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California Test 301 <br /> 1973 <br /> These defects can affect the results+Without it becotn. C. CONTROL <br /> ^pparent to the operator. 1. The hrass shirts und,r the sprit• stcel I,ar of the <br /> ittg immediately <br /> 3. Care must be taken that moisture docs not�ccp k xpansion pressure device must be aur ustcd properly <br /> around the contact points sinev this would cause in order to utaintain the eurrcct rtltiionship <br /> electrical shorts to occur in the~tiring and result ill between the deflection of the spring steel bar and <br /> crroncous exudation pressures.Detection of this cots the expansive force generated by lite test specimen. <br /> dition may be difficult since the shorting is often not The{?roper adjust;ncnt is eletcrsr:snc d by recons of an <br /> complete until the contact plate is loaded during the expansion pressure calibration deuce. <br /> test. A check may be rnadr by using a 4-inch diame- <br /> ter dry felt pad '/-inch thick in the place of the test <br /> specimen.If after loading,any lights go or,the plate <br /> should be replaced. <br /> 4. The operator must .ripe the contact plate dry <br /> bctwec:t tests since any moisture remaining will <br /> , <br /> prematurely dampen the newfilter paper and cause <br /> crroncous exudation pressure r.^^.sults. <br /> F_ NOTES <br /> Occasionally, material from exceptionally heavy <br /> clay test specimens will extrude f.o-n tinder the maid <br /> and arot:nd the follower rain during the loading o{a• <br /> eration. Yet,.then the SW psi point is reached, less �al� <br /> th::n five lights are lit.When this occurs the soil is of <br /> very poor quality and should be reported as less than <br /> 11-value. <br /> There are many cases where hie h quality materials <br /> of a gravelly-sandy nature, such as untreated bases, <br /> will have exudation pressures that are extremely sen- <br /> sitive to slight changes in moisture content. Very <br /> often these pressures will appear erratic and out of <br /> step.tith the sequence of moistures.11owever,these <br /> materials generally exhibit uniform H-values having <br /> relatively small variation throughout the entire <br /> range of exudation pressures and moisture contents. FIGURE 9 <br /> The 11-value-exudation curve is drawn as ar average Care.at,a ' <br /> s c. «t 13�r'{ <br /> value in these cases. x <br /> - ��.�' ���IlE'uttabre Gau a Au <br /> PART IV. <br /> MEIi;OD OF DETERMINING THE •^; "'::(` <br /> EXPANSION PRESSURE OF R-VALUE uoae�enr <br /> TEST SPECIMENS tuminn cf hrou. ., <br /> A. APPArATUS S,edm.n tuptit <br /> �•1 <br /> Ak 6 ! <br /> 1. Expansion press:rc device (Figure 9)• <br /> 2. 1'/:o,000 inch deflection gauge (exp;:nsiott pros- N,ra,c„a ®® f °ef1Ctioa c°`a• <br /> sure dial) (figure 10). a;, e <br /> 3" Allyn wrench. r1 , <br /> 4. Small pan. r-.~ <br /> B. MATERIALS <br /> Irilter papers, 11 centimeter 111(11 shark skin,cata- <br /> log No.28314,or equivalent. F:GURE 10 <br /> 12 <br /> 1. <br /> t <br />