T!e "ctivit# "ims to intro$%ce to t!e st%$ents t!e st"n$"r$ met!o$ o& $eterminin' t!e stren't! o& b"se s%bb"se "n$ s%b 'r"$e m"teri" %sin' t!e C"i&orni" Be"rin' R"tio. T!e st%$ents s!" be "be to + Conn Connec ectt t!e t!e CBR CBR v"% v"%ee in t!e t!e $et $eter ermi min" n"tition on o& o& t!e t!e t!ic t!ic,n ,nes esss o& s%b s%b 'r" 'r"$e $e soi soi &or &or " spec speci&i&ic ic -!e -!ee e o" o"$. $. + ete eterm rmin inee t!e t!e C" C"i&i&or orni ni"" be" be"ri rin' n' r"ti r"tioo in " 'iv 'iven en soi soi s"mp s"mpe e.. $escribe t!e met!o$s o& !o- t!e C"i&orni" be"rin' test is per&orme$
T!e C"i&orni" Be"rin' R"tio test (CBR) -"s $eveope$ b# t!e C"i&orni" ivision o& 0i'!-"#s "s " met!o$ o& c"ssi&#in' t!e sois &or s%it"biit# &or %se in !i'!-"# constr%ction especi"# &or t!e c"ssi&ic"tion o& b"se co"rse m"teri"s &or t!e s%pport o& &exibe p"vements. !ort# "&ter t!e st"rt o& 2or$ 2"r II t!e 3 Arm# En'ineers "$opte$ t!e CBR test &or %se in $esi'n "n$ constr%ction o& b"ses &or "ir&ie$ r%n-"#s. T!e "rm# en'ineers 're"t# improve$ t!e test proce$%re b# s%bstit%tin' " $#n"mic met!o$ o& comp"ctin' t!e soi "n$ t!is c!"n'e is no"ccepte$ "s t!e st"n$"r$ proce$%re. T!e CBR test is " me"s%re o& t!e s!e"rin' resist"nce o& t!e soi %n$er controe$ $ensit# "n$ moist%re con$itions. T!ere&ore t!e test c"nnot be consi$ere$ "s " c"ssi&ic"tion test since t!e res%ts "re not const"nt &or 'iven sois b%t $epen$ent on s%c! &"ctors "s $ensit# "n$ moist%re content "s -e "s si4e "n$ s!"pe o& t!e 'r"ins. T!e CBR v"%e is expresse$ "s " percent"'e o& t!e %nit o"$ re5%ire$ to &orce " piston into t!e soi $ivi$e$ b# t!e %nit o"$ re5%ire$ to &orce t!e s"me piston to t!e s"me $ept! into " st"n$"r$ s"mpe o& comp"cte$ cr%s!e$ stone. CBR CBR 6
test test %nit %nit o"$ o"$ t"n$"r$ %nit o"$
x 177
T!e st"n$"r$ %nit o"$ obt"ine$ &rom t!e "ver"'e o& " "r'e n%mber o& tests on $i&&erent cr%s!e$ stones "n$ "re "s &oo-s
(7.1) *.: (7.*) :.7 (7./)?.: (7.>) 17.7 (7.:) 1*.:
(1777) ;.<=: (1:77) 17./>* (1=77) 1/.177 (*/77) 1:.<:< (*;77) 1?.=*;
T!e CBR %s%"# seecte$ is "t 7.1@inc! penetr"tion. I& t!e CBR 7.*@inc! penetr"tion is 're"ter t!"n "t t!e 7.1 inc! penetr"tion t!e test s!o%$ be rer%n i& t!e c!ec, test 'ives simi"r res%ts. T!e v"%e &or t!e 7.*@inc! penetr"tion is %se$. T!e CBR test c"n "so be m"$e in p"ce on
1. CBR 9o$ *. 0"mmer /. p"cer $i $is,
>. :. ;. ?. <. =. 17. 11. 1*. 1/.
