1、BRITISH STANDARD BS3712-2: 1973 Incorporating Amendment Nos.1 and2 Building and construction sealants Part 2: Methods of test for seepage, staining, shrinkage, shelf life and paintability UDC 691.58:620.1BS3712-2:1973 This British Standard, having been approved by the BuildingDivisional Council, was
2、published under the authorityofthe Executive Boardon 19October1973 BSI 08-1999 First published April1964 First revision October1973 The following BSI references relate to the work on this standard: Committee references B/89, B/89/1 Draft for comment72/11191 DC ISBN 0 580 07626 1 Co-operating organiz
3、ations The Committee, under whose supervision 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 A
4、ssociation British Rubber Manufacturers Association 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 Manufactu
5、rers Association Greater London Council Institution of Civil Engineers Insulation Glazing Association Mastic Asphalt Council and Employers Federation Metal Window Federation of Great Britain National Association of Putty and Building Mastics Manufacturers National Council of Building Material Produc
6、ers National Federation of Building Trades Employers Natural 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 Counc
7、il Individual manufacturers Amendments issued since publication Amd. No. Date of issue Comments 4861 August 1985 6818 September 1991 Indicated by a sideline in the marginBS3712-2:1973 BSI 08-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 General 1 1.1 Scope 1 1.2 De
8、finition 1 1.3 Sampling 1 2 Tests and methods 1 2.1 Seepage 1 2.2 Staining 1 2.3 Shrinkage 2 2.4 Text deleted 3 2.5 Shelf life 3 2.6 Paintability 4 Figure 1 Seepage test ring 5 Publications referred to 6BS3712-2:1973 ii BSI 08-1999 Foreword This British Standard was originally issued under the autho
9、rity of the Building Divisional Council, B/-, in1973 and has been amended and confirmed under the direction of the Elements and Components (of Diverse Materials) for Buildings Standards Committee in1985. For further information see the foreword in BS3712-1:1991 and the following standards: BSEN27390
10、, BSEN28394, BSEN29046, BSEN29048 and ISO9047. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligat
11、ions. Summary of pages This document comprises a front cover, an inside front cover, pagesi andii, pages1 to6, an inside back cover and a back 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 ins
12、ide front cover.BS3712-2:1973 BSI 08-1999 1 1 General 1.1 Scope This Part of BS3712 describes test methods for the following properties of building and construction sealants. 1) Seepage. 2) Staining. 3) Shrinkage. 4) Shelf life. 5) Paintability. NOTEThe titles of the British Standards referred to in
13、 this standard are listed on the page 6. 1.2 Definition For the purpose of this Part of this British Standard, the following definition applies: 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 bet
14、ween 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 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 t
15、he following determinations and methods of test shall be taken as follows: Select at random original unopened packages to provide sufficient material for the tests. Alternatively, select sufficient material at random from the bulk supply. Report any skin formation (which should be removed), any sepa
16、ration of components or foreign matter, and any variability between one sample and another. In special circumstances it may be appropriate to take single samples from a gun for specific tests. The method of sampling shall be reported. 2 Tests and methods 2.1 Seepage 2.1.1 General. The object of the
17、seepage test is to ascertain the extent to which the medium of a sealant may be liable to be removed from the solids of the sealant. This test is particularly applicable to one component non-curing sealants. 2.1.2 Apparatus. Three sets each comprising: 1) A brass ring conforming to Figure 1. 2) A fl
18、at bottomed metal200g weight greater than22mm diameter. 3) 10Whatman No. 1filter papers. 4) A piece of non-absorbent film such as polyethylene greater than25mm in diameter. 5) A glass plate of convenient size. 2.1.3 Procedure. Prepare3test assemblies, each as follows: Stand one brass ring, with its
19、chamfered edge downwards, centrally on a pad of10filter papers, which has previously been placed on a glass plate. Fill the brass ring with sealant and knife off level with the top of the ring. Place a piece of non-absorbent film on top of the ring, then stand a200g weight on top of the film central
