The high-level points are: 1) Four concrete mix designs were discussed in detail for the CRT Facility construction project: high early strength concrete, fiber reinforced concrete, shotcrete, and controlled density fill. 2) The mixes used various cement types, aggregates, fly ash, and chemical admixtures to achieve the required properties for different locations in the facility. 3) Unique aspects of the project included its hillside location near the Hayward fault, extensive foundation work, and a seismically isolated computing floor housing supercomputers.

1. COMPUTATIONAL RESEARCH AND THEORY FACILITY
LAWRENCE BERKELEY NATIONAL LABORATORY
Ana Lua
Melissa Meikle
Chwei Peng Tieng
Qudsia Wahab
April 22, 2014
CEE 165: Concrete Materials and Construction
Professor Monteiro

2. 2
Abstract ...................................................................................................................................................... 3
Introduction ................................................................................................................................................ 4
Mix Design.................................................................................................................................................. 6
High Early Strength Concrete ......................................................................................................... 8
Fiber Reinforced Concrete .............................................................................................................. 9
Shotcrete........................................................................................................................................ 10
Controlled Density Fill.................................................................................................................. 12
Reinforcement ........................................................................................................................................... 13
Mixing and Transportation........................................................................................................................ 15
Placement .................................................................................................................................................. 16
Formwork.................................................................................................................................................. 17
Consolidation ........................................................................................................................................... 18
Curing........................................................................................................................................................ 18
Finishing.................................................................................................................................................... 19
Conclusion................................................................................................................................................. 21
Acknowledgements................................................................................................................................... 21
References ................................................................................................................................................. 22
Appendix................................................................................................................................................... 23
TABLE OF CONTENTS

3. 3
The Computational Research and Theory (CRT) Facility at Ernest Orlando Lawrence Berkeley National
Laboratory is currently under construction with an expected completion date of late December 2014 or early
2015. This is a unique construction project due its location on a hillside, proximity to the Hayward fault, and
use to accommodate multimillion dollar supercomputers. DPR Construction is working as the construction
management firm on the project in combination with LBNL, the owner representative. Out of the approximate
twenty mix designs, four have been discussed extensively: high early strength, fiber reinforced concrete,
shotcrete, and controlled density fill. The mix designs commonly used Portland cement types I, II, and V with
coarse and fine aggregates, fly ash class F, and admixtures. DPR Construction has worked with two different
subcontractors to obtain the required concrete: CEMEX and Central Concrete. The centrally mixed concrete
has been delivered to the facility through concrete trucks and has been placed primarily through concrete
pumps, with select structures being casted using pneumatic guns for shotcrete placement. The facility’s
exposure to seismic risk necessitated heavy reinforcement in some locations of the building, and a variety of
rebar sizes are used, albeit not coated with epoxy. The majority of formwork used is made of Douglas. An
array of finishes have been specified for different levels or sections of the facility with practical and aesthetic
considerations in mind. In this project, there are no known quality assurance issues; however, quality control
problems have arisen throughout the construction of the facility. Overall, this high profile project, like any
other, has involved its fair share of construction issues but is well on its way to becoming a state-of-the-art
computing facility with LEED Gold certification.
ABSTRACT

4. 4
Located on 200 acres in the hills above the
University of California, Berkeley campus lies the
Ernest Orlando Lawrence Berkeley National
Laboratory (LBNL), where multidisciplinary
scientific teams work together to solve global
problems in human health, technology, energy, and
the environment. Ernest Orlando Lawrence laid the
foundation of the laboratory’s creation and his legacy
of team science paved the way for discoveries that
led to 13 Nobel Prizes.
The Computational Research and Theory (CRT)
Facility continues this tradition and encourages
expertise coupled with an optimal environment to
advance research. The CRT Facility will bring
together the Computing Sciences Division within
LBNL for the first time, which includes: The
National Energy Research Scientific Computing
Center (NERSC), The Computational Research
Division, The Scientific Networking Division, and
Computational Science and Engineering at Berkeley
(CSE). Through these divisions, key research areas
including global climate change, fusion energy,
biological and environmental basic energy science,
and astrophysics are expected to greatly benefit from
the CRT Facility. Additionally, the facility’s close
location to the University of California, Berkeley will
enable students, scientists, and faculty a common
meeting place to discuss and carry out research in
science and computing.
Figure 1: Image of Rendered Project
The CRT Facility project, approximately 140,000
gross-square-feet with 4 levels, was broken into two
phases, site preparation involving rerouting utilities,
and excavation and construction. DPR Construction
won the construction management bid for the project
in 2007. After settling a litigation regarding the
buildings’ proximity to Strawberry Creek that put the
project on hold for two years and reevaluating the
budget, the budget became lower than expected in
2011 and construction finally began late that year.
With a budget of $125 million from University of
California and $19.8 million from Department of
Energy (DOE), the project is expected to be
completed by late December 2014 or early 2015 with
LEED accreditation of Gold. By incorporating
Berkeley’s climate, the CRT Facility is anticipated to
greatly improve the efficiency of energy for high-
performance computing and be among the forefront
of high-performance supercomputing research.
With a project of this magnitude and location, many
challenges arose. In regards to the location, the site is
located 100 yards away from the Hayward fault. The
Hayward fault is located along the topographic
interface between the gently sloping plain and hills,
and poses a significant ground-rupture and seismic
shaking hazard to LBNL.
Figure 2: Geographic Location of Hayward Fault
Souce: http://seismo.berkeley.edu/tour/tourmap.html
INTRODUCTION

