*Article* **Composite Soil Made of Rubber Fibers from Waste Tires, Blended Sugar Cane Molasses, and Kaolin Clay**

**Juan E. Jiménez <sup>1</sup> , Carlos Mauricio Fontes Vieira <sup>2</sup> and Henry A. Colorado 1,\***


**Abstract:** The use of different chemical and biological admixtures to improve the ground conditions has been a common practice in geotechnical engineering for decades. The use of waste material in these mixtures has received increasing attention in the recent years. This investigation evaluates the effects of using recycled tire polymer fibers (RTPF) and sugar molasses mixed with kaolin clay on the engineering properties of the soil. RTPF were obtained from a tire recycling company, while the molasses were extracted from a sugar cane manufacturer, both located in Colombia. RTPF is a waste and therefore its utilization is the first positive impact of this research, a green solution for this byproduct. Treated kaolin clay is widely used in many industrial processes, such as concrete, paper, paint, and traditional ceramics. The characterization was conducted with scanning electron microscopy, compression strength, particle-size distribution, x-ray diffraction, compressive and density tests. The results showed that the unconfined compressive strength improved from about 1.42 MPa for unstabilized samples, to 2.04 MPa for samples with 0.1 wt% of fibers, and 2.0 wt% molasses with respect to the dry weight of the soil. Furthermore, it was observed that soil microorganisms developed in some of the samples due to the organic nature of the molasses.

**Keywords:** waste tires; molasses; soil improving
