This paper evaluates the flexural static and cyclic behaviour of cement-treated mixtures of reclaimed asphalt pavement (RAP) and lateritic soil (LS). Flexural strength and resilient modulus increased with RAP percentage. Strain at break increased with higher RAP and lower cement amounts, increasing mixtures flexibility. Higher cement contents led to stronger and stiffer mixtures. Strain-based fatigue relationships were obtained. Mechanistic analyses showed that the fatigue life of cement-treated recycled base layers of RAP and LS increases with RAP percentage and with the thicknesses of asphalt wearing course and recycled base layer. The effect of cement content depends on the thickness of the layers.

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.

Lime stabilization is a sustainable technique due to its use of local materials, increased durability, reduced maintenance, and improved resistance to water action. This paper examines the impact of lime stabilization on the mechanical, microscopic, and mineralogical properties of a tropical soil. Two types of lime, calcitic and dolomitic, were tested at 3% and 5% by weight. Compressive, indirect tensile and flexural test results and statistical analysis revealed that calcitic lime mixtures had higher strength and stiffness, whereas dolomitic lime mixtures exhibited greater deformability with higher tensile strain at break. Scanning electron microscopy indicated that the soil’s porous matrix closed within 7 days for both lime types due to flocculation, with increased matrix interlocking over time. The calcitic lime mixture developed a more closed matrix compared to the dolomitic lime, which showed weaker cementing. X-ray diffraction analysis indicated higher consumption of clay minerals and a notable reduction in calcium hydroxide peaks in the lime-treated soils. The study concludes that calcitic lime provides better pavement performance for stabilizing the soil, enhancing its engineering properties while also being sustainable by reducing the need for raw material extraction and improving resilience to climate-related issues such as floods.

Nesse estudo foi verificada a aplicação da metodologia de projeto de experimentos na dosagem de misturas de reciclagem de pavimentos com adição de cimento. Adotou-se um método de dosagem que avalia propriedades mecânicas, volumétricas e de erodibilidade, e foram desenvolvidas todas as etapas que contemplam um projeto de experimentos. O planejamento possibilitou definir as variáveis que exercem maior influência nos resultados, de modo a estabelecer uma matriz experimental abrangente e reduzida. Na análise dos resultados foi possível quantificar o efeito dos fatores controláveis estudados (teor de cimento e porcentagem de fresado) em cada variável de resposta. A partir da otimização multivariada, obteve-se o ajuste ótimo dos fatores controláveis considerando todas as variáveis de resposta simultaneamente. A ferramenta adotada nesse trabalho se mostrou bastante eficiente, podendo ser amplamente empregada na otimização de processos, como é o caso da dosagem de misturas recicladas.