5. 5
In addition to the project’s close proximity to the
Hayward fault, the CRT Facility is uniquely located
on a hillside near the Blackberry entrance to the
laboratory. The steep hillside and small roads
presented many obstacles with excavation, step
footings, and tie-backs. The combination of these
caused the first 18 months of the project to be
dedicated solely to foundation work, which is
typically longer relative to most projects. The
foundation work was taken into special consideration
to ensure the building performs satisfactorily during a
seismic event, especially since the building will
contain a computing floor level that will house
multimillion dollar supercomputers. Having this
computing floor level with a seismically isolated
floor system makes this project unique and
innovative compared to other construction projects.
A construction project at LBNL also presents a
uniqueness in terms of safety regulations.
Supplementary to standard Occupational Safety and
Health Administration (OSHA) regulations, the
project must also follow DOE and LBNL policies
and coordinate with the City of Berkeley and
University of California. LBNL implements their
own safety inspectors that are on-site to ensure their
policies along with all other policies and regulations
are being met.
All four group members had the opportunity to
explore the CRT Facility construction site and learn
the procedures and processes involved in the creation
of the facility. Site visits were conducted in 2014 on
February 19th and 20th, and March 26th and 28th.
Through these site visits, contact with Tim Hart
(Structural Engineer and Consultant), Tim Kemper
(Construction Manager), Ian White (Project
Manager), Rory Shortreed (Inspector of Record)
from LBNL and Mike Miller (Project Engineer) from
DPR Construction assisted with providing
information on mix design, concrete transportation,
reinforcement, concrete placement, finishing, and
construction issues of the CRT Facility project.

6. 6
For a project with several different needs, such as the
CRT Facility, it has been necessary for the contractor
to use a variety of unique concrete mix designs to
implement at different areas throughout the building.
Table 1 summarizes properties of the concrete
required for various locations.
Table 1: Required Concrete Properties for Different
Locations
Approximately 20 mix designs have been used for
different components of the building. Four mix
designs, including mixes for high early strength
concrete, fiber reinforced concrete, shotcrete, and
controlled density fill (CDF) are discussed in detail.
In these diverse concrete mixes, some of the
properties for cement, aggregate, and admixtures
overlap. With the exception of the fiber reinforced
concrete mix design, the concrete mixes are provided
by CEMEX at their Berkeley and Oakland mixing
plant locations. These mix designs were submitted
for review to satisfy the engineer of records
specifications.
Cement
Portland cement is a hydraulic cement capable off
setting, hardening, and remaining stable under water.
Through various tests, CEMEX had certified that the
Portland cement in all the mixes (except fiber
reinforced concrete mix) met or exceeded the
chemical and physical specifications of ASTM C-
150, ASTM C-1157, and AASHTO M 85. The
source of most of the cement was from the CEMEX
Construction Materials Pacific LLC plant in
Victorville, CA, which is located 340 miles from the
project site. This cement was then transported to the
mixing plants in Berkeley and Oakland, located 5
miles and 10.5 miles away respectively. According to
the Cement Mill Test Report provided by CEMEX
that compares the standard chemical and physical
requirements, high early strength concrete, shotcrete,
and CDF qualified as Type I, Type II, and Type V.
Aggregate
Aggregates are broken into two categories - coarse
and fine - and are used to provide dimensional
stability for concrete. The specifications for both
types of aggregates used in the project were provided
mostly to CEMEX by Thornton Tomasetti.The
aggregates for all of the mixes discussed in this
section except those for high early strength concrete
were mined in Eliot Quarry in Pleasanton, CA,
located 37 miles from the project site, and processed
in the Bay Area. The Eliot Quarry produces
MIX DESIGN
Location
28-Day
Strength
(psi)
Slump +/-
1 (in)
Min – Max
Fly Ash (%)
Footings /
Grade
Beams
3,000 4 20 - 40
Slab-on-
Grade
3,000 2 - 4 15 – 25
Fiber
Reinforced
Slab
3,000 4 15 – 25
Walls /
Columns
5,000 4 15 – 25
Elevated
Beams,
Slabs and
Flll on Metal
Deck at HPC
Level
5,000 4 15 – 25
Fill on Metal
Deck
(Except for
HPC
Level)
4,000 2 – 4 -
Shotcrete for
Temporary
Walls
4,000 4 15 – 25
Cantilever
Retaining
Walls and
Their
Footings
4,000 4 15 – 25

7. 7
greywacke and sandstone aggregates, an inexpensive
source of moderately shrinking aggregate that is
suitable to use for normal strength concrete. For high
early strength concrete, the aggregates were imported
over 1,000 miles away from Polaris’ Orca Quarry in
British Columbia, Canada to Pleasanton, CA. The
cost of the aggregates for all the mixes is unknown.
Admixtures
Admixtures are additions to the concrete mix other
than cement, water, and aggregates to improve or
modify some or several properties of concrete. In this
project, both types of admixtures were used: mineral
and chemical. The decision to incorporate admixtures
in the mix design and their proportions was made by
CEMEX and approved by Thornton Tomasetti based
on tests.
Mineral admixtures are fine-grained materials that
are added to the concrete mix in large amounts to
improve its properties. They are by-products of coal,
iron, steel, and other industries that reduce the
environmental impacts of dumping the waste into
landfills and streams. This environmental impact was
taken into consideration when selecting a mineral
admixture. In this project, fly ash was the mineral
admixture used in the fiber reinforced concrete,
shotcrete, and CDF mix designs to improve the
workability, durability, cohesiveness, and ultimate
strength of concrete. Fly ash was also used to assist
with the reduction of thermal cracking, bleeding, and
segregation. Most of the fly ash used in mix designs
was Class F (low calcium) Jim Bridger fly ash
provided by Headwaters Resources from Wyoming
located 1,105 miles away from the project site. The
choice to use fly ash, an increasingly common choice
in construction, came from a desire to receive LEED
certification points for the substitution of cement
with a mineral admixture; fly ash was deemed a
better choice than slag because it was less costly and
had a more predictable behavior.
Properties
High Early
Strength Concrete
Fiber Reinforced
Concrete
Shotcrete
Controlled
Density Fill
28-Day Compressive
Strength (psi)
5,000 @ 3-days 3,000 5,000 100
w/c 0.39 0.55 0.42 0.86
Slump (in) 4 4 2 NA
Air Content (%) 2.5 7.6 2.5 10
Clinker Composition (%)
C3S 60 64 61 60
C2S 15 11 13 14
C3A 4 8 4 4
C4AF 11 8 11 12
Mix Material Percentage of Total Weight (%)
Cement 19 6 17 1
Fly Ash Class F 0 6 3 8
Coarse Aggregate 42 40 21 43
Fine Aggregate 33 41 50 39
Water 7 7 9 8
Table 2: Properties and Compositions of Four Different Mixes

