discharged from the dryer. Equipment for heating the asphalt shall consist
of a retort or steam coils so designed that steam will not be introduced into
the asphalt.

The mineral aggregate and the liquid asphalt shall be mixed in a
pugmill type plant in accordance with the following: All lumps in the plant-
mix material shall be broken up thoroughly before the mixture is placed on
the lining. Mixing shall continue for a period of at least 30 seconds after
all ingredients are in the mixer and until a uniform mixture of unchanging
appearance is obtained, with all of the particles or aggregate thoroughly
coated with liquid asphalt. The mineral aggregate shall be furnished in
two sizes, and shall be stored in separate bins. The two sizes shall be
combined in proper proportions as directed at the time of mixing. The aggre-
gates shall be heated before entering the mixer, to a temperature not in ex-
cess of that consistent with proper mixing and laying, but in no case shall the
temperature exceed 350° F. The placing temperature of the material shall
be held as near 325° F as practical. All material shall be proportioned
accurately by weight.

Additional filler, if required, shall be proportioned and blended
with the mineral aggregate before screening into the separate bins, Filler
may be added to the aggregate at the mixing plant by thoroughly premixing
it with the other fine aggregate. Spreading filler over the top of aggregate
pits or dumping it indiscriminately into the hopper at crushing plants will
not be permitted.

The amount of liquid asphalt may vary between 8 and 10 percent,
by weight, of the mineral aggregate, and the exact percentage will be fixed
by the contracting officer. When a greater amount of liquid asphalt is re-
quired to produce a satisfactory mixture, due to the porosity of the rock,
the quantity shall be increased above the limits herein specified. The
liquid asphalt shall be added to the mixture at a temperature of not less
than 250° F nor more than 325° F. The contractor shall furnish, and
keep on the work at all times, an accurate thermometer suitable for deter-
mining the temperature of the liquid asphalt being added. The amount of
liquid asphalt to be added shall be accurately weighed by means of an ap-
proved weighing device.

The contractor shall furnish a set of platform scales of sufficient
size to weigh the trucks loaded with the prepared plant-mix material.

(b) Transporting--The mixture shall be transported from the
mixing plant to the site of the work in trucks having tight, clean, and
smooth beds which have been oiled with a minimum amount of approved
thin oil to prevent adhesion of mixture to the beds. Each load shall be
covered with canvas or other suitable material of ample size to protect
the mixture from the weather, Deliveries of material shall be made so
that spreading and rolling of all mixtures can be completed during day-
light, unless artificial light satisfactory to the contracting officer is pro-
vided. Hauling over the newly completed lining will not be permitted.

br



of the coating had been lost in the 8 years of service, as shown below,

and the remaining portion of the filled asphaltic-emulsion was thin,
oxidized and brittle.

Coal Tar

In a short reach of the test section, a coal tar waterproofing
was placed on the surface of the old concrete lining. The condition of
this resurfacing material after 8 years of service and exposure is shown
in the photograph below. At least 50 percent of the resurfacing material
has been eroded and that remaining is thin, badly oxidized and brittle.

Asphaltic Concretes

; Two types of asphaltic concrete were also placed over the dis-
integrated and weathered concrete lining. Both were placed to a minimum

ty 12


*TYPICAL ESTIMATE OF QUANTITIES AND PAY ITEMS

Item Work or material Quantity
1 Preparation of existing
canal surfaces 3,611 square yards ©
2 Furnishing and applying

asphalt emulsion for
prime coat

Furnishing and applying
asphalt cement for tack
coat

Furnishing asphalt ce-
ment for plant-mix as-
phaltic concrete

Furnishing and applying
plant-mix asphaltic con-
crete

1.5 tons

4 tons

26 tons

285 tons

*Assumed: (a)

2,500 linear feet of canal

(b) 11-foot bottom width

(c) Resurfacing to extend 1 foot up both
side slopes

(d) Asphaltic concrete at 140 lb/cu ft

(e) Asphalt content of mix = 10 percent.

