1、BRITISH STANDARD BS 812-104: 1994 Testing aggregates Part 104: Method for qualitative and quantitative petrographic examination of aggregatesBS812-104:1994 This British Standard, having been prepared under the direction of Technical Committee B/502, was published under the authority of the Standards
2、 Board and comes into effect on 15 September 1994 BSI 01-1998 The following BSI references relate to the work on this standard: Committee reference B/502 Draft for comment 88/13739 DC ISBN 0 580 22643 3 Committees responsible for this British Standard The preparation of this British Standard was ent
3、rusted by Technical Committee B/502 Aggregates, to Subcommittee B/502/6 Test methods, upon which the following bodies were represented: British Aggregate Construction Materials Industries British Civil Engineering Test Equipment Manufacturers Association British Steel Industry County Surveyors Socie
4、ty Department of Trade and Industry (National Measurement Accreditation Service) Department of Transport PSA Projects Ltd. Sand and Gravel Association Ltd. Coopted members Amendments issued since publication Amd. No. Date CommentsBS812-104:1994 BSI 01-1999 i Contents Page Committees responsible Insi
5、de Front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Principle 2 5 Sampling 2 6 Apparatus 2 7 Qualitative examination of the laboratory sample 2 8 Preparation of the test portions for quantitative evaluation 3 9 Quantitative examination of a test portion 4 10 Report 6 Annex A (norma
6、tive) Calculation of the required test portion masses for analysis 10 Annex B (normative) Determination of constituent proportions and calculation of relative errors and 95 % confidence limits 12 Annex C (informative) Bibliography 17 Figure 1 Mass of each test portion necessary to achieve a relative
7、 error of 10 % for a given constituent when using duplicate test portions 5 Figure 2 Chart for estimating errors involved in point-counting 8 Table 1 Minimum size of laboratory sample 2 Table 2 Minimum mass of each test portion required to give a relative error of 10 % for an estimated proportion of
8、 a constituent of interest of 20 %, when using duplicate test portions 3 Table 3 Preferred form for reporting the sample details and results of the qualitative examination 9 Table 4 Preferred form for tabulating the results of the quantitative examination 9 Table A.1 Minimum mass of test portion nee
9、ded for sieving 10 Table A.2 Recommended form for setting out the calculation of the required test portion mass of a coarse aggregate 11 Table A.3 Example of the calculation of the required test portion mass of a coarse aggregate 11 Table A.4 Recommended form for setting out the calculation of the r
10、equired test portion mass of a sand and of the number of points to count on thin sections 11 Table A.5 Example of the calculation of the required test portion mass of a sand 11 Table B.1 Recommended form for the calculation of the constituent proportions and standard deviations for coarse aggregates
11、 13 Table B.2 Example of the calculation of constituent proportions and standard deviations for coarse aggregates 14 Table B.3 Recommended form for combining the results from the analysis of duplicate test portions 14 Table B.4 Example of combining the results from the analysis of duplicate test por
12、tions 14 Table B.5 Recommended form for the calculation of constituent proportions and standard deviations for sand 15 Table B.6 Example of the calculation of constituent proportions and standard deviations for sand 16 List of references Inside back coverBS812-104:1994 ii BSI 01-1999 Foreword This P
13、art of BS812 has been prepared under the direction of Technical Committee B/502, Aggregates, and gives a method for the petrographic examination of aggregates. It is not intended that such an examination should form part of the routine assessment of the suitability of aggregates. However, there may
14、be circumstances in which petrographic examination will be the only satisfactory means of assessment. In other cases it can enhance and clarify results obtained from other forms of assessment. In some cases a less rigorous examination of aggregates may be sufficient and it is recommended that the qu
15、alitative examination given in clause 7 is used. Any such decision is, however, a matter for agreement between the client and the body undertaking the petrological examination and as such is outside the scope of this standard. It has been assumed in the drafting of this Part of BS812 that the execut
16、ion of its provisions is entrusted to appropriately qualified people, experienced in aggregate petrography, and with access to an appropriately equipped laboratory. In certain special cases, other analytical techniques (including chemical analysis, X-ray diffraction and scanning electron microscopy)
17、 may provide useful additional information, but these are outside the scope of this standard. Work on testing procedures for aggregates is being carried out in Europe under the auspices of CEN/TC154, Aggregates. The method described in this Part of BS812 is included in the programme of work of CEN/T
18、C 154. It is envisaged that a European Standard, based on this method, will be published in due course. Selected references on petrographic examination additional to those referenced in the text are included in annex C. A British Standard does not purport to include all the necessary provisions of a
19、 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 pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 to 18, aninside bac
