 a.m. Cemex is at 18208 S.E. First St. The company uses propane burners to heat and liquefy asphalt, Murray said. It was during that process that a fire started. Several engines arrived to find the fire already extinguished. The damage was believed to be minimal.A shop building at what was then called Western States Asphalt Co. was destroyed by a fire in 2004.