Mechanical and Dynamic Behavior of an Elastic Rubber Layer with Recycled Styrene-Butadiene Rubber Granules

Abstract

This study evaluates the tensile properties, including the tensile strength and elongation at break, and dynamic behavior, including shock absorption and vertical deformation, of an elastic rubber layer in synthetic sports surfaces produced using waste tire chips containing styrene-butadiene rubber (SBR). The primary variables of the investigation were the number of compactions, resin-rubber granule ratio, and curing conditions, such as aging, the temperature, and the relative humidity. The test results showed an increase in the tensile strength of the elastic rubber layer with recycled SBR as the number of compactions, resin-rubber granule ratio, curing period, and temperature increased, while the elongation at break was affected by the curing temperature and period. Shock absorption and vertical deformation decreased with an increasing resin-rubber granule ratio and number of compactions due to the increased hardness. However, these properties were not significantly affected by the curing conditions. Furthermore, the test results indicated that the curing temperature has a pronounced effect on the tensile properties of the elastic rubber layer, and maintaining the appropriate curing temperature-approximately 50 °C-is a possible solution for improving the relatively low tensile properties of the elastic rubber layer.

Keywords: elastic rubber layer; shock absorption; styrene-butadiene rubber; synthetic sports surface; tensile properties; vertical deformation.

Figure 1

Structure of a synthetic sports surface.

Figure 2

Production process of test samples.

Figure 3

Direct tensile test procedure.

Figure 4

Shock absorption test equipment and procedure: (a) Artificial athlete apparatus used for the shock absorption test (impact tester) and (b) the shock absorption test procedure.

Figure 5

Vertical deformation test equipment and procedure: (a) Artificial athlete apparatus used for the vertical deformation test, and (b) the vertical deformation test procedure. LVDT: linear variable differential transducer.

Figure 6

Effects of the number of compactions: (a) Tensile strength; (b) elongation at break; (c) shock absorption; and (d) vertical deformation.

Figure 7

Effects of the curing age: (a) Tensile strength; (b) elongation at break; (c) shock absorption; and (d) vertical deformation.

Figure 8

Effects of the curing temperature and resin–rubber granule ratio: (a) Tensile strength; (b) elongation at break; (c) shock absorption; and (d) vertical deformation.

Figure 9

Failure surfaces of elastic rubber layers after the direct tensile test: Curing at (a) −10 ± 2 °C, (b) 20 ± 2 °C, and (c) 50 ± 2 °C.

Figure 10

Effects of the relative humidity and resin–rubber granule ratio: (a) Tensile strength; (b) elongation at break; (c) shock absorption; and (d) vertical deformation.