🧱 Flexural and compressive strength of hardened mortar — cement/air-lime, air-lime, hydraulic-binder and retarded mortars: 160 × 40 × 40 mm prisms from three-gang moulds, three-point bending to failure, compression of both halves, PN-EN 1015-11

Construction PN-EN 1015-11

Overview

WHAT THE STANDARD COVERS. Scope from the PKN catalogue card of PN-EN 1015-11:2020-04, in full (our translation of the Polish card text): “This document describes a method for determining the flexural and compressive strength of hardened mortar specimens. This document applies to cement/air-lime mortars, air-lime mortars, mortars with hydraulic binders and retarded mortars.” We read the text of the standard in the preview of SIST EN 1015-11:2020 (EN 1015-11:2019) from the cover to subclause 7.2.3 (preparation of specimens from air-lime mortars, page 7); we do not have the rest — storage conditions (7.3, Tables 1 and 2), determination of flexural strength (Clause 8) and of compressive strength (Clause 9), the test report and the annexes.

ACCORDING TO THE TEXT OF EN 1015-11:2019 (foreword, clauses 1–7.2.3). The standard was prepared by CEN/TC 125 “Masonry”; it replaced EN 1015-11:1999. The foreword lists the main changes: editorial revision (inversion of Clauses 3 and 4, Clause 3, 5.1); Clause 6 changed — the time of starting and ending the test is indicated; in 7.2.3 an additional type of compaction was added; different storage conditions for air-lime mortars and air-lime/cement mortars with cement not exceeding 50 % of the binder mass (Tables 1 and 2); in 9.1.2 a tolerance for the plate width was added. Normative references: EN 196-1 (strength of cement), EN 998 (all parts — specifications for mortar for masonry), EN 1015-2 (bulk sampling and preparation of test mortars), EN 1015-3 (consistence by flow table), EN ISO 5436-1 (surface texture measurement standards) and EN ISO 6507-1 (Vickers hardness). Definition (3.1.1): air-lime — lime mainly consisting of calcium oxide or hydroxide which slowly hardens in air by reacting with carbon dioxide and generally does not harden under water. Symbols (3.2): F — maximum load applied to the specimen (N), l — distance between the axes of the support rollers (mm), b — width, d — depth of the specimen (mm). Principle (Clause 4): flexural strength is determined by three-point loading of hardened prisms to failure, and compressive strength — on both parts remaining after the flexural test; where flexural strength is not required, the parts for compression can be produced from the prisms in any way that does not damage them. Apparatus (Clause 5): metal moulds — an open frame of removable walls forming three compartments (Figure 1, Annex A) — for mortars with hydraulic binders and air-lime mortars with air-lime not exceeding 50 % of the binder mass a typical mould as in EN 196-1 (5.1.1), separate moulds for air-lime/cement mortars with cement not exceeding 50 % of the binder mass (5.1.2); tamper — a rigid, non-absorptive rod of square cross-section (12 ± 1) mm, with a flat tamping face, mass (50 ± 1) g; storage chamber maintaining 20 °C (+3 °C/−2 °C) and a relative humidity of (95 ± 5) % or (65 ± 5) %; white cotton gauze — four sheets of about 150 mm × 175 mm; absorbent filter paper of (200 ± 20) g/m² with a water absorption capacity of (160 ± 20) g/m² — twelve sheets of about 150 mm × 175 mm (the number of sheets may be changed for a different absorption capacity); polyethylene bags holding the moulds; non-absorptive plates covering the mould and supporting a mass of 5 kg; palette knife or metal straight edge; metal grid for storage; trowel; further apparatus — in 8.1 and 9.1. Sampling (Clause 6): at least 1,5 l of fresh mortar or 1,5 times the quantity needed for the test (whichever is greater), by reduction of the bulk sample according to EN 1015-2 (divider or quartering) or prepared in the laboratory; two test samples are prepared. Laboratory-prepared mortars (6.2): the mixing time is counted from the moment all constituents are in the mixer; the mortar is brought to a defined flow value according to EN 1015-2, determined according to EN 1015-3 or EN 1015-4, and this value is reported; the test starts after mixing and is completed within the declared workable life of the mortar (preferably within 30 min after completion of mixing); before testing the mortar is gently stirred by hand with a trowel or knife for 5 s to 10 s (against false setting), without additional mixing. Other mortars (6.3): ready-to-use retarded factory-made wet mortars and pre-batched air-lime/sand wet mortars without hydraulic binder are moulded within their declared workable life; the flow of the bulk sample is determined according to EN 1015-3 and reported. Specimens (7.1): prisms of 160 mm × 40 mm × 40 mm, three of them; for compression they are broken into halves — six halves. Preparation (7.2.1): mortars based on hydraulic binders (retarded or not) and air-lime/cement mortars with air-lime not exceeding 50 % of the binder mass — according to 7.2.2; air-lime mortars and air-lime/cement mortars with cement not exceeding 50 % of the binder mass — according to 7.2.3; mortars of unknown composition — according to the manufacturer's instructions, in one of these two ways; at least three prisms for testing at an age of 28 days (more when the mortar contains a retarder), unless otherwise specified; the inside of the moulds is coated with a thin layer of mineral oil that does not affect setting. 7.2.2: the mould is filled in two approximately equal layers, each compacted with 25 strokes of the tamper — or the mould is tilted by about 30° and tapped ten times, returned to horizontal, and tilted and tapped ten more times; the compaction method must be reported; excess mortar is skimmed off with a knife so that the surface is plane and level with the top of the mould. 7.2.3: the assembled mould frame, clamped at right angles, is placed on a non-absorptive plate covered with two layers of dry white cotton gauze and filled as in 7.2.2 (tamper or tilting and tapping; method — to the report); here the read preview ends.

