1、BRITISH STANDARD BS 1446:1973 Specification for Mastic asphalt (natural rock asphalt fine aggregate) for roads and footways UDC 625.851+625.885.1:665.775.4BS1446:1973 This British Standard having beenapproved by the Road Engineering Industry StandardsCommittee, was published under the authority ofth
2、e Executive Board on 20July1973 BSI 07-1999 First published as BS 596:1935 First revision 1945 Second revision as BS 1446 August 1948 Third revision August 1962 Fourth revision July 1973 The following BSI references relate to the work on this standard: Committee reference RDE/3 Draft for comment 70/
3、33874 ISBN 0 580 07734 9 Co-operating organizations The Road Engineering Industry Standards Committee, under whose supervision this British Standard was prepared, consists of representatives of the following Government departments and scientific and industrial organizations: Asphalt and Coated Macad
4、am Association* Association of Consulting Engineers British Quarrying and Slag Federation* British Tar Industry Association Cement and Concrete Association Concrete Society Contractors Plant Association County Surveyors Society* Department of the Environment* Department of the Environment (Transport
5、 and Road Research Laboratory)* Federation of Civil Engineering Contractors Federation of Manufacturers of Construction Equipment and Cranes Greater London Council* Institute of Petroleum* Institute of Quarrying Institution of Civil Engineers Institution of Highway Engineers* Institution of Municipa
6、l Engineers* Institution of Structural Engineers Ministry of Defence (Army) Refined Bitumen Association* Road Emulsion Association Road Surface Dressing Association Sand and Gravel Association* Society of Chemical Industry* Individual experts The Government departments and scientific and industrial
7、organizations marked with an asterisk in the above list, together with the following, were directly represented on the committee entrusted with the preparation of this British Standard: London Chamber of Commerce Incorporated Individual experts Amendments issued since publication Amd. No. Date of is
8、sue CommentsBS1446:1973 BSI 07-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Definitions 1 3 Sampling and testing 1 4 Asphaltic cement 1 5 Natural rock asphalt fine aggregate 2 6 Coarse aggregate 2 7 Manufacture and composition 2 8 Remelting on site 3 App
9、endix A Recommendations for laying 4 Appendix B Information to be given with enquiry and/or order 5 Appendix C Grading of coarse and free aggregate using imperial screeningequipment 5 Table 1 Properties of asphaltic cement 2 Table 2 Percentage and grading of coarse aggregate 3 Table 3 Composition by
10、 analysis of mastic asphalt 3 Table 4 Percentage and grading of coarse aggregate (imperial sieves) 5 Table 5 Composition by analysis of mastic asphalt (imperial sieves) 5 Publications referred to Inside back coverBS1446:1973 ii BSI 07-1999 Foreword This British Standard was first published in1948, u
11、nder the authority of the Road Engineering Industry Standards Committee, and revised in1962. The standard has now been revised as part of the national policy to change to the metric system. NOTEAttention is drawn to certification facilities offered by the British Standards Institution. Seethe inside
12、 back cover of this standard. 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 obligations. Summary of
13、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 inside front cover.B
14、S1446:1973 BSI 07-1999 1 1 Scope This British Standard gives requirements for mastic asphalt with natural rock asphalt fine aggregate for roads and footways. Appendix A and Appendix B contain, respectively, recommendations for laying and a list of information to be given in enquiries and/or orders.
