Investigation of Rutting Performance in Geogrid-Reinforced Asphalt by Penetration Test.

Permanent deformation, or rutting, is one of several critical distresses in flexible pavements. This paper introduced a novel experimental method, a penetration test, for asphalt mixtures to quantify the effects of glass fibre geogrids embedded in asphalt under repeated loading. It was found that the evolution of permanent deformation (εp) and its strain rate have three clearly identifiable stages. It was also observed that the presence of the geogrid increased the flow number and the number of cycles to failure significantly compared to control samples. Some of the current εp fitting models were found to be valid for deformation prediction under penetration. In addition, a new simple FN calculation method was also proposed based on strain rate and it showed consistent results. In particular, geogrid type "Grid10", which has smaller aperture size (12.7 mm) had slightly better reinforcement performance regarding the rutting resistance due to its larger contact area. Overall, the test and data analysis method presented in this study could be an important reference for future investigations on geosynthetic-reinforced pavement materials.

Characteristics of Lightweight Cellular Concrete and Effects on Mechanical Properties.

This study investigated the pore structure and its effects on mechanical properties of lightweight cellular concrete (LCC) in order to understand more and detailed characteristics of such structure. As part of investigation, environment scanning electron microscopes (ESEM) and industrial high-definition (HD) macro photography camera were separately used to capture and compare images of specimens. Physical properties of the pore structure, including pore area, size, perimeter, fit ellipse, and shape descriptors, were studied based on the image processing technology and software applications. Specimens with three different densities (400, 475, and 600 kg/m3) were prepared in the laboratory. Firstly, the effects of density on the characteristics of pore structure were investigated; furthermore, mechanical properties (compressive strength, modulus of elasticity and Poisson's ratio, flexural strength and splitting tensile strength of LCC) were tested. The relationships among pore characteristics, density, and mechanical properties were analyzed. Based on the results obtained from the lab test-comparisons made between specimens with high-densities and those with low-densities-it was found significant variability in bubble size, thickness, and irregularity of pores. Furthermore, the increase of density is accompanied by better mechanical properties, and the main influencing factors are the thickness of the solid part and the shape of the bubble. The thicker of solid part and more regular pores of LCC has, the better mechanical properties are.

Evaluation of Mechanical Properties and Microscopic Structure of Coal Gangue after Aqueous Solution Treatment.

Coal gangue, a solid waste produced in coal production, had caused serious environmental pollution due to accumulation on dumps. Embankment filling can solve the problem while significantly consuming the amount of coal waste for mining. The main purpose of this study is to investigate the mechanical properties and microscopic structure of coal gangue when it is subjected to erosion from water environment with different acidity. Using immersion testing to evaluate its stability in different hydro-chemical environments. Mechanical property parameters of coal gangue treated by solutions were investigated. The action microstructure of coal gangue was revealed through a series of X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), scanning electron microscopy (SEM), and energy dispersive spectrometry (EDS). The results show that acidic solution behaved better improvement effect on compressive modulus and fraction of coal gangue samples owing to the generation of quartz and the reduction of aluminum, dissolving of some substances, and transforming of small scattered angular grains through soaking treatment. Alkalinity treatment can be chosen to improve cohesion of coal gangue as a result of polymeric silicon aluminum salt, with high viscosity, was produced by chemical reaction during immersion. Therefore, aqueous solution treatment contributes to engineering properties and presents great potential in both supplement road building materials and recycling of coal gangue.