What Are Fly Ash Bricks?

Autoclaved fly ash bricks are fly ash bricks made of fly ash, lime or cement as the main raw material, mixed with an appropriate amount of gypsum and aggregate, prepared by compression molding, high pressure or atmospheric curing or natural curing. . It is made of fly ash and lime as the main raw material, mixed with appropriate amount of gypsum and aggregate, prepared by blank material, press-molded, and high-pressure steam curing, referred to as fly ash brick. ^[1]

The dimensions of autoclaved fly ash bricks are exactly the same as ordinary solid clay bricks, 240mm x 115mm x 53mm, so autoclaved bricks can directly replace solid clay bricks.

There are two types of fly ash bricks: autoclaved fly ash bricks and steam-cured fly ash bricks. Autoclaved fly ash bricks are fly ash bricks made by high pressure steam curing. Steam-cured fly ash brick refers to fly ash brick made by steam curing under normal pressure. The raw materials and manufacturing process of these two types of bricks are basically the same, except that the curing techniques of the two are different, and there are different

According to the industry standard "Fly Ash Bricks" (JC 239--2001), fly ash bricks are divided into MU30, MU25, MU20, MUl5, MUl0 and other strength levels according to compressive strength and flexural strength. According to dimensional deviation, appearance quality, strength grade and dry shrinkage, it is divided into superior product (A), first-class product (B) and qualified product (C). The dimensions are 240 mm × 115 mm × 53 mm.

The compressive strength, flexural strength value and frost resistance index of each grade of brick shall meet the requirements of the figure.

figure 1

The autoclaved fly ash brick is dark gray, with a bulk density of 1400 to 1500 kg / m³ and a thermal conductivity of about 0.65 W / (m · K). Large drying shrinkage (JC 239-2001)] stipulates that the dry shrinkage of superior products and first-class products shall not be greater than 0.65 mm / m; qualified products shall not be greater than 0.75 mm / m. Carbonization coefficient 0.8.

Fly ash bricks can be used for walls and foundations of industrial and civil buildings, but for foundations or for construction parts susceptible to freeze-thaw and wet and dry interaction, bricks of strength class MUl5 and above must be used. Fly ash bricks should not be used in construction parts that are subject to long-term heating (above 200 ° C) and alternating cold and rapid heat or acidic media. To avoid or reduce the occurrence of shrinkage cracks, buildings built with fly ash bricks, Ring beams and expansion joints should be appropriately added. ^[2]