No abstract

No abstract

In this paper, Class F fly ash, sulphate-resistant cement, ground granulated blast furnace slag (GGBFS) and lime mixed with fibres are evaluated as potential stabilisers in enhancing the strength and volume change properties of soft, expansive and sulphate-rich soils. As part of the research evaluation, a comprehensive laboratory experimental programme was designed and conducted on four different subgrade soils. Two dosage levels of each stabiliser and three curing periods were investigated. Strength and volume change behavioural tests, including unconfined compressive strength, vertical swell, linear shrinkage and Atterberg tests, were conducted on both control and stabilised soils. Test results showed that the sulphate-resistant cement and lime mixed with fibres provided the most effective stabilisation on all four soils. Both fly ash and GGBFS stabilisation methods provided average-to-moderate improvements in soil properties. Statistical ANOVA analysis of variance on all test results indicated that the effectiveness of all four stabilisation methods is statistically significant. Mechanisms that influence each soil property variation due to chemical treatments, dosage levels and curing periods are explained. Additionally, cost comparisons among the stabilisers are presented. Dans cet exposé, nous avons évalué le potentiel stabilisant de la cendre volante de classe F, du ciment résistant au sulfate, du sable de laitier broyé (GGBFS) et de la chaux mélangée à des fibres pour améliorer la résistance et les propriétés de changement volumique des sols tendres, expansifs et riches en sulfate. Dans le cadre de cette étude, nous avons mis au point un programme complet d'essais en laboratoire, essais menés sur quatre sols différents de fond de forme. Nous avons étudié deux niveaux de dosage pour chaque stabilisateur et trois périodes de traitement. Nous avons fait des essais Atterberg et des essais de comportement pour la résistance et le changement volumique avec essais de résistance à la compression libre, de gonflement vertical et de retrait linéaire sur des sols étalon et des sols stabilisés. Les résultats ont montré que le ciment résistant au sulfate et la chaux mélangée à des fibres donnaient la stabilisation la plus efficace sur les quatre sols. Les méthodes de stabilisation à la cendre volante et GGBFS ont donné des améliorations moyennes à médiocres des propriétés du sol. Les analyses statistiques ANOVA sur tous les résultats des essais ont indiqué que l'efficacité des quatre méthodes de stabilisation était signifiante statistiquement. Nous expliquons les mécanismes qui influent sur chaque variation de propriété des sols due aux traitements chimiques, aux niveaux de dosage et aux temps de traitement. De plus, nous présentons des comparaisons de coûts entre divers stabilisateurs.

No abstract

Even though low-volume roads usually serve as secondary roads on the entire road network, they are of great importance for the distribution of goods to a number of rural areas in Thailand. However, the budgets for evaluation of the physical condition of the pavement structure of roads in this category and for their subsequent maintenance are surprisingly limited. In addition, the number of specialists required to perform visual inspections is small, and simple static tests on road surfaces are time-consuming and thus expensive. Consequently, it is difficult, if not impossible, to evaluate the physical conditions of pavement structures at a sufficient number of locations. To mitigate this, it becomes necessary to develop a simple test device and a simple means of test analysis to evaluate the physical condition of the pavement structure. This paper introduces a dynamic hammer and discusses a procedure for analysis of the test data. Experiments were performed on both asphalt-paved and unpaved surfaces, which are usually used for low-volume roads. In addition, plate load tests were performed in parallel to compare the test results and validate the analytical framework. It was found that the test device and the framework for analysis of the test data presented in this paper are relevant for use, in particular because of the simplicity of device production, the ease of device use, the time-effectiveness of test performance, and the procedures used for data analysis. Therefore, maintenance can be performed at sufficient numbers of locations of low-volume roads to keep them in good physical condition for serving the entire road network.

This paper presents the current research and case studies regarding the use of geosynthetic-reinforced flexible pavement in Thailand. Physical model tests have been conducted to investigate the efficiency of using geosynthetics for flexible pavement, and the results indicate that geosynthetics can significantly decrease the permanent deformation of flexible pavement for new pavement and overlay subjected to cyclic loading. The permanent deformation of flexible pavement reinforced with geotextiles was significantly lower than that of flexible pavement reinforced with a geogrid. The permanent deformations of overlays reinforced with geogrids and geotextiles were approximately identical. Moreover, the shear strain base layer of reinforced flexible pavement was lower than that of pavement without reinforcement. The fabric effective factors are presented for different types of reinforcement utilised in flexible pavement design. For practical cases in Thailand, ‘paving fabric' geosynthetics have been successfully employed in highway projects for overlays on rigid pavements to reduce reflective cracking. This paper also presents the construction sequence and engineering properties of geosynthetics for reinforced flexible pavement.

No abstract

No abstract