Effect of the Mold Size on the Compaction Parameters of the Soils

*Mustafa Özer and Ahmet Erdağ*

#### **Abstract**

 In this study, the effect of the mold size on the compaction parameters of the soils was investigated. For this purpose, a coarse-grained (finer than 19.00 mm) and a fine-grained (finer than 4.75 mm) soil were used in the tests. Compaction tests were conducted according to the current version of the ASTM D698 standard. In order to determine the effect of mold size, each soil used in study was compacted with both 6 in and 4 in diameter molds (with a volume of 2124 and 943 cm3 respectively). According to the results obtained, slightly greater values of density/unit weight were obtained with the 4 in diameter mold (with a volume of 944 cm3 ). These results are compatible with the results mentioned in the ASTM D698.

**Keywords:** compaction, dry unit weight, mold size, optimum water content, proctor

#### **1. Introduction**

 In many engineering structures such as highway, railway, airfield, and earth dam, loose soils need to be compacted to increase their dry density. The meaning of the verb "compact" in soil mechanics is to press the soil particles tightly together by expelling air from void spaces [1]. Compaction process increases the strength characteristics and settlement properties of soils. Compaction is actually a rather cheap and effective way to improve the properties of a given soil [1]. In order to obtain proper compaction in situ, laboratory compaction tests must be conducted prior to in situ compaction. Maximum dry unit weight and optimum water content under given compaction effort are obtained from laboratory compaction test to guide to the in situ compaction. According to current ASTM D698 [2], two different molds in terms of size can be used in laboratory compaction tests. One of these molds has a volume of 2124 cm3 , while the other has a volume of 943 cm3 . The selection of the mold is made according to the coarseness of the material to be tested. In ASTM D698 [2] three methods named Methods A, B, and C were identified in terms of mold size and coarseness of the material to be tested. In Method A, 101.6 mm (4 in) diameter mold (with a volume of 943 cm3 ) shall be used. This method may be used if 25% or less by mass of the material is retained on the No. 4 (4.75 mm) sieve. In Method B, 101.6 mm (4 in) diameter mold (with a volume of 943 cm3 ) shall be used. This method may be used if 25% or less by mass of the material is retained on the 3/8 in (9.5 mm) sieve. In Method

C, 152.4 mm (6 in) diameter mold (with a volume of 2124 cm3 ) shall be used. This method may be used if 30% or less by mass of the material is retained on the 3/4 in (19.0 mm) sieve.

 In ASTM D698 [2], it was highlighted that the 152.4 mm (6 in) diameter mold shall not be used with Method A or B. Besides, it was also noted that the results have been found to vary slightly when a material is tested at the same compactive effort in a different size mold, with the smaller mold size typically yielding larger values of density/unit weight. However, it was not specified in ASTM D698 [2] that this situation is valid for coarse-grained soils or fine-grained soils or both. Besides, there is no opinion in ASTM D698 [2] as to how the density/unit weight will be affected when using 4 in diameter mold with Method C (viz., with coarse-grained soils). In this study, how density/unit weight will be affected when using 4 in diameter mold with coarse-grained soils (i.e., with Method C) and 6 in diameter mold with finegrained soils (i.e., with Method A) was investigated.

#### **2. Soil materials used in the study**

Three soil materials were used in the study. The soil material-1 (named as S1) is a natural gravelly silty soil that contains coarse-grained particles. The soil material-2 (named as S2) was obtained from S1 by sieving through 4.75 mm sieve. That is, S2 is a fine-grained soil finer than 4.75 mm. The soil material-3 (named as S3) is a mixed gravelly silty clayey material which is obtained by mixing a coarse-grained gravelly material and fine-grained clayey soil. The soil material-3 was sieved through 19.0 mm sieve. That is, S3 is a coarse-grained soil finer than 19.0 mm.

 Sieve analysis, hydrometer analysis, liquid limit, and plastic limit tests were conducted on these samples according to relevant standards to characterize it (Refs. [3, 4], respectively). Particle size distribution of the materials is depicted in **Figure 1**. Liquid limit, plastic limit, and plasticity index of the soils are also shown in **Figure 1**.

**Figure 1.**  *Particle size distribution of the soil materials used in the study (Atterberg limits are also shown).* 

### **3. Experimental program**

 The tests conducted in the study were held in three sections. Standard Proctor effort according to ASTM D698 [2] was performed in all tests. Hence, 24.5 N hammer, 305 mm high of drop, and three layers were applied in the compaction tests. Twenty-five blows for 4 in diameter mold and 56 blows for 6 in diameter mold were performed for each layer. The detail of the tests and the results of it were given below.