8. 8
Chemical admixtures can have different purposes
depending on the type used. The types of chemical
admixtures used in this project are Type A water-
reducing, Type D water-reducing and retarding, and
air-entraining. All of the chemical admixtures used in
the project were manufactured and supplied by Grace
Construction Products, W.R. Grace & Co. - Conn.
(W.R. Grace) and formulated to comply with
Specifications for Chemical Admixtures for
Concrete. W.R. Grace was located in Livermore, CA,
37 miles away from the project site. All of the
recommended dosages were followed.
Table 2, on the previous page, summarizes details
provided by manufacturers and general contractor of
these four diverse mixes. This table allows for the
comparison of properties and compositions between
the mixes.
These four mixes and their individual properties are
discussed extensively as follows.
High Early Strength
High early strength concrete is the type of concrete
that develops relatively high compressive strength in
a shorter span of time when compared to normal
strength concrete. On occasions, this concrete can be
used to accelerate a project’s schedule. As a result of
the higher early compressive strength, loads can be
applied sooner to the casted concrete, and the next
dependent task in the schedule can commence. Most
of these mixes are more expensive than typical
concrete mixes.
In this project, high early strength concrete was used
for walls of the CRT Facility footings with tiebacks
that required a compressive strength of 3,000 psi
within 7 days, and slabs on deck. This section will
specifically cover high early strength concrete used
for walls, which did not use the concrete properties
for its high early strength but rather used it for
scheduling purposes. The use of this concrete mix
design allowed for formwork to be removed after one
day, in addition to allowing the concrete to achieve
60-70% compressive strength gain in four days.
The concrete was specified to achieve a compressive
strength of 5,000 psi at three days [Table 2], after
which a compressive strength test was conducted to
verify this before proceeding with formwork
removal. The water-to-cement ratio, at 0.39
[Table 2], was relatively low compared to other
mixes, which can help assist with its high strength.
Table 3, below, describes the material composition of
high early strength concrete mix design.
Cement
The composition of C3S in cement used in the project
Material Description Source Oz/yd Weight (lb)
Volume
(ft3
)
Cement Type I/II/V CEMEX - 776.0 3.95
Coarse
Aggregate
Orca ½” x #4
Polaris Minerals
Corp.
- 1750.0 9.70
Fine Aggregate
Orca Concrete
Sand
Polaris Minerals
Corp.
- 1365.2 7.87
Type A Water
Reducer
WRDA 64 W.R. Grace
2.0 – 4.0 oz/
cwt C
- -
Water - - 36.0 gal 300.4 4.81
Air - - - - 0.68
Table 3: Mix Design of High Early Strength Concrete

9. 9
is somewhat high at 60% [Table 2], which assisted
with high early strength development. Although
sulfate resistance was not required for the concrete
walls, the mix contained less than 5% of C3A which
will provide high resistance against sulfate attacks.
Aggregates
Unlike the other mixes, aggregates in this mix were
from Orca Sand & Gravel in British Columbia,
Canada and supplied by Polaris Minerals Corp. ½” x
#4 gravel was used as coarse aggregate and concrete
sand was used as fine aggregate.
Mineral Admixture
No mineral admixtures were used in the high early
strength concrete mix, making it the only mix out of
the four discussed to not contain any fly ash. This is
because substitution of cement with fly ash will
reduce the amount of C3S in the mix, which is
responsible for high early strength development.
Although fly ash could be added instead of
substituted into the mix, this is likely not practical
since fly ash does not play an important role in high
early strength development and its addition would
increase costs without any energy savings.
Chemical Admixture
The high early strength was achieved by using a
Type A water-reducing admixture from Grace
Concrete Products, which produces concrete with 8-
10% less water. Since the amount of water reduction
is less than 15%, this admixture is simply a
plasticizer. This water-reducing admixture was used
to reduce the required amount of water, lowering the
water-to-cement ratio. This allowed for higher
strength without the addition of cement. The addition
of this admixture also increased the consistency of
the mix without the addition of cement, reducing the
amount of water needed for the same slump.
Concerns of corrosion from the use of admixtures is
eliminated through the use of this particular product,
which does not contain calcium chloride. For every
100 pounds of concrete, 3-6 ounces of the water-
reducing admixture was used.
Fiber Reinforced Concrete
Fiber reinforcement was used as a means to reduce
shrinkage cracking that often occurs in slabs with
large exposed surfaces. The proper use of these fibers
makes for efficient load distribution, and is typically
cheaper than placing reinforcement or wiremesh that
may be susceptible to corrosion. Due to scheduling
problems, the fiber reinforced concrete mix could not
be brought in by CEMEX and was instead brought in
by Central Concrete from San Jose. Table 4, below,
describes the material composition of fiber reinforced
concrete mix design.
Material Description Source
lbs/cu
yd
Weight
(lb)
Volume
(ft3
)
Cement Type II/V CalPortland - 243.0 1.24
Fly Ash Class F Four Corners Flyash Salt River Materials - 243.0 1.59
Coarse Aggregate Eliot 1” x #4 CEMEX - 1675.0 10.02
Fine Aggregate
Top Sand
Vulcan Materials
Company
- 812.0 4.94
Fine Aggregate Oakland Concrete
Sand
Hanson Aggregates - 812.0 4.95
Fiber
Reinforcement
MasterFiber M 70 BASF
0.75-
1.50
- -
Water - - - 267.0 4.28
Table 4: Mix Design of Fiber Reinforced Concrete

