Performance of high strength concrete containing recycled rubber Ayman Abdelmonem a , M.S. El-Feky b , El-Sayed A.R. Nasr a , Mohamed Kohail a,⇑ a Structural Engineering Department, Faculty of Engineering, Ain Shams University, Cairo, Egypt b Department of Civil Engineering, National Research Centre, Cairo, Egypt highlights  Waste rubber was used in high strength concrete as an alternative to aggregates.  The hardened properties and impact resistance are discussed.  The compressive and tensile strength decreases with increasing rubber content.  Waste rubber increases the impact resistance of rubberized concrete.  The mix with 30% rubber content can be used in bridges and harbors. article info Article history: Received 13 May 2019 Received in revised form 6 July 2019 Accepted 5 August 2019 Keywords: High strength concrete Rubberized concrete Crumb rubber Waste tires Impact resistance Seawater Recycling abstract Recycling and Utilizing waste rubber as a replacement of natural aggregate in concrete is a promising environmentally friendly solution. The objective of this study is to evaluate the performance of high strength concrete where the recycled rubber partially replace the fine aggregate. Four different mixes were produced in which crumb rubber partially replaced fine aggregate by 0%, 10%, 20%, and 30% of vol- ume. Slump, compressive strength, tensile strength, flexural strength, density, abrasion resistance, sea- water effect on rubberized concrete, impact resistance, and microstructural analysis were evaluated. The rubberized concrete mixes showed good workability and slightly lower density than the control mix. A systematic reduction of almost up to 50% in compressive, tensile, and flexural strength was wit- nessed with increasing the rubber content up to 30%. Lower abrasion resistance was obtained with increasing the rubber content. The rubberized concrete mixes displayed good behavior in seawater. The rubberized concrete mixes also showed up to 83% higher impact resistance compared to the control mix. The findings of this study give an overview of the effect of addition of recycled rubber on concrete of high strength. Ó 2019 Elsevier Ltd. All rights reserved. 1. Introduction The tires demand is anticipated to grow yearly, in emergent countries, the growing income will stimulate development in the quantity of vehicles being used, and there will be more need for tires. In 2017 almost 287.3 million waste tires were manufactured in USA, while about 60 million tyres are stockpiled [1]. Although there is no official statistic in Egypt stating the total number of tires generated annually, it is estimated that the number of tires generated annually could be as about 10 million tires [2]. The inad- equate disposal of these tires in landfills after they reach their ser- vice life and become waste is becoming one of the foremost challenging issues causing several health and environmental prob- lems [3,4]. Thus legislations have been introduced by some coun- tries to ban the disposal of tires in landfills and encourage the reuse of waste tires in other applications [3,5,6]. Concrete is from the dominated materials in the construction industry and green construction has been an essential aspect by using pozzolans to replace cement and recycled materials instead of aggregate [7–9], therefore utilizing waste rubber in conventional concrete can be considered as a one step forward towards sustainable construction. Within the last 20 years, quite a few researches were performed investigating the reuse of recycled tire rubber as replacement of fractions of mineral aggregate [10–18]. Several researchers reported that the increase in the rubber content adversely affect the workability of the fresh rubberized concrete [19–23]. The slump of the rubberized concrete decreased with increasing the rubber content, the reduction was more severe in case of using the relatively larger tire chips compared to using https://doi.org/10.1016/j.conbuildmat.2019.08.041 0950-0618/Ó 2019 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: m.kohail@eng.asu.edu.eg (M. Kohail). Construction and Building Materials 227 (2019) 116660 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat