Besides providing the durability, fire resistance, economy, and easy maintenance common to all masonry materials, today's concrete brick also offer the aesthetic factors of scale, texture, and color associated with brick masonry. PHYSICAL PROPERTIES Concrete brick are composed of portland cement mixed with aggregates such as gravel, crushed stone, sand, and manufactured lightweight aggregate to produce either normal-weight or lightweight units. Their properties are governed by ASTM C 55, "Standard Specification for Concrete Brick." AESTHETIC FACTORS Various colors, textures, and shapes can be achieved in manufacture. After brick are cured, antiquing, slurrying, rolling, coating, tumbling, or dusting them with various coloring agents further expands aesthetic possibilities. WATER ABSORPTION AND MOISTURE RESISTANCE Concrete brick's inherent high compressive strength, combined with the aesthetic need for a denser, finer texture, dictate that their cement-to-aggregate ratio be much higher than that of standard concrete block. COST The cost of concrete brick ranges widely, from about $110 to $250 per 1,000. The low end represents modular fill brick, typically used in combination with standard block. In the higher range, cost increases depend on a number of factors, including the size of the units.