10. 10
Cement
Central Concrete chose a combination of Type II and
V cement, which was called “Mojave” by the
company they received it from, CalPortland located
527 miles away from the project in Mojave, CA. The
clinker composition was 64% C3S, 11% C2S, 8.3%
C3A, and 7.5% C4AF, which reveals a significantly
larger amount of C3A than found in any of the other
mix designs. The use of such a mix indicates that a
high heat of hydration was desired. Although using a
large amount of C3A can cause concerns of sulfate
attack, the location shows little possibility of sulfate
attack occurring.
Aggregate
The coarse aggregate, 1” x #4, were obtained from
Eliot Quarry in Pleasanton, CA.
Fine aggregates were Vulcan sand brought in from
Pleasanton, and Oakland concrete sand. Unlike the
other three mixes, two types of fine aggregates were
incorporated into the mix: top sand and concrete
sand. The top sand is processed in Pleasanton, CA
whereas the concrete sand is processed in Oakland,
CA.
Mineral Admixture
Fly ash was the only type of admixture used in the
mix design of fiber reinforced concrete. The fly ash
used was a Class F fly ash, a low calcium fly ash,
which is nonreactive on its own at ordinary
temperatures. The Four Corners Fly Ash is sourced
from Fruitland, New Mexico, located over 1,000
miles away from the CRT Facility job site. There was
a 15-25% fly ash content substitution for the fiber
reinforced concrete mix design.
Fibers
The fiber reinforced concrete was used for the
topping slab of the floors on top of their metal decks.
This was specified by the architect so as to control
the formation and propagation of any unsightly
cracks. The fibers, which were supplied by BASF
Corporation, were “MasterFiber M70”, a
monofilament microsynthetic fiber, and the fibers
increased the concrete’s tensile strength to about
25,000 psi. A low volume fraction of fibers was used
to have an efficient load distribution over the length
of the slabs. The plastic fibers were of uniform size,
with a diameter of 33 microns and a length of three
fourths of an inch. For every cubic yard of concrete, a
pound and a half of fibers were added, with around
27 pounds of fiber being added for every cubic yard
of concrete.
Shotcrete
Shotcrete is a technique used to apply concrete in
locations where thin sections are required and in
locations that are difficult to reach with typical
concrete placement methods. For the CRT Facility,
shotcrete was used to place the concrete on some
walls and stairs. This was chosen due to its
advantages of vertical placement and ability to travel
faster after placement. While two types of shotcrete
mixes were used for this project, the alternate
shotcrete mix design with Recover® will be
discussed here. CEMEX was responsible for
providing the mix design. Table 5 outlines properties
used in this mix.
Cement
The base cement phase composition consists of 61%
C3S, 13% C2S, 4% C3A, and 11% C4AF shown in
Table 2. This mix has a slightly higher C3S, lower
C3A, and slightly higher C4AF content relative to
normal strength concrete. The higher C3S content
alone provided higher heat of hydration and early
strength, while the lower C3A content offered a lower
heat of hydration. This cement composition qualified
as Type I, Type II, and Type V.
Aggregate
Both the coarse aggregate and fine aggregate, ⅜” x

11. 11
#8 gravel and fine concrete sand respectively, were
sourced from Eliot Quarry in Pleasanton, CA. These
were approved and certified from tests conducted at
Aggregate Technical Services in the same region.
The coarse aggregate used was finer than the ones
used for high early strength concrete and fiber
reinforced concrete.
An interesting aspect to note is the fine/coarse
aggregate ratio, in which there is a disproportionately
high amount of fine aggregate compared to those
ratios used in the other mixes. From Table 2, it can
be seen that coarse aggregate constitutes only 21% of
the total mass of the mix, approximately half of the
percentages in the other mixes. The proportion of
fine aggregate is also relatively high at 50%. This
fine /coarse aggregate ratio is likely optimized to
reduce aggregate void content to increase the
workability -- and hence, pumpability -- of shotcrete,
while including cost considerations.
Mineral Admixture
Fly Ash Class F, low-calcium, was used in this mix
design for shotcrete. The Jim Bridges Fly Ash is
provided by Headwaters Resources, sourced from the
Jim Bridger Plant in Rocksprings, Wyoming. A small
amount of approximately 3% of fly ash was used
relative to the overall mix.
Chemical Admixtures
In this shotcrete mix design, a chemical admixture of
Type D, water-reducing and retarding, was used to
control the setting time in order to maintain the
workability and pumpability of the shotcrete. The
admixture product selected for this purpose was
Recover®, which was manufactured and supplied by
W.R. Grace. Recover® is an aqueous chemical
solution used to stabilize the hydration of Portland
cement and provide extra workability time by
preventing the concrete mix from reaching initial set
and setting for a given period of time. This retarding
admixture was used to lengthen the set time of
shotcrete, extending the required delivery time for
the shotcrete mix from 60 minutes to 90 minutes.
Another chemical admixture, Type A water-
reducing, was used to increase the concrete
consistency, achieve a higher compressive strength,
and save cement. While all three of these benefits
cannot be obtained at the same time, at most two can
be achieved. The water-reducing admixture selected
for this purpose was WRDA 64, also manufactured
and supplied by W.R. Grace. WRDA 64 is a polymer
based aqueous organic compound solution that
Material Description Source Oz/yd Weight (lb) Volume (ft3
)
Cement Type I/II/V CEMEX 679.0 3.45
Fly Ash Class F
Headwaters
Fly Ash
Headwaters
Resources
120.0 0.81
Coarse Aggregate
Eliot 3/8” x
#8
CEMEX 821.0 4.91
Fine Aggregate
Eliot Natural
Sand
CEMEX 1953.8 11.81
Type A Water Reducer WRDA 64 W.R. Grace
2.0 – 4.0
oz/cwt C
Type D Water
Reducer & Retarder
Recover W.R. Grace 13.6 oz
Water 40.0 gal 333.8 5.35
Air 0.67
Table 5: Mix Design of Shotcrete

