<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>The use of waste materials (including rubber) in industry is one of the most important issues in terms of environmental protection. One of such applications is the use of soil–rubber mixtures in backfills or lower layers of embankments or road structures. The numerical analyses of the behavior of a clay–rubber mixture layer built into a road embankment are presented in this article. An elastic-perfectly plastic model with a Coulomb–Mohr yield surface was used in the finite element analysis. The parameters of soil–rubber mixtures adopted for the analysis were estimated on the basis of triaxial tests: monotonic (UU—unconsolidated undrained, and CU—consolidated undrained) and cyclic (CU) performed with low frequency (<italic>f</italic> = 0,001 Hz). The triaxial tests were carried out on mixtures of kaolin (K) and red clay (RC) with the addition of 1–5 mm rubber granulate (G) in the amount of 5–25% by weight. Numerical analyses included a static plate load test (VSS) of a layer made of a rubber–soil mixture built into the embankment and testing the stability of embankments using the <italic>c</italic>–ϕ strength reduction procedure. The results of laboratory tests confirm the necessity of testing soil–rubber mixtures each time before their use in embankments. The observed overall decrease in shear strength and stiffness of the tested material is variable and depends on the type of soil and the content of rubber waste. Satisfactory results of the analysis were obtained, both in terms of the values of layer stiffness modules and slope safety factors, which allows for the conclusion of the possibility of using soil–rubber mixtures (with the recommended granulate addition up to 30% by weight) in the layers of road embankments and (depending on the road class) in the lower layers of the pavement structure.</p>
</abstract>

The use of waste materials (including rubber) in industry is one of the most important issues in terms of environmental protection. One of such applications is the use of soil–rubber mixtures in backfills or lower layers of embankments or road structures. The numerical analyses of the behavior of a clay–rubber mixture layer built into a road embankment are presented in this article. An elastic-perfectly plastic model with a Coulomb–Mohr yield surface was used in the finite element analysis. The parameters of soil–rubber mixtures adopted for the analysis were estimated on the basis of triaxial tests: monotonic (UU—unconsolidated undrained, and CU—consolidated undrained) and cyclic (CU) performed with low frequency (f = 0,001 Hz). The triaxial tests were carried out on mixtures of kaolin (K) and red clay (RC) with the addition of 1–5 mm rubber granulate (G) in the amount of 5–25% by weight. Numerical analyses included a static plate load test (VSS) of a layer made of a rubber–soil mixture built into the embankment and testing the stability of embankments using the c–ϕ strength reduction procedure. The results of laboratory tests confirm the necessity of testing soil–rubber mixtures each time before their use in embankments. The observed overall decrease in shear strength and stiffness of the tested material is variable and depends on the type of soil and the content of rubber waste. Satisfactory results of the analysis were obtained, both in terms of the values of layer stiffness modules and slope safety factors, which allows for the conclusion of the possibility of using soil–rubber mixtures (with the recommended granulate addition up to 30% by weight) in the layers of road embankments and (depending on the road class) in the lower layers of the pavement structure.

Application of Clay–rubber Mixtures for the Transportation Geotechnics—the Numerical Analysis

Katedra Geotechniki i Dróg, Wydział Budownictwa

Studia Geotechnica et Mechanica

This work is licensed under the Creative Commons Attribution 4.0 International License.

The use of waste materials (including rubber) in industry is one of the most important issues in terms of environmental protection. One of such applications is...

Type of material	CU triaxial tests (cyclic/^(*) monotonic)		CU triaxial tests (monotonic)

	Internal friction angle ϕ [°]	Cohesion c [kPa]	Internal friction angle ϕ [°]	Cohesion c [kPa]
RC-G-10	24	61	24	62
RC-G-25	15	30	28	22
K-G-25	9	70	–	–
RC	–	–	21	167
K	25*	11*	–	–

Material zone	Volumetric weight [kN/m³]	Cohesion c [kPa]	Internal friction angle ϕ [°]	Stiffness modulus E [MPa]
The corpus of the embankment (soil–rubber mixture)	15.0	30	15	60
Subsoil under the embankment	21.0	5	30	40
Pavement structure	22.0	Elastic material		800

Application of Clay–rubber Mixtures for the Transportation Geotechnics—the Numerical Analysis

Article Category: Special Issue 19th KKMGiIG

Published Online: Oct 18, 2023

Page range: 370 - 381

Received: Feb 01, 2023

Accepted: Aug 31, 2023

DOI: https://doi.org/10.2478/sgem-2023-0020

Keywords
clay–rubber waste mixtures, cyclic loads, road layer stiffness, stability of road embankment, VSS load tests

© 2023 Małgorzata Jastrzębska et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1:

Figure 2:

Figure 3:

Figure 4:

Figure 5:

Figure 6:

Figure 7:

Figure 8:

Figure 9.

The strength parameters obtained from CU/UU triaxial tests.

Parameters taken for numerical analyses.

Application of Clay–rubber Mixtures for the Transportation Geotechnics—the Numerical Analysis

Article Category: Special Issue 19th KKMGiIG

Published Online: Oct 18, 2023

Page range: 370 - 381

Received: Feb 01, 2023

Accepted: Aug 31, 2023

DOI: https://doi.org/10.2478/sgem-2023-0020

Keywordsclay–rubber waste mixtures, cyclic loads, road layer stiffness, stability of road embankment, VSS load tests

© 2023 Małgorzata Jastrzębska et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Figure 1:

Figure 2:

Figure 3:

Figure 4:

Figure 5:

Figure 6:

Figure 7:

Figure 8:

Figure 9.

The strength parameters obtained from CU/UU triaxial tests.

Parameters taken for numerical analyses.

Keywords
clay–rubber waste mixtures, cyclic loads, road layer stiffness, stability of road embankment, VSS load tests