BS EN 771-4 pdf free download

BS EN 771-4 pdf free download.Specification for masonry units — Part 4: Autoclaved aerated concrete masonry units.
5.4.3 Limit deviations The limit deviation of the measured dry density from the declared dry density shall not exceed ± 50 kg/m³. NOTE Closer deviations may be declared. 5.5 Compressive strength The strength of the masonry units in compression shall be declared in N/mm² by the manufacturer and shall not be less than 1,5 N/mm² (declared value – for definition see 3.15) It shall be expressed as one of: a) the mean compressive strength of the unit; b) the characteristic compressive strength of the unit. The manufacturer shall also declare the normalised compressive strength when relevant. EN 772-1 gives instructions on how to convert the declared compressive strength into the normalised compressive strength. In addition, the manufacturer shall declare whether the autoclaved aerated concrete masonry unit is Category I or Category II (see clause ZA.2). If AAC masonry units are sampled from a consignment in accordance with Annex A and tested in accordance with EN 772-1, with surface preparation and conditioning as given below, the compressive strength shall not be less than the declared value and no individual AAC masonry unit shall have a compressive strength of less than 80 % of the mean declared value or 90 %of the characteristic declared value. The specimens sampled in accordance with Annex A shall be conditioned to 6 % ± 2 % moisture content in accordance with 7.3.4 of EN 772-1: 2000. The moisture content of the specimens shall be determined in accordance with EN 772-10. The surfaces of the specimens shall be prepared in accordance with 7.2.4 of EN 772-1: 2000. When not using whole masonry units refer to clause B.2 for the cutting scheme. The dimensions of such specimens shall be declared. 5.6 Thermal properties When relevant to the uses for which the unit is put on the market and in all cases for units intended to be used in elements subject to thermal requirements, the manufacturer shall provide information on the thermal properties of AAC masonry units by reference to EN 1745. 5.7 Durability When relevant to the uses for which the units are put on the market, the manufacturer shall evaluate and declare the freeze/thaw resistance of the units by reference to the provisions valid in the intended place of use of the units until an appropriate European Standard is available. 5.8 Moisture movement When relevant to the uses for which the unit is put on the market and in all cases for units intended to be used in elements subject to structural requirements, the shrinkage of AAC masonry units shall be determined in accordance with EN 680 from units sampled in accordance with Annex A. 5.9 Water vapour permeability When relevant to the uses for which the masonry unit is put on the market and in all cases for units intended to be used in external elements, the manufacturer shall provide information on the water vapour permeability through the water vapour diffusion coefficient tabulated values given in EN 1745 or determined in accordance with EN ISO 12572. 5.10 Water absorption When relevant to the uses for which the unit is put on the market and for all units intended to be used in external elements with exposed face, the maximum water absorption of masonry units at times of 10, 30 and 90 min shall be declared by the manufacturer. If sampled in accordance with Annex A and tested in accordance with EN 772-11, using the procedure for aggregate concrete units and a drying temperature of 70 °C ± 5 °C, the results shall be less than those declared by the manufacturer. The measuring periods shall be 10, 30 and 90 min. The samples shall be prepared as three cubes cut from units in accordance with Annex B.BS EN 771-4  pdf download.