Date of Award

6-16-2025

Thesis Type

PhD

Document Type

Thesis

Degree Name

Doctor of Philosophy (PhD)

Divisions

Faculty of Engineering

Department

Department of Civil Engineering

Institution

Universiti Malaya

Abstract

Economic development results in a rise in the demand for different items, such as rubber products. Consequently, there is a continuous growth in the amount of waste rubber products generated globally each year. The waste generated from solid tires, composed of non-biodegradable substances, poses significant environmental and public health concerns. Protecting critical buildings, bridges, potentially hazardous industrial operations, and valuable equipment against earthquakes is crucial for ensuring safety and minimizing economic losses. This study aims to evaluate rubber tires' damping mechanical and dynamic properties by optimizing the rubber tire composition. Various rubber compositions were examined to determine the most efficient combinations of natural rubber (NR) and devulcanized crumb rubber (DVR). The research examined two batches of devulcanized rubber from truck tread tires (T) and whole truck tires (W). This study employed the Gopi Sekhar (GPS) patented method (US 9550880B2, 2017) by Sekar Research Innovations Sdn.Bhd. for method in producing the DVR. During the vulcanization process, NR was combined with varying proportions of DVR, 0%, 10%, 20%, and 30% of the total volume, along with activators, accelerators, and fillers. The selected tests for mechanical and dynamic damping properties included tensile strength (ISO 37:2017), elongation at break (ISO 37:2017), tear test (ISO 34-1:2015), hardness test (ISO 48-4:2018), compression stress-strain testing (ISO 7743:C:2017), stress relaxation testing (ISO 3384:B:2011), accelerated aging test (ISO 188:2011), and double shear test (BS EN 15129:2018). The performance of the rubber composition in terms of its damping properties was satisfactory, demonstrating long-lasting performance, particularly in batch T with 20% DVR in the composition, which was deemed ideal due to a tensile strength of 21.5 MPa, an elongation at break of 530%, tear strength with 18.6 MPa, and a hardness of 66 International Rubber Hardness Degree (IRHD). Additionally, stress relaxation at 7 days/23°C was 14%, and at 100 days/23°C was 22%, and compression at strains of 10% and 20% were 5.5 MPa and 6.0 MPa, respectively. Moreover, accelerated aging in the air for 7 days at 100°C showed a change in tensile strength of -77% and elongation at break of -65%. The damping ratio and shear modulus were 6.3087 and 0.6947 MPa, respectively, indicating superior dynamic performance. After careful consideration, a batch and content with optimal properties have been chosen to manufacture a block rubber damper in the energy dissipation damper system.

Initial

khm

Additional Information

Thesis (PhD) - Faculty of Engineering, Universiti Malaya, 2026.

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