**3.1 Example 1: Drake equation**

Since 1959, SETI has yet to find an alien signal. Two questions arise as a result what is the probability of there being life in the galaxy, and why have not we received a response to our transmissions? In 1959, a US astronomer, Frank D. Drake, a NASA employee who carried out the first SETI radio telescope experiments, outlined an equation for finding communicable civilizations [40, 41]:

$$N = RL \tag{1}$$

Which was later expanded to : *R f p ne fi ft f c L*.

where *N* is the number of communicable civilizations, *R* is the rate at which stars are born in the galaxy, *fp* is the fraction of stars with planetary systems, *ne* is the number of planets that might hold life, *ft* is the fraction of planets with life, *fi* is the fraction of planets with life that have evolved, *fc* is the number of civilizations of evolved civilizations with the ability to communicate, and *L* is the length of time over which the communication is possible. An additional factor named *C* is a recent suggestion for colonization [42]. Bloetscher [3] suggested that the factor *ne* actually comprises four factors: planet size (PS), presence of a moon (M), location within the "Goldilocks" or habitable zone (HZ), and the correct star type (ST), creating four unknowns from one. None of the 7–12 factors is fully known, so no specific answer on the likelihood of intelligent life on another planet communicating with Earth is possible. However, hierarchical Bayesian methods can be used to investigate the probability of intelligent life on another planet communicating with Earth. This approach involves the assignment of probability distributions to the underlying factors and using those to develop an MCMC protocol to determine the final predictive solution [3]. Subjective data, shown in **Table 1**, were included when little or no data were available to specify the parameters of these distributions [3]. Then probability distributions were assigned to the prior parameters within the initial distributions to determine the location and scale parameters of the factor distribution (**Table 2**). The subjective information serves to create these prior distributions until such time as real data are developed or become available [3].

**Table 1.**

*Summary of Drake parameters used in Bayesian calculations and comparison to prior estimates.*

*Applications of Hierarchical Bayesian Methods to Answer Multilayer Questions with Limited… DOI: http://dx.doi.org/10.5772/intechopen.104784*

#### **Table 2.**

*Monte Carlo results for parameters used in MCMC.*

For the Drake equations, a distribution for *N* was developed through using the Hierarchical Monte Carlo distributions for the factors of the equation run 10,000 times (see **Figure 1**). A series of Hierarchical Monte Carlo algorithms were developed for each parameter, and the means were inserted into a Monte Carlo Markov Chain program that uses a Metropolis-Hastings algorithm with a Gibbs sampler to develop a final probabilistic result [43–49] that was solved for *N*. Based on suggestions by Glade et al. [50] and Maccone [51], the target MCMC distribution was proposed to be lognormal. Given the uncertainly involved, the standard deviation used for the target distribution was assumed to be the square root of 6, after Wu et al. [52]. Given a multivariate distribution, like the example above, Gibbs sampling breaks down the problem by drawing samples for each parameter directly from that parameter's

**Figure 1.** *Development of HPB for Drake.*

#### **Figure 2.**

*Results for the probability of* N *using the Monte Carlo calculation of the factors placed into a MCMC predictive Bayesian MATLAB calculation. Note that the number of other planets is constantly small despite three options as noted above (reproduced from Bloetcher [3]).*

*conditional distribution* or the probability distribution of a parameter *given* a specific value of another parameter [53].

The solution is shown in **Figure 2** (red data points). Of importance, there is nearly a 50% probability that we are alone in the galaxy. The graph indicates that there is a 95% probability that there are less than 100 communicating civilizations concurrent with Earth, and a 99% that there are 1000 such civilizations.


**6. Conclusions**

The magnetic field strength of this power line was found to exceed the numerical values permitted by the Hygiene Standard HN 104:2011 HN, revealing that any person living or working in these areas was in serious danger. Any individual or commercial activities performed by the residents closer than 15 m to the double-circuit 400 kV overhead power line must be restricted.

For these reasons, the magnetic field in these locations must be reduced by installing higher support bars, and persons must wear appropriate personal protective equipment to protect them from exposure to electromagnetic field. For the purpose of more comprehensive analysis, it is recommended that experimental measurements should be made.

The distribution of the magnetic field strength at the high-voltage, double-circuit transmission line could be calculated using the methods of the magnetostatic field or by simulation using the finite element method (FEM). The difference is less than 5% between the results of the mathematical calculation and FEM simulation.

