Concrete international / july 2009 51

By KeisuKe MatsuKawa, taKashi Matsuno, satoru yoshiMoto, Masatoshi Kagaya, and taKashi ueno

Cold Weather Foundation

Construction for Sakhalin II

overcoming material and curing challenges in an international setting

Sakhalin Island, located on the east coast of Russia and north of Japan (Fig. 1), has rich reserves of oil and

gas. Recently, several large-scale projects related to offshore oil and gas exploration have been started. Sakhalin II, one of the largest and most complete of these projects, was constructed by Sakhalin Energy Investment Company, a consortium comprising Royal Dutch Shell, Mitsui & Company, Mitsubishi Company, and Gazprom. The company commenced commercial production and export of liquefied natural gas (LNG) in March 2009.

LNG pLaNtThe LNG will be processed at a plant located at

Prigorodnoye in the Korsakov district on the southernmost part of the island. The major facilities at the plant include:■ Two LNG production lines with a total production

capacity of 4.4 million tonnes (4.8 million tons) per year;■ Two 100,000 m3 (131,000 yd3) LNG tanks;■ Two 100,000 kL (630,000 barrel) crude oil tanks; and■ An LNG jetty consisting of an 810 m (2660 ft) long steel

bridge and 25 concrete drilled piers. The entire LNG plant construction project was executed

on an engineer/procure/construct, turnkey basis by CTSD, a joint venture company of the Japanese engineering firms Chiyoda Corporation and Toyo Engineering Corporation started in 2003. The total volume of concrete used for LNG plant and oil export terminal construction was 145,000 m3 (190,000 yd3).

During February, the coldest month of the year, the daily mean temperature at the construction site is Fig. 1: Location of the Sakhalin II liquefied natural gas (LNG) plant

52 july 2009 / Concrete international

−11.4 °C (11.5 °F), the mean daily minimum temperature is −17.6 °C (0.3 °F), and the design minimum temperature for a 10-year return

TabLe 1:Specification requirementS and phySical propertieS for blended cement uSed on the project

eN 197-1,1 CeM III/brequirement Test result

slag content, % 66 to 80 68

density, kg/m3 (lb/ft3) — 2990 (187)

Blaine fineness, cm2/g — 4060

set time, minutesinitial set ≥ 60 170

Final set — 285

Compressivestrength, MPa (psi)

2-day ≥ 10 (≥ 1450) 10.6 (1540)

7-day — 31.5 (4570)

28-day42.5 to 62.5

(6160 to 9060)52.5 (7610)

TabLe 2:propertieS and mixture proportionS for Structural concreteS

LNG plant structure Marine structure

russian code nomenclature B35 B40

designrequirements

designcompressivestrength, MPa (psi)

35 (5080) 40 (5800)

target compressivestrength, MPa (psi)

44.9 (6510) 51.4 (7450)

Freeze-thawresistance class3 F200 F300

Maximum size of aggregate, mm (in.) 20 (0.79) 20 (0.79)

slump, mm (in.) 100 ± 25 (4 ± 1) 180 ± 25 (7 ± 1)

w/cm 0.38 0.375

air content, % 5 ± 2 5 ± 2

Mixture proportions

Cement, kg/m3 (lb/yd3) 447 (753) 440 (742)

water, kg/m3 (lb/yd3) 170 (287) 165 (278)

Fine aggregate, kg/m3 (lb/yd3)

800 (1348) 829 (1397)

Coarse aggregate, kg/m3 (lb/yd3)

995 (1677) 969 (1633)

hrwra, l/m3 (oz/yd3) 1.9 (49) 1.54 (40)

ae agent, l/m3 (oz/yd3)

0.004 (0.10) 0.01 (0.26)

total, kg/m3 (lb/yd3) 2412 (4065) 2403 (4050)

period is −32.0 °C (−25.6 °F). Cold weather concreting was therefore used for a large part of the project. An additional technical challenge

was that the concrete contained a blended cement with a high slag cement content specified principally for enhanced durability.

CemeNtA CEM III/B cement per EN 197-1,1

which is required to contain 66 to 80% slag cement, was specified for the project. The actual slag cement content was about 68%. This level of slag content is higher than in Japan where the level is typically around 40 to 50%. The cement is specified by the owner worldwide, regardless of the project location, and is characterized by enhanced durability and low heat of hydration. The cement used on the project was made in Japan, and its physical properties are shown in Table 1.

