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1、1AS 1289.7.1.21998 Australian Standard Methods of testing soils for engineering purposes Method 7.1.2: Soil reactivity tests Determination of the shrinkage index of a soilLoaded shrinkage index 1SCOPEThis Standard sets out a method for the determination of the shrinkage index of a soil (see AS 2870)
2、 using a spring-loaded shrinkage cell. 2REFERENCED DOCUMENTSThe following documents are referred to in this Standard: AS 1289Methods of testing soils for engineering purposes 1289.0Part 0: General requirements and list of methods 1289.2.1.1Method 2.1.1: Soil moisture content testsDetermination of th
3、e moisture content of a soilOven drying method (standard method) 1289.2.2.1Method 2.2.1: SoilmoisturecontenttestsDeterminationofthetotal suction of a soilStandard method 2870Residential slabs and footingsConstruction 3APPARATUSThe following apparatus is required: (a)Thin-walled sampler consisting of
4、 a tube with a bevelled cutting edge machined directly on the sample tube. The bevelled cutting edge shall make an angle not exceeding 15 to the axis of the tube with a permitted land width at the cutting edge not exceeding 0.5 mm. The ratio of net projected area of sampler to projected area of samp
5、le core shall not exceed 10%, and any internal clearance shall not exceed 1% of the diameter at the cutting edge. (b)Drying oven complying with AS 1289.0. (c)Balance of 500 g capacity and limit of performance not exceeding 0.05 g. (d)Spatula or palette knife of convenient size. (e)Flat glass plate a
6、pproximately 10 mm thick and at least 400 mm square. (f)Vacuum desiccator with stopcock to accommodate a vacuum pump. (g)Vacuum pump or similar system capable of achieving a minimum vacuum pressure of 600 mm Hg (80 kPa) (see Note 1). (h)Loaded shrinkage cell similar to that illustrated in Figure 1.
7、(i)Vernier callipers to measure spring compression. (j)Comparator with a reference rod, similar to that illustrated in Figure 2, or other length-measuringsystem. Thedialgaugeshallbegraduatedatintervalsnot exceeding 0.005 mm. COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.7.1
8、.219982 (k)Saturated copper sulfate solution. (l)Drying room with temperature controlled at 23 2C. (m)Apparatus to measure total soil suction in accordance with that described in AS 1289.2.2.1. 4SAMPLEAn undisturbed soil sample shall be obtained from a thin-walled sampler pushed into the soil. The s
9、ample shall have a minimum diameter of 38 mm and a minimum length of 50 mm. A visual description of the soil shall be recorded. 5PROCEDUREThe procedure shall be conducted in a drying room as follows: (a)Determine the mass of the assembled apparatus without the soil sample (mc) and the height of the
10、sample ring (y). (b)Taking care to minimize loss of moisture, press the sample into the sample ring of the loaded shrinkage cell and trim the ends level. Retain and seal the sample trimmings. Determine the soil suction (uo) using the sample trimmings in accordance with AS 1289.2.2.1 and determine th
11、e moisture content (wo) of the remainder of the soil in accordance with AS 1289.2.1.1. (c)Assemble the shrinkage cell and apply a seating pressure of 5 kPa by compressing the calibrated springs the required distance. Measure the total mass of the assembled apparatus with the soil sample (mo), and re
12、cord the initial dial gauge reading from the comparator for the apparatus with the soil sample (Ho) (see Note 2). (d)Increase to 25 kPa the pressure applied to the sample and record the dial gauge reading from the comparator (see Note 3). (e)Place the loaded shrinkage cell in the vacuum desiccator o
13、ver the saturated copper sulfate solution. Apply a vacuum pressure of not less than 600 mm Hg and close the stopcock. (f)On each of the first three days thereafter, remove the loaded shrinkage cell from the desiccator, determine the total mass (mt) and record the dial gauge reading (Ht) from the com
14、parator. Adjust the spring compression if required to maintain the pressure on the sample. Replace the loaded shrinkage cell in the desiccator and reapply the vacuum. (g)Thereafter, take mass and comparator dial gauge readings at intervals of not less than one week. Adjust springs as required to mai
15、ntain the sample pressure. Readings may be terminated once three successive comparator dial gauge readings are within 0.05 mm and three successive readings of mass are within 0.05 g. (h)Remove the sample from the loaded shrinkage cell and determine the final soil suction (uf), in accordance with AS
16、1289.2.2.1, using subsamples taken near the centre of the sample. Determine the final moisture content (wf) of the remaining soil in accordance with AS 1289.2.1.1. (i)Break the specimen apart and inspect for uniformity and for rock, gravel or organic inclusions. Estimate the percentage by volume of
17、significant inert inclusions. 6CALCULATIONSThe following calculations shall be performed: (a)Calculate the sample strain (t) at each time of measurement t from the following equation (see Note 4): . . . 6(1) COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 3AS 1289.7.1.21998 where t=