App"r"t%s &or me"s%rin' exp"nsions i" in$ic"tors %rc!"r'e -ei'!t 8enetr"tion piston Lo"$in' $evice o",in' t"n, r#in' oven 9isce"neo%s toos s%c! "s mixin' p"ns poons str"i'!t e$'e b""nce $r#in' oven esicc"tor "n$ $r#in' c"n
"mpe 8rep"r"tion
1. Air@$r# "n$ p%veri4e "pproxim"te# 177 Ib o& m"teri" screen t!ro%'! " inc! sieve -ei'! t!e m"teri" *.
/.
>. :. ;.
ret"ine$ "n$ $isc"r$ t!is m"teri". Rep"ce t!e -"ste$ m"teri" -it! "n e5%" -ei'!t o& m"teri" p"ssin' t!e inc! sieve "n$ ret"ine$ on t!e inc! sieve. etermine t!e optim%m moist%re content o& t!e m"teri" %sin' t!e mo$i&ie$ AA0O 9et!o$ (see Comp"ction Test) -it! t!e &oo-in' exceptions. ". 3se inc! m"xim%m si4e m"teri" inste"$ o& t!e inc! m"teri". b. 3se t!e CBR comp"ction mo$ (-it! * inc! sp"cer $is, in bottom) inste"$ o& t!e 1D/7 c% &t mo$ c. Comp"ct m"teri" -it! :: bo-s per "#er inste"$ o& *: $. Comp"ct in : "#ers inste"$ o& / "#ers. T!e comp"cte$ specimen s!o%$ consist o& : one@inc! "#ers e. 3se &res! m"teri" &or e"c! comp"ction s"mpe inste"$ o& p%veri4in' "n$ recomp"ctin' t!e s"me m"teri" Con$%ct t!e contro comp"ction test -it! " s%&&icient n%mber o& specimens to $e&inite# est"bis! t!e optim%m moist%re (-"ter) content &or 177 percent o& mo$i&ie$ AACO $ensit#. At e"st > to : specimens s!o%$ be comp"cte$ -it! -"ter contents -it!in p%s or min%s * percent o& t!e optim%m moist%re content so t!"t t!e optim%m con$ition c"n be ri'i$# est"bis!e$. Note 0ei'!t o& &" o& t!e !"mmer m%st be c"re&%# controe$ "n$ t!e bo-s %ni&orm# $istrib%te$ over t!e specimen 3pon est"bis!in' t!e optim%m moist%re content mix "bo%t /7Ibs (1/.;> ,') o& t!e "ir@$rie$ m"teri" -it! eno%'! -"ter to brin' t!e moist%re content to t!e optim%m v"%e $etermine$ in step (*) "n$ (/). Cover t!e m"teri" -it! " $"mp cot! to prevent t!e oss o& moist%re -!ie prep"rin' t!e specimens. N%mber "n$ -ei'! t!e t!ree CBR mo$s "n$ "tt"c! extension co"rs "n$ b"se p"tes. Insert one o& t!e * (*:7 mm) sp"cer $is,s on t!e b"se p"te o& e"c! mo$ "n$ p"ce " ; inc!es (1:7 mm) $i"meter &iter p"per or -ire mes! on top o& e"c! $is,s. Comp"ct t!e soi@ -"ter mixt%re into t!e CBR mo$ in "ccor$"nce -it! t!e proce$%res st"te$ in step * "n$ / "n$ Comp"ction Test o& previo%s experiment Note
1. 8rior to comp"ction o& t!e soi m"ss t",e " represent"tive s"mpe o& *7 to :7 'm o& soi s"mpes &rom t!e top "n$ bottom "#ers o& e"c! mo$ &or -"ter content $etermin"tion. *. Remove t!e extension co"r "n$ c"re&%# trim t!e comp"cte$ soi. Even -it! t!e top o& t!e mo$ b# me"ns o& " str"i'!t e$'e or ,ni&e p"tc! -it! sm"er si4e m"teri" "n# !oes t!"t m"# !"ve $eveope$ in t!e s%r&"ce b# t!e remov" o& co"rse m"teri". Remove t!e -ei'!t o& t!e mo$ "n$ comp"cte$ soi. /. 8"ce " $is, o& &iter p"per or -ire mes! on t!e b"se p"te invert t!e mo$ "n$ comp"cte$ soi "n$ c"mp t!e b"se p"te to t!e mo$ -it! t!e comp"cte$ soi in cont"ct -it! t!e &iter p"per. T!e
