CHAPTER ONE
INTRODUCTION
Road pavement construction has experienced many significant problems mainly in sub-base and base design and construction over the years in this country (Nigeria). Roads in Osun State have a very high volume of traic which comprises of many type of commercial vehicles, cars and trucks. Roads have been constructed for more than 2000years. Even the earliest engineers practiced drainage of the pavement’s sub-surface layers in order to keep the highway functioning. Nowadays, many billions of Naira are spent on road construction and maintenance each year, and road transport in the primary method of mobility for Nigeria people or goods, Transport constitutes about 10% of the gross national product of the Nigerian union and more than 80% of the total transport of people and goods is provided y the infrastructure. Investment in road construction and maintenance in Nigeria is therefore at a very high level and any improvement can have a significant effect on the Nigeria economy. Not only will well maintained roads and highway contribute economically, for they are also essential for social development of Nigeria. On the other, the deterioration of roads can have serious consequence for the safety and comfort of roads user.