BS DD CEN TS 772-22-2006 Methods of test for masonry units - Determination of freeze thaw resistance of clay masonry units《砌块的试验方法 测定黏土砌块的耐冻融性》.pdf

1、 g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58resistance of clay masonry unitsICS 91.100.15Methods of test for masonry units Part 22: Determinati

2、on of freeze/thaw DRAFT FOR DEVELOPMENTDD CEN/TS 772-22:2006DD CEN/TS 772-22:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2006 BSI 2006ISBN 0 580 49100 5a European Standard, to extend the life of the Technical Specification o

3、r to withdraw it. Comments should be sent to the Secretary of the responsible BSI Technical Committee at British Standards House, 389 Chiswick High Road, London W4 4AL.The UK participation in its preparation was entrusted by Technical Committee B/519, Masonry and associated testing, to Subcommittee

4、B/519/1, Masonry units.A list of organizations represented on B/519/1 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Amendments issued since publicationAmd. No. Dat

5、e CommentsComments arising from the use of this Draft for Development are requested so that UK experience can be reported to the European organization responsible for its conversion to a European standard. A review of this publication will be initiated not later than 3 years after its publication by

6、 the European organization so that a decision can be taken on its status. Notification of the start of the review period will be made in an announcement in the appropriate issue of Update Standards.According to the replies received by the end of the review period, the responsible BSI Committee will

7、decide whether to support the conversion into National forewordThis Draft for Development was published by BSI. It is the UK implementation of CEN/TS 772-22:2006.This publication is not to be regarded as a British Standard.It is being issued in the Draft for Development series of publications and is

8、 of a provisional nature. It should be applied on this provisional basis, so that information and experience of its practical application can be obtained.TECHNICAL SPECIFICATIONSPCIFICATION TECHNIQUETECHNISCHE SPEZIFIKATIONCEN/TS 772-22June 2006ICS 91.100.15English VersionMethods of test for masonry

9、 units - Part 22: Determination offreeze/thaw resistance of clay masonry unitsPrfverfahren fr Mauersteine - Teil 22: Bestimmung desFrost-Tau-Widerstandes von MauerziegelnThis Technical Specification (CEN/TS) was approved by CEN on 21 March 2006 for provisional application.The period of validity of t

10、his CEN/TS is limited initially to three years. After two years the members of CEN will be requested to submit theircomments, particularly on the question whether the CEN/TS can be converted into a European Standard.CEN members are required to announce the existence of this CEN/TS in the same way as

11、 for an EN and to make the CEN/TS availablepromptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in parallel to the CEN/TS)until the final decision about the possible conversion of the CEN/TS into an EN is reached.CEN members are the na

12、tional standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kin

13、gdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TS 772-22:2006: E2 Co

14、ntents Page Foreword .3 1 Scope4 2 Normative references4 3 Principle4 4 Symbols4 5 Apparatus.4 6 Materials .5 7 Preparation of specimens.5 8 Construction of test panel6 9 Procedure.8 10 Evaluation of results .10 11 Test report10 Annex A (normative) Types of damage possible in the freeze-thaw test 12

15、 Annex B (normative) Determination of water absorption16 Annex C (normative) Measurement of heat transfer rate 17 CEN/TS:772-22:20063 Foreword This Technical Specification (CEN/TS 772-22:2006) has been prepared by Technical Committee CEN/TC 125 “Masonry”, the secretariat of which is held by BSI. Acc

16、ording to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

17、Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. CEN/TS:772-22:20064 1 Scope This Technical Specification specifies a method for determining the freeze/thaw resistance of clay masonry units that are decla

18、red by the manufacturer as meeting the requirements for HD units and as suitable to be subjected to severe (F2) exposure. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undate

19、d references the latest edition of the referenced document (including any amendments) applies. EN 771-1, Specification for Masonry Units Clay Masonry Units 3 Principle A panel of clay masonry units is assembled either from units which have been immersed in water for a prescribed period of time and w

20、hich are separated from one another by a specified rubber jointing material or from units and rapid hardening mortar which when sufficiently hardened is immersed in water for a prescribed period of time. The panel is subsequently cooled for a specified period and the water near to one face is repeat