GPO #43543


The total cost of
resurfacing by con-
tract in 1944 was re-
ported to be $1.27 per
square yard for the
13-inch thick mat of
asphaltic concrete,

Performance

In September 1944,
an inspection of the lin-
ing constructed in April
1944, revealed that the
upstream edge of the
asphaltic concrete had
separated from the old

portland cement concrete and several square yards of the asphaltic lin-

ing had floated away.

To prevent further damage and to complete re-

habilitation of the old lining, the asphaltic concrete lining was extended
upstream to the end of the old concrete lining and secured with a cut-

off wall,

Constructed at the end of and adjacent to the old concrete lin-

ing, the cut-off wall consisted of a 12-inch wide trench 36 inches deep

filled with asphaltic concrete.
in the trench by hand tamping.

The asphaltic concrete was compacted

The September 1944 inspection also revealed some slight

erosion on the surface of the lining which had not been sealed. Generally,
however, the lining was in excellent condition after one season of opera-

tion.

An inspection in April 1952, after 8 years of service, photograph

below, revealed little
change in the general
condition of the lining.
Close examination of
several representative
areas, photograph at
top of the following page,
showed little, if any,
erosion and no deleter-
ious effects from mud
curling. Bond between
the portland cement con-
crete and the asphaltic
concrete appeared to be
excellent throughout the
length of the repaired
sections. The Manager
of the Board of Control
reported in 1952 that no


(c) Spreading and compacting--The plant-mix resurfacing mate-
rial shall be spread by means of a self-propelled type paver. The paver
shall be equipped with an agitator, preferably of the pugmill type, and
shall spread the material evenly and with uniform density and strike it off
true to the required cross section. Screeds shall not follow minor irreg-
ularities on the existing canal surfaces, shall be readily adjustable and
shall be provided with gages for accurate control of depth of spread. The
required compacted thickness will be 1-1/2 inches. To obtain this required
thickness, the contracting officer will determine the depth to which the
screed is to be adjusted.

The asphaltic concrete resurfacing material shall be extended
12 inches up the canal side slope measured from the toe of the slope.
The required compacted thickness shall be 1-1/2 inches. The upper edge
of the asphaltic concrete resurfacing on the slopes shall be neatly trimmed
and finished.

Material at joints shall be evenly spread by rakes immediately
after the adjoining strip has been laid and before the roller has compacted
the material.

The resurfacing material shall be compacted by rolling. Rolling
shall begin as soon as possible after the material is spread: Provided, That
no rolling will be permitted so long as the material "shoves" In front of the
roller. A light 1-1/2- to 2-ton roller shall be used for the initial compaction
followed by a 6- to 8-ton tandem roller.

All areas not accessible to the roller shall be compacted by hand
tampers, approved by the contracting officer.

During rolling, all lumps or compressed masses of the mixture
shall be removed and disposed of and the area filled with additional mate-
rial and again rolled. The edges of the completed surfacing shall be trimmed
uniformly to the required cross section before they are finally rolled and
shaped. The completed surfacing, when ready for acceptance, shall be thor-
oughly compacted, smooth, true to grade and cross section, and free from
ruts, humps, depressions, or irregularities.

The cost of all labor and materials used in furnishing, spreading
and rolling plant-mix bituminous material shall be included in the unit
price per ton bid therefor in the schedule.

6. Materials, Materials required for the repair and resurfacing
shall be Turnished in accordance with the following specifications. Num-
ber and symbols refer to Federal specification unless otherwise indicated.

(a) Emulsified asphalt--Emulsified asphalt for use as prime coat
for the resurfacing shall conform to Federal Specification SS-R-674b, Type
SS-1.

(b) Mineral aggregate--Mineral aggregate for use in plant-mix
material shall be furnished by the contractor, shall be uniform in quality

3 va



7, Measurement for payment. Measurement for payment for the various
items of work to be performed in Gonnection with the resurfacing will be in
accordance with the following:

(a) Preparation of existing canal surfaces--The unit of measure-
ment for payment will be the square yard and measurement will be made in
the field of the actual surface area prepared.