#### **3.1 Test 1 (previously compacted sample)**

 In the first section of the study, four compaction tests were conducted and the soil material S1 was used. First, the material S1 was compacted with 6 in diameter mold (Test 1-1). The remaining three tests in this section were conducted on the same material batch to eliminate the sampling effect. So, after the Test 1-1 was completed, the test material S1 was dried in room temperature (in laboratory atmosphere) and was crushed by rubber hammer. Then, this material was recompacted with 4 in diameter mold in the second test (Test 1-2). Hence, the test material was recompacted secondly in Test 1-2. For the third test, the test material was sieved through 4.75 mm sieve and then dried and crushed as in the case in Test 1-2. The fine-grained material (−4.75 mm) was recompacted with 4 in diameter mold (Test 1-3). Hence, the test material was recompacted thirdly. Finally, this soil material was recompacted with 6 in diameter mold (Test 1-4) after and dried and crushed as in the previous case. Hence, the test material was recompacted fourthly.

#### **3.2 Test 2 (not previously compacted sample, finer than 4.75 mm)**

In this section of the study, two compaction tests were conducted and the soil material S2 was used in these tests. Before the compaction tests, the material S2 was divided into two parts by using riffle box according to ASTM C702 [5]. It was demonstrated by [6] that soil samples can be divided into representative subspecimens reasonably with riffle box according to ASTM C702 [5].

One part of the sample was compacted with 6 in diameter mold (Test 2-1), and the other parts of the sample were compacted with 4 in diameter mold (Test 2-2). Hence, the soil that has been previously compacted in the laboratory has not been reused in the compaction tests. However, a compaction test was conducted on the same batch. That is, data points within a compaction test were obtained from the same batch of the soil.

#### **3.3 Test 3 (not previously compacted sample, finer than 19.0 mm)**

In the last section of the study, two compaction tests were also conducted and the soil material S3 was used in these tests. Before compaction tests, the material S3 was divided into two parts by using riffle box according to ASTM C702 [5]. One part of the sample was compacted with 6 in diameter mold (Test 3-1), and the other parts of the sample were compacted with 4 in diameter mold (Test 3-2). Hence, the soil that has been previously compacted in the laboratory has not been reused in the tests. As in case Test 2, a compaction test was conducted on the same batch.

#### **4. Results and discussion**

The results obtained from each section were given in a separate section.

#### **4.1 Test 1 (previously compacted sample)**

 The results obtained from coarse-grained materials (−19.0 mm) (i.e., from Test 1-1 and 1-2) were given in **Figure 2**, and results obtained from fine-grained materials (−4.75 mm) (i.e., from Test 1-3 and 1-4) were depicted in **Figure 3**.

 As can be seen in **Figure 2a**, a moderately higher maximum dry unit weight was obtained from 6 in diameter than the 4 in diameter mold (1.72, 1.79 g/cm3 , respectively) on the coarse-grained soils. However, as in the case of fine-grained soils (**Figure 2b**), a considerably higher maximum dry unit weight was obtained from 4 in diameter mold than the 6 in diameter mold (1.66, 1.34 g/cm3 , respectively).

 As it will be remembered, according to ASTM D698 [2], typically slightly larger values of maximum dry unit weight may be expected from the smaller mold size (e.g., 4 in diameter). In this respect, it can be seen that while the results shown in **Figure 2b** are compatible with ASTM D698 [2], the results presented in **Figure 2a** are not consistent with ASTM D698 [2] with respect to mold size. Namely, while smaller value of maximum dry unit weight was obtained from 4 in diameter mold in the case of coarse-grained soils (**Figure 2a**), larger value of maximum dry unit weight was obtained from 4 in diameter mold in the case of fine-grained soils (**Figure 2b**).

Although the results shown in **Figure 2b** seem to be consistent with the results specified in ASTM D698 [2], the fact that the difference between the results is higher than expected should draw attention. It was argued that the only reason for obtaining lower value of maximum dry unit weight (both **Figure 2a** and **b**) is not only the size of the mold but also disintegration of the particles due to recompaction.

Sieve analysis was performed on the sample S1 after the last compaction test (Test 1-4) to verify (to check) this argument, and results obtained were presented in **Figure 3** with the particle size distribution of the original sample (before compaction). Particle disintegration is shown clearly in **Figure 3**. Hence, it was considered that the low maximum dry unit weight shown in **Figure 2b** is mainly due to the disintegration of the particles as well as the mold diameter.

#### **Figure 2.**

*Compaction curves obtained from soil (previously compacted samples were reused in the tests from Test 1-2 to Test 1-4). (a) Compaction curves obtained from coarse-grained (−19.0 mm) soils (Test 1-1 and Test 1-2). (b) Compaction curves obtained from fine-grained (−4.75 mm) soils (Test 1-3 and Test 1-4).* 

*Effect of the Mold Size on the Compaction Parameters of the Soils DOI: http://dx.doi.org/10.5772/intechopen.87836* 

**Figure 3.**  *Particle size distributions of soils (S1) performed after and before compaction tests.* 

#### **Figure 4.**

*Compaction curves obtained from soil (not previously compacted samples were used in these tests). (A) Compaction curves obtained from fine-grained (−4.75 mm) (Test 2-1 and Test 2-2) soils. (B) Compaction curves obtained from coarse-grained (−19.0 mm) soils (Test 3-1 and Test 3-2).* 

#### **4.2 Test 2 and test 3 (not previously compacted samples)**

The results obtained from fine-grained materials (−4.75 mm) were given in **Figure 4A**, and the results obtained from coarse-grained materials (−19.0 mm) were depicted in **Figure 4B**.