20、k 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 theinside front cover.BS812-104:1994 BSI 01-1999 1 1 Scope This Part of BS812 describes a general method for the examination of sam
21、ples of coarse or fine aggregates to determine petrographic composition and to assist in the assessment of those aggregates for potential suitability for the intended use. The results relate only to the sample received at the laboratory and not necessarily to the deposit from which the samples are d
22、erived. The method is applicable to the determination of the proportion of any recognizable mineral or rock type, irrespective of the amount of such material, in the sample. The major application of the method described is in the examination and assessment of processed aggregates. 2 References 2.1 N
23、ormative references This Part of BS812 incorporates, by dated or undated reference, provisions from other publications. These normative references are made at the appropriate places in the text and the cited publications are listed on the inside back cover. For dated references, only the edition cit
24、ed applies; any subsequent amendments to or revisions of the cited publication apply to this Part of BS812 only when incorporated in the reference by amendment or revision. For undated references, the latest edition of the cited publication applies, together with any amendments. 2.2 Informative refe
25、rences This Part of BS812 refers to other publications that provide information or guidance. Editions of these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest editions. 3 Definitions For the purposes of this P
26、art of BS812, the definitions given in BS812-101, BS812-102, BS6100-5.2 and BS6100-6.3 apply, together with the following. 3.1 alteration mineralogical changes imposed upon a rock or rock body by secondary geological activity NOTEAltered rocks thus contain secondary minerals which may or may not be
27、detrimental to the properties of those rocks. In petrographic examination geological alteration should be distinguished from “weathering” (see 3.8). 3.2 microcrystalline composed of crystals so fine that they can be resolved only under a microscope NOTEThe term is often confused with “cryptocrystall
28、ine” but may be distinguished by the fact that a cryptocrystalline texture is so fine-grained that it specifically requires a high power microscope to resolve individual crystals. Thus the term “microcrystalline” indicates a relatively coarser grain size than “cryptocrystalline” and does not necessa
29、rily require a high power microscope to resolve the individual crystals. 3.3 monomictic aggregates essentially comprising particles of one rock or mineral type 3.4 petrography the systematic description of rocks, usually in hand-specimen and thin section NOTEThe petrographic examination of aggregate
30、s comprises a description of that aggregate in terms of the constituent rock (or discrete mineral) types. 3.5 polymictic aggregate comprising particles of many different rock or mineral types 3.6 qualitative examination an examination in which some or all of the constituents of a sample are identifi
31、ed and described, but the proportions of those constituents are not established 3.7 quantitative examination an examination in which the amounts and proportions of one or more constituents of a sample are determined 3.8 weathering the process by which rocks are broken down and decomposed by the acti
32、ons of external agencies such as wind, rain, temperature changes, plants and bacteria NOTEIn petrographic examination “weathering” should be distinguished from “alteration”.BS812-104:1994 2 BSI 01-1999 4 Principle 4.1 The method involves the visual recognition and quantification of rock and mineral
33、constituents of an aggregate sample to determine the petrographic composition. NOTEIt is assumed that the analyst is competent to recognize unambiguously the relevant mineral constituents in the sample. 4.2 The laboratory sample is first subjected to a qualitative examination. Duplicate representati
34、ve test portions are then prepared and subjected to a more detailed examination, employing both macroscopical and microscopical techniques. Methods are given to quantify the petrographic composition of the aggregate sample. These procedures allow for the thorough and statistically reliable petrograp
35、hic examination of an aggregate sample. 5 Sampling 5.1 The laboratory sample shall be taken in accordance with the procedures described in clause 5 of BS812-102:1989. 5.2 The minimum size of the laboratory sample aggregate shall be as given in Table 1. NOTE 1The minimum sample sizes given in Table 1
36、 take precedence over the recommendations of clause 5 of BS812-102:1989 for this procedure. NOTE 2The sample should be accompanied by a certificate of sampling as required in clause 9 of BS812-102:1989. Table 1 Minimum size of laboratory sample 5.3 The aggregate samples shall be taken from processed
37、 material at a suitable stage of production. NOTE 1All aggregate sources exhibit some variability. It is therefore important to ensure that an adequate and well defined sampling scheme is used. NOTE 2Particular sampling difficulties may be encountered with crushed rock aggregate sources that exhibit
38、 varying degrees and intensities of veining, weathering and other exceptional non-uniformly distributed features. Special procedures may be necessary which are outside the scope of this standard. NOTE 3The sampling methods described are intended primarily for the examination of processed aggregates.
