CR 13933-2000 Masonry Cement - Testing for Workability (Cohesivity)《圬工水泥可使用性(粘度)测试》.pdf

1、PUBLISHED DOCU1MENT Masonry cement - Testing for workability (cohesivity) ICs 91.080.30; 91.100.10 N OPWNG WHO BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGE“ LAW PD CR 13933:2000 CR 13933:ZOOO PD CR 13933:2000 National foreword This Published Document reproduces verbatim CR 13933:2000. The UK parti

2、cipation in its preparation was entrusted by Technical Committee B/516, Cement and Lime, to Subcommittee B/516/10, Masonry cement, which has the responsibility to: - aid enquirem to understand the tee - present to the responsible inte - monitor related international and European developments and pro

3、mulgate them in the UK A list of organizations represented on this subcommittee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Standards Catalogue under the section en

4、titled “Intedonal Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a conbrad. Users of British Standards are responsible for their correct application. Compliance

5、 with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, the CR title page, pages 2 to 22, an inside back cover and a back cover. The BSI copyright notice displayed in this document indicates wh

6、en the document was last issued. This British Standard, having been prepared under the Amendments issued since publication direction of the Sector Amd. No. Iate Icomments Committee for Buildine and Civil Engineering, was publkhed under the authority of the Standards Committee and comes into effect o

7、n 15 July 201 O BSI 07-2001 ISBN O 680 36747 9 PD CR 13933:2000 CEN REPORT CR 13933 RAPPORT CEN CEN BERICHT July 2000 ICs English version Masonry cement - Testing for workability (cohesivity) This CEN Report was approved by CEN on 3 June 2000. It has been drawn up by the Technical Commitee CEN/TC 51

8、. CEN members are the national standards bodies of Austria, Belgium, Czech Republic. Denmark, Finland, France, Germany, Grew, Iceland. Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Swizerland and United Kingdom. EUROPEAN COMMTITEE FOR STANDARDIZATION COMIT$ EUROPEEN DE NO

9、RMALISATION EUROPAISCHES KOMITEE FOR NORMUNG Central Secretariat: rue de Stassart, 38 81050 Brussels Q 2000 CEN AI1 rights of exploitation in any form and by any means resewed worldwide for CEN national Members. Ref. No. CR 13933:2000 E PD CR 13933:2000 Foreword This CEN Report has been prepared by

10、Technical Committee CEN/TC 51 Cement and building limes“, the secretariat of which is held by IBN. 2 PD CR 13933:2000 Contents Introduction 1 Scope 2 Normative references 3 Equipment 4 Test Procedure 4.1 Introduction 4.2 Principle 4.3 Apparatus 4.4 Calibration of the Flow Table 4.5 Procedure for the

11、 assessment of the Cohesivity of Test Mortars 4.6 Calculation of Results 5 Results from the Co-operative Test Programme 6 Re-appraisal of calibration 7 Assessment 8 Future Work Bibliography Page 4 4 4 5 6 6 6 6 7 7 8 8 17 21 21 22 3 PD CR 13933:2000 Introduction Mortars incorporating masonry cements

12、 are used for bedding masonry units and also for rendering and plastering. In 1988 the CEN Technical Committee responsible for Cements and Building Limes (TC 51) charged its Working Group 10 to produce a Standard for Masonry cements and for the test methods to support that Standard. Test methods for

13、 setting time, soundness and strength are common requirements in most cement standards. However, where the cement is specifically designed to adhere to and subsequently provide a good bond with masonry units it is important that an adequate level of workability is achieved. In contrast to the concep

14、t of workability as applied to concrete, workability in mortars is not just a question of adjusting the “wetness“ of the mortar by adding more or less water. In masonry work the craftsman requires rather more of his materials in that he expects them to flow easily from the trowel and to spread on to

15、 the masonry unit evenly and without segregation. It is only when these properties are present that he can expect to achieve the consistent degree of bonding necessary to produce durable watertight joints and renderings. The appropriate RILEM Committee considered that workability comprised two main

16、components, notably consistence and plasticity. These they defined as follows: Consistence: That property of a mortar by virtue of which it tends to resist deformation. Plasticity: That property of a mortar by virtue of which it tends to retain its deformation after reduction of the deforming stress

