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1、BRITISH STANDARD BS 1881-104: 1983 Incorporating Amendment Nos. 1 and 2 Testing concrete Part 104: Method for determination of Vebe time UDC 666.972.017:691.32:620.1 Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:1983 This Briti
2、sh Standard, having been prepared under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Committee, was published under the authority of the Board of BSI and comes into effect on 31 May 1983 BSI 12-1998 ISBN 0 580 11924 6 Committees responsible for this British Standard
3、This British Standard was published under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Committee CAB/-. Its preparation was entrusted to Technical Committee CAB/4 upon which the following bodies were represented: British Aggregate Construction Materials Industries Br
4、itish Precast Concrete Federation Ltd. British Ready Mixed Concrete Association Cement Admixtures Association Cement and Concrete Association Cement Makers Federation Concrete Society Limited County Surveyors Society Department of the Environment (PSA) Department of the Environment (Building Researc
5、h Establishment) Department of the Environment (Transport and Road Research Laboratory) Department of Transport Electricity Supply Industry in England and Wales Federation of Civil Engineering Contractors Greater London Council Institute of Concrete Technology Institution of Civil Engineers Institut
6、ion of Highway Engineers Institution of Municipal Engineers Institution of Structural Engineers Institution of Water Engineers and Scientists National Federation of Building Trades Employers Royal Institute of British Architects Royal Institution of Chartered Surveyors Sand and Gravel Association Li
7、mited Society of Chemical Industry The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Civil Engineering Test Equipment Manufacturers Association Coopted members Amendments issued since publication Amd. No.Date of issueComments 6088Ju
8、ly 1989 6725July 1991Indicated by a sideline in the margin Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:1983 BSI 12-1998i Contents Page Committees responsible Inside front cover Foreword ii 1Scope1 2Definitions1 3Apparatus1 4S
9、ampling1 5Preparing the sample for test1 6Procedure3 7Expression of results4 8Report4 Figure 1 Vebe apparatus2 Figure 2 Forms of slump3 Publications referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:198
10、3 ii BSI 12-1998 Foreword This Part of this British Standard, prepared under the direction of the Cement, Gypsum, Aggregates and Quarry Products Standards Committee, is a revision of clause 4 of BS 1881-2:1970. Minor modifications have been made to the method for determination of Vebe time. Testing
11、in accordance with this Part of this standard will comply with ISO 4110. Together with Parts 102, 103, 106 and 107, this Part of BS 1881 supersedes BS 1881-2:1970, which is withdrawn. Four methods of determining the workability of concrete are given in BS 1881, these being the slump, compacting fact
12、or, Vebe and flow. The methods are appropriate to concrete mixes of different workability as follows: There are no unique relationships between the values yielded by the four tests. Relationships depend upon such factors as the shape of the aggregate, the sand fraction and the presence of entrained
13、air. This test is not suitable for concrete having a measured Vebe time of less than 3 s nor more than 30 s. No estimate of repeatability or reproducibility is given in this Part of this British Standard. Reference should be made to BS 5497-1 for further information on the determination of repeatabi
14、lity and reproducibility. 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. WorkabilityMeth
15、od Very lowVebe time LowVebe time, compacting factor MediumCompacting factor, slump HighCompacting factor, slump, flow Very highFlow 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 cover. This standard has b
16、een updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:1983 BSI 12-19981 1 Scope This Pa
17、rt of this British Standard describes a method for determination of Vebe time of concrete of very low to low workability. The method applies to plain and air-entrained concrete made with lightweight, normal weight or heavy aggregates having a nominal maximum size of 40 mm or less but not to aerated
18、concrete, no-fines concrete and concrete which cannot be compacted by vibration alone. NOTEThe titles of the publications referred to in this standard are listed on the inside back cover. 2 Definitions For the purposes of this British Standard the definitions given in BS 5328 and BS 1881-101 apply.
