Evaluation of Mechanical and Microstructural Properties of Waste Tire Improved Cemented Clay

ABSTRACT

Each year, an enormous number of tires approach the end of their useful lives, posing threats to human health and the environment. On the other hand, cement is frequently used to treat soils in geotechnical applications, while its production causes a significant environmental impact. Thus, this study provides a disposal alternative by investigating the influence of tire rubber fiber (TRF) as a partial replacement of cement in artificially cemented soils. Unconfined compressive strength (qu) and ultrasonic pulse velocity (UPV) were measured on the various mixtures to assess strength, stiffness, and ductility index. Statistical analysis and regression models were conducted, and a novel approach to estimate rubberized-cemented-clay was proposed to determine G_o, q_u, and E from a single nondestructive test. Moreover, SEM was performed to observe the interaction of the TRF and cement with the clay on a microscopic scale. The results showed that the 2.5% TRF content improves rubberized cemented clay’s strength, stiffness, and ductility index by around 12–15%. Furthermore, up to 10% of the TRF blends achieved the minimum requirements for rammed earth, base, and sub-base treated soils. However, 20% of TRF reduces G_o, and q_u, by around 20–30% while improving the ductility index by 35–40%.

摘要

每年，大量轮胎的使用寿命即将结束，对人类健康和环境构成威胁. 另一方面，水泥在岩土工程应用中经常用于处理土壤，而其生产会对环境产生重大影响. 因此，本研究通过研究轮胎橡胶纤维（TRF）作为人工水泥土中水泥的部分替代品的影响，提供了一种处理方案. 测量了各种混合物的无侧限抗压强度（qu）和超声脉冲速度（UPV），以评估强度、刚度和延性指数. 进行了统计分析和回归模型，并提出了一种新的方法来估计橡胶胶结粘土，以从单个无损检测中确定Go、qu和E. 此外，用扫描电镜在微观尺度上观察了TRF和水泥与粘土的相互作用. 结果表明，2.5%的TRF含量可使橡胶胶结粘土的强度、刚度和延性指数提高约12-15%. 此外，高达10%的TRF混合物达到了夯实土、基底和底基层处理土壤的最低要求. 然而，20%的TRF将Go和qu降低约20–30%，同时将延性指数提高35–40%.

KEYWORDS:

• Clays
• soil stabilization
• compressive strength
• stiffness
• waste

关键词:

• 粘土
• 土壤稳定
• 抗压强度
• 刚度
• 浪费

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The corresponding author may provide some or all of the data utilized upon request.

Highlights

• The most significant are the dry density and the curing period, respectively.

• 2.5% TRF of partial cement replacement is the optimum dosage.

• Denser samples showed higher increase in q_u, G_o, and E than less compacted ones.

• Porosity/binders index (ɳ/X_iv^0.32) is a strong factor to determine the mechanical parameters.

• The tire rubber increases the blends’ ductility behavior with high energy absorption.

• The hard shell developed around the rubber particles increases the compatibility in stiffness.

Additional information

Funding

This project received fund from Middle East Technical University (FEN-20-YG-4).