Investigation of the Use of Limestone Screenings in Roadway Construction

Abstract

Disposal of limestone screenings, or limestone fines, creates problems for many quarry operations. Much of the fines is either stockpiled or deposited back into the quarry pit. A laboratory study and pilot project were conducted to determine if limestone screenings could be stabilized and used as a structural layer in road construction and, if so, to evaluate their effectiveness through performance monitoring. Compaction, unconfined compression, freezing and thawing durability, and wet–dry durability tests were performed. Falling weight deflectometer tests were used to compare stiffness differences, and temperature data were used to determine the number of freezing and thawing cycles that each test section underwent. Laboratory compaction and unconfined compression test results confirmed that limestone screenings can be stabilized for use as a structural layer. Freezing and thawing and wet–dry durability test results showed that cement kiln dust (CKD) is not an acceptable stabilizer because of its poor durability performance. Class C fly ash (FA) and CKD mixtures were determined to be acceptable. Test Section 1 (30% CKD) most likely failed due to freeze–thaw action. Visual observations showed good performance of Test Section 2 (15% FA and 15% CKD), and the two control sections showed no rutting or pothole formation.