s"mpe is no- re"$# &or so",in'. A. -e Test To sim%"te &ie$ con$itions t!e specimen is so",e$ %n$er " s%rc!"r'e -ei'!t -!ic! is e5%iv"ent to t!e -ei'!t pro$%ce$ b# t!e soi b"se or p"vement -!ic! -i overie t!e m"teri" in t!e compete$ str%ct%re. T!ree inc!es o& over#in' m"teri" is "ss%me$ e5%" to : Ib (*.*? ,') s%rc!"r'e o"$ on t!e s"mpe t!e tot" s%rc!"r'e -ei'!t s!" not be ess t!"n 177 Ib (>.:> ,')
1. 8"ce t!e "$j%st"be stem "n$ per&or"te$ p"te on t!e comp"cte$ soi specimen in t!e mo$ "n$ "pp# -ei'!t to pro$%ce " s%rc!"r'e e5%" to t!e -ei'!t speci&ie$ or re5%ire$. An$ p"ce t!e port"be tripo$ -it! '"'e ($i" extensometer) on t!e rim o& t!e mo$ "n$ m"r, its oc"tion. A$j%st stem o& per&or"te$ p"te recor$ t!e initi" $i" re"$in' "n$ remove t!e tripo$ -it! '"'e. *. Immerse t!e specimen in t!e -"ter t"n, in &o%r $"#s (=; !rs) b# m"int"inin' " const"nt -"ter eve $%rin' t!is perio$. E"c! $"# $%rin' t!e so",in' perio$ p"ce t!e tripo$ c"mp on t!e mo$ in its m"r,e$ oc"tion "n$ recor$ t!e $i" re"$in' "n$ time. /. A&ter so",in' perio$ remove t!e mo$ &rom t!e -"ter !o$ t!e s%rc!"r'e -ei'!t "n$ per&or"te$ p"te &irm# in p"ce "n$ po%r t!e excess -"ter &rom t!e s%r&"ce "n$ t!en et t!e specimen $r"in in " vertic" position &or 1: min%tes. Remove t!e s%rc!"r'e -ei'!t per&or"te$ p"te "n$ &iter p"per or -ire mes! "n$ -ei'! >. C"c%"te t!e percent"'e o& -"ter "bsorbe$ b# t!e specimen "n$ t!e s-e in percent o& t!e initi" !ei'!t B. C"i&orni" Be"rin' R"tio Test
1. 8"ce t!e s%rc!"r'e o"$ (-ei'!ts) $irect# on t!e s"mpe "n$ center it %n$er t!e penetr"tion piston in t!e o"$in' "pp"r"t%s "n$ brin' t!e penetr"tion piston in cont"ct -it! t!e soi t!ro%'! t!e "nn%"r s%rc!"r'e -ei'!t. A$j%st t!e $i"meter '"'e &or me"s%rin' t!e penetr"tion so t!"t its stem be"rs on t!e rim o& t!e mo$ "n$ recor$ t!e initi" re"$in'. *. App# t!e o"$ smoot!# so r"te o& penetr"tion is 7.7: inc! (n 1.*? mm) per min%te. C!ec, t!e r"te o& o"$ "ppic"tion b# %sin' " stop-"tc!. Recor$ t!e o"$ re"$in's "t penetr"tions 7.7*: (7.;> mm) 7.7:7 (1.*? mm) 7.7?: (1.=1 mm) 7.177 (*.:> mm) 7.1*: (/.1< mm) 7.1:7 (/.<1 mm) 7.1?: (>.>: mm). 7.*77 (:.7: mm) 7./77 (?.;* mm) 7.>77 (17.1; mm) "n$ 7.:77 inc! (1*.?7 mm) Note For m"n%"# oper"te$ o"$in' m"c!ine it m"# be necess"r# to t",e o"$ re"$in's "t coser interv"s to contro t!e r"te o& penetr"tion. /. Ree"se t!e o"$ remove t!e mo$ &rom t!e o"$in' m"c!ine "n$ remove s%rc!"r'e -ei'!t "n$ b"se p"te. T",e *7@:7 'r"ms &or moist%re content &rom top "n$ bottom o& t!e specimen "n$ recor$.