This paper has studied the magnetic field distribution resulting from all six groups with six types of long-distance distributing transposition. As a result, we can see how the impact of the calculation of the six groups' long-distance distribution transposition changes the magnetic field surrounding the transmission line.

The developed mathematical model for the calculation of the magnetic field generated by the conductors in the double-circuit 400 kV overhead power line can be used for the identification of hazardous areas and cases of electromagnetic pollution.

**Author Contributions:** Conceptualization, R.D.; Methodology, R.L.; Software, R.D.; Validation, R.L.; Formal analysis, R.D.; Investigation, R.D., R.L.; Resources, R.L.; Data curation, R.L.; Writing—Original draft preparation, R.L.; Writing—Review and editing, R.D., R.L.; Visualization, R.L.; Supervision, R.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.


6.2.2. Future Promising PET Tracers

Similar to conventional scintigraphy, specific PET tracers can be used to visualize inflammation in pSS. A case report showed intense uptake of 68Ga-pentixafor, a radioligand of the chemokine receptor CXCR4. This receptor is involved in, among others, migration of leukocytes toward sites of inflammation. In this pSS patient, the increased uptake in salivary glands and lymph nodes was histologically proven to be attributed to inflammatory cell infiltration [120]. To further investigate the overexpression of somatostatin receptors in salivary glands and joints of pSS patients, as shown by 99mTc-HYNIC-TOC scintigraphy, the specific PET tracer 68Ga-DOTATOC can be used [121]. Another pathological feature in pSS that could be visualized is the increased number of B-lymphocytes within salivary glands. Furthermore, by using whole-body B-lymphocyte imaging, not only B-lymphocytes within the salivary glands can be visualized, but also B-lymphocytes that are present in other organs associated with pSS. We previously showed that high numbers of B-lymphocytes within salivary glands of pSS patients predict response to rituximab (anti-CD20) therapy [122]. Whole-body imaging of B-lymphocytes could be an improved and noninvasive method to select pSS patients who are likely to respond to rituximab treatment. In rheumatoid arthritis and orbital inflammatory diseases, imaging of B-lymphocytes by using 89Zr-rituximab has shown potential in the detection of B-lymphocyte-mediated diseases, in the evaluation of rituximab treatment, and also in the selection of rituximab responders [123,124]. Therefore, it is of interest to study whole-body B-lymphocyte imaging by using PET/CT in pSS patients, and to assess whether this specific PET tracer can detect treatment response and can identify rituximab responders at baseline. Since T-lymphocytes are thought to be predominant in salivary glands in early stages of pSS [125], imaging of these lymphocytes could also be of added value. Radiolabeled interleukin-2 (IL-2) can detect activated T-lymphocytes within affected organs in pSS since IL-2 receptors are overexpressed on activated T-lymphocytes [126].

Overall, PET seems to be a promising imaging technique in pSS. Although the added value of PET in the diagnostic process of pSS remains to be shown, FDG-PET/CT was found to be useful in the assessment of disease activity, the systemic staging of pSS-associated lymphomas, and the evaluation of treatment response.


**6. Nutritional and feeding strategies to minimize effects of heat stress in dairy cattle**

Dairy cows reduce their feed intake during heat stress, so more nutrients need to be consumed into a smaller volume of feed. Maintaining adequate nutrient intake becomes vital to avoid a reduction in milk production. Some alternatives to increase dietary nutrient density include feeding high quality forage, feeding more grain and use of supplemental fats. Reducing the forage to concentrate ratio may result in more digestible rations that may be consumed in greater amounts. However, feeding more concentrate would have problems of acidosis and cows stop feeding. Sodium bicarbonate may help buffer the rumen to adapt to a higher levels of concentrate. Other feed additives that have been successful in heat stress conditions to stabilize rumen health from dietary modifications are yeast, which improves fiber digestion, and fungal cultures and niacin, which improves energy utilization. As a practical recommendation, do not use together these additives (Escobosa et al., 1984; Zimbelman et al., 2010).

Dairy cows experiencing heat stress often shows a negative N balance because of reduced feed intake. Increasing the level of crude protein may increase energy requirements and excess of dietary protein is converted to urea and excreted, causing problems of environmental pollution. It is suggested that during heat stress the level of crude protein in the diet should not exceed 18%, while the level of rumen-degradable protein should not exceed 61% of crude protein or 100 g/N/d (Huber et al., 1994).