STATUS (cards as of 02.10.2026). The card of PN-EN 1015-11:2020-04 (English version) has no “Withdrawn” header — the standard is CURRENT: published 14-04-2020, 17 pages, price group J, Construction Sector, KT 233 Masonry Structures, ICS 91.100.10, “Introduces: EN 1015-11:2019 [IDT]”, “Replaces: PN-EN 1015-11:2001/A1:2007 - English version, PN-EN 1015-11:2001 - Polish version, PN-EN 1015-11:2001/A1:2007 - German version”. There is no Polish version of the 2020 edition in the catalogue: the PKN search for “PN-EN 1015-11” (02.10.2026) shows PN-EN 1015-11:2020-04 (English), PN-EN 1015-11:2001 (Polish) and PN-EN 1015-11:2001/A1:2007 (English and German). Card of PN-EN 1015-11:2001 (Polish version, 14 pages, introduces EN 1015-11:1999): “Withdrawn and replaced by PN-EN 1015-11:2020-04 - English version”, withdrawal date 14-04-2020. Card of PN-EN 1015-11:2001/A1:2007 (English version, 3 pages, introduces EN 1015-11:1999/A1:2006; “Scope” field: “Changes were made to Clauses 2, 9.2.2 and Annex B”): “Withdrawn and replaced by PN-EN 1015-11:2020-04”, withdrawal date 14-04-2020.

