As 1012.11-2000 Methods of Testing Concrete - Determination

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AS 1012.11-2000 1012.11-2000 Methods of testing concrete - Determination Determination of the modulus of of rupture

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AS 1012.11—2000

TM

Australian Standard A S 1 0 1 2 .1 1

Methods of testing concrete Method 11: Determination of the modulus of rupture 1 SCOPE This Standard sets out a method for determining the modulus of rupture of concrete test specimens prepared in accordance with AS 1012.8.2 tested as simple beams with third-point loading. NOTES: 1

. d e t i b i h o r p k r o w t e n n o e s

This Standard may involve hazardous materials, operations and equipment. This Standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine th e applicability of regulatory limitations before use. Relevance of this Standard to fibre-reinforced concrete is to be further investigated. Committee BD/42 is seeking information from all interested parties.

2 REFERENCED DOCUMENTS The following documents are referred to in this Standar d: AS

1

AS 1012.11—2000

TM

Australian Standard A S 1 0 1 2 .1 1

Methods of testing concrete Method 11: Determination of the modulus of rupture 1 SCOPE This Standard sets out a method for determining the modulus of rupture of concrete test specimens prepared in accordance with AS 1012.8.2 tested as simple beams with third-point loading. NOTES: 1

. d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u e l g n i S . 2 0 0 2 n u J 4 0 n o H S E R U S . S . E o t d e s n e c i L

This Standard may involve hazardous materials, operations and equipment. This Standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine th e applicability of regulatory limitations before use. Relevance of this Standard to fibre-reinforced concrete is to be further investigated. Committee BD/42 is seeking information from all interested parties.

2 REFERENCED DOCUMENTS The following documents are referred to in this Standar d: AS 1012 1012.1 1012.8.2 1012.9 2193

Methods of testing concrete Met hod 1: Sampling of fr esh concrete Method 8.2: Method for making and curing concrete — Flexure test specimen concrete specimens Method 9: Determination of the compressive strength of concrete specimens Methods for the calibration and grading of force-measuring systems of testing machines

3 ACCEPTANCE OF TEST SPECIMENS Moulded flexure test specimens shall be accepted for testing if they have been moulded in accordance with the provisions of AS 1012.8.2, and if they are free from defects likely to affect their strength. Where specimens liable to rejection are tested, all apparent defects shall be noted in accordance with Clauses 9 and 10 of this Standard. Specimens shall be liable to rejection if any of the following conditions exist: (a)

Chipped edges, surface cracking or honeycombing are apparent anywhere in the tested span.

(b)

The surfaces of the specimen are out of plane such that any of the lines of contact between the bearing surfaces on which the rollers bear are out of plane by more than 0.1 mm.

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AS 1012.11—2000

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4 APPARATUS 4.1 Testing machines The testing machine shall comply with the following requirements: (a)

It shall meet the requirements for Grade A machines, as defined in AS 2193 for the relevant range of compressive forces. NOTE: The machine needs to be suitable for the range required since this test is normally carried out at a lower range of force than AS 1012.9.

(b)

It shall be power operated and capable of applying compressive forces increasing continuously at the rate of loading a nd in the manner specified in Clause 6.

(c)

The machine shall be fitted with a device for controlling rate of loading which can operate at a rate of loading specified in Clause 6.

4.2 Flexure testing apparatus


The force shall be applied to the specimen through a frame containing two supporting rollers and two loading rollers. The frame shall consist of two parts (upper and lower) each of which shall be precisely located in the testing machine so that loading is applied evenly and precisely at the third points of the span. This frame may be incorporated either in the testing machine or in an accessory that can be used with, or between, the platens of a suitable compression-testing machine. The application of the force shall be through the spherical seat or a loading ball (see Figure 1) that is centrally placed between the loading rollers. The rollers shall be suitably articulated to ensure that— (a)

the force is divided equally between t he loading rollers;

(b)

the force is applied normal to t he specimen surface; and

(c)

the specimen is not restrained or subject t o torsion.

