HomeMy WebLinkAbout3188; COLLEGE BLVD EXTENSTION; VISUAL INSPECTION AND CORE TEST RESULTS; 1987-04-02CONSTRUCTION LABORATORIES
________ ________ . .. ENGINEERING • INSPECTION • TESTING
April 2, 1987.
0 '
The Koll Company ' . S
' . 'Prjéct No. 7679 7330 Engineer' Road
. Log No, 7-1381 San Diego, California, 921,11
Attention: Mr." Tony German
SUBJECT: VISUAL INSPECTION AND CORE'TEST RESULTS
' 84" Cast-In-Place 'Pipe
CRC Phase- ,3&4
' ' ' Carlsbad, California'
Gentlemen:
Per your request, a'visual inspection.was'performed on. Marc
h
1
0
,
1987 on the 84-inch cast-in-place concrete pipe.
The purpose of this inspection was to investigate 'the circu
m
-
férential cracks and render an opinion as to the,. effect and
recommendation for' corrections. :
A series of circumferential' cracks. were noted along the l
e
n
g
t
h
o
f
pipe starting at a, point '600 feet westerly of the north/south
section of Faird'ay Avenue, and continueswesterly for about 1,
4
0
0
feet.
At. the, time of our inspection, most of the significant cracks ha
d
been sacked over with a mortar-like- material. 'Some areas showed
additional cracking through this repair, while other areas sh
o
w
e
d
the repair to be stable.
Between 'the downstream 'end and the first manhole
, number #11 , no
' circumferential cracking was observed. ..At both manhole #
1
a
n
d
manhole #2, cracks or cold joints, were noted, possibly as
s
o
c
i
a
t
e
d
with the manhole construction'.'
•• . ,.
0
,
SUBSIDIARY CORPORATION OF IRVINE CONSULTING GROUP, INC.'
6455 NANCY RIDGE DRIVE • SUITE 200 SAN DIEGO, CA 92121 • (619)587-0250
. • The Koli Company Project No. 7679 April 2, 1987 : Log Nb. 7-1381
Page 2
Between manhole ff1 and manhole #2,. two cracks were noted with.
widths from 0.03 to 0.05 inches. There were three othe
r
a
r
e
a
s
where there seemed to be a '!tension pull" in the concrete rather.
than an actual open crack. From manhole #2 to manhole
#
3
,
f
o
u
r
cracks were seen with widths from 0.05 to 0.07 inches.
F
r
o
m
manhole #3 to the upstream end, eight actual or app
a
r
e
n
t
circumferentially cracked areas were observed, varyi
n
g
i
n
w
i
d
t
h
s
from 0.01 to 0.07 inches.
Starting at the downstream end to a point: about 100 feet east of
manhole'#3, seepage or dampness was noted at most crac
k
s
The remainder of the pipe appeared to be dry. The cracks
w
i
t
h
i
n
t
h
e
pipe were generally flush across the; width and onl
y
i
n
a
f
e
w
instances did a slight offset of 0.01±inch appear.
/
The cracking does not seem to: be structural in nature
.
I
t
m
i
g
h
t
be the -result of concrete shrinkage effects. As noted above,
t
h
e
widest crack was 0.07 inches which is:near the size of the
smallest sand particle.
• . . •. •. •• • • • • •
It is felt that a crack this size will not permit si
g
n
i
f
i
c
a
n
t
soil migration into the pipe, however, water can f
l
o
w
i
n
t
o
o
r
o
u
t
of the pipe
. If water inflow/outflow is not a problem, we do not fe
e
l
t
h
a
t
filling the cracks is necessary. However, if the crack
s
h
a
v
e
n
o
t
stabilized, the situation should be reviewed again if
t
h
e
. • . cracking expands to 0.10.to 0.15 inches.
•
.
•
. The Koll Company : Project No. 7679
. April 2, 1987
. . Log No. 7-1381
. . .Page3
On March 10, 1987, Construction Laboratories core-drilled eight
four-inch diameter cores to obtain data for. analysis
o
f -concrete
acceptability and extent of cracking. Using the criteria
o
f
t
h
e
Uniform Building Code, Chapter 26, Section 2604 (j) fourth
paragraph: . . .
Concrete in an area represented by core tests
shall be considered struätually adequate if the
average of three cores is equal to at least 85
percent of f'c and if no single core is. less
than 75 percent of f'c.".
. . . .
.The cores were drilled and tested in accordance with the
requirements of ASTM C42, "Stabdard Method of Obtaining and
Testing -Drilled Cores and Sawed Beams of-Concrete,'.' except as
modified by the pre-test conditioning detailed in Section .
2
6
0
4
.(j). Accordingly, the cores were tested dry after storage for
seven days at a relative humidity less than 60. percent a
n
d
a
temperature.beteen 60-80F.
. The strength correction.factors from
C42 were applied -to the tested core strengths.where the ratio of.
height-to-diameter was less than 1.94.
(a) . The average of three cores. at least equals
.85 f'.c.85 X3,000 = 3,400 psi
. .
(b) No single core is less than .75 f'c
75 X.3,000"= 2,250 psi
Based upon the test results in Table A, the concrete
r
e
p
r
e
s
e
n
t
e
d
by these cores is in compliance with a design strength
o
f
.
4
,
0
0
0
psi. • . • . . . .
/ . . H
TABLE
•
• COMPRESSION TEST OF DRILLED CORES
Location Core#3 Core #5 • Core #7 Core. #8
.• Core Diameter: 3.70 3.70 3.69 • 3.69
Tested Heiht,in. 7.06 7.63 0 763 7.59
Total Load, lbs. • 59,000 51,900 43,900 62,800 0
Correction Factor 0.99 N.A. N.A N.A.
. Corrected Compressive
• 5430 • 4830. 4110. 5880