ISO 13765-7:2021

Refractory mortars - Part 7: Determination of permanent change in dimensions on heating

This document describes the method for determining the permanent change in dimensions on heating (drying and/or firing) of refractory mortars.

Mortiers réfractaires — Partie 7: Détermination des variations dimensionnelles permanentes lors du chauffage

General Information

• Status: Published
• Publication Date: 26-Sep-2021
• ICS: 81.080 - Refractories
• Technical Committee: ISO/TC 33 - Refractories
• Drafting Committee: ISO/TC 33/WG 27 - Refractory mortars – Determination of permanent change in dimension on heating
• Current Stage: 6060 - International Standard published
• Start Date: 27-Sep-2021
• Due Date: 03-Apr-2021
• Completion Date: 27-Sep-2021

Overview

ISO 13765-7:2021 - Refractory mortars: Determination of permanent change in dimensions on heating specifies a laboratory method to measure the permanent dimensional change (shrinkage or expansion) of refractory mortars when subjected to drying and/or firing. The procedure quantifies dimensional stability after heating by measuring distances between marks on mortar-bonded refractory bricks before and after heat treatment and expressing changes as percentage values.

Key topics and technical requirements

• Scope: Method for determining permanent change in dimensions on heating (drying and/or firing) of refractory mortars.
• Test specimens: Each specimen is formed by two compatible refractory bricks (recommended size: 114 ± 1 mm × 65 ± 1 mm × 32 ± 1 mm). Initial mark spacing on diagonals: 90–100 mm.
• Joint preparation: Mortar joint thickness 2–4 mm using a 2 mm thick rectangular frame; nylon filter cloth and fine refractory powder (≤ 0.1 mm) are used during assembly.
• Apparatus and conditions:
  • Mixer and balance (≤ 10 kg, 1 g resolution).
  • Drying oven capable of 110 °C ± 5 °C and electrical temperature control.
  • Furnace with maximum temperature ≥ 1 600 °C, temperature uniformity ±10 °C.
  • Length measuring device with 0.05 mm accuracy.
• Heating regime:
  • Air-dry then oven-dry at 65 °C (4 h) followed by 110 °C (24 h).
  • Firing heating rate normally 5 °C/min (silica mortar 3 °C/min); soak 3 h ± 0.5 h (silica 5 h ± 0.5 h) at agreed temperature; oxidizing atmosphere; cooling in furnace to room temperature.
• Calculations & reporting:
  • Permanent change on drying, firing and overall heating expressed as percentage change: (l_after − l_before) / l_before × 100.
  • Test requires three specimens; report individual values and mean to nearest 0.1%. Use “+” for expansion and “–” for shrinkage.
• Precision: Interlaboratory tests and precision data are provided (Annex A). Repeatability and reproducibility clauses apply.

Applications and users

• Quality control and acceptance testing of refractory mortars used in furnaces, kilns, boilers and high-temperature linings.
• Product development and R&D for mortar formulations to assess dimensional stability during drying/firing.
• Test laboratories, refractory manufacturers, specification engineers, procurement teams and construction/installation contractors who require documented performance data on mortar shrinkage/expansion.

Related standards

• ISO 13765-1 (consistency - penetrating cone method)
• ISO 13765-2 (consistency - reciprocating flow table method)
• ISO 13765-3 (joint stability)
• ISO 8656-1 (sampling of raw materials and unshaped products)

Keywords: ISO 13765-7:2021, refractory mortars, permanent change in dimensions, dimensional stability, drying and firing test, shrinkage, expansion, refractory testing, furnace testing, oven drying.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 13765-7
First edition
2021-09
Refractory mortars —
Part 7:
Determination of permanent change
in dimensions on heating
Mortiers réfractaires —
Partie 7: Détermination des variations dimensionnelles permanentes
lors du chauffage
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
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below or ISO’s member body in the country of the requester.
ISO copyright office
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Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
6 Test preparation . 2
6.1 Sampling . 2
6.2 Preparation of the refractory bricks . 2
7 Procedure. 3
7.1 Preparation of the test specimens . 3
7.2 Measurement of test specimens . 4
7.3 Drying the test specimens . 4
7.4 Firing the test specimens . 4
7.5 Measurement of test specimens after heating (drying or firing) . 5
8 Calculations. 5
8.1 The permanent change in dimensions on drying . 5
8.2 The permanent change in dimensions on firing . 5
8.3 The permanent change in dimensions on heating . 5
9 Precision . 6
9.1 Interlaboratory tests . 6
9.2 Repeatability . 6
9.3 Reproducibility . 6
10 Reporting . 6
Annex A (informative) Results of interlaboratory tests. 7
Foreword
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 33, Refractories.
A list of all parts in the ISO 13765 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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iv © ISO 2021 – All rights reserved

INTERNATIONAL STANDARD ISO 13765-7:2021(E)
Refractory mortars —
Part 7:
Determination of permanent change in dimensions on
heating
1 Scope
This document describes the method for determining the permanent change in dimensions on heating
(drying and/or firing) of refractory mortars.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 8656-1, Refractory products — Sampling of raw materials and unshaped products — Part 1: Sampling
scheme
ISO 13765-1, Refractory mortars — Part 1: Determination of consistency using the penetrating cone
method
ISO 13765-2, Refractory mortars — Part 2: Determination of consistency using the reciprocating flow
table method
ISO 13765-3, Refractory mortars — Part 3: Determination of joint stability
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
A mortar sample is heated and the dimensional change after heating is determined. Place the test
specimens of refractory mortars, whose length between two marks has been determined, in a drying
oven or furnace. Heat (drying and/or firing) to a specified temperature for a specified time and then
cool to room temperature. Measure the length between two marks again. Calculate the permanent
change in dimensions on heating.
5 Apparatus
5.1 Mixer, as specified in ISO 13765-1 or ISO 13765-2.
5.2 Balance, with a maximum weighing capacity of 10 kg and capable of weighing to the nearest 1 g.
5.3 Cutting device, a trowel.
5.4 Nylon filter cloth, single layer nylon mesh filter cloth, 80 mesh~200 mesh.
5.5 Electrical drying oven, fitted with a temperature controller and capable of operating at
110 °C ± 5 °C.
5.6 Furnace, the maximum temperature for the furnace should not lower than 1 600 °C. And the
temperature difference shall not exceed ±10 °C in the furnace.
5.7 Refractory powders, the particle size shall less than 0,1 mm.
5.8 Refractory bricks, (114 ± 1) mm × (65 ± 1) mm × (32 ± 1) mm, which should be the same as the
br
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