21、edly thawed and refrozen. Damage caused by the freezing and thawing action is assessed and used to determine the freeze/thaw resistance of the bricks. 4 Symbols mdis the mass of the specimen after drying, in grams (g) mw is the wet mass of the specimen, in grams (g) wmis the water absorption of an i

22、ndividual specimen, in mass percent (%) 5 Apparatus An appropriate testing machine capable of generating the freeze-thaw cycles specified in clause 8.3 and ensuring unidirectional freezing and thawing through one face of the units. Several different designs of testing machine are suitable all of whi

23、ch use a fan to circulate air in the machine. It is important that the machine circulates the air such that the flow is essentially parallel to the face of the panel under test. A water tank, made of plastic or steel. A drying oven capable of maintaining a temperature of 105 C 5 C and of providing f

24、orced air circulation. A weighing instrument capable of weighing specimens to an accuracy of 1 g. A heat flow meter suitable for carrying out the calibration procedure. A suitable heat flow meter can be constructed by bonding an electrically heated resistance mat of appropriate rating to an aluminiu

25、m plate of the same shape and size, typically 2 mm thick 200 mm 400 mm and a sheet of extruded polystyrene foam 100 mm thick (see Figure 1). The polystyrene sheet should be of sufficient size to fill the opening in the cabinet which is normally occupied by the test panel of masonry units. The alumin

26、ium plate, which shall be painted matt black, is sealed to the centre of this opening with a thermocouple attached to its external surface CEN/TS:772-22:20065 at the approximate centre of the plate. The heated mat is connected to a continuously variable transformer with a means of measuring current

27、and voltage. Dimensions in mm 11234100Key 1 Insulation 3 Matt black aluminium sheet 2 Electric resistance mat 4 Foam rubber Figure 1 Heat flow meter 6 Materials Foam rubber with closed pores 10 mm 2 mm thick and which does not absorb water during the test. High alumina cement Sand with a maximum gra

28、in size of 1 mm 7 Preparation of specimens 7.1 Sampling The method of sampling shall be in accordance with EN 771-1. Sufficient units shall be sampled in order to construct a panel with a face which has a surface area of between 0,25 m2 and 0,5 m2. 7.2 Preliminary examination of specimens Each unit

29、shall be numbered and examined. Any existing defects shall be noted. The descriptions given in Table 1 and shown diagrammatically in Annex A may be used for guidance. Only defects with a damage type 4 and above need be recorded. CEN/TS:772-22:20066 7.3 Conditioning of Specimens Water absorption may

30、be determined using the method described in Annex B. If the construction method described in 8.2 i.e. with rubber joints is to be used, then each unit is placed in the tank of water at room temperature. That water is to be in contact with all faces of the unit and this may be achieved by the resting

31、 of the units on small pads which act as spacers. The units are left submerged for 7 days. If the construction method described in 8.3 i.e. with mortar joints is to be used, the conditioning of the test panels shall be in accordance with 8.3.2. 8 Construction of test panel 8.1 General Test panels ma

32、y be constructed using either foam rubber or mortar as jointing materials. However in cases of dispute the jointing medium should be the same as that upon which the declaration of the freeze/thaw category was based. NOTE Current scientific knowledge indicates that the results from tests carried out

33、using rubber or mortar for panel construction are, within the natural variation of results, the same. All faces of the panel except that exposed to freeze/thaw cycling conditions shall be enclosed in a close fitting jacket of extruded polystyrene foam with a density of less than or equal to 50 kg/m3

34、. The minimum thickness of the jacket shall be 50 mm at the back and 25 mm around the perimeter of the test panel. The joint between the polystyrene outer wall and the test panel shall be finished so that melt water is prevented from running behind the test panel. This may be achieved by placing a l

35、ayer of the foam rubber around the perimeter of the test panel. 8.2 Rubber Joints Remove the units from the water and assemble them into a panel using the closed pore foam rubber (10 mm 2 mm thick) as a jointing material. The units shall be arranged so that the vertical joints in one course are appr