39、 The overall resource evaluation of a quarry, quarry site or rock mass is outside the scope of this standard. NOTE 4It is important that the laboratory sample should be neither oven-dried nor wetted until the qualitative examination has been initiated. 6 Apparatus 6.1 Sieves, conforming to BS410, of
40、 appropriate mesh size. 6.2 A sample divider, appropriate to the maximum size of sample to be handled, as described in 4.5 of BS812-102:1989. 6.3 A low-power microscope, capable of magnifications up to 40. NOTEStereoscopic and zoom facilities are desirable. 6.4 Apparatus and machinery suitable for t
41、he manufacture of 30 m thick geological thin sections. Sand samples and some coarse aggregates will also require materials and apparatus suitable for resin consolidation prior to manufacture of the thin section. NOTEGeneral guidance on the equipment required for making geological thin sections, and
42、the various procedures to be employed, is given in Allman and Lawrence 1. 6.5 A petrographic (i.e. polarizing) microscope, capable of high-resolution at magnifications up to500. 6.6 Point-counting apparatus for use with the petrographic microscope, e.g. an electro-mechanical stage linked to a counti
43、ng device, such that operation of any one of the counters automatically moves the thin section one further step along the traverse. 6.7 Balances, for various mass ranges each capable of weighing the test portion to an accuracy of 0.1%. (See Table 2.) 7 Qualitative examination of the laboratory sampl
44、e 7.1 Aggregate type Examine the laboratory sample to ascertain the general character of the aggregate, including its moisture condition, and record the approximate maximum particle size and whether it is natural or crushed. Make preliminary visual estimates of the proportions of constituents of int
45、erest. NOTEThe moisture condition of the sample should be a subjective assessment of whether the sample is dry, damp or wet. Distinguish between natural sand or gravel aggregates, aggregates produced by crushing rock and artificial aggregates and record any observations. When aggregates have been pr
46、oduced in part by the crushing of coarse gravels or boulder deposits, or when aggregates, especially sand, have been produced by blending natural and crushed rock materials, state that the aggregate type is blended (see BS6100-6.3 for definitions of different types of aggregates). Maximum particle s
47、ize Minimum mass mm kg 50 200 40 100 20 13 # 10 2BS812-104:1994 BSI 01-1999 3 7.2 Particle description Describe the general character of the aggregate particles in terms of nominal maximum size, grading, shape and surface texture. Note in particular the presence of any fine material and any particle
48、 coatings or encrustations before the sample is wetted. NOTE 1Guidance on the terminology used in describing particle shape and surface texture is given in Neville 2. NOTE 2To carry out the particle examination and description it may be necessary first to examine the sample as received and then wash
49、 it in order to make the required observations and comments. 7.3 Petrographic description Identify and record the main rock (or mineral) types using the terms and definitions given in appendix A of BS812-102:1989. When the rock type is uncertain (for example in fine-grained rocks), distinguish the types on the basis of visual appearance including colour, grain size and any other distinctive features. In a polymictic aggregate, when possible, indicate the rock type that is clearly dominant. Consider the petrographic composition in
