*Article* **Incorporation of Recycled Tire Products in Pavement-Grade Concrete: An Experimental Study**

**Sayed Mohamad Soleimani \*, Abdel Rahman Alaqqad, Adel Jumaah, Naser Mohammad and Alanoud Faheiman**

Department of Civil Engineering, Australian College of Kuwait, P.O. Box 1411, Safat 13015, Kuwait; a.alaqqad@ack.edu.kw (A.R.A.); 1414700@go.ack.edu.kw (A.J.); n.mohammad@ack.edu.kw (N.M.); a.faheiman@ack.edu.kw (A.F.)

**\*** Correspondence: s.soleimani@ack.edu.kw; Tel.: +965-1828225 (ext. 4046)

**Abstract:** The phenomenon of dumping used tires in Kuwait has reached critical levels, with a landfill containing millions of tires being formed in a remote area, which is a major environmental hazard. Nowadays, recycled rubber is used as a suitable and useful material in civil engineering applications, particularly in the production of "green concrete". This study aims to see whether recycled tire by-products can be used to make "green concrete" for pavements. Each type of tire by-product was tested individually to examine its properties and effects on a benchmark mix before creating hybrid mixes that contain a combination of the materials. Eleven mixes containing different doses of shredded or crumbed rubber or steel fibers contained within the tires were made to evaluate their impact on the concrete's slump, compressive strength, split tensile strength, and modulus of rupture. Additionally, twelve hybrid concrete mixes containing different doses of various tire by-products were developed. Preliminary results show that the incorporation of rubber products has a reduction on the concrete's properties. The use of replacement materials sourced from recycled tires using the dosages investigated in this study does not detract from the usability of green pavement concrete suited for hot weather. The concrete produced in this study could be evaluated for specific properties relating to its road safety in further studies. Additionally, long-term effects of using the concrete can be studied using finite element analysis.

**Keywords:** green concrete; shredded rubber; crumbed rubber; steel fiber; recycled tire; pavement; waste materials; sustainability
