Cahit Gürer

Assessment of sand stabilization potential of a plant-derived biomass

Abstract Lignin is a coproduct of biofuel and paper industries, which exhibits binding qualities when mixed with water. Lignin is an ideal candidate for a sustainable stabilization of unpaved roads. To this end, an experimental program was devised and carried out to quantify effects of lignin on compaction and early age shear strength behaviors of sand. Samples were prepared by mixing a particular type of coproduct called calcium lignosulfonate (CaL) with sand and water. Based on the extensive analyses of six series of strength tests, it was found that a normalized cohesion increased with an increasing normalized areas ratio. Normalizations were carried out by dividing the cohesion and area ratio by gravimetric CaL content whereby the area ratio was obtained by dividing the portion of the cross-sectional area occupied with lignosulfonate-water (CaL-W) paste by the total cross-sectional area. While the increase in the normalized cohesion eventually leveled out, the cohesion peaked at 6% of CaL. Thus, sand-CaL-water (S-CaL-W) mixes sustained larger shear stresses than dry sand for a range of normal stresses below the limiting normal stress. Consequently, the early age behavior indicates that adding CaL-W to sand is clearly beneficial in the near-surface applications in dry sand.

Investigation of chip seal performance under cold climate conditions

Abstract The chip seal is an economical type of asphalt pavement that was constructed for single- or double-layer aggregate-bitumen. Chip seals are applied to prime-sealed granular pavement surfaces in order to waterproof the surfaces of sub-layers, produce smooth and high-skid-resistance surfaces for vehicles and protect pavements against the detrimental effects of traffic and climate. Unlike bituminous hot mixtures, numerous factors can affect the performance of chip seal. One of the most important factors is climate. The aim of this study is to determine the performance variation of chip-sealed pavements under cold climate conditions. Three different chip-sealed roads in Erzurum, which is in one of the coldest regions of Turkey, were examined with non-destructive tests. Sand-patch, British pendulum, light weight deflectometer and dynamic cone penetrometer tests were performed. Chip-sealed pavements’ densities and surface temperature variation and base courses layer’s thicknesses were also measured, and deteriorations were observed and scored by researchers. Test results showed that flushing due to the higher temperatures during the short summer season, deficiency of the base course’s bearing capacity and moisture in the base course are the most important causes of deterioration in this type of chip seal, and the chip seals in this region must be resealed in <1 year because of the premature deterioration.

Effect of Aggregate Embedment On Chip Seal Retention Performance

The aim of this study is to evaluate chip seal retention performance with two type of aggregate depending on the various embedment depths using Accelerated Chip Seal Simulation Device (HSKSC). To simulate the worst condition in field for chip seal in respect to aggregate retention performance, the water was poured on the specimens and performance tests were conducted in water. Major findings of this research include that increasing the aggregate embedment significantly reduces the aggregate loss. However, it correspondingly reduced the macrotexture value of the chip seal which is very important parameter for chip seal service life.

Monitoring The Condition of Surfacing Seals With Nondestructive Tests at Field

Surfacing seal is an asphalt pavement type preferred because of its simplicity of application and economic viability. It enables waterproof surfaces for sub-layers and creates smooth and high skid resistance for vehicles. Therefore, surfacing seals constructed on unbound base are widely used such as New Zealand, Australia and South Africa. However the performance of surfacing seals can be affected by a number of factors. If these factors are not considered, they will need to be reconstructed after a very short period. In this study, performances of surfacing seals under heavy traffic were observed for 2 years, and routine tests were performed to determine the surfacing seal’s performance in relation to traffic and climate and to determine the kind of deteriorations which occurred. In this study variety of test such as sand-patch, British pendulum, density measurement with electromagnetic method, measuring surface temperature with thermal camera, light weight deflectometer, dynamic cone penetration test and layer thickness measurement were performed with ground penetrating radar technique. The results of the study show that loss of macro texture, and raveling and flushing are the most common types of deterioration especially at road sections with longitudinal slope. Furthermore, skid numbers decrease during the rainy seasons when the bearing capacity of layers also decreases, the trend of raveling deterioration decreases at roads with high traffic volume and average maximum surface temperature. However, it was determined that trend of flushing deterioration increase.

The effects of different dusty aggregate on bituminous hot mixtures

Abstract Adhesion between aggregate and bitumen is an important parameter of the performance of bituminous hot mix pavements. Dust on the aggregate surface adversely affects bituminous hot mix pavement performance and leads to some types of deterioration, such as raveling, rutting, stripping, and segregation, decreasing long-term pavement performance. The main objective of this study is to determine the effects of different dust contents of the aggregate surface on the bituminous hot mixture. Two separate aggregate specimens with contents of three different dusts were used to produce bituminous hot mixture specimens. Specific gravity, unit weight, gradation analysis, water absorption, Los Angeles abrasion, aggregate impact, freezing and thawing, Nicholson stripping, and Vialit adhesion tests were performed as aggregate tests, whereas Marshall stability and flow, Marshall mechanical immersion, and indirect tensile tests were performed as bituminous hot mixture tests. The study results show that dust content on the aggregate surface weakens adhesion, leading to the gradual deterioration of the characteristics of the hot bituminous mixtures. Because dust contents on the aggregate surface can vary according to the aggregate type, the progression of the deterioration of bituminous hot mixtures can also vary.