1、BRITISH STANDARD BS4046:1991 Specification for Compressed straw building slabsBS4046:1991 This British Standard, having been prepared under the directionof the Timber StandardsPolicy Committee, waspublished under the authorityof the Board ofBSIandcomes into effect on 28February1991 BSI 11-1999 First
2、 published July1966 Metric version published as BS4046-2: November 1971 Second edition February1991 The following BSI references relate to the work on this standard: Committee reference TIB/10 Draft for comment89/17168DC ISBN 0 580 19168 0 Committees responsible for this British Standard The prepara
3、tion of this British Standard was entrusted by the Timber Standards Policy Committee (TIB/-) to Technical Committee TIB/10, upon which the following bodies were represented: Association of Building Component Manufacturers British Woodworking Federation Department of the Environment (Building Researc
4、h Establishment) Department of the Environment (Construction Industries Directorate) Department of the Environment (Property Services Agency) Fibre Building Board Organisation (FIDOR) Furniture Industry Research Association Royal Institute of British Architects Timber Research and Development Associ
5、ation Timber Trade Federation Amendments issued since publication Amd. No. Date CommentsBS4046:1991 BSI 11-1999 i Contents Page Committees responsible Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Classification 1 4 Tests for performance and physical characteristics 2 5 Dimensional tole
6、rances 2 6 Taper profile 2 7 Squareness 2 8 Mass 3 9 Moisture content 3 10 Modulus of elasticity 3 11 Bending strength 3 12 Resistance to impact 3 13 Screw holding 3 14 Thermal conductivity 3 15 Boron content 3 16 Dimensional changes associated with changes in relative humidities 3 17 Marking 3 Appe
7、ndix A Methods of test 4 Appendix B Guidance on the use of compressed straw building slabs 14 Figure 1 Typical arrangement of longitudinal voids 1 Figure 2 Profile of taper edged slabs 3 Figure 3 Positions for measurements of slab thickness and taper depth 5 Figure 4 Measurement of squareness of boa
8、rds 6 Figure 5 Test apparatus for determining the modulus of elasticity and bending strength 8 Figure 6 Load deflection curve for determining the modulus of elasticity 9 Figure 7 Impact strength test rig 11 Table 1 Summary of tests for performance and physical characteristics 2 Table 2 Test levels f
9、or dimensional tolerances 2 Table 3 Test levels for slab mass 3 Table 4 Test levels for modulus of elasticity and bending strength 3 Publication(s) referred to Inside back coverBS4046:1991 ii BSI 11-1999 Foreword This British Standard has been prepared under the direction of the Timber Standards Pol
10、icy Committee. It supersedes BS4046-2:1971, which is withdrawn. The first standard for compressed straw building slabs was published in1966. A metric version was published in1971 as BS4046-2. The first edition then became BS4046-1 and was withdrawn in1983. This revision includes a number of alterati
11、ons and additions to reflect changes in the manufacture and applications of compressed straw slabs in recent years. Compressed straw slabs are no longer used for roof decking applications, and references to such applications have been deleted. Similarly, reference to facings treated to meet class1 s
12、pread of flame in accordance with BS476-7 has been deleted as such slabs are no longer manufactured. Requirements for both50mm and58mm thick slabs are now included, with both square and tapered edges. The composition has been extended to include the incorporation of additives to the straw core to av
13、oid insect infestation in certain environments of use. It is indicated which test methods are routine tests carried out as part of the production process, and which are considered as type tests required when a change in the manufacturing method occurs which may affect performance characteristics. Ad
14、ditional test methods are included, covering the determination of tapered edge profile, bending strength, modulus of elasticity, resistance to impact, withdrawal of wood screws, boron content, and dimensional changes associated with changes in relative humidities. The question of providing precision
15、 data for the methods of test has been considered by the technical committee, but it is deemed that such data is not applicable to non-homogeneous materials. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for thei
16、r 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, pagesi andii, pages1 to14, an inside back cover and a back cover. This standard has been updated (see co
17、pyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS4046:1991 BSI 11-1999 1 1 Scope This British Standard specifies requirements for compressed straw building slabs when used internally in buildings. The classification of
18、slab types, their performance characteristics and physical properties, test methods and marking requirements are specified. Appendix A gives methods of sampling, conditioning and preparation of test specimens and test pieces and methods of tests. Appendix B gives guidance on the use of compressed st