15、NOTE 1It is appreciated that with the publication of this metric standard it would be impractical for suppliers to be contractually obliged to supply to the metric grading limits given in Table 2 and Table 3. During the transitional period from imperial to metric units and until such time as screeni
16、ng equipment based on imperial sizes is replaced by new equipment conforming to metric requirements, material supplied to the grading limits given in BS1446:1962will be considered equally applicable with material supplied to the grading limits given in Table 2 and Table 3 of this standard. For this
17、purpose the1962limits are given in Appendix C of this edition. The supplier should, however, state in his advice note to the purchaser whether he has supplied to imperial or metric grading limits. NOTE 2The titles of the British Standards referred to in this standard are listed on the inside back co
18、ver. 2 Definitions For the purposes of this British Standard the following definitions, which have been extracted from BS892, apply: 2.1 bitumen a viscous liquid, or a solid, consisting essentially of hydrocarbons and their derivatives, which is soluble in carbon disulphide; it is substantially non-
19、volatile and softens gradually when heated. It is black or brown in colour and possesses water proofing and adhesive properties. It is obtained by refinery processes from petroleum and is also found as a natural deposit or as a component of naturally occurring asphalt, in which it is associated with
20、 mineral matter 2.2 asphalt a general term for certain mixtures of asphaltic cement and mineral matter NOTEThis term is normally qualified by the indication of the origin (e.g.natural rock asphalt, Trinidad Lake asphalt) or type (e.g.mastic asphalt, rolled asphalt). 2.3 natural rock asphalt a natura
21、lly occurring calcareous rock impregnated with bitumen by a natural process NOTEThe term is here interpreted in a restricted geological sense and specifically excludes all other types of rock such as result from sporadic bitumen in any mode of occurrence in non-bituminous limestone, or in limestone
22、of low grade impregnation, non-bituminous limestones, and artificial mixtures thereof with any bitumen of any source and description. 2.4 lake asphalt a highly viscous natural asphalt found in well-defined surface deposits 2.5 asphaltic cement bitumen, a mixture of lake asphalt and bitumen, or lake
23、asphalt and flux oils or pitch or bitumen, having cementing qualities suitable for the manufacture of asphalt pavements 2.6 mastic asphalt a type of asphalt composed of suitably graded mineral matter and asphaltic cement in such proportions as to form a coherent, voidless, impermeable mass, solid or
24、 semi-solid under normal temperature conditions, but sufficiently fluid when brought to a suitable temperature to be spread by means of a float 3 Sampling and testing When samples, whether of the asphaltic cement, the aggregate or the mastic asphalt, are required for testing, the purchaser and the s
25、upplier shall agree on the number of samples to be taken. The samples so taken shall be identified by the supplier and one-half retained by the purchaser for the purpose of such tests as he may require. Sampling and testing shall be carried out in accordance with the appropriate British Standards, a
26、s follows: 4 Asphaltic cement The asphaltic cement shall comply with Table 1, Column1,2 or3 as specified by the purchaser. Asphaltic cements and their constituents: determination of ash content BS 4450 determination of solubility BS 4690 determination of penetration BS 4691 determination of softenin
27、g point (ring and ball) BS 4692 determination of loss on heating BS 4707 Natural rock asphalt (as specified inclause5) BS 598 Coarse aggregate (as specified in clause6) BS 812 Mastic asphalt BS 598BS1446:1973 2 BSI 07-1999 Table 1 Properties of asphaltic cement 5 Natural rock asphalt fine aggregate
28、The natural rock asphalt shall be imported in its raw state as mined, so as to be available to the Engineer for sampling and testing. The mass of the natural rock asphalt in any specific contract shall be certified, if desired, by the purchaser. The natural rock asphalt, after crushing and grinding,
29、 shall comply with the following requirements: 1) It shall contain not less than6% and not more than10% inherent bitumen. The bitumen content shall be determined by the appropriate method described in BS598, except that: a) Tests shall be carried out on two separate samples, each weighing not less t
30、han50g, dried at100 C to constant mass. b) The value reported shall be the mean of the two results, provided that neither result differs from that mean by more than0.25%. Should the difference be greater than0.25% the test shall be repeated. 2) The apparent specific gravity shall be not less than1.9
31、nor more than2.5. 3) The limestone after extraction not the bitumen shall contain not less than 90% of calcium carbonate. 6 Coarse aggregate The coarse aggregate shall be of approved quality and free from dust. It shall consist of clean crushed igneous or calcareous rock. For use on footways it may
32、alternatively consist of siliceous material obtained from natural deposits either directly or by screening, crushing, or other mechanical process. The percentage and size of the coarse aggregate incorporated in the mastic asphalt will depend primarily on the thickness of the finished course, and sha