Using a method similar to ASTM C1202 to evaluate resistance to chloride ion penetration, the cement manufacturer compared concrete mixtures made using the blended cement and a reference portland cement. Each mixture had a water-cementitious material ratio (w/cm) of 0.4 and was tested at 91 days. The mixture made with the blended cement had a diffusion coefficient of 0.27 × 10–12 m2/s (2.9 × 10–12 ft2/s), while the mixture made with the reference cement had a diffusion coefficient nearly 10 times larger at 2.1 × 10–12 m2/s (22.6 × 10–12 ft2/s).

As there was concern about slow hydration rate of the blended cement in cold weather, the strength development of concrete cured at 5 °C (41 °F) was studied prior to the start of the project. This study showed that hydration was not significantly delayed compared to portland cement concrete, mainly due to the relatively high reactivity of the slag cement ground in Japan.

mIxture proportIoNSThe mixture proportions for

concrete used in the LNG plant structure and the marine structures are shown in Table 2. The Russian

Concrete international / july 2009 53

code bases concrete compressive strength on tests of 150 mm (6 in.) cube specimens. The target com-pressive strength considering an allowance for variation at the batch plant in accordance with the Russian code, however, is about 12.8% higher than the design strength. The mixtures had high cementitious material contents of at least 440 kg/m3 (742 lb/yd3) and a w/cm around 0.38. Because of the high fine powder content and low w/cm, autogenous shrinkage was also a concern. To avoid cracking, moist curing by covering with polyethylene sheet was specified until the concrete reached 70% of the design strength.

ruSSIaN CodeSThe LNG plant owner usually

requires design of their facilities to comply with international codes (either American or European), but the engineering work for this project also had to be consistent with Russian codes, such as the Construction Codes and Regulations (Stroitelnye Normy i Pravila [SNIP]) 2 design code and the State Standard (Gosudarstvenii Standart [GOST]) material and testing standards. Therefore, concrete structural design initially performed by Japanese engineering firms in accordance with international codes had to be reviewed by a Russian design institute to obtain its endorsement of design consistency with the Russian codes. Similarly, for concrete material testing, the most stringent requirement among international codes and Russian codes had to be satisfied. For example, the mixtures had to meet a test for resistance to cyclic freezing and thawing specified by the Russian code—one of the most stringent in the world.

FreezING-aNd- thaWING teSt

The Russian cyclic freezing-and-thawing resistance test is described in the GOST 10060 series3 and applies to both concrete and aggregate.

Three similar test methods are specified. According to Method One, also known as the Basic Method specified in GOST 10060.1,4 a 150 mm (6 in.) cube specimen is soaked in water and exposed to a cycle of

freezing in air at −18 °C (0 °F) and thawing in water at 18 °C (64 °F) for a specified number of cycles. This is similar to ASTM C666 procedure A. Compressive strength is then measured. The mixture is acceptable if the

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availableaCI Foundation Fellowshipsgraduate and undergraduate students studying concrete are eligible to apply for the aCi Foundation annual fellowships. Fellowship recipients receive an educational stipend valued at $7000 to $10,000, in addition to travel/expenses for participation in two aCi conventions, assignment of an industry mentor, and the opportunity for a summer internship.

aCI Foundation Scholarshipsgraduate students studying concrete are eligible to apply for these scholarships annually, valued at $3000 each.

obtain all application information and requirements at:www.scholarships.concrete.org

to be considered, students must attend school in the u.s. or Canada and send completed applications and all required documents to aCi by Friday, october 30, 2009.

54 july 2009 / Concrete international

model used to find the best fit between the predicted temperatures (solid lines in Fig. 3) and the actual temperatures (dashed lines in Fig. 3) included the adiabatic temperature rise of the concrete, T, which was estimated using the following formula:

T = Q (1 – e–γ(t – to)β)where t is the concrete age in days, to is the delay of heat initiation estimated at 0.25 days, β is a modification factor estimated at 1.0, γ is a constant for rate of temperature rise estimated at 1.8, and Q is the ultimate adiabatic temperature rise estimated at 44 °C (79.2 °F).