19、raw building slabs. This includes particular reference to the need for proper sealing of the cut edges to provide continuity of the surface covering and protection from moisture, mould growth and insect pests. NOTEThe titles of the publications referred to in this standard are listed on the inside b
20、ack cover. 2 Definitions For the purposes of this British Standard, the definitions given in BS6100-4 apply together with the following. 2.1 compressed straw slab slab consisting of natural straws compressed by heat and pressure, encased in and firmly bonded to facings of paper or other materials to
21、 form rectangular slabs NOTEThe core may contain insecticides and other additives. 2.2 lot quantity of slabs manufactured under conditions which are presumed uniform 2.3 test slab slab required for testing or from which pieces are cut for testing 2.4 test piece piece cut from a test slab 2.5 test sp
22、ecimen piece cut from a test piece to comply with the dimensional requirements specified in any of the appropriate tests. 3 Classification 3.1 General Compressed straw slabs are classified according to the composition of the core, the facings used and the profile of the longitudinal edge. 3.2 Compos
23、ition of core The composition of the core shall be as follows. Type A: with a solid core formed of untreated straw. Type B: with a solid core formed of straw treated during manufacture with boron-based insecticides. Type C: as A but with continuous voids formed longitudinally centrally in the straw
24、core, not exceeding23mm diameter, capable of accepting a conduit of20mm overall diameter and as shown in Figure 1. Type D: as B but with continuous voids arranged as described in C. 3.3 Facings The facings shall be of the following paper types. Type a: plain: paper facings suitable for accepting dir
25、ect decoration. Type b: plastering: paper facings suitable for accepting gypsum plaster skim coat (seeBS1191-1). Type c: showerproof: paper facings complying with the requirements for class A papers as specified in BS1521. Figure 1 Typical arrangement of longitudinal voidsBS4046:1991 2 BSI 11-1999 T
26、able 1 Summary of tests for performance and physical characteristics Table 2 Test levels for dimensional tolerances 3.4 Edge profile The profile of the longitudinal edge shall be of the following types. Type1: Square edge. Type2: Tapered edge, of which the dimensions of the taper shall be as given i
27、n clause6 and as shown in Figure 2. The following is an example of a full classification of a slab type: type Db(2), a boron-treated slab with longitudinal voids and plastering type facings and tapered longitudinal edges. 4 Tests for performance and physical characteristics NOTEMethods of sampling,
28、conditioning and preparation of test specimens and test pieces are given in A.1 and the methods of test for the various performance and physical characteristics are given inA.2 toA.13. 4.1 Routine tests Table 1 lists the routine tests that shall be carried out regularly during production. 4.2 Type t
29、ests Table 1 lists the type tests that shall be carried out whenever a change of method of manufacture is made that may affect the performance characteristics of the product. 5 Dimensional tolerances When measured in accordance withA.2 the dimensions of the slab shall be as given in Table 2. 6 Taper
30、 profile When measured in accordance withA.3, the tapered edges shall be within the following dimensions: a) depth of taper1.0mm to2.0mm; b) width of taper60mm to80min. 7 Squareness When measured in accordance withA.4, the deviation shall be not more than5mm/m measured on the1200mm side. Performance
31、/physical characteristics Size of test specimen Number of tests Test method appendix reference Requirement clause reference Routine Type Dimensional tolerances Taper profile Squareness Mass Moisture content Moisture content Modulus of elasticity Bending strength Resistance to impact Screw holding Th
32、ermal conductivity Boron content Dimensional changes Whole slab Whole slab Whole slab Whole slab 50g Whole slab 1200mm 300mm 1200mm 300mm Whole slab 100mm 100mm 300mm 300mm 5g to10g 1000mm 1000mm 1in20 1in100 1in100 1in20 1in100 1in100 1in300 6 6 6 6 6 6 2 2 2 4 2 6 2 A.2 A.3 A.4 A.5 A.6.1 A.6.2 A.7
33、 A.8 A.9 A.10 A.11 A.12 A.13 5 6 7 8 9 9 10 11 12 13 14 15 16 Work size Maximum manufacturing Minimum manufacturing Method of test Length mm 1 800 to3 600 in10mmincrements mm work size1.0 mm work size7.0 A.2.1 Width 1200 work size1.0 work size3.0 A.2.1 Thickness 50 and58 work size+3.0 work size1.0 A
34、.2.2 Thickness variation The thickness of the centre of the slab shall not exceed that at100mm from an edge by more than1.5mm. A.2.2BS4046:1991 BSI 11-1999 3 8 Mass When weighed in accordance withA.5, the mass of slabs shall be as given in Table 3. Table 3 Test levels for slab mass 9 Moisture conten
35、t When determined in accordance with one of the two methods described inA.6, the moisture content of the slabs when leaving the place of manufacture shall be within the range10% to18%. 10 Modulus of elasticity When tested in accordance withA.7, the modulus of elasticity shall be as given in Table 4.
