Study on factors affecting the mechanical behavior of soil-aggregate-cement mixtures

• Ano de defesa: 2021
• Autor(a) principal: Valoura, Luíza Rijo
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: base cimentada; cemented base course; cimento Portland; estabilização de solos; Portland cement; soil stabilization; soil-aggregate-cement; solo-agregado-cimento
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/18/18143/tde-12112021-095527/

Stabilization is a practice that improves the properties of geotechnical materials for application in pavement layers. Moreover, this technique presents a practical and economical solution for soils considered problematic in pavement constructions. The soil-aggregate-cement (SAC) mixture results from the chemical and physical stabilization and has been used in pavements for high and very high-traffic volume roads, mainly due to its mechanical behavior. However, there are few studies in the technical literature addressing the mechanical behavior of SAC mixtures, in addition to the absence of a specific standard for the dosage of this mixture. The objective of this research was to contribute to the study of the mix design of soil-aggregate-cement mixtures (SAC) and to understand the effect of factors, such as materials proportion, cement type, and composition of the aggregate, on their mechanical behavior. As a complement to the study, in order to improve the production efficiency and ensure traffic operational safety in situations of pavement construction and rehabilitation, the possibility of reducing traffic opening time was also analyzed. The experimental program aimed to compare SAC mixtures using two soil:aggregate ratios 20:80 and 30:70) with three cement contents (3, 5 and 7%) and at three curing times (0, 7 and 28 days). In order to analyze the optimum cement content, the compressive and tensile strengths obtained in the laboratory tests were compared with stresses obtained by the mechanistic analyses of hypothetical pavements. Finally, at the optimum cement content, SAC mixtures were studied at 3 days of curing and with two types of cement (HE and PCC-IP). Besides that, a comparative study of the use of basaltic aggregate replaced by recycled masonry aggregate (RMA) was performed. The results led to the conclusion that SAC mixtures exhibited high values of compressive and tensile strength, and stiffnesses over the curing time and with the increase of cement content. Moreover, SAC mixtures with a higher proportion of the stone skeleton (20:80) showed higher values for the properties analyzed. The study of the cement dosage leads to indicate a cement content of 5% for all SAC mixtures. At 3 days of curing all mixtures showed values of UCS and ITS higher than the stresses computed, but it should be highlighted that mixtures with HE presented the highest strength values. The mixtures with RMA showed feasibility for use on low-volume roads.