1、 Shape and size. Ordinary sintered bricks are rectangular prisms with standard dimensions of 240mm × 115mm × 53mm. Adding the thickness of the mortar joints used for masonry, 4 bricks are long, 8 bricks are wide, and 16 bricks are exactly 1m thick. Therefore, 512 bricks are required for each cubic meter of brick masonry.

2、 Intensity level. The strength grade of ordinary sintered bricks is pided into five grades: MU30, MU25, MU20, MU15, and MU10, based on the average, standard, or minimum compressive strength of 10 bricks. When evaluating the strength grade, if the coefficient of variation of strength is ≤ 0.21, the average standard value method is used; If the coefficient of variation of strength δ is greater than 0.21, the mean minimum method is used. The strength standards for each level should comply with the values specified in the table below.

3、 Anti weathering performance. The anti weathering performance is one of the important durability indicators of ordinary sintered bricks, and the requirements for the anti weathering performance of bricks should be determined according to the degree of weathering in each region (see GB/T5101-1998 for the regional pision of weathering degree). The weathering resistance of bricks is usually pided into three indicators: frost resistance, water absorption, and saturation coefficient. Frost resistance refers to the absence of cracks, delamination, peeling, missing edges, and corners after 15 cycles of freeze-thaw cycles; And the weight loss rate is less than 2%, and the strength loss rate is less than the specified value. The water absorption rate refers to the weight absorption rate of water soaked at room temperature for 24 hours. The saturation coefficient refers to the ratio of the 24-hour water absorption rate at room temperature to the 5-hour boiling water absorption rate.

Ordinary sintered bricks used in areas 1, 2, 3, 4, and 5 with severe weathering must pass the frost resistance test, while frost resistance tests may not be required in other areas.

4、 Lime burst. If lime is carried in the raw materials or CaO is introduced into the internal fuel (fly ash, slag), it will generate burnt lime during the high-temperature melting process. Burnt lime absorbs water and expands inside the brick, causing the brick to expand and break. This phenomenon is called lime cracking. According to GB/T5101-1998, high-quality products are not allowed to have a burst area with a maximum damage size greater than 2mm; First grade products are not allowed to have explosive areas with a maximum damage size greater than 10mm; Each group of brick samples in the qualified product must have no more than 15 explosive areas of 2-15mm, with no more than 7 areas of 10mm or more, and no explosive areas greater than 15mm are allowed.

5、 Frosty. It refers to the gradual precipitation of a layer of white frost on the surface of bricks by soluble salts inside the bricks during their use. These white powdery crystals not only affect the appearance of buildings, but also cause the volume expansion of crystals to loosen the surface of bricks and damage the bond between bricks and mortar layers.

GB/T5101-1998 also stipulates that high-quality products are not allowed to have frosting, and qualified products are not allowed to have severe frosting, and are not allowed to contain undercooked bricks, crispy bricks, and spiral patterned bricks.