01697756

Component

Cement modification of subgrade has been widely practiced for the past few decades. Recently, cement has become a more economical binder to modify in-situ subgrade soil since other binders, such as fly ash, have become less available and therefore their prices have gone up significantly. In addition, a much higher percentage of fly ash needs be used, when compared with cement, to achieve the same subgrade strength and stiffness. However, cement modified subgrade has a major issue with shrinkage cracking, which can eventiually reflect through asphalt pavement surfaces after construction. For some subgrade soils, a high cement content is needed to meet the unconfined compressive strength requirement without jeopardizing durability. A higher cement content will typically result in higher shrinkage cracking potential. To overcome this problem, microcracking technology has been developed and adopted in the field. This technology involves re-compaction of cement-modified soil (CMS) with a roller, 24 to 48 hours after intitial compaction, to induce micro-cracks in the CMS and minimize the potential for large shrinkage cracks. Microcracking of CMS is not expected to significantly reduce the strength and stiffness of CMS, but it is expected to increase its permeability and reduce the potential for large shrinkage cracks. Unfortunately, the procedure to simulate microcracking of CMS in the laboratory and to evaluate its effect on properties of CMS has not been established yet. This paper documents the development of such a procedure and discusses the effect of microcracking on the properties (strength and modulus) of CMS specimens.

This paper was sponsored by TRB committee AFS00 Section - Geotechnical Engineering.

19-02835

English

4p

2019

Transportation Research Board 98th Annual Meeting

Digital/other

References

Laboratory tests; Microcracking; Pavement cracking; Shrinkage; Subgrade (Pavements)

Cement modified soil

Geotechnology; Highways; Maintenance and Preservation; Pavements

Transportation Research Board Annual Meeting 2019 Paper #19-02835

TRIS, TRB, ATRI

Dec 7 2018 9:36AM