The feed manager can provide shades in the feed bunk for added comfort to the cows while they are eating and feeding. It is also recommended to add a water sprinkler system and fans that are directed towards the cows to further reduce the heat felt in the place. Do not spray water on the feed as dry matter intake is important. As much as possible, keep the udders of the cows dry to reduce the possibility of having mastitis. Also make sure that the floor is still good enough for the cows to walk on and prevent injuries due to slipping.

Other strategies that dairy managers consider when feeding lactating dairy cows during heat stress periods are feeding frequency, time of feeding, and adequate feed bunk space. Feeding frequency consists of increasing an extra feeding or two during the day, obviously these extra feedings should be provided during the cooler times of the day. This strategy promotes a reduction of flies around the feed, therefore decreasing the insect population in the dairy barn. Also, increasing the amount of feed during these cooler periods of the day (early morning or late evening) is another alternative to avoid the reduction in feed intake during summer. Providing between 60 to 70 percent of the ration from 20:00 to 08:00 h has proven to have a positive impact on milk yield during periods of hot weather. The objective to provide enough space in the feed bunk is that all dairy cows can eat together without crowding (Hahn, 1999; West, 2003).

174 Milk Production – An Up-to-Date Overview of Animal Nutrition, Management and Health

to improve thermo-tolerance and enhance summer fertility.

exceed 61% of crude protein or 100 g/N/d (Huber et al., 1994).

**dairy cattle**

Zimbelman et al., 2010).

Embryo transfer has been mentioned as a possible solution for improving summer fertility because it has shown a considerably progress in pregnancy rates during the summer months. This is because embryo transfer can escape the period in which the embryo is more susceptible to heat stress, considered before day 7 after AI (Jordan, 2003). However, embryo transfer is not a commonly adopted technique, consequently there is the necessity to improve events such as *in vitro* embryo production techniques, embryo freezing, timed embryo transfer, and decreasing the cost of commercially available embryos before this technique becomes a viable solution. In addition, altering biochemical properties of the embryo, or even its genetic modification before the embryo transfer, could be a possible way

**6. Nutritional and feeding strategies to minimize effects of heat stress in**

Dairy cows reduce their feed intake during heat stress, so more nutrients need to be consumed into a smaller volume of feed. Maintaining adequate nutrient intake becomes vital to avoid a reduction in milk production. Some alternatives to increase dietary nutrient density include feeding high quality forage, feeding more grain and use of supplemental fats. Reducing the forage to concentrate ratio may result in more digestible rations that may be consumed in greater amounts. However, feeding more concentrate would have problems of acidosis and cows stop feeding. Sodium bicarbonate may help buffer the rumen to adapt to a higher levels of concentrate. Other feed additives that have been successful in heat stress conditions to stabilize rumen health from dietary modifications are yeast, which improves fiber digestion, and fungal cultures and niacin, which improves energy utilization. As a practical recommendation, do not use together these additives (Escobosa et al., 1984;

Dairy cows experiencing heat stress often shows a negative N balance because of reduced feed intake. Increasing the level of crude protein may increase energy requirements and excess of dietary protein is converted to urea and excreted, causing problems of environmental pollution. It is suggested that during heat stress the level of crude protein in the diet should not exceed 18%, while the level of rumen-degradable protein should not

The feed manager can provide shades in the feed bunk for added comfort to the cows while they are eating and feeding. It is also recommended to add a water sprinkler system and fans that are directed towards the cows to further reduce the heat felt in the place. Do not spray water on the feed as dry matter intake is important. As much as possible, keep the udders of the cows dry to reduce the possibility of having mastitis. Also make sure that the floor is still good enough for the cows to walk on and prevent injuries due to slipping.

Other strategies that dairy managers consider when feeding lactating dairy cows during heat stress periods are feeding frequency, time of feeding, and adequate feed bunk space. Feeding frequency consists of increasing an extra feeding or two during the day, obviously The increase in respiration rate and perspiration can cause an excessive loss of water, therefore reducing mineral levels in the cow. The recommendation is to increase K content from 1.3 to 1.5% of the total dietary dry matter, Na to 0.3% and Mg to 0.5%. Feed complete mineral mixes with higher K and Na levels only to the milking cows. If fed to dry cows, these mineral mixes may cause increased udder edema.

Water is really a priority when the temperature rises. We can say that management and the feeding of the cows are also part of the process in reducing heat stress in dairy cows. Some responses of the cows, though, can help reduce heat production in them, like selective consumption of feeds and cooling strategies. The dairy cows can only do so much and the dairymen are the one controlling their environment.

