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1、BRITISH STANDARD BS 3712-3: 1974 Incorporating Amendment Nos. 1 and 2 Building and construction sealants Part 3: Methods of test for application life, skinning properties and tack-free time UDC 691.58:620.1 BS 3712-3:1974 This British Standard, having been approved by the Building Divisional Council
2、, was published under the authority of the Executive Board on 31 January 1974 BSI 03-1999 The following BSI references relate to the work on this standard: Committee references B/89, B/89/1 Draft for comment68/26713 ISBN 0 580 07828 0 Co-operating organizations The Committee, under whose supervision
3、 this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Association of Synthetic Rubber Manufacturers British Rubber and Resin Adhesive Manufacturers Association British Rubber Manufacturers Assoc
4、iation British Tar Industries Association British Whiting Federation Chemical Industries Association Limited Confederation of British Industry Department of the Environment Department of the Environment Building Research Establishment Flat Glass Manufacturers Association Greater London Council Insti
5、tution of Civil Engineers Insulation Glazing Association Mastie Asphalt Council and Employers Federation Metal Window Federation of Great Britain National Association of Putty and Building Mastics Manufacturers National Council of Building Material Producers National Federation of Building Trades Em
6、ployers National Rubber Producers Association Royal Institute of British Architects Sealant Applicators Association Sealant Manufacturers Conference Society of Chemical Industry Welwyn Hall Research Association Whiting and Industrial Powders Research Council Individual manufacturers Amendments issue
7、d since publication Amd. No.Date of issueComments 4860August 1985 6819September 1991 Indicated by a sideline in the margin BS 3712-3:1974 BSI 03-1999i Contents Page Co-operating organizationsInside front cover Forewordii 1General1 1.1Scope1 1.2Definition1 1.3Sampling1 2Tests and methods1 2.1Applicat
8、ion life1 2.2Text deleted1 2.3Skinning properties1 2.4Tack-free time2 2.5Text deleted2 Appendix A Text deleted4 Figure 1 Figure deleted2 Figure 2 Figure deleted2 Figure 3 Figure deleted2 Figure 4 Figure deleted2 Figure 5 Tack-free time test specimen3 Figure 6 Figure deleted2 Figure 7 Figure deleted2
9、 Publications referred toInside back cover BS 3712-3:1974 ii BSI 03-1999 Foreword This British Standard was originally issued under the authority of the Building Divisional Council, B/-, in 1974 and has been amended and confirmed under the direction of the Elements and Components (of Diverse Materia
10、ls) for Buildings Standards Committee in 1985. For further information see the foreword in BS 3712-1:1991 and the following standards: BS EN 27390, BS EN 28394, BS EN 29046, BS EN 29048 and ISO 9047. A British Standard does not purport to include all the necessary provisions of a contract. Users of
11、British Standards are responsible for their correct application. Compliance 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, pages i and ii, pages 1 to 4, an inside back cover and a back
12、cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. BS 3712-3:1974 BSI 03-19991 1 General 1.1 Scope This Part of BS 3712 describes test methods for the following properties of bu
13、ilding and construction sealants. 1) Application life. 2) Skinning properties. 3) Tack-free time. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 1.2 Definition For the purposes of this Part of this British Standard the following definition applie
14、s: building sealant a joint sealant for buildings, applied by hand, gun, knife, or trowel, or in strip form, or by pouring, and intended to maintain a seal between the sides of a joint which is subject to some degree of movement. The strip form materials covered by this definition are plastic at the
15、 time of application, i.e. readily deformable but not capable of reverting to their original shape 1.3 Sampling The samples of building sealants to be used in the following determinations and methods of test shall be taken as follows: Select at random sufficient original unopened packages to provide
16、 material for the tests. Alternatively, select sufficient material at random from the bulk supply. Report any skin formation (which should be removed), any separation of components or foreign matter, and any variability between one sample and another. In special circumstances it may be appropriate t
17、o take single samples from a gun for specific tests. The method of sampling shall be reported. 2 Tests and methods 2.1 Application life 2.1.1 General. This test is applicable to multi-part sealants. The object of the test for application life is to provide an indication of the useful life of the sea
18、lant taken from freshly opened containers and mixed in accordance with the manufacturers instructions. 2.1.2 Apparatus. The following apparatus is required: 1) A clean cylindrical container 65 mm diameter and 50 mm height (approx.). 2) Aluminium alloy surface mill finished, of grade 6063 T6 or 6082
19、T6 as specified in BS 1474 or grade 6082 T6 as specified in BS 1470. 3) A flat bladed spatula or power stirrer. 4) Containers for storing components and sealant. 5) Enclosure maintained at 25 2 C and 50 5 % r.h. 2.1.3 Preparation of specimen. The container shall be thoroughly cleaned. Suitable quant
20、ities of the components in closed containers, together with clean cylindrical container, shall be conditioned for at least 16 h at in the enclosure. Appropriate amounts of the base component and of the curing component shall be mixed thoroughly in the cylindrical container at 25 2 C, either by hand
