TABLE OF CONTENTS Concrete is an ancient materal of construction, first used during the Roman Empire, which extended from about 20 BC to 200 AD. The word concrete is derived from the Roman concretus, meaning to grow together. Although this early mixture was made with lime, cement, and a volcanic ash material called pozzolana, concrete today is a sophisticated material in which exotic constituents can be added and, with computer-controlled batching, can produce a product capable of achieving 50,000 psi compressive strength.
The factors contributing to a successful batch of concrete are:
Precise measurement of water content.
Type, size, and amount of cement and aggregate.
Type, size, and location of reinforcement within the concrete pour to compensate for the lack of tensile strength basic in concrete.
Proper curing procedures during normal, hot or cold weather conditions.
With some exceptions, the two most widely used concrete mixtures are:
Normal-weight (stone) concrete with a dry weight of 145 psf (6.93kPa).
Lightweight concrete (LWC) with a weight of approximately 120 psf (5.74 KPa). Extra light concrete, with weights as low as 80 psf (3.82 kPa), can be achieved with the use of special aggregates.
Other Types of Concrete
Lightweight Insulating Containing perlite, vermiculite, and expanded polystyrene, which is used as fill over metal roof decks, in partitions, and in panel walls.
Cellular Contains air or gas bubbles suspended in mortar and either no coarse aggregates or very limited quantities are included...