(b) Furnishing and applying asphalt emulsion for prime coat--The
unit of measurement for payment shall be the ton (2,000 pounds). Measure-
ment will be made of the actual volume of undiluted asphalt emulsion applied
and converted to tons of material in accordance with the following table:

Type of asphalt Gallons per ton at 11° F
SS-1 type asphalt 240
emulsion

(c) Furnishing and applying asphalt cement, AP-6, for tack coat--
The unit for measurement for payment shall be the ton (2,000 pounds). Tne
measurement of asphalt cement will be made of the actual weight of asphait
cement used in the tack coat. If the measurement of asphalt by volume is
used, a gallon shall be construed to be a gallon at 60° F. The following
table shall be used for converting volume to weight:

Type of asphalt Gallons per ton at 50° F
AP-6, 50-60 pene- 235
tration

(d) Furnishing and applying asphalt cement, AP-6, for asphaltic
concrete--The unit of measurement for asphalt used in the asphaltic -con-
crete canal lining shall be the ton (2, 000 pounds). The tonnage to be paid
for shall be the number of tons of asphalt used in the accepted work, as
determined by shipping weights. No payment will be made for asphalt that
is wasted.

(e) Furnishing and applying plant-mix asphaltic concrete resur-
facing--The unit of measurement for payment for plant-mix asphaltic
concrete resurfacing shall be the ton (2,000 pounds). Payment quantities
of asphaltic concrete shall be the ton on the basis of the net weight of as-
phaltic concrete placed in accordance with the area and thickness of lin-
ing shown on the drawings or established by the contracting officer.





been eroded and

that remaining was
soft and badly
spalled and cracked.
This resurfacing
material was applied
after first applying
a tack coat of the
same material to the
old concrete lining.

The asphalt-
emulsion and sand .
mixture was placed
at various thicknesses
over the old concrete
lining; some, after
first treating the old
concrete surface
with a tack coat of
RC-O cut back
asphalt, and some, directly to the untreated concrete surface.

The resurfacing, photograph below had a fair appearance at the
time of placement except for an exceptionally heavy rebound of sand par-
ticles. The re-
bound was largely
uncoated, indicating
that the emulsion
was not coming into
proper contact with
the sand in the pneu-
matic nozzle. Com-
pleted sections, when
swept clear of the
rebound, appeared
firm and quite tight,
with a fairly smooth
surface, The first
part of the emulsion-
sand was constructed
with an RRW asphalt
emulsion, using the
pneumatic gun shown
above. An attempt
was made to use an
NX, quick breaking
emulsion but the emulsion broke in the gun and the material could not be
applied. In order to secure a test application of the NX emulsion, it was
applied by a spray bar attached to a distributor truck, while the sand was
applied with the pneumatic gun, photograph at top of the following page. One
man operated the hand spray bar and applied the asphalt, while a second man
operated the gun. No difficulty was encountered using this method. The sand,
upon striking the emulsion film, broke the emulsion rapidly and there was
very little rebound.

yi

8


Ridenbaugh Canal

The Ridenbaugh Canal is operated by the Nampa-Meridian
Irrigation District, Arrowrock Division, Boise Project, Idaho, to
irrigate 27,000 acres of the Boise River Valley lands in the vicinity
of Nampa and Meridian, Idaho. The old original canal was probably
constructed some time in the 1870's. In 1910-11, a section of the canal
9, 200 feet long was lined with a 4-inch unreinforced concrete lining.

The canal as originally lined with portland cement concrete
had a capacity of 618 cfs, with a bottom width of 10 feet, a velocity
of 5,42 feet per second, and a normal water depth of 6 feet. The 4-
inch unreinforced concrete lining was placed on side slopes of 13:1
and the lining height was 7 feet. Practically all of the concrete lin-
ing was still in place when inspected in 1947, however, longitudinal
and pattern cracking of the concrete was prevalent in practically
every panel. In some panels, the surface had weathered and erosion
and disintegration had progressed to varying depths. In places this
disintegration had progressed completely through the concrete lining.