12. 12
produces a concrete with water content of 8 to 10%
in reduction, greater plasticity, and higher strength.
The recommended dosage was followed in this mix
with a dosage of 2.0 to 4.0 oz/cwt C. This low
viscosity liquid admixture was factory pre-mixed in
exact proportions to avoid mistakes and minimize
handling.
Controlled Density Fill
Self-consolidating concrete was not used in this
project due to budget constraints but there were
several concrete materials used that were self-
compacting or self-leveling. One of these was
controlled density fill (CDF), alternatively known as
controlled low-strength material (CLSM), flowable
fill, soil-cement slurry, unshrinkable fill, plastic soil
cement, or flowable mortar. CDF is a self-
compacting, cementitious material with similar
structural capacity to that of soil.
CDF was mainly used as a substitution to compacted
soil backfill. According to the American Concrete
Institute (ACI), CDF should have a compressive
strength lower than 1,200 psi. The CDF used in the
project had a compressive strength of 100 psi to
match the strength of soil backfill and also to allow
potential excavation. For this construction job, CDF
was specifically used to fill up over-excavated holes
that were dug to about 8 feet to the expected bottom
of the colluvial soil layer. Since the CDF mix was
highly flowable, its placement does not require much
labor or consolidation. CEMEX was responsible for
providing the CDF mix for this project. Table 6
shown below describes its material composition
below.
Cement
Compared to the other mixes, very small proportions
of cement were used in CDF. Cement only
constitutes 1% of the total mass of the mix,
compared to 6-19% for the other three. This was
because CDF only needs to achieve a compressive
strength of less than 300 psi to match the structural
capacity of soil.
Similar to high early strength concrete and shotcrete,
the cement qualifies as Type I, Type II, and Type V.
This suggests that the CDF has high sulfate
resistance, appropriate for its use as soil backfill
since it may be exposed to soil with high presence of
sulfates. Table 2 shows the clinker composition of
the mix juxtaposed with the other four mixes. The
composition of C3A is less than 5%, indicating that
the mix indeed has high sulfate resistance. Since C3A
produces the highest heat of hydration out of all the
clinkers, its low composition reduces the heat of
hydration of the mix. However, this may be offset by
the higher percentage of C3S which contributes to
Material Description Source Oz/yd Weight (lb) Volume (ft3
)
Cement Type I/II/V Cemex 30.0 0.15
Fly Ash Class F Headwaters
Flyash
Headwaters
Resources
300.0 2.02
Coarse Aggregate Eliot 3/8” x #8 Cemex 1533.0 9.16
Fine Aggregate Eliot Natural
Sand
Cemex 1388.5 8.39
Air Entrainer Daravair 1000 WR Grace 2.0 – 20.0
oz
Water 34.0 gal 283.7 4.55
Air 2.73
Table 6: Mix Design of Controlled Density Fill

13. 13
high heat of hydration and early strength
development.
Aggregates
The aggregates used in the mix are ⅜” x #8 gravel as
coarse aggregate and concrete sand as fine aggregate,
both sourced from Eliot Quarry in Pleasanton,
CA. As with all the aggregates from this source, the
tests conducted by Aggregate Technical Services, the
#8 gravel and concrete sand showed that the sodium
sulfate soundness and alkali silica reactivity fell
within allowable limits.
Mineral Admixture
CDF was proportioned with fly ash to improve
workability and reduce bleeding, segregation or
settlement, which is important to produce self-
leveling concrete. Approximately 90% Fly Ash F was
used in this mix design. The maximum compressive
strength of the material was less than the one made
with larger proportions of Portland cement due to the
long term strength development. Fly ash constituted
8% of the total mass of the mix, thus, less cement
was required, resulting in lower costs and lower heat
of hydration which help achieve the required lower
compressive strength of 100 psi.
Chemical Admixture
Chemical admixture was used to entrain air into CDF
which produces a specified air content of 10% by
volume. Air entraining admixture in CDF controls
strength development, improves workability, and
reduces the water content, bleeding, shrinkage and
settlement. In this mix, Daravair 1000, manufactured
and supplied by W.R. Grace, was used. It is a liquid
air-entraining admixture that increases the plasticity
and workability of concrete. Daravair 1000 also
increases the durability of concrete by increasing
resistance to freezing and thawing.
Concrete is a great construction material that has a
high compressive strength, but is approximately ten
times weaker in tension. This is the reason why
concrete is frequently reinforced. Reinforcement,
typically steel, is required in concrete structures to
prevent cracks from initiating and propagating, to
reduce concrete thickness, and to increase the tensile
strength.
Different bar sizes are used for reinforcement of the
structural components of buildings. The ASTM
specifications for each rebar require identification
marks to be rolled into the surface of the bar to
denote the producer’s mill designation, bars size,
type of steel, and minimum yield strength.
Figure 3: Labeling on Reinforcement Bar
In order to prevent rebars from corroding, epoxy
coating is required or a minimum cover over the
rebars has to be maintained as indicated in the code.
In this project, epoxy coating was not used, which is
standard practice in California because it is believed
that the bond between bar and concrete is better
without coating. According to Hart (Structural
Engineer and Consultant), corrosion is not a concern
in this project because a concrete cover of 3 inches is
provided as recommended by the code and the
climate in this region is not as moist compared to
REINFORCEMENT

