Shrinkage of Cold Recycled Cement-Treated Mixtures of Asphalt Pavement Materials
William Fedrigo, Thaís Radünz Kleinert, Washington Peres Núñez, Ângela Gaio Graeff, Luiz Carlos Pinto da Silva Filho, Lélio Antônio Teixeira Brito
Abstract
ABSTRACT As with other chemically stabilized materials, cold recycled cement-treated mixtures inherently shrink. Shrinkage cracks might accelerate the rate of pavement deterioration. The research reported here aimed at studying variables that may affect the shrinkage of recycled mixtures. An experimental plan was set to evaluate the effects of cement and reclaimed asphalt pavement (RAP) contents and curing time on the shrinkage of such mixtures with different recycled base course materials (namely cement-treated base [CTB], soil-cement [SC], and lateritic soil [LS]). Previously studied recycled mixtures with graded crushed stone (GCS) base course material were also considered in the analysis. From test results and statistical analysis, it was concluded that the finer the recycled mixture (with SC and LS base course materials), the higher the shrinkage potential. Conversely, coarser mixtures (with CTB and GCS as base materials) tend to shrink less. Accordingly, increasing RAP contents might help to reduce the shrinkage of finer mixtures because of coarser RAP gradation. Shrinkage increases with time and shows higher increasing rates at the early stages. Statistics showed that a stronger curing time effect occurs by the third week, and because of that, it is important to avoid moisture loss at the early stages. For the levels considered (1–7 %), cement content did not greatly impact the shrinkage, although it was statistically significant in most cases. Statistical analysis confirmed this, contradicting the practice of often adopting low cement contents to reduce shrinkage hazards.