Investigation of the effects of aggregates obtained from different sources on chip seal design performance

Chip seals are widely applied in newly constructed road pavements and for pavement maintenance and repair. It is applied in most of the road network as a surface layer in Turkey. Chip seals are an economical type of pavement coating. This coating application consists of compacting the aggregate layer, which can be laid as a single or double layer on the bitumen bonding or prime coat. It provides a smooth rolling surface with high skid resistance for vehicles and protects the pavement from the destructive effects of traffic and climate. In this study, it is aimed to examine and improve the performance of chip seal. Aggregate-bitumen adhesion are important for this surface coating type. In the study, the chip seal design performances of different types of aggregates obtained from selected sources (limestone, basalt, gabbro and steel slag) were investigated. In order to improve bitumen-aggregate adherence and stripping resistance, aggregate surfaces were treated with slurry method using hydrated lime, fly ash and blast furnace slag and their effects on chip seal design performance were investigated. With this study, besides improving the performance of chip seal, an environmentally friendly and more economical design is aimed to reduce the use of natural resources. For this purpose, iron-steel slag, which has a durable structure and a roughly surface, was used as aggregate. The properties of the aggregates used in the laboratory work were determined and chip seal design tests were conducted. In the study, in which the effect of aggregate type and some physical properties on the chip seal performance were determined, the performances of hydrated lime, fly ash and blast furnace slag adhered to the aggregate surface by slurry method were compared with the commonly used anti-stripping additives (DOP). It has been determined that natural aggregates generally meet the surface coating specification limits, and only the water absorption value of the steel slag aggregate is above the specification limit value. The results show that the use of anti-stripping additives is necessary for the aggregates to be generally used in chip seal. Vialit test results of limestone and basalt aggregates are much better than gabbro and steel slag. Hydrated lime modification improves the stripping resistance of aggregates and is more effective than DOP in gabbro and steel slag aggregates. It was determined that the hydrated lime modification was more effective on the chip seal performance than the other additives.