20、ly over the ring. Store each of the test assemblies at room temperature in the dark, one for72h, one for7days and one for14days. Examine each assembly at the end of the storage period. 2.1.4 Reporting. Record the degrees of seepage spread (S 1 , S 2 , S 3 ) and seepage depth (d 1 , d 2 , d 3 ) 2.2 S
21、taining 2.2.1 General. The staining tests are used to assess the visual effect which any separated medium may have on an absorbing building material. 2.2.2 Staining by seepage. The seepage values obtained in the test described in2.1 indicate the extent to which the specimen may lose its medium to th
22、e surrounding surface when in use. where d 1 = the number of filter papers penetrated by the medium of the sealant after72h, d 2 = the number of filter papers penetrated by the medium of the sealant after7days, d 3 = the number of filter papers penetrated by the medium of the sealant after14days. S
23、1 = the distance in millimetres from the periphery of the brass ring to the farthest point of seepage on the top filter paper after72h, S 2 = the distance in millimetres from the periphery of the brass ring to the farthest point of seepage on the top filter paper after7days, S 3 = the distance in mi
24、llimetres from the periphery of the brass ring to the farthest point of seepage on the top filter paper after14days.BS3712-2:1973 2 BSI 08-1999 Whether staining takes place or not, undue seepage represents a defect in the sealant under test. Nevertheless the degree to which the colour of a stain con
25、trasts with the colour of the material stained is the real criterion of the effect of staining. This can best be assessed by observing the effect of the sealant on a sample of the substrate to be used in practice. 2.2.2.1 Apparatus. The following apparatus is required: 1) Sample of substrate. 2) Con
26、stant temperature enclosure at40 2 C. 2.2.2.2 Procedure. Take a sheet, slab, tile or block of the relevant building material, having first applied any sealer recommended by the sealant manufacturer, and press a pad of sealant not less than25mm 25mm 5mm thick firmly into contact with the particular s
27、urface of the material to which it is desired to apply the sealant in practice. After two weeks at room temperature and after a further two weeks in the constant temperature enclosure controlled at40 2 C, observe and report any staining of the building material. 2.2.3 Staining by alkaline reaction.
28、Some sealants and/or primers may stain due to reaction with the free lime in fresh mortar or concrete. The test below is suggested as a means of assessing such eventualities. 2.2.3.1 Apparatus. The following apparatus is required: 1) A freshly prepared mortar block. 2) A constant temperature enclosu
29、re at25 1 C and50 5% relative humidity. 3) A split ring mould12mm deep 75mm diameter. 4) A glass plate of convenient size. 5) A piece of polyethylene, polypropylene or nylon to form a cylindrical mandrel12mm deep 20mm diameter. 6) Gummed paper tape. 7) A beaker containing400ml of distilled or deioni
30、zed water. 2.2.3.2 Procedure. The mortar mix shall consist of: 1part by weight of white Portland cement complying with the requirements of BS12; 0.2parts by weight of hydrated high calcium lime complying with BS890; 3.5parts by weight of white sand complying with BS4550-6; and sufficient water to fo
31、rm a smooth paste. The cement, lime and sand shall be mixed dry with a trowel on a non-absorbent, non-metallic surface until the mixture is uniform. The water shall then be added and the whole mixed thoroughly. The mortar mix shall then be cast in a split ring mould approximately10mm in depth and75m
32、m in diameter stood on a smooth glass plate. A central smooth bore cylindrical hole, about20mm diameter, shall be formed by standing in the centre of the ring a20mm cylindrical mandrel of polythene or similar material to which the mortar will not adhere. The mortar shall be allowed to set for3 h at2
33、5 C in moist air under a damp cloth. After setting, the central mandrel shall be removed. When the sealant manufacturer recommends that a primer shall be used on concrete, half the area of the upper surface of the mortar block and the inner surface of the central hole shall be coated with primer acc
34、ording to the manufacturers directions. Sufficient of the sealant, mixed if multi-part, shall then be applied to the mortar block by first completely filling the hole and then spreading the remainder evenly over the whole of the top surface of the mortar block to a thickness between6mm and10mm. If t