33、ll lie within the applicable limits given in Table 2 (Table 4, Appendix C, for imperial gradings). 7 Manufacture and composition The natural rock asphalt shall be ground to a powder so that it shall all pass a2.36mm sieve and not less than5% shall pass a75mm sieve. The rock asphalt powder shall be m
34、ixed with the requisite percentage of asphaltic cement at a temperature of from175 C to215 C and when not required for immediate use shall be cast into blocks weighing about25kg. At this stage the mastic asphalt shall show on analysis a composition within the limits of Column1 or2 of Table 3. When t
35、he mastic asphalt is to be transported direct from the factory to the site of work in portable mechanically driven mixers the requisite percentage of coarse aggregate shall be added after the addition of the rock asphalt as provided for above. The composition of the mix shall on analysis conform to
36、the requirements of Table 3 (or Table 5, Appendix C, for imperial gradings) after the percentage mass of material retained on the6004mBS sieve has been allowed for. Property Asphaltic cement 1 2 3 Bitumen Refined lake asphalt (fluxed) Equal proportions by mass of bitumen of appropriate penetration a
37、nd refined lake asphalt min. max. min. max. min. max. Penetration at 25 C Softening point (ring and ball) Loss on heating for 5 hours at163 C Penetration of residue after heating (percentage of original penetration) Solubility in carbon disulphide or trichloroethylene Mineral matter (ash) ( C) (%) (
38、%) (%) 5 65 60 99 20 95 2.0 0.5 5 65 60 55 29 20 95 2.0 65 35 5 65 60 75 17 20 95 2.0 79 19BS1446:1973 BSI 07-1999 3 Table 2 Percentage and grading of coarse aggregate Table 3 Composition by analysis of mastic asphalt 8 Remelting on site For the remelting of the mastic asphalt on site the blocks sha
39、ll be broken into pieces of suitable size and loaded into a mechanically agitated mixer, conveniently placed in relation to the site. The material shall then be heated to a temperature of175 C to230 C and thoroughly incorporated with the requisite quantity of coarse aggregate (see Table 2 and Table
40、4) which shall be added to the mixer. After all the coarse aggregate has been incorporated, the material shall be mixed continuously for a period of not less than one hour before laying is begun and mixing shall be continued until laying operations are completed so as to maintain the coarse aggregat
41、e in suspension. At no stage during the process of mixing shall the temperature exceed230 C. Work Percentage of coarse aggregate Grading of coarse aggregate Passing BS sieve Percentage Footways finished course thickness 20 mm 35 mm 1530 6.3 mm 600 4m 100 015 Carriageways finished course thickness 25
42、 mm 40 mm 3040 20 mm 14 mm 2.36 mm 100 90100 05 40 mm 50 mm 4050 1 2 (Swiss rock asphalt) (All other natural rock asphalt) Percentage by mass of mastic asphalt min. max. min. max. Soluble bitumen 13 16 17 20 Mineral matter: Passing BS sieve 75 4m 212 4m 600 4m 2.36 mm Retained BS sieve 75 4m 212 4m
43、600 4m 45 5 5 0 65 20 20 5 45 5 5 0 65 20 20 5 NOTEWhen rock asphalts to which Column 2 is applicable are blended with rock asphalts to which Column 1 is applicable, the percentage of soluble bitumen in the resultant mastic asphalt is adjusted in accordance with the proportion of each type of rock a
44、sphalt so used, and the proportions of the rocks used and the soluble bitumen used are stated. The mastic asphalt so produced should comply in all other respects with the provisions of this specification.BS1446:1973 4 BSI 07-1999 Appendix A Recommendations for laying A.1 General The surface on which
45、 the mastic is to be laid should be made good and adjusted to a contour approximating to the final contour and swept clean. The method of laying should be in accordance with the following recommendations. A.2 Contour The crossfall of roads with a straight crossfall should be not more than2.5% and no
46、t less than2.0% unless otherwise directed by the Engineer. With roads to be cambered the average fall of the finished surface from the crown to the channel should be not more than3.3% and not less than2.2%. These recommendations for crossfall do not apply to curves with superelevation. A.3 Spreading
47、 The mastic asphalt when prepared should be laid, normally in one coat, at a temperature between175 C and230 C and spread uniformly by hand with wooden floats on the prepared and regulated surface. The thickness of the mastic asphalt and percentage of added coarse aggregate should be in accordance w
48、ith the provisions of Table 2 or Table 4 or as specified by the Engineer. Where necessary, battens of the requisite dimensions should be employed. A.4 Surface finish of carriageways Unless otherwise specified by the Engineer the asphalt for carriageways, while still warm and in a plastic condition,
49、should be covered with a layer of approved coated, hard14mm or20mm chippings. The chippings, prior to application, should comply with BS63and be clean; the coating should be1.5% to2.5% of asphaltic cement of medium penetration (e.g.4080penetration at25 C). To enable the chippings to carry the specified proportion of asphaltic cement2% to3% of filler should be added either before or after the addition of the asphaltic cement. The chippings should be evenly distributed at the rate of7.5kg/m 2to10.0kg/m 2for14mm chippin