Before performing any critical modification to the diet during heat stress periods, be sure to ask for advice from a feed consultant. This is because we have to remember that dairy cows are under severe heat stress and any drastic change could be detrimental. Maintaining cows comfortable is the key to hold them eating which is critical in keeping them productive.


**Author details**

Tadashi Ito

Address all correspondence to<EMAIL_ADDRESS>
Three‐dimensional motion analysis room, Aichi Prefecture Mikawa Aoitori Medical and Rehabilitation Center for Developmental Disabilities, Okazaki‐shi, Aichi, Japan


**1. Introduction**

LNG (Liquefied Natural Gas) has been regarded as the most realistic alternative to reduce global warming from petroleum energy because it emits very little sulfurous acid gas (SO2) recognized as a major cause of environmental problems.  Most of all, Asia is the world's largest importing region of LNG and accounts for two-thirds of global consumption [1–4].

Natural gas is cooled to about −163 ◦C to convert the gaseous gas to a liquid state for storage. Therefore, many kinds of research have been conducted to minimize heat loss and ensure safety against gas leakage [5–7].

LNG storage tanks can be largely divided into above-ground, in-ground and underground depending on the installation location. According to the type of inner tank, it can be roughly classified into a 9%-nickel steel tank and membrane tank. Based on the definition of NFPA 59 A (2001), BS EN 1473 (1996) and BS 7777 (1993), a 9%-Ni steel tank is classified into single, double and fully containment LNG storage tanks. The full containment LNG storage tank with relatively high safety is a double tank structure in which the inner tank and the outer tank can independently store LNG at cryogenic temperatures [8].

**Citation:** Lee, G.; Na, O. Assessment of Mechanical, Thermal and Durability Properties of High-Volume GGBS Blended Concrete Exposed to Cryogenic Conditions. *Materials* **2021**, *14*, 2129. https://doi.org/10.3390/ ma14092129

Academic Editor: Alessandro P. Fantilli

Received: 1 April 2021 Accepted: 20 April 2021 Published: 22 April 2021

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

The inner tank stores cryogenic LNG under normal operating conditions and the outer tank is located between 1 m and 2 m from the inner tank and functions as a dike as well as has a function to support the outer roof. The tank has a prestressed concrete outer container with a flexible inner container and insulation supported by an outer tank wall. Prestressed concrete (PC) structures are suitable for storing LNG and their design incorporates special loads and a special performance at cryogenic temperatures [4,8–10].

Nevertheless, the inner and outer storage tanks of LNG involve several potential risks. Sudden failure of LNG storage tank is not acceptable, since the escaped liquid would vaporize, mix with air and form an explosive cloud. The explosions or fires resulting from such an event could lead to an unacceptable loss of life and damage to the plant and environment. To reduce the potential risks and safety issues of a concrete storage tank, design guidance is given in BS 7777, NFPA 95A and BS EN 1473 [10,11]. Moreover, Jeon et al. (2003) studied the liquid tightness design associated with the cryogenic temperature under the emergency condition of LNG leakage [6]. After then, Jean et al. (2004) focused on the major factors deciding the shape of the large LNG tank [12]. Hoyle (2013) in Chevron presented the modular design of the precast concrete outer wall, instead of the in-situ concrete wall for the full containment storage tank. It concluded that this modular concept could replace the 9%-nickel steel with concrete and reduced the material cost and construction time [13]. Based on the composite concrete cryogenic tank (C3T) of Chevron, Jeon et al. (2014) and Jo et al. (2015) also studied the precast concrete module with outer liners to shorten the construction period [14,15]. Even though the concrete module could make construction time to be saved, the connection between concrete panels and countermeasures of emergency leakage should be supported with sufficient researches.

Generally, impermeable insulations such as PUF (Poly Urethane Foam) have been located between the inner tank and outer concrete wall to prevent direct contact as demonstrated in Figure 1. Recently, to remove the impermeable insulation, cryogenic rebars as reinforcement at the inner surface of the concrete wall were partially used. Yoon (2012) suggested the application of cryogenic rebar to LNG storage outer tank [16]. Cryogenic steel rebar is used to prevent the brittle failure of concrete outer wall when the leakage of LNG occurs. Cryogenic steel rebar is a specially-designed concrete reinforcing steel for cryogenic applications and is suitable for use in storage tanks with temperatures down to −170 ◦C in accordance with EN 14620-3:2006. In fact, cryogenic rebar has been manufactured by Commercial Metals Company (CMC) in USA and ArcelorMittal in Luxembourg City.