NOTE: This may be achieved by incorporating a suitable system of transverse rollers and either a spherical seat or a ball in both the supporting group and loading group of rollers.

A suitable arrangement of the loading appara tus is illustrated in Figure 1. The dimensions and spacing of the rollers shall c omply with the following requirements: (i)

Two hardened steel rollers of 38 mm to 40 mm nominal diameter shall be provided to support the specimen. The centre-to-centre distance of the supporting rollers ( L ) shall be in accordance with Table 1.

(ii)

Two hardened steel rollers of 38 mm to 40 mm nominal diameter shall be used to apply the load at the third points of the supporting span. The centre-to-centre distance of the loading rollers ( l ) shall be in accordance with T able 1.

(iii)

The length of both the supporting and loading rollers shall be at least equal to the width of the specimen being tested. To ensure that the rollers bear uniformly on the width of the specimen, the surface of the rollers along any contact edge shall not deviate from a straight line by more than ±0.02 mm in 150 mm.

4.3 Measuring apparatus Vernier calliper or ruler readable to at least 1 mm.

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AS 1012.11—2000

5 CONDITIONING OF TEST SPECIMENS PRIOR TO TEST The specimen shall be cured in accordance with AS 1012.8.2 to ensure that the surface of the specimen has been maintained wet for 48 h prior to testing and that they are saturated and kept wet immediately prior t o testing. At the end of the conditioning period, the specimen shall be kept wet and shall be tested promptly. The surfaces of the specimens that are loaded shall be free from grit, and all surfaces shall be wiped, if necessary, to remove surplus water.

TABLE 1 CENTRE-TO-CENTRE DISTANCES OF THE SUPPORTING AND LOADING ROLLERS Centre-to-centre distance of rollers Nominal size of specimens mm

150 × 150 . d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u e l g n i S . 2 0 0 2 n u J 4 0 n o H S E R U S . S . E o t d e s n e c i L

100 × 100

Supporting rollers ( L )

Loading rollers (l )

mm

mm

450 300

+ 10, − 5 + 8, − 3

L 3

±1

FIGURE 1 DIAGRAMMATIC VIEW OF A SUITABLE FLEXURE TESTING APPARATUS

6 PROCEDURE The procedure shall be as follows: www.standards.com.au


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AS 1012.11—2000


(a)

Remove grit from the surface of the specimen that is loaded and, if necessary, wipe to remove the surplus water.

(b)

Turn the specimen on its side with respect to its position as moulded and then centre it on the supporting rollers. Although it is necessary to locate the specimen centrally with respect to its width, it is neither necessary nor always desirable that it be located centrally with respect to its length. The position of the specimen may be arranged such as to avoid any defects that may occur near one end.

(c)

Bring the loading rollers into contact with the top, apply a seating load not exceeding 100 N, check the uniformity of bearing of the rollers, and mark their position on the sides of the specimen before proc eeding with the loading.

(d)

Apply the force without shock and increase continuously at a rate equivalent to 1 ±0.1 MPa/min extreme fibr e stress until no increase in force can b e sustained. Record the maximum force applied to the specimen as indicated by the testing machine.

(e)

Determine the average width and average depth of the specimen at the section of failure to the nearest 1 mm.

(f)

Note the appearance of the concrete and t he type of fracture, if the fractur e is unusual.

(g)

If the fracture occurs outside the middle third of the span length, do not calculate the modulus of rupture but measure and record the distance from the nearest supporting roller to the section of failure.

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CALCULATION

When the fracture occurs within the middle third of the specimen, the modulus of rupture shall be calculated as follows: f cf =

PL (1000) BD

2

where f cf

= modulus of rupture, in megapascals

P

= maximum applied force indicated by the testing machine, in kilonewtons

L

= span length, in millimetres

B

= average width of the specimen at the section of failure, in millimetres

D

= average depth of specimen at the section of failure, in millimetres

8 PRECISION STATEMENT For pairs of beams made from the same sample, cured in similar conditions and tested in accordance with this standard, the repeatability expressed as a percentage of the mean of the two strengths obtained, is 18 percent a t the 95 percent probabilit y level. NOTE: This statement on repeatability is based on limited Australian data and may be amended when more data is collected.