18、the sample strain at time t, in percent Ho= the initial comparator dial gauge reading, in millimetres Ht= the comparator dial gauge reading at time t, after recording Ho, in millimetres y= the sample ring height, in millimetres (see Note 4). (b)Calculate the soil moisture content (wt) in percent at
19、each time of measurement t after measuring the initial mass (mo) from the following equation: . . . 6(2)wt= wo+ 100(mt mo) (1 + wo100) (mo mc) where wt= the soil moisture content at time t, in percent wo= the moisture content of the sample trimmings, in percent mt= the total mass of the apparatus an
20、d sample at time t, in grams mo= the initial total mass of the apparatus and sample at time t = 0, in grams mc= the mass of the apparatus without the sample, in grams. Calculate the final soil moisture content at the time of the final set of measurements on the apparatus with the sample, and record
21、the value as wfest(estimated final moisture content). (c)Plot sample strain (t) versus moisture content (wt) and compute the slope (S = t/wt) of the linear portion of the plot after initial sample compression under loading. (d)Calculate the soil moisture characteristic (c) from the following equatio
22、n: . . . 6(3)c = wo wf uo uf where c= the soil moisture characteristic, percentage moisture content change per pF change in soil suction wo= the moisture content of the sample trimmings, in percent wf= the final measured moisture content of the soil, in percent uo= the average soil suction of the sa
23、mple trimmings, in pF uf= the average soil suction of sub-samples taken after removal of the sample from the apparatus, in pF. (e)Calculate the loaded shrinkage index (Ils), from the following equation: . . . 6(4)I1s=c.S 100 where Ils= the loaded shrinkage index c= the soil moisture characteristic (
24、see Clause 6(d) S= the slope t/wt(see Clause 6(c). COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.7.1.219984 7TEST REPORT 7.1Test resultsThe following shall be reported: (a)The loaded shrinkage index (Ils) to the nearest 0.01. (b)The soil moisture characteristic (c) percenta
25、ge moisture content change per pF change in soil suction. (c)The measured final moisture content of the soil (wf), in percent. (d)The calculated final moisture content (wfest), in percent. Where the suction change from beginning to the end of the test is less than 0.2 pF, neither Ilsnor c shall be r
26、eported. 7.2General informationThe following general information shall be reported. (a)A visual description of the soil. (b)The estimated percentage of significant inert inclusions in the soil specimens. (c)The number of this Australian Standard, i.e. AS 1289.7.1.2. NOTES ON TEST: 1Vacuum need not b
27、e applied to the desiccator in which case a vacuum pump will not be required. Without vacuum, longer equilibration times may be expected. 2If a comparator is used, a reference reading should be taken with a reference rod or slip gauge prior to taking measurements. 3If the estimated overburden pressu
28、re of the soil in situ is greater than 25 kPa, this greater value should be used in the test and the value used reported with the results. 4The sample cell height is assumed to be equal to the height of the sample ring. A correction should be made where this is not so. COPYRIGHT Accessed by TAFE QUE
29、ENSLAND INSTITUTES on 19 Dec 2007 5AS 1289.7.1.21998 DIMENSIONS IN MILLIMETRES FIGURE 1TYPICAL LOADED SHRINKAGE CELL DETAILS COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.7.1.219986 FIGURE 2DETAILS OF COMPARATOR COPYRIGHT Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 200
30、7 7AS 1289.7.1.21998 NOTES Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 AS 1289.7.1.219988 This Australian Standard was prepared by Committee CE/9, Testing of Soils for Engineering Purposes. It was approved on behalf of the Council of Standards Australia on 2 January 1998 and published on 5
31、 April 1998. The following interests are represented on Committee CE/9: Australian Geomechanics Society AUSTROADS Crushed Stone Association of Australia Department of Industry, Sport and Tourism, Scientific Services Laboratory, AGAL Institution of Engineers Australia National Association of Testing
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35、ty found in an Australian Standard should be made without delay in order that the matter may be investigated and appropriate action taken. Originated as AS 1289.7.1.21992. Second edition 1998. This Standard was issued in draft form for comment as DR 96561. CopyrightSTANDARDS AUSTRALIA Users of Stand
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40、d date of the Standard should therefore be clearly identified. The use of material in print form or in computer software programs to be used commercially, with or without payment, or in commercial contracts is subject to the payment of a royalty. This policy may be varied by Standards Australia at any time. ISBN 0 7337 1836 1 Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007 Thi s page has been l ef t i nt ent i onal l y bl ank. Accessed by TAFE QUEENSLAND INSTITUTES on 19 Dec 2007