The section of deteriorated concrete lining was selected as
the site for obtaining information relating to the restoration and re-
habilitation of old concrete irrigation canal linings in connection with

ow


maintenance has been per-
formed in the sections
since they were com-
pleted in 1944,

Again inspected dur-
ing the summer of 1955,
as shown in the photo-
graphs below and on the
following pages, it is
in excellent condition
after 103 years of serv-
IC@s

The middle photo-
graph on this page is
a general view of the
Main Canal looking up-
stream from approx-
imately Mile 1.

Although there was
a thin sheet of water
over much of the lin-
ing the asphalt mat was
discernible and there
did not appear to be any
evidence of cracks in
the older concrete lin-
ing being reflected or
transmitted through
the asphaltic concrete
mat.

The lower photo-
graph on this page is
a view of the 14-inch
thick asphaltic concrete
on the bottom of the
canal at approximately
mile 2.8 after 103-years
of service. In the photo-
graph at the top of the
following page a close
up of the asphaltic con-
crete surface is shown.
The surface has been
roughened over the inter-
vening 103 years, but
there were few cracks
and little errosion was
apparent,


TENTATIVE
SPECIFICATIONS FOR ASPHALTIC CONCRETE RESURFACING

1. Asphaltic concrete canal resurfacing. General. --The asphaltic con-
crete resurfacing shall consist of a mixture of mineral aggregate, and as-
phalt, all mixed hot and laid in accordance with these specifications. The
thickness of the asphaltic concrete resurfacing shall be as shown on the draw-
ings. Prior to spreading and compacting the asphaltic concrete resurfacing,
the contractor shall prepare the existing surfaces as hereinafter specified.

2. Preparing existing concrete canal surface,

(a) General. --Prior to applying prime and tack coats, the existing
surfaces shall be prepared by cleaning.

(b) Cleaning existing canal surfaces--Just prior to applying the as-
phalt emulsion prime coat, the entire area to receive resurfacing shall be
cleaned by power brooming. The brooming shall remove all dirt, sand, and
broken pavement. Following the brooming, the area shall be cleaned with a
suitable air-water jet removing all other deleterious materials which would
prevent the prime coat from bonding to the pavement. The cost of all labor
and materials used in cleaning shall be included in the unit price per square
yard bid in the schedule for preparation of existing canal surfaces,

3. Prime coat. Immediately following the cleaning of the existing con-
crete canal surfaces, the contractor shall apply as asphalt emulsion prime
coat. All puddles, pools, and free surface water shall be removed from the
old lining just prior to the application of the prime coat. The prime coat
shall consist of an SS-1 asphalt emulsion uniformly applied at a rate of 0.05
to 0.1 gallon per square yard by pressure spraying. The asphalt emulsion
shall be applied over the entire area to be resurfaced.

4, Tack coat. A tack coat consisting of a 50-60 penetration asphalt
cement shall be uniformly applied while hot at a rate of 0.15 to 0. 25 gallon
per square yard over the moisture free primed surface. The tack coat shall
be applied by means of a pressure-type spraying distributor.

5. Asphaltic concrete.

(a) Mixing--The mixing plant used by the contractor shall be a pug-
mill type, designed and assembled so as to properly dry, heat, screen and
mix the materials. The plant shall have screens capable, at normal speeds,
of separating all aggregate to the required sizes. At least two storage bins,
proportioned so as to insure adequate dry storage of the appropriate sizes
of the aggregate, shall be provided. The break in gradation to determine
limiting sizes of fine and coarse aggregate shall be determined in the field
by the contracting officer. The plant shall be equipped for accurately pro-
portioning the two sizes of aggregates and asphalt by weight, using either
dial scales or multiple beam scales of a type approved by the contracting
officer. Scales shall be accurate within one-half percent of all loads,
The plant shall have a dryer, suitably designed to heat and dry the aggre-
gate to specification requirements. Suitable accurate thermometric equip-
ment shall be furnished for ascertaining the temperature of the aggregate



Pneumatically Applied Portland Cement Mortar

The 13-inch thick pneumatically applied portland cement mortar
or shotcrete resurfacing had a very good appearance at the time it was
placed, as shown in the upper photograph on the previous page. After 8
years, in addition to the spalling and cracking apparent in the lower photo-
graph on the pre-
ceding page and
in the photograph
at left, the resur-
facing material
was drummy, with
voids apparent be-
tween the old port-
land cement con-
crete and the re-
surfacing of port-
land cement mortar.