9 RECORDS The following information shall be r ecorded for each test specimen: (a)

Identification of the concrete.

(b)

Job site or laboratory where tested.

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AS 1012.11—2000

(c)

Date and time of test.

(d)

Moisture condition of specimen, as received.

(e)

Any apparent defects of the specimen, as r eceived.

(f)

Age of specimen at the date of test, if known.

(g)

Failure load.

(h)

Span length.

(i)

Average width and depth of the specimen at the s ection of failure.

(j)

Modulus of rupture, calculated to the nearest 0.1 MPa, or the position of the fracture, if it occurs outside the middle third of the span length.

(k)

Appearance of the concrete in the fracture surface and the type of fracture, if these are unusual.

(l)

Any other significant factors noted before, during or a fter testing.

(m)

Identification of the testing operator.

(n)

Reference to this Standard, i.e. AS 1012.11.

10 REPORT . d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u e l g n i S . 2 0 0 2 n u J 4 0 n o H S E R U S . S . E o t

The following information shall be reported: (a)

Identification of the concrete.

(b)

Date and location of test.

(c)

Age of specimen at the date of test, if known.

(d)

Nominal size of specimen.

(e)

Modulus of rupture, calculated to the nearest 0.1 MPa, or the position of the fracture if it occur outside the middle thir d of the span length.

(f)

Any apparent defects, any relevant comments on the moisture condition of the specimen, as received, or any other significant factor(s) noted before, during or after testing.

(g)

Reference to this Standard, i.e. AS 1012.11.

(h)

Such other information contained in the sampling records (see AS 1012.1) as may be requested.

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AS 1012.11—2000

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NOTES


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NOTES


AS 1012.11—2000

AS 1012.11—2000

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This Australian Standard was prepared by Technical Committee BD/42, Methods of Testing Concrete. It was approved on behalf of the Council of Standards Australia on 28 April 2000 and published on 18 May 2000.

The following interests are represented on Committee BD/42: Association of Consulting Engineers Australia AUSTROADS Australian Chamber of Commerce and Industry Australian Pre-mixed Concrete Association CSIRO—Building, Construction and Engineering Cement and Concrete Association of Australia Concrete Institute of Australia National Association of Testing Authorities Australia University of New South Wales University of Technology, Sydney . d e t i b i h o r p k r o w t e n n o e s u r o n o i t u b i r t s i d , e g a r o t S . y l n o e c n e c i l r e s u e l g n i S . 2 0 0 2 n u J 4 0 n o H S E R U S . S . E o t d e s n e c i L

Keeping Standards up-to-date Standards are living documents which reflect progress in science, technology and systems. To maintain their currency, all Standards are periodically reviewed, and new editions are published. Between editions, amendments may be issued. Standards may also be withdrawn. It is important that readers assure themselves they are using a current Standard, which should include any amendments which may have been published since the Standard was purchased. Detailed information about Standards can be found visiting the Standards Australia web site at www.standards.com.au and looking up the relevant Standard in the on-line catalogue. Alternatively, the printed Catalogue provides information current at 1 January each year, and the monthly magazine, The Australian Standard , has a full listing of revisions and amendments published each month. We also welcome suggestions for the improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at [email protected], or write to the Chief Executive, Standards Australia International Ltd, PO Box 1055, Strathfield, NSW 2135.

Originated as AS A106—1985. Previous edition AS 1012.11—1985. Third edition 2000.

This Standard was issued in draft form for comment as DR 98462.

COPYRIGHT © S tand ards Aus tra li a I nter nat ion al All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher. Published by Standards Australia International Ltd PO Box 1055, Strathfield, NSW 2135, Australia ISBN 0 7337 3392 1

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As 1012.11-2000 Methods of Testing Concrete - Determination

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