35、he sealant is of the self-levelling type it will be necessary to erect a temporary barrier, which may be of gummed paper tape, around the periphery of the block to prevent the sealant flowing over the edge. The assembly shall be then stored in a conditioning chamber at25 1 C and50 5% relative humidi
36、ty for24h, after which it shall be removed from the conditioning chamber and inspected for staining. The specimen shall be completely immersed in400ml of distilled or deionized water at room temperature for1min, and then returned to the conditioning chamber. This process shall be repeated every24h f
37、or14 days. The first appearance of discolouration shall be taken as evidence of staining. If no discolouration occurs after14days the test shall be terminated. The report shall state whether the staining occurred on the primed surface or the unprimed surface. 2.3 Shrinkage 2.3.1 General. The object
38、of the shrinkage test is to provide a measure of the reduction of the volume of a sealant with age. The test must therefore be continued over a period until it appears that significant shrinkage has ceased. Shrinkage at room temperature may be very slow, and an accelerated test is therefore given, t
39、he results of which must be assessed in conjunction with those obtained at room temperature. Care should be taken in interpreting results of accelerated tests as blowing may occur with some sealants at elevated temperatures.BS3712-2:1973 BSI 08-1999 3 2.3.2 Apparatus. The following apparatus is requ
40、ired: 1) A tin or aluminium flanged dish50mm to75mm in diameter, 6 2mm deep. A small hole is made in the flange through which a fine wire may be threaded. The other end of the wire is looped for attachment to the stirrup of a balance. 2) A balance capable of weighing up to200g and accurate to0.01g.
41、3) A beaker of suitable dimensions containing sufficient water at20 2 C to cover the suspended dish. A small quantity 1)of wetting agent shall also be added to the water. 4) An Archimedes bridge. 5) An oven complying with the requirements of BS2648. 2.3.3 Preparation of the specimen 1) For single pa
42、rt sealants. No preparation is necessary for single part sealants except that pre-formed sealants should be moulded with as little effort as possible into shapes capable of fitting into the test dish. 2) For multi-part sealants. Mix together the constituent parts of the sealant in any convenient con
43、tainer before placing immediately into the test dish, after previously having determined the volume of the dish by the method described below. 2.3.4 Procedure 1) Weigh the dish in air (W 1 ) and in water (W 2 ). 2) Dry the dish and fill it with sealant, taking care not to occlude air; strike off the
44、 sealant level with the top of the dish. Weigh in air (W 3 ) and in water (W 4 ). 3) Allow as much water as possible to drain from the sample after determining initial volume, and leave the dish in a ventilated dust-free atmosphere at room temperature for14days. Weigh in air and in water. Repeat, at
45、 intervals of7days, until both weights do not differ from the corresponding penultimate weights by more than0.1%. The final weights shall be W 5and W 6in air and water respectively. 4) Allow as much water as possible to drain from a fresh sample after determining initial volume, and leave dish in th
46、e oven at70 2 C for7days. Allow to cool in a dust-free atmosphere for at least20 min; weigh in air and in water. Return to the oven and repeat at convenient intervals of not less than24h, until both weights do not differ from the corresponding penultimate weights by more than0.1%. The final weights
47、shall be W 7and W 8in air and water respectively. 5) Reporting. Calculate the volumes as follows: The percentage volume shrinkage at room temperature (L n ) is given by: The percentage volume shrinkage by accelerated test (L a ) is given by: 2.4 Text deleted. 2.5 Shelf life The shelf life of a build
48、ing sealant is the period of time during which the sealant in its original unopened containers and packages and stored in defined conditions remains unimpaired. It shall be workable, capable of application by its appropriate method and shall behave satisfactorily in practice, even though some unimpo
49、rtant changes in properties may have occurred in storage. 1) 1:10000 appropriate. V 0 = W 1 W 2 V 2 = W 3 W 4 V 1 = V 2 V 0 V n = W 5 W 6 V 0 V a = W 7 W 8 V 0 where V 0 = volume of apparatus in ml V 2 = volume of sealant and apparatus in ml V 1 = initial volume of sealant in ml V n = final volume of sealant after shrinkage in ml V a = final volume of sealant after accelerated shrinkage in ml L n V 1 V n ()100 V 1 - = L a V 1 V a ()100 V 1 -