Pneumaticaily Applied
Asphalt-sand Mixtures

In the photo-
graph at the bottom
of this page are
shown two types of
asphalt-sand mixtures, also placed pneumatically. The resurfacing mate-
rial at the left in the photograph is a mixture of asphalt emulsion and sand
and that toward the right is a mixture of RC-O cutback asphalt and sand.
(The light colored
surfacing material
at the extreme right
in the photograph is
a portion of the pneu-
matically applied
portland cement
mortar described
previously.)

The RC-O as-
phalt and sand was
placed to a minimum
thickness of 1/2-inch,
It was soft and ap-
peared to have a
permeable structure.
The softness was
considered to be due
to the inability of
the cut back asphalt to properly cure under this condition of use. The photo-

“aph at the top of the following page is a view of thi f
iter 8 years of exposure. Large areas of the resur

resurfacing material
g material had

8

oy

p


Guo 640

Department of the Interior

Bureau of Reclamation

OPERATION AND MAINTENANCE
EQUIPMENT AND PROCEDURES

RELEASE NO. 18

October, November and December 1956

CH= 467-28

CONTENTS

Resurfacing Deteriorated Concrete Linings



Mineral Filled Asphalts

In the photograph immediately below, a section of the old
portland cement concrete lining was resurfaced with a mineral filled
asphaltic cement. It was applied as a relatively thin membrane by spray.
The resurfacing
was primarily a
seal coat and con-
sisted of 23 per-
cent diatomaceous
earth and 77 per-
cent, 85-100 pene-
tration asphaltic
cement.

The material
applied, thoroughly
coated and water-
proofed the con-
crete lining, re-
sulting in a slick,
tough surface. A
part of the section
treated was resurfaced by spraying the material directly upon the old con-
crete surface and the balance was applied after first applying a tack coat
of RC-O cutback asphalt to the old concrete.

At the time of placement, this section did not look as good as
the pneumatically applied resurfacing material due to the relative thin-
ness of the coating. All rough and eroded areas of the old concrete lin-
ing were still visible after the resurfacing had been applied, due to lack
of a''build-up'' of the more deeply eroded and rough surfaces.

The condition
of the thin membrane
after 8 years of ser-
vice is shown in the
photograph at left.
For practical pur-
poses, the mem-
brane has been
eroded from the
surface of the old
concrete where the
surface was not
primed with the
RC-O cutback as-
phalt, prior to
application of the
filled asphalt ce-
ment. There is
much sagging, curling and erosion apparent wnere wie suriace was primed,
as’ shown in the photograph at the top of the following page.

fe- vA, 10


A firm, smooth
surface with a good
buildup of material
over the concrete
lining was obtained.
Previously tried in
the laboratory, with
RC- cut-back as-
phalt and with hot
asphalt cement this
method produced
negative results.
The emulsion as
used in the canal
resurfacing work
was very satis-
factory.

Views of the
asphalt emulsion
resurfacing after 8
years of service
are shown in the two
lower photographs
on this page. Severe
disintegration and
spalling is apparent
in the first treat-
ment as shown at
left, with total
erosion in some
areas.

That placed by
the simultaneous
application by hand
spraying the asphalt
emulsion and pneu-
matic application
of the sand, is in
better condition,
as shown in the
lower photograph,
Although in some-
what better con-
dition than that
shown above, it
also was badly
spalled and cracked
and the remaining
material was soft.


the Bureau of Reclamation's Lower-cost Canal Lining Program, Ac-
cordingly, in 1947, several different materials and methods of placing
these materials were tried. The various types of resurfacing mate-
rials used are described and photographs of the linings at the time of
placement in 1947 are compared with photographs of the same mate-
rials as they appeared at the time of inspection in 1955, after 8 years
of service.