17、 to its yield point. It may be interpreted that consistence is a measure of wetness and could be measured using a penetration device, but that plasticity required a more dynamic assessment such as could be achieved by using apparatus which caused the mortar to move. However, in order to obtain any m

18、eaningful numerical measure of plasticity it was adjudged important to ensure that the testing for this characteristic was carried out on mortars where the consistence had been controlled to a narrow band. 0 Since the testing procedure adopted in the CEN Standard EN 41 3-2:1994 Masonry cement - Part

19、 2: Test methods involved the preparation of a mortar using standard sand and with sufficient water to achieve a narrow band of consistence as assessed using a plunger (Penetration) test, this was considered as the starting point for the work to assess workability, or as was deemed more appropriate

20、“cohesivity“. Early work involved measuring the time taken for a mortar of standard consistence to flow between two points in the AFNOR workability meter. This method was incorporated into EN 413-2:1994 as a test method, but on account of the limited amount of experience available no limits were set

21、 in the Masonry cement Prestandard ENV 413-1. Subsequently, further testing revealed significant calibration problems between laboratories and consideration was given to the use of a flow table as an alternative means of providing the dynamic component of the test. This CEN report deals with the dev

22、elopment of the test using flow tables. 1 Scope the workability (“cohesivity“) imparted to mortar by masonry cements. The adaption of existing test methods and equipment to provide a repeatable and reproducible means of assessing 0 2 Nonnative references This CEN report incorporates by dated or unda

23、ted reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this CEN report only when incorpo

24、rated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies. EN 196-1 :1994 EN 41 3-2: 1994 Methods of testing cement - Part 1: Determination of strength Masonry cement - Part 2: Test methods 4 PD CR 13933:2000 3Equipment As has been discus

25、sed in the introduction, there is considerable merit in using the standard consistence mortar produced in EN 413-2:1994 as the starting point forthe cohesivity test. Such a pracce requires no equipment beyond that already required for masonry cement testing. The mortar is prepared in the mixer defin

26、ed in EN 196-1:1994 and the sand used and the plunger device for measuring consistence are those specified in EN 413-2:1994. Since flow tables are not uncommon in cement testing laboratories it was decided to evaluate these in order to provide a measure of cohesiviiy. However, previous experience su

27、ggests that even where these pieces of equipment are covered by strict specification requirements, their performance can be expected to vary from table to table. A review of the flow tables in use in various European testing laboratories revealed considerable differences as is shown in Table I. Cali

28、bration of the tables was therefore considered to be an essential step in the test procedure. In order to keep this calibration procedure as simple as possible, the first attempts at calibration were effected using the EN 196-1:1994 sand damped with a fixed amount of water. The results from this cal

29、ibration as carried out in the nine laboratories participating in the co-operative test programme are given in Table 1. Table 1 - Calibration Results DBDK was the German Lime Association, ENCI was the Netherlands cement manufacturer and Norcem was the Norwegian cement manufacturer. 5 PD CR 13933:200

30、0 The number of jolts and the log10 of the number of jolts for a spread of 145 mm is shown in Table 2. The log of the number of jolts is given since the relationship between the log of the number of jolts and the spreads approaches linearity. Table 2 - Number of Jolts and the log10 of the number of

31、Jolts for a spread of 145 mm TestLaboratory I Flow Table I Jolts required for a spread of 145 mm. The results obtained revealed large differences between the design of the flow tables in common use in the different laboratories and also in the spread of mortar obtained from a given number of jolts.

32、However, despite these differences, there was good agreement between the ASTM tables in three of the laboratories in achieving a spread of 145 mm and a tolerable level of agreement between the ASTM tables and the EN 459 tables. The Italian table and those in use in Norway and Portugal however, gave

33、very different results. At this stage of the evaluation there was promise that an effective means of calibration was possible and it was encouraging to proceed further with this type of test procedure. An attempt was also made to calibrate the flow tables using mixtures of EN 196-1:1994 sand and aqu

34、eous solutions of cellulose ethers and standard viscosity oils. The rheological properties of these materials proved to be markedly different from those of the mortars to be tested and they were not proceeded with. 4 Test Procedure The test procedure adopted for evaluation in a co-operative test pro