Separate compressive strength data for cubes cured in 5 °C (41 °F) water was obtained and expressed as a function of maturity M obtained from the equation

(SI units)

(in.-lb units)

where θ is the concrete curing temperature in °C (°F) and Δt is time fraction at temperature θ in days. Maturity data for concrete specimens cured in 5 and 20 °C (14 and 68 °F) water are compared in Fig. 4. By using a thermal analysis model, temperature and thermal stresses were calculated, and the strength was also predicted as a function of maturity, considering slow hydrating slag cement at lower temperatures. This analysis was able to predict whether the curing scheme was sufficient to keep the concrete temperature above 20 °C (68 °F) for better early-age strength development. The probability of cracking was then estimated by a factor called the cracking index, which is the safety factor for cracking. The curing scheme was designed to keep the cracking index at or above 1.8 for this particular case.

After examining different combinations of heating the

reduction in compressive strength is not more than 5% of the compressive strength of specimens that were not subject to cycles of freezing and thawing. The durability class is designated as an F-number, such as F200, where 200 corresponds to the number of freezing-and-thawing cycles passed in the Method One test.

Because the Basic Method usually takes about 6 months to complete, two rapid methods are specified in GOST 10060.2.5 These rapid tests produce more severe freezing conditions as summarized in Table 3. For example, Method Two requires specimens to undergo a freezing cycle down to −18 °C (0 °F) and then be immersed in a 5% NaCl solution to thaw. Method Three requires a lower freezing temperature of −50 °C (−58 °F) while immersed in the 5% NaCl solution. The number of freezing-and-thawing cycles in these extreme test conditions can be translated into an equivalent F-number for the Basic Method, as shown for F200 and F300 in Table 3. The test period can be reduced to less than a month for Method Three.

CoLd Weather CoNCretINGFrom November to April, the concrete was mixed at

the batch plant with 60 °C (140 °F) water. The initial concrete temperature at the batch plant was kept at least 15 °C (59 °F), and various types of cold weather curing were adopted, such as heating or insulating the formwork.

Several large generator foundations cast during the winter were considered to be mass concrete. Sudden exposure to low ambient temperatures at an early age would initiate thermal shock and raise the risk of cracking. Thus, a curing scheme for cold weather was established through the engineering analysis procedure shown in Fig. 2.

In November, temperatures were monitored on a 2 x 2 x 1.3 m (6.6 x 6.6 x 4.3 ft) trial block of concrete to obtain parameters that could be used to estimate concrete temperatures in other placements and under different ambient temperature conditions. The finite element

TabLe 3:Summary of GoSt 100603 SerieS teSt requirementS for reSiStance to freezinG-and-thawinG cycleS

Method no.

Freezing cycles Thawing cycles

Number of freezing-and-

thawing cycles

MediumTemperature,

°C (°F)Duration,

hours MediumTemperature,

°C (°F)Duration,

hoursF200 class

F300 class

Methodone

air–18 ± 2(0 ± 4)

3.5 water18 ± 2

(64 ± 4)3 ± 0.5 200 300

Methodtwo

air–18 ± 2(0 ± 4)

3.55% naCl solution

18 ± 2(64 ± 4)

3 ± 0.5 45 75

Methodthree

5% naCl solution

–50 ± 5(–58 ± 9)

2.5 ± 0.55% naCl solution

18 ± 2(64 ± 4)

2.5 ± 0.5 5 8

Concrete international / july 2009 55

air around the formwork and insulating the formwork, a successful curing scheme was established. The concrete was cast in plywood forms covered with 50 mm (2 in.) thick polystyrene foam board, and a shelter was constructed out of polyethylene sheet around the entire foundation. Jet heaters were set up to warm the air inside the shelter, as shown in Fig. 5, and were operated to maintain a temperature inside the shelter of 22 °C (72 °F) for 3 days. After the first 3 days, the temperature was decreased in a controlled manner to 12 °C (54 °F) over a period of 2 days by reducing the number of heaters. After the termination of heating, the insulated formwork was left in place until the foundation reached an age

Fig. 2: Flowchart for developing a cold weather curing scheme

Fig. 4: Strength as a function of maturity for concrete samples cured at different temperatures (1 MPa = 145 psi; 1 °C-day = 0.56 °F-day)

Fig. 3: Temperature history for a 2 x 2 x 1.3 m (6.6 x 6.6 x 4.3 ft) trial concrete block (°F = °C × 9/5 + 32)

of 3 to 4 weeks. Using this curing procedure, no harmful cracking was observed.