A typical view of a portion of the canal at the time some of
the linings had been placed in 1947 is shown in the first photograph
below. The old concrete lining in the foreground has been resurfaced
with pneumatically applied portland cement mortar. Other resurfacing
materials are being applied to the old concrete lining in the background.
The lower photograph is a view of a portion of the resurfaced concrete
lining after it has been in service for 8 years. Again the pneumatically
applied portland cement mortar is shown in the immediate foreground,
extending from right to left, with the other resurfacing materials to-
ward the left. Practically all of the experimental resurfacing mate-
rials showed some signs of deterioration, with several being so badly
weathered or eroded as to be no longer serviceable.



and grading, and shall be free from adobe, vegetable matter, and other
deleterious substances. The following designations in parentheses refer
to method of test described in the fifth edition of the Bureau of Reclama-
tion Concrete Manual:

(1) Grading--The mineral aggregate when tested by means of
standard screens (Designation 4) shall conform to the following limits of
gradation:

Percentage by weight

Sieve opening passing sieve
1/2 inch 100
No. 4 95-80
No. 10 80-60
No. 40 35-14
No. 200 6-14

No rock larger than 6 inches in any diameter shall be used in the
rock crusher, in the event the contractor produces aggregates by crushing
rock,

(c) Asphalt cement for tack coat and plant-mix--Asphalt cement for
tack coat and plant-mix shall conform with the requirements of Federal
Specification SS-A-706b, Designation AP-6, 50-60 penetration. Tests shall
be in accordance with Federal Specification SS-R-406c.

REQUIREMENTS
TESTS

Flash point, not less than ........
Softening point ......... te eeeee
Penetration at 77° F, 100 grams,
5 seconds ........ tee e ee eeee tee w eee e ec ceee 50-60
Loss at 325° F, 5hr., not more than . 1 percent

(a) Penetration of residue at 77° F,
100 grams, 5 sec., as compared
to penetration before heating,

not less than ... 60 percent

Ductility at 77° F, not less than ............. 40 cms
Bitumen (soluble in carbon disulphide)
not less than ............. Seem eee aneeee 99.5 percent

(a) Organic matter insoluble,
not more than...............00c00e 0. 2 percent

g-1


In 1926, operation of the canal was transferred from the
Bureau of Reclamation to the Boise Board of Control, an agency com-
posed of representatives of the several water user organizations which
receive water from the canal, During April and November 1944, ap-
proximately 7, 200 square yards of badly eroded portland cement con-
crete lining in the bottom of the canal were rehabilitated by placing a
z-inch thick asphaltic concrete mat over the old concrete lining.

Construction

The 13-inch thick asphaltic concrete mat was laid over the

old concrete in one layer. Before the mat was placed, the surface of

the old lining was cleaned with a rotary brush, primed with kerosene,
and given a tack coat of hot 50-60 penetration asphalt. The work was ac-
complished by contract.

The resurfacing
material consisting of
10-percent asphalt of
50-60 penetration and
aggregate was hot mixed
in the contractor's plant
in Boise. The hot mix
was transported by truck
to the site of placement
where it was dumped
on the old concrete lin-
ing ahead of and spread
by a paver, photographs
at left.

The temperature of
the mix delivered to the
site of the work was
around 300° F. Most
of the lining was later
sealed with an applica-
tion of hot asphalt of
the same grade used in
the mix,

As shown in the
photograph at the top of
the following page, the lin-
ing was rolled with a 12-
ton standard roller, no par-
ticular trouble being ex-
perienced, other than that
at was usually necessary

to wait for some cooling before rolling.


thickness of 1/2-inch. One was an asphaltic-emulsion concrete and the
other an asphaltic-cement concrete, both were 'hot-mixed' in a central
plant.