36、 Table 4 Test levels for modulus of elasticityand bending strength 11 Bending strength When tested in accordance withA.8, the bending strength shall be as given in Table 4. 12 Resistance to impact When tested in accordance withA.9, the slab shall not fracture or exhibit residual deflection. 13 Screw
37、 holding When tested in accordance withA.10, the screw holding shall be not less than175N. 14 Thermal conductivity When measured in accordance withA.11, the thermal conductivity shall be not more than0.108W/(mK). 15 Boron content When measured in accordance withA.12, the mean boron content shall be
38、not less than0.1%, with a minimum of0.06%. 16 Dimensional changes associated with changes in relative humidities When measured in accordance withA.13 the increase in length and width after reconditioning at85% r.h. and35% r.h. shall be not more than0.3%. NOTEThickness swelling with change in relativ
39、e humidity has not been included because it is insignificant. 17 Marking Each slab shall be clearly and indelibly marked by the manufacturer on one edge with the following information: a) the number and date of this British Standard, i.e.BS4046:1991 1) ; and b) the manufacturers name, trade mark or
40、identification mark; and c) the slab classification, e.g.type Db(2). Thickness Minimum mass Maximum mass mm 50 58 kg/m 2 16.5 18.5 kg/m 2 22.5 24.5 Direction of test specimen Minimum modulus of elasticity Minimum bending strength Specimen cut parallel to longitudinal edge of slab N/mm 2 200 N/mm 2 0
41、.70 Specimen cut at right angles to longitudinal edge of slab 600 1.20 1) Marking BS4046:1991 on or in relation to a product represents a manufacturers declaration of conformity, i.e.a claim by or on behalf of the manufacturer that the product meets the requirements of the standard. The accuracy of
42、the claim is therefore solely the responsibility of the person making the claim. Such a declaration is not to be confused with third party certification of conformity, which may also be desirable. Figure 2 Profile of taper edged slabsBS4046:1991 4 BSI 11-1999 Appendix A Methods of test A.1 Methods o
43、f sampling, conditioning and preparation of test specimens and test pieces A.1.1 Sampling A.1.1.1 Samples for quality control tests during production shall be taken at random, and at a frequency as specified in Table 1. A.1.1.2 When a consignment (lot) is to be tested for type testing, six slabs sha
44、ll be taken at random. In order to enable all tests to be carried out on a consignment, the tests described inA.2 andA.5 shall be carried out first on each slab. Two slabs shall be taken and test specimens taken for the tests described inA.7 andA.8. Two further slabs shall be taken and test specimen
45、s taken for the test described inA.9. Two remaining slabs shall be taken and test specimens taken for the test described inA.13. One test specimen shall then be taken from each slab for the tests described inA.6 andA.12. One test specimen shall be taken from four slabs for the test described inA.10.
46、 One test specimen shall be taken from two slabs for the test described inA.11. A.1.2 Conditioning Unless precise conditioning is specified, the test specimens shall be conditioned by freely exposing them for at least48h to the atmosphere of a well-ventilated room. Where precise conditioning is spec
47、ified, the test specimens shall be conditioned to constant mass in an atmosphere of20 2 C and65 5%. NOTEConstant mass is considered to be achieved when two successive weighing operations carried out at an interval of24h do not differ by more than0.1% of the mass of the board or test piece. A.1.3 Pre
48、paration of test specimens Test specimens shall be whole slabs, or cut from whole slabs as specified in Table 1. All edges shall be cleanly cut at right angles to the slab surface. A.2 Determination of dimensions of slabs A.2.1 Determination of length and width A.2.1.1 Principle The length and width
49、 of whole slabs are determined by measurement with a metal tape or rule. A.2.1.2 Test specimens The test specimens shall be whole slabs of any size supplied by the manufacturer and conditioned in accordance withA.1.2. A.2.1.3 Apparatus A.2.1.3.1 General. Where the accuracy of the apparatus is specified the apparatus shall be periodically calibrated. A.2.1.3.2 Steel tapes, or rules of sufficient length to measure the greatest dimension of the test specimen graduated to allow a reading to an accuracy of1.0mm. A.2.1.4 Pr