14. 14
other regions. However, in a meeting with Miller
(Project Engineer), he expressed that there might be
some issues with corrosion due to the difficulty of
maintaining a 3 inch cover on heavily reinforced
walls.
Figure 4: Heavily Reinforced Walls
During construction, some locations had concrete
cover of only 1 or ¾ of an inches. This was a critical
concern because the purpose of the concrete cover is
to provide reinforcing bars with sufficient
embedment to enable the rebars to be stressed
without slipping. As a result, close inspection was
conducted to ensure corrosion and rebar slippage
would not become an issue.
To resolve the lack of clear cover, DPR Construction
consulted with Thornton Tomasetti to approve areas
where less coverage would be acceptable. In these
areas, an extra layer of waterproofing was added to
accommodate for the coverage that was less than 3
inches. In other locations, subcontractors solved the
problem by applying crowbars to wrench the rebar
back into its place. The concrete cover issue confused
some subcontractors since the ACI 318-11 code
expressed a concrete cover that was less than the
cover desired per Thornton Tomasetti’s request. In
addition to a cover smaller than specified, the loss of
concrete cover occurred in places where all the
reinforcement was packed into the walls, which
provided the opportunity for rebar to shift out of
alignment. One case that illustrates a similar issue
was on the computing floor level. The reinforcement
in the slab was placed too high and caused the top
concrete layer to spall off.
Figure 5: Concrete Layer
LBNL believes this will be fixed by patching the
area. When the area is patched, the method should be
done with caution to avoid and eliminate thermal
mismatch, cracking, elastic mismatch, and mismatch
in strength. The combination of these obstacles that
arose caused a delay in the CRT Facility project
schedule due to the large amount of time lost having
to redo and properly fix the placement of
reinforcement.

15. 15
CEMEX was responsible for the majority of the
concrete used in the project and delivered the
concrete from their central mixing plants in Berkeley
and Oakland, situated approximately 5 miles and
10.5 miles away from the job site, respectively. Most
of the mixes used in the project were transported and
derived from the Berkeley plant with the exception of
the shotcrete mix which was obtained from Oakland.
The other concrete mixes were supplied from Central
Concrete in San Jose, located 46 miles away from the
site, in the case of fiber reinforce concrete and one
other mix that was switched from CEMEX due to
delivery issues. This shift in mixing plant assisted
with the project schedule to avoid delays pertaining
to delivery.
Figure 6: Concrete Truck
Despite the specification stating for concrete in
trucks to be delivered within the standard 90 minutes,
DPR Construction adhered to a more stringent
requirement of 60 minutes for concrete delivery time.
According to DPR project engineer, Mike Miller,
meeting this requirement was especially crucial for
shotcrete, where they have confronted issues of
shotcrete setting in the hose that only had a 2 or 3
inch diameter as opposed to 4 inches. As part of their
quality control, the loading, departure, arrival, and
unloading times for each batch of concrete were
recorded in concrete tags as shown in Fig. 7 below:
MIXING AND TRANSPORTATION
Figure 7: Concrete Tag
Ensuring timely transportation of concrete - and
consequently, obtaining the correct quantity of
concrete for placement - constituted some of the
major challenges in the project. As a result of the
stringent delivery time requirement, a number of
concrete trucks that failed to arrive within 60 minutes
after loading had to be turned around. This not only
delayed the start of the next activity but also incurred
additional cost: a single turn around for a cement
truck with a 9 cubic yard capacity costs $1,000. The
issue of delayed transportation resulting in the
unsatisfactory concrete workability for placement
was dealt with through the use of an alternate
shotcrete mix described earlier. This mix
incorporated a Type D retarder, W.R. Grace
Recover® to extend the setting time. This allowed
for the required delivery time to be extended from 60
minutes to 90 minutes. In the case where trucks went
past the 90 minute limit, they were refused and asked
to leave the job site.
The topography of the site also presented another
challenge in terms of transportation. The location of
LBNL in the hills created concerns of concrete in the
cement truck falling out due to the steep slope. As a
precaution, concrete trucks were limited to transport
8 instead of 9 cubic yards of concrete.

16. 16
Concrete Pumps
The concrete used in the project was placed primarily
through the use of pumps attached to the concrete
truck, performed by CF&T Concrete Pumping. The
pumps delivered concrete from the central discharge
to the formwork. The main advantage in using this
method for the project was that pipes occupied
minimal space. DPR project engineer Mike Miller
described how space was limited such that tailgating
(placing concrete directly from the truck into the
formwork) was not possible and pumps had to be
used to keep the road leading to the job site available
for use. The pipe lengths could also be adjusted and
extended to deliver concrete to formwork in required
places, hence eliminating the need for conveyor belts.
Figure 8: Concrete Truck with Pump
As part of quality control, American Concrete
Institute (ACI) recommends performing the slump
test at the end of the pipeline. This is to provide
information on whether retempering should be
performed within controlled limits. Flat slump tests
were performed in this project and the workability of
the concrete mix was analyzed from the diameter
covered by the concrete after the test was performed.
Due to stringent quality control in this project, the
flat slump test was performed at both the truck and
the end of the pipeline. However, this raised
manpower issues as it required two inspectors on site
instead of one.
Figure 9: Workers Handling Pump
Pneumatic Guns
For some parts where concrete was not cast-in place,
pneumatic guns were used to deliver shotcrete,
concrete that’s ‘shot’ at high velocity onto a surface
using a hose. Dees-Hennessey Inc. was
subcontracted to perform the placement of shotcrete.
Pneumatic guns were used for the vertical
application of shotcrete on walls and to produce a
good finish. The shotcrete was placed in 300MDO
formwork. Guide wires, which are tensioned wires,
were utilized to control the thickness of the shotcrete
wall. Panels 18” x 18” for testing were specified to
be used for aggregate size greater than ⅜” per UBC
section 1922.
The use of shotcrete was unique because the quality
of the work depends on the skill of the nozzlemen.
For this reason, they must be certified and approved
to perform the task. Typically, they are approved by
demonstrating their shotcrete ability on a series of
test panels that are evaluated on their consistency and
quality. One occurrence of a construction issue with
shotcrete involved the certification but not approval
of a nozzleman who was operating and placing
concrete. When this was discovered, the unapproved
nozzleman was replaced with an approved one to
complete the remaining shotcrete. Due to this
happening while in the middle of shotcreting a series
of stairs, the problem was solved by replacing the
operator to continue the process and submitting a
Request For Information (RFI) change order.
PLACEMENT