CE:17 * EB3EN ENN AI0AI9A 1. E8OAO HI9 O03A *. E8EON 9ARIN /. FRANCICO 9ARH EFFERON >. GAN O0N :. GILE RAC0EL
1 CE:*FC1 NOE9BER *> *7*? ECE9BER ? *71? ENGR. ENNIFER L. CA9INO
escription o& "mpe "n$# "mpe$ "t Ros"rio 8"si' Cit# CONITION OF A98LE ( ) OAHE A ENIT Be&ore o",in' 6 1.:: 'Dcm/ 6=>:.=?** m m/ A&ter o",in' 6 1.?* 'Dcm/ 6=>:.=?** cm/ 2"ter Content 6 *7 '@s"mpe oven@$rie$ re$%ce$ to 1? '. w61?.;>?J 2ELL (8ERCENTAGE OF INITIAL 0EIG0T) 6 *.7*:J o& 1>./* cm 3RC0ARGE 2EIG0T 6 *7 ' 8ENETRATION N39BER
LOA
AREA OF 8ENETRATION
mm *.: :.7 ?.: 17.7 1*.:
,N 1.: /.: >.? ; ;./:
8iston (in*) * * * * *
3NIT LOA IN 98"
1.1;*:7* *.?1*:7: /.;>*:7? >.;:777= >.=*1*;
CONITION OF A98LE (
) OAHE
8ENETRATION N39BER 9m *.: :.7 ?.: 17.7 1*.:
LOA ,N 1./ 1.? *./ *.? /.7
AREA OF 8ENETRATION 8iston (in*) * * * * *
3NIT LOA IN 98" 1.77?:7* 1./1?:7/ 1.?<*:7> *.7=*:7> *./*:77:
8rovin' rin' n%mber *> ,N
On t!is experiment it c"n be conc%$e$ t!"t !e C"i&orni" Be"rin' R"tio test me"s%res t!e s!e"rin'
resist"nce o& t!e soi %n$er controe$ $ensit# "n$ moist%re con$itions. 0o-ever "s experiment" $"t" res%ts c"nnot be "c5%ire$ -it! "cc%r"c# -it! "n# t!eoretic" v"%e &or it re5%ires ste"$# "ttention on monitorin' t!e penetr"tion n%mber "n$ "mo%nt o& o"$. Comp"rin' t!e t-o s"mpes K so",e$ "n$ %nso",e$ K i'!ter o"$ -"s nee$e$ in or$er to penetr"te t!e comp"cte$ s"mpe &rom previo%s test $%e to its -"ter content..
8er&orm"nce
Be'inner
in$ic"tor I$enti&# t!e proce$%res invove$ in $esi'nin' t!e experiment
1
Accept"be
8ro&icient
* / esi'ns "n esi'ns "n F"is to $esi'n "n experiment s"tis&#in' experiment experiment &oo-in' t!e minim%m excee$in' t!e proce$%res re5%irements o& t!e re5%irements o& t!e proce$%res proce$%res eveops " protoco eveops " protoco to con$%ct "n eveop " protoco F"is to $eveop " to con$%ct "n experiment to con$%ct "n protoco to con$%ct experiment s"tis&#in' excee$in' t!e experiment "n experiment t!e minim%m minim%m re5%irements re5%irements Tot" core 9e"n score6(Tot" coreD*) 8ercent"'e core6 (Tot" coreD;) x 177J
core
B%$!% 9. (*77<). Fo%n$"tions "n$ E"rt! Ret"inin' tr%ct%res . Ne- erse# o!n 2ie# "n$ ons Americ"n ociet# &or Testin' "n$ 9"teri"s (1===). t"n$"r$ Test 9et!o$ &or CBR o& L"bor"tor# Comp"cte$ ois (1<