35、gramme followed that given in the papers by Slavin see (i) in Bibliography and by Bowler, Jackson i Monk see (2) in Bibliography and was as follows: 4.1 Introduction Recently published work (1) and (2) provide details of a method for the determination of the cohesivity (at a given level of consisten

36、ce) provided by binders when used to prepare mortars for use in masonry applications (brick and block laying and rendering). This property should not be confused with consistence which for building mortars implies “wetness“ whereas cohesivity describes the ability of the mortar to flow in the desire

37、d manner from the craftsmans trowel and to form a coherent mass when placed upon masonry units. This document describes its application to masonry cement. 4.2 Principle The mortar is prepared in accordance with the method given in EN 413-2:1994. This mortar is placed in a mould on a calibrated flow

38、table and the spread measured after the appropriate number of jolts. Cohesive materials give either a significantly lower spread or an increased number of jolts than the less cohesive materials. Cohesivity is expressed as Indices which incorporate the calibration of the flow table. 4.3 Apparatus 4.3

39、.1 Flow tables: For reference purposes, see the flow table described in EN 459-2. Other flow tables and their moulds, the performance of which is related to the reference table, may be used. The important requirement is that the EN 196-1:1994 sandlwater calibration material remains cohesive up to th

40、e required spread. If a flow table does not permit this, then it is not suitable for this test and an alternative is required. 6 PD CR 13933:2000 It is important that the flow table is tightly secured to a horizontal, firm and non-plastic base. A monolithic cast concrete base weighing at least 50 kg

41、 is suitable. NOTE The ASTM C-230 flow table and the BS 4551 flow table and their moulds have been shown to be satisfactory. The BS 890:1972 flow table and its mould is not satisfactory. 4.3.2 Calliper with jaws opening to the diameter of the flow table. This may incorporate a measuring device calib

42、rated in units of 1 mm or may be used in conjunction with a ruler also calibrated In units of 1 mm. 4.3.3 Timer indicating seconds or better. 4.3.4 Mortar mixer and associated equipment described in EN 196-1:1994. 4.3.5 Consistence plunger and associated equipment as described in EN 413-2:1994. 4.3.

43、6 Tamper to use with the flow table mould. Made of non-absorptive, non-abrasive, non-brittle material and having a cross section of 13 mm by 25 mm and a length of 127 mm to 152 mm. The tamping face to be flat and at right angles to the length of the tamper. 4.3.7 Metal straight edge as described in

44、5.3.2 of EN 413-2:1994. 4.4 Calibration of the Flow Table If the flow table has not been used during the previous hour, jolt the empty table several times before use. Ensure that the table top and also the inner surface of the mould are dry and free from any dullness due to the presence of moisture.

45、 Place (1350 f 5)g of CEN standard sand complying with 5.1.3 of EN 196-1:1994 into the bowl of the mixer complying with 4.4 of EN 196-1:1994. Add (203 f 1) g of water and proceed through the mixing procedure described in 6.3b1 6.3 and 6.3d of EN 196-1:1994. Place the mould in the centre of the flow

46、table top and fill it in two layers each of approximately the same height. Tamp each layer 10 times using the tamper described in 4.3.6 above. Strike off excess material, avoiding any spillage onto the table surface. There should be no water separation between the base of the mould and the table top

47、. If this occurs, then the tamping has been too vigorous. Remove the mould and spread the mix by jolting the table top at a rate of one jolt every second. Jolting to commence within 2.0 minutes of the mixing procedure having been completed. Measure the spread in two directions at right angles to eac

48、h other after 5,10,15,20 and 25 or more jolts of the table (sufficient to give a minimum spread of 145 mm). NOTE More than 25 jolts may be necessary with some flow tables to achieve the required spread to calculate Report the average of the two measurements to 1 mm. Complete the full number of jolts

49、 within 5.0 minutes of the first jolt. Prepare two further fresh batches of the sandiwater mix and repeat the test described above In order to provide an average of three results. Use the average spread on the flow table ater 15 jolts in the calculation of Cohesivity Index “A“. Use the number of jolts to give a spread of 145 mm established by interpolation from the spread obtained at 5, 1 O, 15,20 and 25 jolts in the calculation of Cohesivity Index “B“. Cohesivity Index “B“. 4.5 Procedure for the assessment of the Cohesivity of Test Mortars 4.5.1 Prepare the test