17. 17
Formwork was required to prevent leakage of cement
mortar and to provide concrete with resistance against
spreading and shifting. In this project, the majority of
the formwork used was made out of wood and a
select few out of metal.
Wood
Most of the formwork utilized in the project was
made out of Douglas fir of either Medium Density
Overlaid (MDO) or Hard Density Overlaid (HDO).
The following types of formwork have been
specified:
For exposed concrete, plywood that complies
with U.S. Product Standard PS-1, HDO
Plyform Class 1, Exterior Grade, or better is
specified.
For panel forms, an exterior grade plywood
with sealed edges of at least ⅝” thick, PS 1
grade Plyform Class I and II B-B Exterior or
HDO Exterior is specified.
For columns, a brand of formwork specialized
for columns, SONOTUBE, or an equivalent
product is specified.
HDO formwork is supposed to provide superior
concrete finish and has been specified for exposed
surfaces. However, according to the general
contractor, there is minimal visible differences
between concrete surfaces from MDO formwork and
HDO formwork. Despite its higher cost, HDO was
still preferred as it allows for higher number of reuse.
The wood formwork in this project was reused up to
a maximum of two to three times. Before reuse,
formwork has to be straight and free from nails, dirt,
and hardened concrete. Reuse of formwork with
repairs or patches was not allowed as this may affect
architectural concrete finish.
FORMWORK
Metal
The only metal formwork used in this project is Stay-
form®. It is a mesh-like leave-in-place form and is
used to make keyway for the next concrete pour. The
keyway allowed proper adhesion to the adjoining
wall and alleviated the effect of cold joints.
Figure 10: Metal formwork, Stay-form®, used for
keyway in Mechanical Level
Formwork Removal
The formwork in this project was typically kept on
for 7 to 14 days, and was tied into the 7-day test
strength. For high early strength concrete, formwork
could be removed as early as 3 days and a 3-day
strength test would be performed. Formwork for
structures such as elevated beams were left on for 14
days.
Different concrete structures must attain a certain
percentage of their ultimate strength before their
formwork can be removed. For vertical surfaces of
walls, columns, beams, and girders, the concrete must
attain a strength of 0.60 times the compressive
strength prior to form removal. For beams, soffits,
slabs, and girders, a strength of 0.75 times the
compressive strength was specified.
.

18. 18
Vibrators were used to consolidate concrete,
including mat slabs and structural slabs. Exposed
concrete was vibrated with rubber type heads, which
is more protective for the formwork and creates
denser concrete with fewer voids to patch. The
majority of consolidation was executed using internal
vibration. Vibrating formwork was also utilized for
larger retaining walls.
Figure 11: Concrete Consolidation
Issues arose in the consolidation of concrete in
heavily reinforced grade beam. Internal vibrators
could not be used in these regions effectively. The
use of self-consolidating concrete was considered but
not used due to financial reasons. This construction
issue was solved by reducing the number of
reinforcement bars in the grade beam that was
designed conservatively due to the facility’s
proximity to an active fault.
CONSOLIDATION
Typically 28-day curing was specified, where
concrete was cured for 7-days before the addition of
curing compounds were applied either on the top
layer or mixed in with the concrete. Curing
compounds were used to protect fresh concrete from
direct sunshine and drying winds. The amount used
was per manufacturers’ recommendations, with the
exception of slabs-on-grade where 150% of the
manufacturer’s recommended application was
specified. During one of the site visits, a large
amount of excess water was discovered on one of the
floor levels after it had been cured for 7-days. This
violated the curing general requirement of avoiding
alternate wetting. Later, a leak in the waterline was
found by the LBNL maintenance crew, and it was
determined that this waterline had sprayed water on
the floor and caused the floor to become saturated
with the excess water. To ensure this would not
happen again, traps were installed to keep water out.
An exception to the 28-day requirement for curing
was the curing for the lightweight concrete fill used
on the roof. For the roof, 56-days was required
before load could be applied. However, the long
curing time created scheduling problems and due to
time constraints, a cover worth $100,000 was place
over the concrete to curb evaporation and hasten the
curing process.
Figure 12: Roof Covering to Reduce Curing Time
from 56-Days to 28-Days
CURING

19. 19
trowel finish due to concerns of dusting caused by
potential movement of heavy objects on floor during
earthquake. Dusting may rise and affect the
building’s ductwork, along with the sensitive
equipment that will be brought into the Computing
Level.
Broom finish
Broom finish was to be applied to exterior concrete
platforms, steps, and ramps that have to be non-slip.
Broom finish was observed on the ramp in the
Mechanical Level.
Figure 15: Broom Finish
Trowel and Fine Broom Finish
Trowel finish followed by fine brooming was
required on surfaces where ceramic or quarry tile
will be installed with thin-set mortar.
Dry Shake Hardener, Wear-Resistant Finish
This finish was required for floor slabs at the loading
dock.
Rough Form Finish
Rough form finish achieved after the removal of
formwork, was to be performed on formed concrete
surfaces that will not be visibly exposed. Patchwork
was then applied to fix and hide defects.
Smooth Form Finish
Smooth form finish was to be achieved through the
use of chosen form facing material organized in an
orderly and symmetrical manner that minimizes
FINISHING
The project required different types of finish to be
applied for various types of surfaces as follow:
Float Finish
Application of such finish was to be done on
concrete slabs that will have trowel finish and other
finishes. Float finish was also required on slabs with
membrane or elastic waterproofing, membrane or
single-ply roofing, sand-bed terrazzo, or raised
access floor.
Figure 13: Float Finish
Trowel Finish
Trowel finish was required on concrete slabs that
will be visibly exposed and those with resilient
flooring, carpet, ceramic or quarry tile, paint, or other
thin film coats.
Figure 14: Trowel Finish
Compact power trowels were used on the project
when more ground needed to be covered. On the
Computing Level, float finish was preferred over