HOW MANY LABORATORIES AND IN WHAT FORM (copy of the accreditation scope database, data up to 17.09.2026, read 02.10.2026). The number 1015-11 appears in 16 records of 8 laboratories: AB 023 (5), AB 054, AB 499, AB 535, AB 556 (2 each), AB 011, AB 580, AB 1703 (1 each). Current scopes on the PCA website (read 02.10.2026, scope issues from 03.10.2023 to 25.06.2026): the number appears in 18 items — eight at AB 023 (the database copy has five of them; missing are the item for admixtures for concrete, mortar and grout and two for cement, gypsum, lime and masonry mortars). Forms: “PN-EN 1015-11:2020-04” — AB 011, AB 499, AB 556, AB 1703; “PN-EN 1015-11:2020-04 p. 8 i 9” — AB 580; the withdrawn “PN-EN 1015-11:2001+A1:2007” next to “PN-EN 1015-11:2020-04” in the same two items — AB 535; undated — AB 023 (in two items with the note “pkt 9” and “pkt 8”, in one next to EAD 350140-00-1106) and AB 054. None of these items is suspended (at AB 054 the footnotes on suspension concern lines set in bold italics — the lines with 1015-11 are not set that way). The “Laboratories” tab searches for entries BEGINNING WITH “PN-EN 1015-11” and shows all 8 laboratories — checked with the tab query on the production server labcoda.pl on 02.10.2026: 8 laboratories and 15 items in total (AB 023 — 4, because the item beginning with “EAD 350140-00-1106” does not match the prefix; AB 054, AB 499, AB 535, AB 556 — 2 each; AB 011, AB 580, AB 1703 — 1 each); under “EN 1015-11” — 1 Czech laboratory (1181).

WHAT THE LABORATORIES TEST (items in PCA). Object: mortars (AB 011, AB 535), masonry mortars (AB 054 — also admixtures for masonry mortar, AB 499, AB 556, AB 1703), building mortars, cement, gypsum, lime, cement-lime, gypsum-lime and masonry mortars and plaster compounds for thin-coat finishes, renders and mortars, admixtures for concrete, mortar and grout (AB 023), repair mortars (AB 580 — “Repair mortars and coatings”). Quantities: flexural and compressive strength — at seven laboratories; compressive strength only — AB 1703. Force ranges in compression: (0,2–150,0) kN (AB 499), (1,0–100,0) kN (AB 054), (1–300) kN (AB 011), (1–3000) kN (AB 535), (2,0–100) kN (AB 1703), (4,0–300) kN (AB 556), (0–250) kN (AB 580), at AB 023 in different items — up to 10 kN, up to 100 kN, up to 200 kN, from 3 kN to 300 kN and (5–3000) kN; in bending: (0,05–6,0) kN (AB 054), (0,1–10) kN (AB 556), (0,2–10,0) kN (AB 499), (1–15) kN (AB 011), (0–15) kN (AB 580), (1–100) kN (AB 535), at AB 023 — up to 10 kN, up to 100 kN, (0,1–100) kN and up to 200 kN. Method: “Method: constant force increase” (AB 054), “Method of constant load increase” (AB 556), “Compression test” and “Bending test” (AB 023), “direct strength measurement” (AB 580). At AB 023 the item for renders and mortars (next to EAD 350140-00-1106) has an exclusion: “Except air-lime mortars and air-lime/cement mortars with cement mass not exceeding 50% of the total binder mass”, range up to 10 kN — i.e. without the mortars prepared according to 7.2.3. The items of AB 023 and AB 054 are marked “E” — flexible scope of accreditation.

WHERE A SEEMINGLY CORRECT RESULT IS EASY TO GET. With the sample: the test must start after mixing and end within the declared workable life of the mortar (preferably within 30 min) — prisms moulded later do not meet the condition of the standard; the flow value must be determined and reported. With moulding: mortars in which air-lime predominates (cement not more than 50 % of the binder mass) are moulded according to 7.2.3 — on gauze and under different storage conditions (Tables 1 and 2) from mortars with hydraulic binders, and air-lime/cement mortars with cement ≤ 50 % of the binder mass — in separate moulds (5.1.2); moulding them like cement mortars does not meet the requirements of the standard; the compaction method (tamper or tilting and tapping) must be reported. With the count: the compression result comes from six halves of three prisms, and the flexural result — from three prisms; retarded mortars require more prisms. With the edition: PN-EN 1015-11:2001 and A1:2007 have been withdrawn since 14-04-2020 — AB 535 gives them next to the 2020-04 edition in the same items; the 2019 edition changed, among other things, the storage conditions of air-lime mortars and the tolerance of the plate width, so the report should state the edition. With the object: the scope of the standard lists cement/air-lime, air-lime, hydraulic-binder and retarded mortars; the items with gypsum and gypsum-lime mortars (AB 023) go beyond this list — the read text contains no rules for them; repair mortars (AB 580) fall within it only if they are based on hydraulic binders — the item does not say which they are.