 As can be seen from **Figure 4A**, slightly higher maximum dry unit weight was obtained from 4 in diameter mold than the 6 in diameter mold (1.64, 1.62 g/cm3 , respectively) on the fine-grained soils as expected due to ASTM D698 [2]. However, as in the case of coarse-grained soils (**Figure 4B**), unlike ASTM D698 [2], slightly lower maximum dry unit weight was obtained from 4 in diameter mold than the 6 in diameter mold (1.85, 1.86 g/cm3 , respectively). Although slightly different results were obtained from both molds, the differences between results shown in **Figure 4** are within "acceptable range of two results" given in ASTM D698 [2]. Hence, it can be said that the difference between the results is insignificant.

### **5. Conclusions**

Two main conclusions were drawn from this study:


#### **Author details**

Mustafa Özer1 \* and Ahmet Erdağ<sup>2</sup>

1 Department of Civil Engineering, Gazi University, Ankara, Turkey

2 Department of Civil Engineering, Kafkas University, Ankara, Turkey

\*Address all correspondence to: ozerm@gazi.edu.tr

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Effect of the Mold Size on the Compaction Parameters of the Soils DOI: http://dx.doi.org/10.5772/intechopen.87836* 

#### **References**

[1] Liu C, Evett JB. Soils and Foundations. 6th ed. Upper Saddle River, NJ: Pearcon-Prentice Hall; 2003. p. 496. ISBN 0-13-048219-6

[2] ASTM D698. Standard Test Method for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3 )). Annual Book of ASTM Standards, PA, United States; 2012

[3] EN ISO 17892-4. Geotechnical investigation and testing—Laboratory testing of soil—Part 4: Determination of particle size distribution: International Organization for Standardization; 2016

[4] ASTM D4318. Standard Test Method for Liquid Limit, Plastic Limit and Plasticity Index of Soils. PA, United States: Annual Book of ASTM Standards; 2017

[5] C702 ASTM. Standard Practice for Reducing Samples of Aggregate to Testing Size. PA, United States: Annual Book of ASTM Standards; 2018

[6] Özer M. Comparison of sample dividing (reducing) methods used in soil mechanics tests. Journal of Polytechnic. 2014;**17**(4):167-176. DOI: 10.2339/2014.17.4

**737**

**Chapter 60**

Lot

**Abstract**

**1. Introduction**

Evaluation of Energy Potential and

Investment Costs of Solar Power

*Ahmet Nazım Akkaya, Harun Varlı and Seyfettin Kurt*

Due to the world population growth and industrialization process, energy demand in every sector is increasing day by day. Considering the amounts generated, energy sources are categorized as primary and secondary energy sources. While primary energy sources are classified as fossil sources, hydraulic energy, and nuclear energy, secondary energy sources are solar, geothermal, wind, and fusion energy. In order to meet the energy demand in the world today, most of the energy consumed is obtained from fossil sources. Nonrenewable and fossil-based sources, which have limited reserves, such as coal, oil, and natural gas are frequently used in all sectors. This case brings environmental pollution to more dangerous levels. It is of great importance to use renewable energy sources, which do not require imports and are low in cost, in order to contribute to the prevention of environmental pollution in Turkey. In this context, the biggest theme park of Europe, Ankapark, Turkey, was examined in this paper in terms of solar energy. The Ankapark parking lot project, built as the largest solar power plant in the world, was evaluated in terms

**Keywords:** theme park, Ankapark, solar parking lot, solar energy, solar power plant

Considering the amount produced in general, energy sources are examined in two groups as "primary energy sources" and "secondary energy sources." Primary energy sources are comprised of fossil resources such as coal, petroleum products, hydraulic energy and nuclear energy, while secondary energy sources include solar energy, geothermal energy, tidal energy, wave energy, wind energy, fusion energy, etc. The most widely used energy sources, petroleum and its derivatives as fossil sources, are the resources that will be exhausted in the near future due to rapid consumption, and thus they are depleted, ultimately causing ecological deterioration and even debalancing the climatological equilibrium arising from burning of these resources for energy production. This reveals that there is a serious problem to be solved. For these reasons, new quests have been embarked on for obtaining the energy needed in the future from sources such as solar energy, wind energy, tidal energy, and wave energy. Particularly the importance of solar energy

of solar energy potential and investment costs.

Plants: Case of Ankapark Parking

#### **Chapter 60**
