Valid DOT medical card Knowledge, Skills, and Abilities DOT regulations OSHA & EPA regulations Familiarity with concrete production characteristics Meticulous Excellent communication skills (written and spoken) Highly organized Critical thinking A member of the S&P 500 Index, Martin Marietta is an American-based company and a leading supplier of heavy building materials – including aggregates, cement, ready-mixed concrete and asphalt. Martin Marietta's Magnesia Specialties business produces high-purity magnesia and dolomitic lime products used worldwide in environmental, industrial, agricultural and specialty applications.