🛣️ Determination of the net and gross dry density of masonry units (except natural stone) — at least 6 specimens, drying to constant mass (loss up to 0.2 % in 24 h) at (105 ± 5) °C for clay, calcium silicate and autoclaved aerated concrete units or at (70 ± 5) °C for aggregate concrete and manufactured stone, or three representative portions of at least 100 g each; net volume by weighing in water (clay), sand filling (calcium silicate) or from dimensions minus recesses and voids (concrete), density in kg/m3 to 5 or 10 kg/m3, PN-EN 772-13

Construction PN-EN 772-13

Overview

WHAT THE STANDARD COVERS. We read the text of the standard in the iTeh sample of SIST EN 772-13:2002 (text of EN 772-13:2000, English) — a scan, read from page images: from the title page through the foreword and Clauses 1–6 up to and including the beginning of 7.2.2 (net density of representative portions). Outside the sample remain the rest of 7.2.2, 7.3 (gross density) and the further clauses (expression of results, test report).

ACCORDING TO THE TEXT OF EN 772-13:2000 (foreword, Clauses 1–6, 7.1–7.2.2). The standard was prepared by CEN/TC 125 “Masonry” (secretariat BSI). Scope (1): a method for determining the net and gross dry density of masonry units, except natural stone masonry units. Normative references (2): drafts prEN 771-1 to 771-5 (specifications for clay, calcium silicate, aggregate concrete, autoclaved aerated concrete and manufactured stone masonry units), prEN 772-3 (net volume and percentage of voids of clay units by hydrostatic weighing), prEN 772-9 (volume and percentage of voids of calcium silicate units by sand filling), prEN 772-16 (dimensions). Principle (3): after drying to constant mass and calculating the net and gross volume, the net and gross dry density are calculated. Definitions (4.1): gross dry density — mass per unit gross volume after drying to constant mass; gross volume — from length, width and height, with a deduction of the volume of perforations, voids, recesses or indentations intended to be filled with mortar; net dry density — mass per unit net volume; net volume — gross volume less the volume of perforations or voids not intended to be filled with mortar. Symbols (4.2): dimensions, masses of unit and portions before and after drying, moisture content of portions, volumes and densities in kg/m3. Apparatus (5): ventilated oven (105 ± 5) °C for clay, calcium silicate and autoclaved aerated concrete units; oven (70 ± 5) °C for aggregate concrete and manufactured stone units; weighing instrument accurate to 0.1 % of the mass of the unit or portion. Sampling (6): according to the relevant part of prEN 771; at least 6 specimens, unless the product specification requires more. Dry mass (7.1): whole units are dried to constant mass at 70 °C or 105 °C depending on the material; constant mass — when in two successive weighings 24 h apart the loss does not exceed 0.2 % of the mass; instead of whole units three representative portions without voids of at least 100 g each may be used: the whole unit is weighed before drying, then the group of three portions before and after drying, the moisture content of the group is calculated by equation (1) and the dry mass of the whole unit by equation (2). Net density of whole units (7.2.1): net volume — a) clay: weighing in water according to prEN 772-3; b) calcium silicate: sand filling according to prEN 772-9; c) manufactured stone and solid aggregate concrete units: volume from dimensions (length × width × height according to prEN 772-16) minus the volume of recesses and indentations measured with a suitable device; d) aggregate concrete units with formed voids: as c) and in addition minus the volume of all voids; net volume to 10^4 mm3; net density ρ = m / V × 10^6 kg/m3 (equation 3), for each unit to the nearest 5 kg/m3 for densities up to 1000 kg/m3 and 10 kg/m3 above, result — the mean. Portions (7.2.2, beginning): dry mass of each portion according to 7.1.2, volume from length, width and height measured to the nearest 1 mm.

STATUS (as of 03.10.2026). The PKN search (term “PN-EN 772-13”, 03.10.2026) shows one item: PN-EN 772-13:2001 (Polish version, “Methods of test for masonry units — Part 13: Determination of net and gross dry density of masonry units (except for natural stone)”, “Introduces: EN 772-13:2000 [IDT]”), without a withdrawal note. In the iTeh catalogue (read on 03.10.2026) EN 772-13:2000 has the status “Published” and stage 90.93 “Decision to confirm” (review from 22.03.2022, completed on 30.09.2026), with a link to Regulation (EU) No 305/2011 on construction products. The standards referenced by EN 772-13:2000 were drafts (prEN) at the time of its publication; we did not check their current editions for this entry. Compressive strength of masonry units is described in a separate entry on PN-EN 772-1.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, load up to 17.09.2026, read on 03.10.2026). The number 772-13 appears in 19 records at 7 laboratories: AB 011, AB 023, AB 054, AB 251, AB 535, AB 619, AB 687. In the current PCA documents (read on 03.10.2026, issues from 16.07.2025 to 13.08.2026) the number appears in 18 rows of the same 7 laboratories (AB 054 — 6, AB 251 — 4, AB 023 — 3, AB 687 — 2, the others 1 each; the PDF file of the AB 251 scope contains the same document twice — we count it once); the numbers of rows and records differ for individual laboratories (AB 054 — 6 rows and 5 records, AB 251 — 4 rows and 6 records). The form “PN-EN 772-13:2001” at five laboratories, without year at AB 011 and AB 023 (in the flexible scope “E”); at AB 054 once with clauses (“p. 7.1, 7.2” for net and “p. 7.1, 7.3” for gross), at AB 023 once together with PN-EN 772-3. None of these items is suspended. The “Laboratories” tab (“PN-EN 772-13”) shows the same 7 laboratories — checked with the tab query on the production server labcoda.pl on 03.10.2026.