The "hot-mix'' asphalt-emulsion, shown in the photograph be-
low, was composed of an RX emulsion and a graded aggregate. The
aggregate was heated to about 225 degrees F, before adding the emulsion.
Eleven percent of emulsion was added, giving the mix an asphalt content
of approximately 5.5 percent. Placement and rolling of the asphaltic-
emulsion as shown was preceded by the application of a tack coat of RC-O
cutback asphalt to the old portland cement concrete lining and hand raking
to assure a minimum resurfacing material thickness of 1/2-inch after
compaction,

Due either, possibly, to too low an aggregate temperature or to
too 1ean a mix, the in-place asphaltic-emulsion concrete lining was brown
in color and lacked cohesiveness, the completed surface being easily
abraded. Approxi-
mately a 30-foot
length of this mate-
rial was sealed
with an application
of 0. 25 gallon of
RC-O cutback as-
phalt per square
yard of surface.

The asphaltic-
emulsion concrete,
as shown at left,
after 8 years of
service is still in
place. It exhibits
numerous cracks
and is soft in spots.



filled hot-applied asphalt cement. From the standpoint of service, one
would probably rate the "hot-mixed' asphaltic-cement concrete first,
followed by the asphalt-emulsion concrete and the pneumatically applied
portland cement mortar.

In general the entire resurfaced section of canal is considered
in poor condition with the exception of the hot-mixed asphaltic-cement
concrete. This latter shows some cracks and roller marks. Both these
deficiencies probably could be eliminated partially by increasing the
thickness of the resurfacing material and more careful rolling at the time
of placement.

Many of the other resurfacing materials could have been more
effective with continued maintenance, but the overall experienced gained
is of considerable value, and that was the purpose of the experimental
installations.

From the information gained from the experimental installations,
a tentative specifications for the asphaltic concrete resurfacing of portland
cement concrete has been prepared. These specifications are attached.

xR KKK



RESURFACING DETERIORATED CONCRETE LININGS

Rehabilitation of portland cement concrete linings has been
one of the many problems facing operation and maintenance personnel
on our irrigation projects over the years. In the attempt to keep our
canals in service, various materials have been used to rehabilitate
and resurface the concrete linings. To briefly evaluate some of the
methods and materials used in resurfacing, so far as durability and
performance are concerned, there is being summarized herein the
results of inspections made on the Boise Project in Idaho.

The rehabilitation of deteriorating or aging linings was re-
viewed primarily in an effort to guide repairs to be made on the canals
of the Boise Project and the Kittitas Division of the Yakima Project,
Washington. The condition of the existing lining and the subgrade, and
the conditions under which the canal must be operated will govern the
repairs that can be made.

Main Canal - Boise Project

Asphaltic Concrete

One of the early uses of asphaltic concrete for the purpose of
rehabilitating portland cement concrete, is an installation made on the
Boise Project inIdaho. This installation on the Main Canal (formerly
the New York Canal) was made in 1944 with the placement of approxi-
mately 7, 200 square yards of a 13-inch thick asphaltic concrete mat
over the badly eroded concrete lining which had been in service since
1909 and 1910, Inspected and tested in 1955, the asphalt 'half-sole"
was still in good condition after having been in service for 11 years,

The canal was originally constructed by a private canal com-
pany beginning about 1895. In 1906, the canal was transferred to the
Reclamation Service, the forerunner of the Bureau of Reclamation,
and it was enlarged and extended in 1906 and 1908. At the conclusion
of this work, the canal had a bottom width of 40 feet, but provision
had been made for future development to a bottom width of 70 feet.

From the diversion point to approximately Mile 10, the canal
is in sidehill location and is excavated through a gravelly soil. To in-
sure the safety of the canal and prevent seepage, el2ven sections
totaling 5.8 miles in length within the first 10 miles were lined with
concrete in 1909 and 1910. In several of these sections, the lining
covers only the lower bank, or the lower bank and the right half of
the bottom. From 1909 and 1912, the earth sections between the lined
section and the remainder of the canal below the last lined section
were enlarged to a base width of 70 feet.