**Figure 1.** Full containment LNG storage tank.

Concrete used as the outer shell can be directly exposed to the LNG leakage and the inner surface of outer concrete can be cooled lower than −165 ◦C of cryogenic temperature. The concrete used to contain the liquefied natural gas must withstand sub-arctic

temperatures as low as −165 ◦C and is called "cryogenic concrete". However, concrete behavior at cryogenic conditions has been not elucidated. Kogbara et al. (2013) reviewed the concrete properties under cryogenic temperatures such as permeability, coefficient of thermal expansion (CTE), tensile strength, bonding strength, compressive strength and so on [17]. Kogbara et al. (2014) investigated the damaged microstructure of concrete due to cryogenic temperature including the effect of aggregate type and introduced the design method of a damage-resistance cryogenic concrete. To demonstrate the damage effects before and after freezing, acoustic emission (AE) and X-ray computed tomography (XRCT) methods were employed. The results indicated that microcracking resistance of concrete after the cryogenic condition was very related to the type of coarse aggregate [18]. Dahmari et al. (2007) mentioned the basic cause of concrete failure under cyclic freezing resulted from the transition to ice from free water in the pores and lead to the reduction in strength and structural damage [19]. Especially, Kwak et al. (2008) studied to measure the change in mechanical properties of concrete exposed to a specific temperature range from −20 to −60 ◦C [7]. To reveal the fracture properties at temperatures ranging from 20 to −170 ◦C, Rocco et al. (2001) conducted three-point bending tests on notched beams and determined the fracture parameters with the cohesive crack model, in terms of tensile strength, fracture energy, softening curve (stress vs. crack opening), characteristic length and modulus of elasticity [20]. Recently, for developing outer concrete, Kim et al. (2018) investigated the flexural and cracking behavior of ultra-high-performance fiber-reinforced concrete (UH-PFRC) before and after exposure to cryogenic temperatures through four-point bending tests. The test results indicated that UHPFRC had higher resistance to microcrack formation and better flexural performance rather than normal concrete [21]. Moreover, Mazur et al. (2019) also carried out laboratory tests to reveal the negative effect under low temperature and suggest the improved ways of mix design with respect to decease in *w/c* ratio, type of cement and aggregate and use of aeration admixture [22].

As shown in Figure 1, concrete outer wall in LNG tank is generally designed as mass concrete with 1 m thick and more and most of LNG tanks are located in coastal area. Thus, this concrete outer wall can be easily exposed to chloride-rich environment. To enhance the concrete durability in corrosive environment, high-volume of GGBS (Ground Granulated Blast-furnace Slag) should be added. Based on ACI 233 and some references, basically, more than 50% of GGBS replacement in concrete mixture has an influence on the improvement of the durability and the reduction of the heat of hydration in mass concrete [23–27]. Rashad et al. (2017) and Rachel et al. (2019) investigated the mechanical and durability properties of the high-volume GGBS mixture with metakaolin and flyash. Even though the replacement of GGBS increased, test results of RCPT (Rapid Chloride Permeability Test), sorptivity and water permeability were lower than those of conventional concrete mixture [25,26]. Recently, Lee et al. (2020) evaluated the optimal CaO content range to secure the durability performance. As a result, the optimal CaO content was within range of about 55% and the replacement ratio of GGBS was about 50% [27]. Therefore, highvolume of GGBS replacement would be necessary to improve the durability performance of concrete outer tank installed on the coastal area.

Despite the progress of many types of research about the properties of cryogenic concrete, there are some limitations of the researches using the composition of high-volume GGBS binder in mix design. In addition, sufficient research results about the practical procedure of cryogenic tests have not been provided significantly with focus on the concrete properties. Therefore, the purpose of this study is to suggest the optimum mix design with a high volume of GGBS replacement and the procedure of the cryogenic test to consider mechanical and thermal properties, and durability performance based on the review of ACI 376 [28].

Above all, ACI 376 was reviewed to define the investigation items about mechanical and durability properties under cryogenic environment. Then, all raw materials used in mix design were tested to compare the test results with requirements in ASTM and BS codes. Particularly in this study, high-volume of GGBS and air entrainer admixture were used to the control of heat of hydration and durability for the increase of freeze-thawing resistance in accordance with emergency condition of LNG leakage. Two types of cryogenic conditions were employed, and various specimens were tested to measure the mechanical, thermal and durability properties. Finally, with mock-up specimens, productivity and semi-adiabatic tests were carried out.