19、3 Apparatus 3.1 Consistometer. Consistometer comprising a container, a mould, a transparent disc and a vibrating table; the consistometer and its essential dimensions are shown in Figure 1. The container (A) shall be made of metal not readily attacked by cement paste. It shall be of cylindrical shap
20、e, the thickness of the wall being 3 mm and of the base being 7.5 mm. The container shall have an internal diameter of 240 5 mm and a height of 200 mm and shall be watertight and of sufficient rigidity to retain its shape under rough usage. It shall be fitted with handles and with brackets, the latt
21、er enabling it to be clamped to the top of the vibrating table (G) by wing nuts (H). The mould (B) shall be rigid and made of metal1) not readily attacked by cement paste and not thinner than 1.5 mm. The interior of the mould shall be smooth and free from projections such as protruding rivets and sh
22、all be free from dents. The mould shall be in the form of a hollow frustum of a cone having the following internal dimensions: The base and top shall be open and parallel to each other and at right angles to the axis of the cone. The mould shall be provided with two handles about 250 mm from the bas
23、e. The transparent disc (C) shall be horizontal and attached to the end of a rod (J) which slides vertically through a guide sleeve (E) mounted on a swivel arm (N). The guide sleeve (E) shall be fitted with a screw (Q) to enable the rod (J) to be fixed in position. The swivel arm (N) also carries a
24、funnel (D) the bottom of which locates on the top of the mould (B) when this is positioned concentrically in the container (A). The swivel arm (N) is located by a holder (M) and can be fixed in position by a set screw (F). When in the appropriate positions, the axes of the rod (J) and of the funnel
25、(D) shall be coincident with the axis of the container. The transparent disc shall be 230 2 mm in diameter and 10 2 mm in thickness. A weight (P) shall be located directly above the disc such that the moving assembly, comprising rod, disc and weight, shall weigh 2750 50 g. The rod shall be provided
26、with a scale to enable the slump of the concrete to be recorded. The vibrating table (G) shall be 380 mm in length and 260 mm in width and shall be supported on four rubber shock absorbers. A vibrator unit (L), carried on a base (K) resting on three rubber feet, shall be securely fixed beneath it. T
27、he vibrator shall operate at a frequency of 50 Hz and the vertical amplitude of the table, with the empty container clamped to it, shall be approximately 0.35 mm about the mean position. 3.2 Scoop, about 100 mm wide. 3.3 Sampling tray, minimum dimensions 5 900 mm 900 mm 50 mm deep, of rigid construc
28、tion and made from a non-absorbent material not readily attacked by cement paste. 3.4 Square mouthed shovel, size 2 in accordance with BS 3388. 3.5 Tamping rod, made out of straight iron or steel bar of circular cross section, 16 1 mm diameter and 600 5 mm long, with both ends hemispherical. 3.6 Sto
29、p watch or stop clock, accurate to 0.5 s. 4 Sampling Obtain the sample of fresh concrete by the procedure given in BS 1881-101 or BS 1881-125. Commence the determination of Vebe time as soon as possible after sampling. 5 Preparing the sample for test Empty the sample from the container(s) onto the s
30、ampling tray. Ensure that no more than a light covering of slurry is left adhering to the container(s). 1) Galvanized steel is suitable. diameter of base:200 2 mm diameter of top:100 2 mm height:300 2 mm Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Cop
31、y, (c) BSI BS 1881-104:1983 2 BSI 12-1998 Thoroughly mix the sample by shovelling it to form a cone on the sampling tray and turning this over with the shovel to form a new cone, the operation being carried out three times. When forming the cones deposit each shovelful of the material on the apex of
32、 the cone so that the portions which slide down the sides are distributed as evenly as possible and so that the centre of the cone is not displaced. Flatten the third cone by repeated vertical insertion of the shovel across the apex of the cone, lifting the shovel clear of the concrete after each in
33、sertion. CAUTION. When cement is mixed with water, alkali is released. Take precautions to avoid dry cement entering the eyes, mouth and nose when mixing concrete. Prevent skin contact with wet cement or concrete by wearing suitable protective clothing. If cement or concrete enters the eye, immediat
34、ely wash it out thoroughly with clean water and seek medical treatment without delay. Wash wet concrete off the skin immediately. Figure 1 Vebe apparatus Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:1983 BSI 12-19983 6 Procedu
