Proper curing of concrete is essential for durable, maintenance free pavement. The following questions and answer discussion is based on our fundamental knowledge of the subject and the techniques used. Why is curing necessary? To assure proper hydration of the cement present in the mix. As hydration proceeds, the properties of concrete ( strength, wear resistance, volume stability, resistance to freeze-thaw) are improved. How is curing achieved? By maintaining freshly placed concrete under controlled conditions for a given period of time. For how long should pavement undergo the curing process? The time element, while dependent on several factors, is largely determined by the method of curing adopted, the temperature at which curing will take place, the rate of hydration, and the availability of sufficient moisture. Generally speaking, the longer the curing time, the better. The minimum period recommended is 4 days. What are the main characteristics of the different methods of water preservation? Ponding requires building up an earth or sand "dike" around the perimeter of the pavement that will trap and confine water within the enclosed area. The sprinkling method should direct water to the area continuously, using a system of nozzles that will produce a constant, fine spray. Wet coverings using earth, sand, straw or hay for curing has largely been discontinued in recent years because of the high cost of materials and labor. Curing with wet coverings can be done much more efficiently with a moisture retaining fabric of burlap, cotton, or other textile. Waterproof paper is also used as an efficient wet covering and offers the significant advantage of eliminating the need for periodic additions of water. Plastic sheets provide another good wet cover curing medium. Membrane forming compounds, correctly used, provide one of the easiest ways of curing pavement by the wet covering method. Where a membrane on the concrete surface will interfere with subsequent treatments such as painting, a silicate base cure may be used. How important is climate? Concrete can be cured successfully over a wide range of temperatures, but some special precautions are necessary during either extreme in the temperature: cold weather curing- under extreme cold conditions, the ingredients of a mix should be heated so that the concrete can be deposited between the edge forms at a temperature of at least 50 degrees. Hot weather curing- under extreme hot conditions, ingredients of the mix should be pre-cooled. Can curing processes by accelerated? Yes, although the practice is not recommended except under special circumstances.