#### **2. Experimental Plan**

#### *2.1. Materials and Mix Design*

All materials used in concrete followed the related standards in Table 1. Cement was combined with Ground Granulated Blast-furnace Slag (GGBS) in conformity to ASTM C 595 [29]. Table 2 shows the requirements for cement from ASTM C 150 and all test results satisfied with the requirements are provided by the supplier [30].

**Table 1.** Concrete Materials and Standards [30–35].

In order to achieve the strength and durability of the concrete, the replacement of GGBS as a mineral admixture is necessary. GGBS decreases a permeability of concrete and improves chemical resistance such as chlorides and sulfates. It also reduces the heat of hydration related to Delayed Ettringite Formation (DEF). The slag constituent shall not exceed 70% of the mass of total cementitious material in the concrete mix. Table 3 shows the requirements for GGBS from ASTM C 989 and all test results satisfy the requirements [31].

**Table 3.** Properties, requirements, and test results for GGBS according to ASTM C 989.

Unwashed original sand contains many fine particles less than the sieve number 200 (0.075 mm) which induce more water and admixture consumption and then weaken the strength and durability of concrete. Sand as fine aggregate was washed at the washing plant before supplied for the test. The grading and the requirement of fine aggregates are shown in Figure 2 and Table 4, respectively. Coarse aggregates were washed gravels or crushed stones in accordance with Table 5. Coarse aggregates were combined with two types of single size, 20 mm and 10 mm and supplied from local providers. In Table 5, all test results for coarse aggregate were compared with the requirements.

In order to improve workability, strength and setting time, a high range and retarding super-plasticizer as a chemical admixture was used, complying with ASTM C 494. Air entrainer admixture shall comply with ASTM C 260. Micro-air 100 as an air entrainer admixture was used for improving a freeze-thaw resistance under a cryogenic environment. Mixing water was used without oil, acid, alkaline and organic matters or deleterious substances, complying with ASTM C 94 as shown in Table 6.

**Figure 2.** Grading of fine aggregate.

**Table 4.** Properties, requirements and test results for fine aggregates [36–42].

**Table 5.** Properties, requirements and test results for coarse aggregates [36,43–48].

**Table 6.** Properties, requirements and test results for mixing water.

### *2.2. Mix Design for Cryogenic Concrete*

The specified compressive strength of cryogenic concrete was 40 MPa and target compressive strength was 50 MPa which was determined by adding 10 MPa to the specified compressive strength due to variations in materials, operations and testing. The maximum size of aggregate was 20 mm. The target slump and slump flow were 220 ± 25 mm and 620 ± 75 mm, respectively. The water/binder ratio was selected with 0.28, and total cementitious content was varied between 475 kg/m3 to 495 kg/m3. Water content was started from 128 to 133 kg/m3 for cryogenic concrete. For water reduction, two types of high-range water-reducing chemical admixtures were applied: Daracem 208 (GCP applied technologies, Cambridge, MA, USA) as naphthalene type and Baxel PC 650 (Baxel, Sharq, Kuwait) as polycarboxylate type. Air content of 4 ± 1.5% was also achieved using a proper air-entraining admixture. Mix proportions are listed as shown in Table 7. Concrete materials were mixed by following ASTM C 192.

Type I: Naphthalene type (Daracem 208), Type II: Polycarboxylate type (Baxel PC 650).

*2.3. Preparation of SPECIMENS and Test Methods*

For fresh concrete, air content and retention time of concrete slump were measured. For hardened concrete, mechanical properties such as compressive strength and elastic modulus were carried out. A total of 15 specimens were prepared in each mixture including reserved samples as shown in Table 8.

**Table 8.** Test method and concrete specimens.

For one-time cryogenic test (Test A method), a total of 38 specimens were prepared as referred to Table 9. Test A method consisted of five specified tests: compressive and tensile strength, elastic modulus, thermal expansion coefficient and thermal conductivity. Each test was conducted under four different temperature conditions. For freeze-thaw cyclic test (Test B method), a total of 12 specimens were cast as referred to Table 10. Test B method was conducted to investigate the compressive strength and elastic modulus after 50-times freeze-thaw cycles.