WorkING INterNatIoNaLLyApart from the technical issues described in this

article, we had to manage associated administrative matters in Russia. For example, the concrete mixture proportions were basically owned by the local registered laboratory. The mixture proportions for concrete with a designated strength and frost resistance class and the relevant material test data could not be disclosed without the permission of the laboratory, even though it was available at the batch plant. Contractors had to contract with the laboratory to “purchase the mixture.” In addition, the laboratory was not just a testing laboratory but also

Fig. 5: To prevent thermal shock, the mat foundation was cured by insulating the formwork, covering the formwork with polyethylene sheet, and heating the air under the polyethylene cover

56 july 2009 / Concrete international

aCi member Keisuke Matsukawa is a Civil engineering Consultant at Chiyoda Corporation in yokohama, japan, and a Visiting Professor at the tokyo institute of technology. he received his Bs from the university of tokyo and Ms and Phd from Purdue university. his research interests include durability design of concrete materials and structures in industrial facilities.

Takashi Matsuno is a Civil senior engineer at Chiyoda Corporation. he received his bachelor’s degree from the waseda university, japan. his research interests include civil and structural engineering in industrial facilities.

Satoru Yoshimoto is a Civil engineer with Chiyoda Corporation. he received his bachelor’s degree from the nihon university, japan. his research interests include civil and structural engineering in industrial facilities.

Masatoshi Kagaya is a senior engineer in the Civil and architectural engineering division of toyo engineering Corporation (teC) in japan. he has worked for teC for 30 years on various projects including fertilizer plants, petrochemical plants, gas processing plants, oil production facilities, lng plants, utility plants, and power generation plants. he received a B.tech.

degree in civil engineering from the Kyoto university, Kyoto, japan.

Takashi Ueno is a technical team Manager in the Civil and architectural engineering division of teC. he has worked for teC for 29 years on petroleum, petrochemical, gas, and power plants and has performed design, analysis, and troubleshooting for structural engineering. he received M. and B.tech degrees in civil engineering from tokyo institute of technology, tokyo, japan.

the authorization agent that would, for example, certify conformance of the concrete to the required durability class. Sometimes this required the authorization agent’s interpretation or judgment on portions of the criteria in the Russian codes that were unclear to us. Therefore, for special tests such as the GOST 10060 series freezing-and-thawing tests that required long testing periods, it sometimes required long, persistent discussion before we obtained the laboratory’s authorized certification.

Another issue was the language barrier. All of the technical documents, such as drawings and specifications, had to be written in both English and Russian. The communication became further complicated because we had to translate them once more in our head into Japanese, which lead to frequent misunderstandings.

In the 5 years we have been working on the project, we have learned plenty of precious lessons and become accustomed to Russian codes and their methods. We hope that we have now become qualified to cast concrete in Russia.

acknowledgmentsThe authors thank Royal Dutch Shell for overall assistance on the

project and Nittetsu Cement Company, Ltd.; Kajima Corporation;

and Toa Corporation for providing data on cement, concrete

production, and construction.

references1. BS EN 197-1:2000, “Cement. Composition, Specifications and

Conformity Criteria for Common Cements,” British Standards

Institute, London, Sept. 2000, 52 pp.

2. SNIP 2.03.01-84, “Concrete and Reinforced Concrete Structures,”

Stroitelnye Normy i Pravila (SNIP), USSR State Committee for

Construction Matters, Moscow, 1984.

3. GOST 10060.0-95, “Methods for the Determination of Frost-

Resistance. General Requirements,” Gosudarstvenii Standart

(GOST), Intergovernmental Scientific and Engineering Commission

on Standardization and Quantity Surveying in Construction

(MNTKS), Moscow, 1995.

4. GOST 10060.1-95, “Concretes, Basic Method for the

Determination of Frost-Resistance,” Gosudarstvenii Standart

(GOST), Intergovernmental Scientific and Engineering Commission

on Standardization and Quantity Surveying in Construction

(MNTKS), Moscow, 1995.

5. GOST 10060.2-95, “Concretes, Rapid Method for the

Determination of Frost-Resistance by Repeated Alternated Freezing

and Thawing,” Gosudarstvenii Standart (GOST), Intergovernmental

Scientific and Engineering Commission on Standardization and

Quantity Surveying in Construction (MNTKS), Moscow, 1995.

Note: Additional information on the ASTM Standards discussed in

this article can be found at www.astm.org.

Selected for reader interest by the editors.