Since 1910, additional concrete lining has been constructed
and most of the lining installed in 1909 and 1910 has been replaced or
resurfaced so that much of it is now 8 inches thick. The canal conveys
approximately 3,000 cfs of water at a velocity of approximately 6 to 7
feet per second. With a high sand load the bottom has been eroded and
scoured, Ca
1 fo


OPERATION AND MAINTENANCE

EQUIPMENT AND PROCEDURES

Release No. 18
October, November, December - 1956
INTRODUCTION

Concrete, for the most part, has given excellent service over the
years as a canal lining material. Some concrete linings have been in ser-
vice for 40 to 50 years. Advances in concrete construction techniques and
the use of air entrained concrete should provide even better service in the
years to come. However, as would be expected from long periods of ex-
posure, some disintegration and deterioration does occur, especially in
concrete surfaces that are constantly exposed to erosion, scour and weather.
Accordingly, some of the older concrete linings are now in need of repair.
This issue ot the Bulletin is devoted to the experimental repair of concrete
linings, and the record of durability of such repair, in an effort to prolong
their servicable lives. Future Bulletins will present other methods of re-
pairing canal linings and reports of the service obtained from these repairs.

This Bulletin, published quarterly, is circulated: for the benefit
of irrigation project operation and maintenance people. Its principal pur-
pose is to serve as a medium of exchanging operation and maintenance in-
formation. Reference to a trade name does not constitute the endorsement
of a particular product, and omission of any commercially available item
does not imply discrimination against any manufacturer. It is hoped that
labor-saving devices or less costly equipment developed by the resourceful
water users will be a step toward commercial development of equipment for
use on irrigation projects in continued effort to reduce costs and increase
operating efficiency.

Error corrected: (pen and ink changes)

In Release No. 16, a Table of Contents was prepared and various
articles from previous issues were reprinted so that those who wished to
could consolidate all items published on weed control into one volume.
We're sorry, but we overlooked three articles in Release No. 9. The page
numbers appearing on the articles as originally released should be changed
as follows: Weed Burner (Oil) ...IA15, sheets 1 and 2; Moss Screens...
IB9, sheets 1 and 2; Weed Cutting Launches ... IIB13, sheets 1 through 4.
The foregoing three articles should be added to the Table of Contents in
Release No. 16 to make it complete. Also the Table of Contents should be
corrected to show that articles appear in Release No. 9 as well as Releases
No. 3 and 8. To follow the key already established, three asterisks (***)
are suggested to designate Release No. 9 articles.

KOR KR
Division of Irrigation Operations

Comissioner's Office
Denver, Colorado.



LT

An applica-
tion procedure,
similar to that
previously de-
scribed, was fol-
lowed in resurfac-
ing a section of con-
crete lining with a
mineral filled as-
phalt-emulsion, as
shown in the middle
photograph, The
thin seal coat was
applied with and
without an RC-O
cutback asphalt
tack coat, and con-
sisted of a soft,
200-penetration,
asphalt cement
having a 23 per-
cent filler of dia-
tomaceous earth
applied at a tem-
perature of 140
degrees F,

A good spray
was obtained at the
application temper-
ature, and the re-
sulting surface was
fairly satisfactory.

As shown in the
lower photograph
this material also
had been badly
eroded from the sur-
face of the old con-
crete lining when
inspected in 1955
after 8 years of
service,

A ''Laykold
Weather Coat", also
a filled asphaltic-
emulsion, was
applied to the sur-
face of the old con-
crete lining by
brush. Approxi-
mately 50 percent


14

The asphaltic-
cement concrete, also
plant mixed, consisted
of a graded aggregate,
100 percent passing
the #4 size screen
and approximately
7 percent of 85-100
penetration asphalt
cement. This mate-
rial was placed ata
temperature of about
350 degrees, and
both side slopes and
bottom were rolled
as shown,

The resurfacing
material was very
good in appearance
at the time placed
and, as shown in
the lower photo-
graph, there are
few cracks and
very little spalling
after 8 years of
service and ex-
posure. Some
roller marks are
still apparent and
the protective
resurfacing mat is
intact and hard.

SUMMARY

By way of com-
parison at the time
of placement, the
pneumatic applied
portland cement con-
crete resurfacing
was the best in
appearance, followed
by the hot-mixed as-
phaltic-cement con-
crete, the pneumatic-
ally applied asphalt-
emulsion, and the