These materials have a long history of use in various parts of the state and are generally the most cost efficient method of treating base and subgrade materials. Construction concerns when using these additives include the extended time necessary prior to opening the roadway to traffic. Additional concerns include inconsistent distribution of additives or mixing additives to the wrong depth when using “road-mixed” procedures. Too much additive, particularly cement, may result in extensive shrinkage cracking that may reflect through the surface of flexible pavements. A mitigation procedure to reduce shrinkage cracking in cement treated base is to microcrack the treated layer with a vibratory roller 24-48 hours after completing compaction and finishing.

Specific design strength requirements when using cement.

To ensure long-term strength and stability of cement treated base (CTB) layers, a mix design must be completed to ensure sufficient amounts of cement are added to the mixture to achieve the target strength. Item 276, Cement Treatment (Plant-Mixed), currently designates three classes of cement-treated flexible base, based on 7-day unconfined compressive strength. Class M is intended for use with flexible pavements, Class L is intended for use with rigid pavements, and Class N may be used if the district has successful long-term experience with other strength values. When specifying Item 275, Cement Treatment (Road-Mixed), the laboratory target strength should be comparable to Item 276 requirements when selecting the appropriate cement content.