36、oximately above the centre of a whole unit in the course beneath it (stretcher bond). Half units at the ends of courses shall be turned so that the uncut end of the unit (header) forms part of the face of the panel to be exposed to the freeze-thaw cycles. Sufficient units shall be used to construct

37、a panel measuring between 0,25 m2 and 0,5m2. It is important that water does not enter the panel at the interfaces between the masonry units and the foam rubber. This may be prevented by lightly precompressing the panel horizontally and vertically using “T” bolts or eye bolts or similar which may be

38、 tightened by hand. A typical panel is shown in Figure 2. CEN/TS:772-22:20067 Dimensions in mm 12345762550Key: 1 Insulation 5 Mortar or rubber joint 2 Stretcher 6 Intimate contact between insulation and brickwork 3 Header 7 Wooden jacket 4 Area for location of thermocouple (shaded) Figure 2 Typical

39、test panel 8.3 Mortar Joints 8.3.1 General Test panels shall be constructed from units and a rapid setting high alumina cement mortar with a cement: sand ratio of 1: 4 by volume. A typical panel is shown in Figure 2. The units shall be arranged so that the vertical joints in one course are approxima

40、tely above the centre of a whole unit in the course beneath it. Half units at the ends of courses shall be turned so that the end of the unit forms part of the face of the panel to be exposed to the freeze-thaw cycles. The mortar joints shall be finished with a steel tool to give a flush or bucket h

41、andled finish as shown in Figure 3. Sufficient units shall be used to construct a panel measuring between 0,25 m2 and 0,5 m2. NOTE There are advantages and disadvantages associated with both jointing mediums. Mortar is more realistic but requires the laboratory to have available a skilled mason and

42、a means of lifting whole panels when they are saturated. Rubber joints may need sealing to prevent failures on the bed faces but are more easily assembled and can if necessary be dismantled after fewer than 100 cycles. It is also easier to freeze and thaw bricks the individual water absorption of wh

43、ich is known. CEN/TS:772-22:20068 8.3.2 Conditioning of Test Panels The test panel shall be allowed to cure in ambient laboratory conditions for 3 days and then completely immersed in a tank of water at room temperature for 7 days. 1213Key 1 Masonry unit 2 Flush finish to mortar joint 3 Bucket handl

44、ed finish to mortar joint Figure 3 Joint Finish 9 Procedure 9.1 General The test regime for mortared panels should commence within 30 minutes of removing the panels from the soaking tank. If this time is exceeded up to a maximum of 4 h then steps shall be taken to limit the evaporation of water by p

45、rotection with thermoplastics sheeting. If 4 h is exceeded then the panel shall be replaced in the immersion tank for a minimum of 20 h and a maximum of 24 h. When the panel is installed in the apparatus it shall be preconditioned before the freeze/thaw cycling commences by spraying the face of the

46、panel with a flood coat of water at ambient temperature at a rate of 6 0,5 l/min.metre width of test panel for 15 min 1 min. Ensure an unbroken flood coat of water through the use of a linear nozzle array at the top of the vertical test panel. Ensure that water does not enter the panel through the t

47、op of the panel. The test regime for rubber panels should commence within 2 h after removing the samples from the soaking tank, alternatively steps shall be taken to prevent drying of the test panels. This can be done by covering them with a plastic sheet or by storing them in a condition of 95 % RH

48、. Place the test panel in the test apparatus. Spray the panel to be tested with water at ambient temperature at a rate of 6 0,5 l/min.metre width of test panel for 15 min 1 min. Ensure an unbroken flood coat of water through the use of a linear nozzle array near the top of the vertical test panel. E

49、nsure that water does not enter the panel through the top of the panel. CEN/TS:772-22:20069 9.2 Freeze/Thaw Cycling 9.2.1 General During the freezing and thawing periods the temperature distributions over the exposed face of the panel and the rates of heat transfer shall be defined in 9.2.2 and 9.2.3. The panel is subjected to 100 freeze/thaw cycles and any damage is assessed as described in 9.3 and 10.1. 9.2.2 Freezing period The first freezing period shall last for 6 h 5 min. Each following freezing period