35、re Place the vibrating table (G) on a rigid, horizontal surface free from external vibration or shock. Clamp the container (A), which shall be clean, to the table (G) by means of the two wing nuts (H). Place the mould (B), the inner surface of which shall be clean and damp but free from superfluous
36、moisture, concentrically in the container (A) and lower the funnel (D) on to the mould. Tighten the screw (F) so that the mould (B) is held in contact with the base of the container (A). Fill the mould (B) with concrete in three layers, each approximately one-third of the height of the mould when ta
37、mped. Tamp each layer with 25 strokes of the tamping rod, the strokes being distributed uniformly over the cross-section of the layer. Tamp each layer to its full depth, ensuring that the tamping rod does not forcibly strike the bottom of the container when tamping the first layer and just passes th
38、rough the second and top layers into the layers immediately below. Heap the concrete above the mould before the top layer is tamped. If necessary, add further concrete to maintain an excess above the top of the mould throughout the tamping operation. After the top layer has been tamped, loosen the s
39、crew (F), raise and swing the funnel (D) through 90 and tighten the screw (F). Strike off the concrete level with the top of the mould with a sawing and rolling motion of the tamping rod. When striking off the concrete, do not allow the mould (B) to rise nor any concrete to fall into the container (
40、A). Figure 2 Forms of slump Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:1983 4 BSI 12-1998 Remove the mould (B) from the concrete by raising it vertically slowly and carefully, in 5 s to 10 s, in such a manner as to impose mi
41、nimum lateral or torsional movement to the concrete. Having removed the mould (B), loosen the screw (F), swing the transparent disc (C) over the container, tighten the screw (F) and lower the disc to touch the highest point of the slumped concrete. If the concrete shears, as shown in Figure 2(b), co
42、llapses, as shown in Figure 2(c), or slumps to the extent that it touches the wall of the container (A), the disc (C) shall be allowed to rest upon the subsided concrete with screw (Q) loose. If the concrete has not slumped into contact with the wall of the container (A) and a true slump, as shown i
43、n Figure 2(a) has been obtained, tighten the screw (Q) when the disc (C) just touches the highest point of the concrete without disturbing it. Read the slump from the scale (J) and then loosen the screw (Q) to allow the disc (C) to rest upon the concrete. Simultaneously start the vibration and the s
44、top watch or clock. Observe the remoulding of the concrete through the transparent disc (C). Stop the watch or clock immediately the lower surface of the disc (C) is completely coated with cement grout and record the time taken. Complete the procedure within a period of 5 min from the commencement o
45、f filling the mould (B). NOTEThe workability of a concrete mix changes with time due to hydration of the cement and, possibly, loss of moisture. Tests on different samples should, therefore, be carried out at a constant time interval after mixing if strictly comparable results are to be obtained. 7
46、Expression of results Record the Vebe time, indicated by the stop watch or clock, to the nearest second. 8 Report 8.1 General. The report shall affirm that the Vebe time was determined in accordance with this Part of this British Standard. The report shall state whether or not a certificate of sampl
47、ing is available. If available, a copy of the certificate shall be provided. 8.2 Information to be included in the test report 8.2.1 Mandatory information. The following information shall be included in the test report: a) date, time and place of sampling and sample identity number; b) time and plac
48、e of test; c) form of slump, whether true, shear or collapse, or into contact with wall of the container; d) slump, if true slump was measured and concrete did not come into contact with wall of the container; e) Vebe time; f) name of person carrying out test. 8.2.2 Optional information. If requeste
49、d the following information shall be included in the test report: a) name of project and place where concrete used; b) name of supplier and source of concrete; c) date and time of production of concrete or delivery to site; d) specification of concrete mix (e.g. strength grade). Licensed Copy: sheffieldun sheffieldun, na, Fri Nov 24 08:25:08 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 1881-104:1983 BSI 12-1998 Publications referred to BS 1881, Testing concrete. BS 1881-101, Method of sampling fresh concrete on site. BS 1881-102, Method fo
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