WHAT WE DO NOT GIVE. We do not have the rest of 7.2.3 — so we do not know how the filter paper, the polyethylene bags and the loaded plates from Clause 5 are used — nor subclause 7.3 with Tables 1 and 2 (storage conditions and times in the moulds and after demoulding), Clauses 8 and 9 (apparatus for bending and compression, roller spacing, plate dimensions, loading rate, formulae, accuracy of the result), Clause 10 (test report) or Annexes A (moulds) and B (suggested loading rates for mortar classes) — so we do not give the storage conditions, the loading rate or the strength formulae. We do not know the content of amendment A1:2007 to the 2001 edition beyond the “Scope” field of the card.

Method principle

From a sample of fresh mortar (at least 1,5 l), brought to a defined flow and used within its workable life, three prisms of 160 mm × 40 mm × 40 mm are moulded in a three-gang metal mould — compacting with a tamper or by tilting and tapping the mould, and mortars in which air-lime predominates on a gauze base — and stored in a chamber at 20 °C and a specified humidity; the hardened prisms are broken by three-point bending to failure, and both halves of each are tested in compression.

Applications

• Masonry mortars, air-lime, cement/air-lime and retarded mortars — flexural and compressive strength in the scopes of 8 laboratories (AB 1703 — compression only)
• Admixtures for masonry mortar and for concrete, mortar and grout — testing of mortar with the admixture (AB 023, AB 054)
• Repair mortars (AB 580 — within the scope of the standard if based on hydraulic binders) and renders and mortars next to EAD 350140-00-1106 (AB 023, without mortars in which air-lime predominates)

Key parameters

Standard

Standard number

PN-EN 1015-11:2020-04 (wersja angielska; EN 1015-11:2019 IDT)

Title (PL)

Metody badań zapraw do murów — Część 11: Określenie wytrzymałości na zginanie i ściskanie stwardniałej zaprawy

Title (EN)

Methods of test for mortar for masonry — Part 11: Determination of flexural and compressive strength of hardened mortar

Step-by-step procedure

1. Fresh mortar sample

   At least 1,5 l (or 1,5 × the quantity needed) by reduction of the bulk sample according to EN 1015-2 or prepared in the laboratory; two test samples; flow according to EN 1015-3 (or EN 1015-4) — to the report. PN-EN 1015-11:2020-04 current (card as of 02.10.2026).

2. Moulding the prisms

   Moulds coated with mineral oil; hydraulic and air-lime/cement mortars with lime ≤ 50 % — two layers of 25 tamper strokes each or tilting and tapping (7.2.2); mortars in which lime predominates — frame on a non-absorptive plate with two layers of gauze (7.2.3); three prisms of 160 × 40 × 40 mm, within the workable life of the mortar.

3. Storage

   In a chamber at 20 °C and humidity of (95 ± 5) % or (65 ± 5) % according to Tables 1 and 2 — conditions and times NOT GIVEN; testing usually at an age of 28 days.

4. Bending

   Three-point loading of each prism to failure (Clause 8); roller spacing, loading rate and formula — NOT GIVEN.

5. Compression

   Both halves of each prism — six results (Clause 9); plate dimensions, loading rate and formula — NOT GIVEN; the report also states the edition of the standard and the compaction method.

Required equipment and apparatus

Reagents, media and consumables

Health and safety (OHS)

• Fresh cement and lime mortar is alkaline and irritates skin and eyes; breaking prisms in the press — fragments; the read text of the standard contains no safety warnings
• TECHNICAL NOTE: the method of moulding and storage depends on the binder type (50 % threshold of lime or cement in the binder mass) — an air-lime mortar moulded like a cement mortar does not meet the requirements of the standard; the 2001+A1:2007 edition has been withdrawn since 14-04-2020

Frequently asked questions