Road - INTRODUCTION
TYPES OF ROADS
Highways
Urban Streets
Rural Roads
ROADWAY ENGINEERING
Roadbed
Base Course
Wearing Course
Bituminous Pavement
Concrete Pavement
ROAD PLANNING AND ADMINISTRATION
HISTORY OF ROAD CONSTRUCTION


AUTOMOBILE
AUTOMOBILE INDUSTRY
PUBLIC TRANSPORTATION
TRUCK


Concrete Pavement






Concrete Pavement | Mix of Portland Cement and Aggregate


Concrete, or rigid, pavements are made from a mix of portland cement and aggregate. Concrete pavements have a long life and require little maintenance. Concrete is generally laid as a single thick layer directly over a base course. For heavily traveled roads, concrete layers can range in thickness from 20 to 36 cm (8 to 14 in). Concrete is usually laid in long sections or slabs of varying length. Metal bars or dowels inserted into the edges of the slabs help connect the joints where one slab ends and another begins. (Concrete Pavement, Mix of Portland Cement and Aggregate)

Concrete is a strong material and can withstand compression, but it has poor tensile strength (resistance to being pulled). When the ground underneath expands and contracts from seasonal or weather changes, the concrete becomes prone to cracking. Cracks can occur at or near the joints where concrete slabs meet or on the slabs themselves. Deep cracks can allow the broken concrete slabs to move upward or downward, creating an uneven road surface. Metal bars or dowels inserted between the slabs help hold the slabs together. Reinforced concrete contains steel bars or mesh imbedded within the concrete layer. The steel helps hold concrete together over time, even if cracks occur. Unreinforced concrete may be used when cost is a factor, or where weather conditions are more mild. Unreinforced slabs have several shallow grooves cut into them, allowing the concrete to crack at defined points. The cracked slabs are kept in place by pressure and by the grainy texture of the concrete itself. (Concrete Pavement, Mix of Portland Cement and Aggregate)

Concrete Pavement | Mix of Portland Cement and Aggregate