20. 20
seams. This finish was is to be performed conducted
on surfaces expected to be exposed-to-view or
covered with a coating or covering material.
Some special areas also demanded architectural
finish, where a sealer was specified to provide a dust-
proof surface. Where appearance is an issue, mock-
ups were requested and joint alignment, finishing,
and spacing was checked and evaluated. Water wash
finish to reveal exposed aggregates were initially
considered but later abandoned due to cost
considerations.
Construction Joints
Construction joints serve the purpose of controlling
crack formation caused by tensile forces that develop
within the concrete due to restraints. Joints that were
seen cut into the concrete were manifested in some of
the large slabs in the project, such as those in the
Mechanical Level flooring as illustrated in Figure 16
below:
Figure 16: Construction Joint on Mechanical Level
Flooring
Reveals were also created on the walls of the
Mechanical Level, as illustrated in Figure 17 below.
According to DPR project engineer Mike Miller, the
reveals served to control cracks, although wall
reveals are usually imprinted for architectural
purposes. However, since the addition of
reveals increased costs, these were omitted from the
cooling tower, where crack formations are causing
current concern. Other concerns regarding cracking
include the concrete ramp in the Mechanical Level,
where construction joints were not added (Figure 18).
Figure 17: Reveal Control Joints on Walls in
Mechanical Level
Figure 18: Potential Problem Area at Ramp Due to
Absence of Contraction Joints

21. 21
The CRT Facility at the Lawrence Berkeley National
Lab has been a fantastic example of both
commonplace construction practices and increasingly
familiar modern day innovations in the field of
concrete. The base of the concrete mix designs were
similar, with most of the Portland cement used able
to fall under the classification of either type I, II, or
V, the main aggregates used all came from
CEMEX’s Eliot Quarry, and the Class F fly ash all
coming from Headwaters Resource in Wyoming. The
real distinctions in the mix designs came from the use
of different types and amounts of admixtures. The
high early strength mix contained water-reducing
admixture as well as special aggregate from Polaris’s
Orca Quarry in British Columbia, the fiber reinforced
mix contained microsynthetic fibers, the shotcrete
mix contained a water-reducing and retarding
admixture as well as a high proportion of fine
aggregates compared to coarse, and the controlled
density fill mix contained an air-entraining admixture
coupled with a low cement content. The adjacent
Hayward fault made the use of reinforcing steel bars
necessary at several locations in the building. The
concrete was placed with pumps and pneumatic guns,
and finished in a multitude of different ways. The
CRT Facility has taken the 2,000 year old practice of
building with concrete to create a state-of-the-art
computing facility.
CONCLUSION ACKNOWLEDGEMENTS
We would like to express our very great appreciation
to the following people:
1. Professor Paulo J. M. Monteiro for expanding our
knowledge of concrete materials and construction.
2. Tim Hart, Structural Engineer and Consultant, for
having a meeting with us and discussing the
details of the project and reviewing some of the
construction problems.
3. Tim Kemper, Construction Manager, for providing
information on the mix design, concrete
transportation, reinforcement, concrete placement,
finishing, and construction issues.
4. Ian White, Project Manager, for providing a
detailed tour of the project.
5. Rory Shortreed, Inspector of Record, for answering
questions about the details of the construction
methods.
6. Mike Miller, Project Engineer, for answering
questions about concrete and discussing
construction issues.

22. 22
"CEMEX Eliot Quarry." Structural Engineers Association of Northern California. Construction Quality Assur-
ance Committee, n.d. Web. <http://www.act-right.net/AggregateProject/ cemex-eliot.shtml>.
Draney, Brent. Presentation on Computational Research and Theory Facility (CRT): Networking and Security.
NERSC. February 2013. Web.
Mehta, P. Kumar; Monteiro, Paulo J. M. Concrete: Microstructure, Properties, and Materials. McGraw-Hill
Professional; 4th
edition, 2013. Print.
Monteiro, P. (January - April 2014). Concrete Materials and Construction Lectures. Lectures conducted at
University of California, Berkeley.
Ragan, Steve. "A Cost-Effective Alternative to Compacted Soil Backfill." Graniterock. Graniterock, n.d. Web.
<http://www.graniterock.com/technical_notes/ cost-
effective_alternative_to_compacted_soil_backfill.html>.
Sloan, D., Wels, D. “The Hayward Fault.” Geological Society of America Field Guide 7 2006: 27-31. Web.
“The Computational and Research Facility: A Catalyst for Scientific Discovery.” Handout. Lawrence Berkeley
National Lab. Berkeley, CA. n.d. Web. April 2014.
"The Purpose of Joints in Concrete Slabs." Concrete Network. Concrete Network, n.d. Web.
<http://www.concretenetwork.com/concrete-joints/purpose.html>.
“UC Berkeley’s Computational Research and Theory (CRT) Facility.” Poster. Lawrence Berkeley National
Lab. Berkeley, CA. n.d. Web. April 2014.
REFERENCES

23. 23
Fiber Reinforced Concrete
Mix Design..................................................................................................................................... A
Trial Mixes......................................................................................................................................B
Strength Gain...................................................................................................................................C
Cement ........................................................................................................................................... D
Coarse Aggregate ............................................................................................................................E
Oakland Sand ..................................................................................................................................F
Vulcan Sand ................................................................................................................................... G
Fly Ash........................................................................................................................................... H
Fiber Details ....................................................................................................................................I
Shotcrete
Mix Design.......................................................................................................................................J
Hydration Stabilizer Admixture..................................................................................................... K
Water Reducing Admixture ............................................................................................................L
Controlled Density Fill
Mix Design.....................................................................................................................................M
Mill Test Report ............................................................................................................................. N
Aggregates...................................................................................................................................... O
Fly Ash............................................................................................................................................P
High Early Strength
Mix Design..................................................................................................................................... Q
Trial Mixes......................................................................................................................................R
Water Reducing Admixtures...........................................................................................................S
APPENDIX