21、for 10 min, using a spatula or by using a power stirrer until uniform mixing is achieved. It is essential that the curing component is evenly dispersed throughout the base component. Particular care shall be taken when mixing the parts to avoid or eliminate all air bubbles. 2.1.4 Cleaning of test su
22、rface. The aluminium test piece shall be cleaned with water, detergent solution or solvents to remove major contamination. The surface shall then be cleaned using butanone (ethyl methyl ketone) or similar solvent and washed with a dilute detergent solution. Finally the surface shall be rinsed in ind
23、ustrial methylated spirits and air dried. 2.1.5 Procedure. The mixed samples shall be stored uncovered at in the enclosure. Not less than h before the expected expiry time of the application life, and thereafter at 10 min intervals, tests shall be performed to check that the sample is capable of bei
24、ng applied by a spatula without difficulty on to the aluminium surface. 2.1.6 Reporting. The application life is reported as the total time between the completion of mixing and the last test in which the sealant is easily applied to and readily adheres to the aluminium surface. 2.2 Change in consist
25、ency (using the constant load penetrometer) Clause 2.2 Text deleted 2.3 Skinning properties 2.3.1 General. This test is particularly applicable to sealants which are intended to form a skin but remain soft underneath. The object of the test is to establish the presence of a skin on the surface. BS 3
26、712-3:1974 2 BSI 03-1999 2.3.2 Apparatus. A shallow tin 50 mm diameter and 10 mm deep approximately. 2.3.3 Preparation of specimen. The tin shall be filled with the sealant and be exposed at room temperature. Other conditions of exposure may be specified. 2.3.4 Procedure. The surface of the sealant
27、is gently drawn back at intervals with a probe or needle. The skin will be indicated as a rupture in the displaced surface. 2.3.5 Reporting. Report the time taken for the skin to form to the nearest 12 h and the conditions under which it was exposed. The specimen may be left for a period and the con
28、dition of the skin reported e.g. smooth, wrinkly, thick, thin, oily or readily detached. 2.4 Tack-free time 2.4.1 General. The object of this test is to determine the time required for the surface of the sealant to become tack-free. The test is applicable to sealants which are intended to develop ta
29、ck-free surfaces within a limited period when exposed to normal atmospheric conditions. 2.4.2 Apparatus. A flat base plate (e.g. aluminium) with a non-absorbent surface 175 mm 75 mm. A flat sheet of metal 50 mm 25 mm weighing approximately 15 g. Pieces of polyethylene sheet 85 mm 30 mm 0.025 mm. A c
30、onstant temperature enclosure unless otherwise agreed controlled at 25 1 C and 80 5 % relative humidity. Care should be taken to provide ample volume when dealing with solvent release sealants. 2.4.3 Preparation of specimen. The metal base plate shall be clean and dry. The polyethylene shall be clea
31、n, dry and free from cuts or wrinkles. The sealant or its components shall be conditioned in closed containers at 25 1 C for not less than 16 h. 2.4.4 Procedure. Spread the sealant (after mixing for multi-part sealants) on to the non absorbent surface and draw a template across the sealant to produc
32、e a layer of sealant with a smooth surface measuring 150 mm 65 mm 3 mm. The sealant shall then be exposed in the constant temperature enclosure or under other conditions as specified. After a specified interval of time place a piece of polyethylene upon the surface of the sealant. Following this, pl
33、ace the metal plate (weight 15 g) upon the polyethylene for not less than 10 s, and not more than 20 s. (see Figure 5). Remove the plate and slowly peel back the polyethylene at 90 from the surface. The test is repeated at suitable intervals after further periods of exposure using fresh pieces of po
34、lyethylene on the undisturbed areas of the sealant. 2.4.5 Reporting. Report the tack-free time as the time between the application of the sealant to the non-absorbent surface and the time when there is no transfer of sealant to the polyethylene. NOTEWith pouring grade sealants a mask or frame to con
35、tain the sealant may be necessary. 2.5 Text deleted Figure 1 Figure deleted Figure 2 Figure deleted Figure 3 Figure deleted Figure 4 Figure deleted Figure 6 Figure deleted Figure 7 Figure deleted BS 3712-3:1974 BSI 03-19993 Figure 5 Tack-free time test specimen BS 3712-3:1974 4 BSI 03-1999 Appendix
36、A. Text deleted BS 3712-3:1974 BSI 03-1999 Publications referred to BS 1470, Wrought aluminium and aluminium alloys for general engineering purposes. Plate, sheet and strip. BS 3712, Building and construction sealants. BS 3712-1, Methods of test for homogeneity, relative density and penetration. BS
37、EN 27390, Building construction Jointing products Determination of resistance to flow1). BS EN 28394, Building construction Jointing products Determination of extrudability of one-component sealants1). BS EN 29046, Building construction Sealants Determination of adhesion/cohesion properties at const
38、ant temperature1). BS EN 29048, Building construction Jointing products Determination of extrudability of sealants using standardized apparatus1). ISO 9047, Building construction Sealants Determination of adhesion/cohesion properties at variable temperature1). 1) Referred to in the foreword only. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - o - o - - - - - - - - - - - - - - - - - - - - - - - - -