WHAT THE LABORATORIES TEST (items in PCA). Clay masonry units (AB 023, AB 054, AB 251, AB 687), calcium silicate units (AB 023, AB 054, AB 251), aggregate concrete and autoclaved aerated concrete units, also prefabricated aerated concrete elements (AB 023, AB 054), masonry units without closer specification (AB 011, AB 535, AB 619), and ventilation blocks of clay and calcium silicate (AB 251, AB 687). Properties tested: net and gross dry density, at AB 251 and AB 687 also dry mass; at AB 023 the range “up to 2500 kg/m3” and items described by a mass range “(1–60) kg” and the gravimetric method. AB 619 repeats the exclusion of natural stone in the name of the property.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the drying temperature: aggregate concrete and manufactured stone are dried at 70 °C, clay, calcium silicate and aerated concrete at 105 °C (5, 7.1.1) — the wrong temperature gives a different dry mass. With constant mass: the criterion is a loss of up to 0.2 % between weighings 24 h apart (7.1.1). With the net volume: the method depends on the material (7.2.1) — weighing in water for clay, sand for calcium silicate, dimensions for concrete; for concrete units with voids the volume of all voids must be subtracted (d). With the definition: the gross volume excludes only voids intended to be filled with mortar, the net volume also the others (4.1) — confusing the definitions changes the result by the volume of perforations. With portions: representative portions must contain no voids and weigh at least 100 g (7.1.2). With rounding: 5 kg/m3 up to 1000 kg/m3, 10 kg/m3 above (7.2.1).

WHAT WE DO NOT GIVE. We did not read 7.3 (gross density) or the further clauses, so we do not give the formula for gross density or the content of the test report. Nor do we give requirements of the EN 771 specifications for declared densities.

Method principle

A masonry unit (or three representative portions without voids) is dried to constant mass at (105 ± 5) °C or (70 ± 5) °C depending on the material and weighed. The gross volume is calculated from dimensions, deducting voids filled with mortar; the net volume — by weighing in water, sand filling or from dimensions after deducting all voids. Net and gross dry density are the dry mass divided by the respective volume, in kg/m3; the result is the mean of the specimens.

Applications

• Clay, calcium silicate, aggregate concrete, autoclaved aerated concrete and manufactured stone masonry units — net and gross dry density (1, 7.2.1)
• Outside the scope: natural stone (1)
• Masonry units, ventilation blocks and prefabricated aerated concrete elements — dry density and mass in the accreditation scopes of 7 laboratories in PCA

Key parameters

Standard

Standard number

PN-EN 772-13:2001

Title (PL)

Metody badań elementów murowych — Część 13: Określenie gęstości netto i gęstości brutto elementów murowych w stanie suchym (z wyjątkiem kamienia naturalnego)

Title (EN)

Methods of test for masonry units — Part 13: Determination of net and gross dry density of masonry units (except for natural stone)

Step-by-step procedure

1. Specimens

   At least 6 units according to the relevant part of EN 771. PN-EN 772-13:2001 in the PKN catalogue without a withdrawal note (03.10.2026).

2. Drying

   To constant mass (loss ≤ 0.2 % in 24 h) at 105 °C or 70 °C depending on the material; or three portions ≥ 100 g and conversion via moisture content (equations 1–2).

3. Net volume

   Weighing in water, sand filling or dimensions minus recesses and voids; to 10^4 mm3.

4. Net density

   ρ = m / V × 10^6 kg/m3; rounding to 5 or 10 kg/m3; mean of the specimens.

5. Gross density

   From the gross volume (dimensions minus voids filled with mortar) — we do not give 7.3.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Handling hot units after drying at 105 °C — protective gloves
• Masonry units may be heavy — lifting according to the rules for heavy loads

Frequently asked questions