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•r I! i CaPfornin Tett 341 1978 2. The calibration preeedure for the expansion E. PRECAUTIONS pressure device is described in California Test 1173. 1. Keep th; gwige surfaces on the top bar and 3. Exp;rasion pressure devices should be rec:di- contact surfaces on the spring steel bar clean and braced at least once every two months. polished. Since deilection measurements are taken D. TEST PROCEDURE to``/Ao,000 inch dust and corrosion on any of the gaurge 1. Alioww specimen to set for at least one-half hour rontact points can result in erroun�,uus measure. stents. after compleliun of Pxudation test (Part III) before 2. Keep the cxpar cion pressure devices free from proceeding vwith the following steps. the influence of any source of vibration during the 2. Clean off all dust and foreign material from the test. If shelving is used to hold the devices, do not spring steel bar and adjustment plug, attach or brace it to any of the building%walls. 3. Place deflection guage in position on top bar of 3. Recaiibrate, before using again,any expansion expansion pressure device. The single bearing end pressure device which has been used with rnaterials must rest on the adjustment plug, which have developed such extreme pressure as to 4. Use an Allen wrench to raise or lower the ad- leave a permanent set in the spring steel bar. A de- justmcnt plug until the deflection gauge is on minus Rection gauge reading at the end of the 16- to 24- 0.0010 inch. (The large needle on the gauge will hour test period of over 0.01 inch (one turn around point to the number 9 on the dial Face.) the dial) is generally considered to indicate that the 5. Place perforated brass plate with stens on tap steel bar has Leen subiected to"extreme pressure", of test specimen, and recalibration is required before again ising the 6. Place mok; on turntable after first placing a device. filter paper on turntable. 4. Exercise caution wvhen turning the table up 7. Seat perforated brass plate firmly on specimen with the specimen in place and engaging the spring with presstwe applied from fingers, steel bar with the stem on the perforated brass plate. R. Turn table up until the dial indicator is on zero. If too much force is applied,a temporary set will be 9. Pour approximately 200 milliliters of water on placed f the bar which will slowly relieve itself dor- the specimen in the mold and allow to stand undis- ing the 16- to 24-hour soaking perir,d,and result in Curbed for a normal test period of 16 to 24 hsurs. erroneous deflec:?ion readings. Extension of this test period over weekends or holi- 5. Do not, under any circumstances, leave a test days is permissible for untreated specimens.Ifowvev- specimen unconfined by the expansion pressure de- er, !.pecimens containing Portland cement or lime vice with the layer of free water existing on the speci- must not remain in the expansion pressure devices men ill the mold. This is particularly serious with for Icss than 16 hours nor mere than 24 hours. p' y expansive clays and silts since this condition permits 10. Read and record deflection gauge reading at the specimen to expand freely liking up excess wva- end of soaking period. If any water has drained ter and disruptin,g the density.The net result will be through specimen into water trap (pan) pour back the unjustifiable reduction of the stabilometer R-val- vn top of specimen, and allow this water to begin ue percolating through specimen before pouring off ex- F. NOTES cess water. Remove mold with specimen, and pour of excess water. In general,specimens which contain predorninant 11. Record whether water drained freely through amounts of silt or clay materials will develop the the specimen into the pan below. gre:.test expansion pressures. 12. Specimens of Class 1 or 2 aggregate base,meet- The expansion pressures developed in any group ing the standard specification grading requirements, of test specimens composed of the same material are may be removed from the expansion pressure device the inverse functions of their moisture contents at after two hours and the stabilometer 11-value deter- compaction. mined if the following conditions are met: PART V. METHOD OF DETERMINING THE a. All tcs'specimens show expansion pressure dial STAB1LOMETER RESISTANCE R-VALUE BY reading of 0.0002 inch or less at the end of the MEAV.5 OF THE STABILIMETER two hour period. b. At least three specimens show water passing A. SCOPC --- through-the specirnerfat the end of the two This method covers theprecedure for dctcrrnin hour period. ing the resistance fl-value of both treated and urn- l 13