Currently, the standard GOST 530-95 "Brick and ceramic stones. Specifications" to replace GOST and GOST 6316-74 648-73 and standard GOST 7484-78 "Brick and ceramic stone facial. Technical conditions."
No marriage means:
- compliance with the real compressive strength of the claimed brand. Produce brick brands M75, M100, Ml25, M150, M200, M250, M300. The figures indicate the tensile strength in kg / cm2; it is necessary to select the material based on the calculation of the load on the wall;
- compliance of porosity to a mark on frost resistance, i.e. to quantity of cycles of alternating freezing/thawing which the brick is capable "to survive", being in water more than days. Marking for this parameter contains the letter "F"; existing brands of frost resistance: F15, F25, F35, F50. In Central Russia use products of the brand F35. For warm regions, as a rule, it is enough if the building brick "suffers" 15 cycles. Facing brick F15 is not mass produced-according to GOST it is allowed to produce only in the southern regions, and only if the experience of past construction in these places with the use of frost-resistant material was positive;
- compliance of water absorption to the standard-not less than 8% for full-bodied brick and not less than 6% for hollow brick;
- conformity of the product to the specified size. As before, the standard – 250×120×65 mm. There are also bricks thick – 250×120×88 mm, single unit dimensions 288×138×63 mm, thickened modular dimensions 288×l38×88 mm. in addition, GOST permits the manufacturers in agreement with the consumer to produce custom products non-traditional dimensions and shapes. Most often meet: one – and-a-half brick-250×120×103 mm and double-250×l20×138 mm. However, in all cases the deviation of the sizes from the standard (or size specified in the contract) must not exceed: length ±5 mm width ±4 mm, thickness ±3 mm. For products facing demands for stricter deviation: length ±4 mm, width ±3 mm, thickness -2..+3 mm.
- a number of so-called "polovnyak" the party does not exceed 5%;* compliance with the appearance of the standard. The surface of the faces should be flat, the edges should be straight. However, the building material allowed rounding of vertical ribs with a radius of 15 mm;
- compliance with environmental regulations. The specific effective activity of natural radionuclides should not exceed 370 Bq / kg;
- the brick must not contain inclusions of lime and stones. In principle, lime is part of the raw clay, but it is finely milled. If there are large particles, they begin to absorb moisture and swell (appears the so-called "sulker"), chipping small pieces of brick;
- the mass of any brick in the dried state should not exceed 4.3 kg.
- For building bricks is not considered marriage the presence of some permissible defects:
- allowed the presence of chipped corners depth of 10..15 mm and (or) damage ribs depth until 10, - 10..15 mm – two defects per piece of brick;
- permitted cracks with a length up to 30 mm – one bonder and stretcher bond face;
- spalling of the surface to a depth of 3..10 mm allowed in an amount of up to 3 pieces per brick.
Requirements to appearance of a facing brick are more strict: on a face surface of a brick there should be no chips (including and and from limy inclusions), stains, fades and other external defects visible from distance of 10 m in the open space at daylight.
Marriage are cases of violation of the regime of firing bricks. Signs of "underburning" – mustard color, a dull sound at impact. The result of this marriage-poor water and frost resistance. For "burnout" is characterized by black scorch marks and swollen, broken form, increased density and thermal conductivity (heat from the premises will "leak" much more intensively).