In a 2019 concrete study, replacing up to 30% of sand with waste tyre rubber increased impact resistance but reduced compressive strength

Every year, millions of tyres reach the end of their useful lives, creating a waste problem that is difficult to manage. One possible use for some of that discarded rubber is in concrete. A study titled Performance of high strength concrete containing recycled rubber, published in Construction and Building Materials, examined what happened when crumb rubber from waste tyres was used to replace part of the fine aggregate in concrete. The researchers tested mixes containing 0%, 10%, 20% and 30% rubber and assessed several properties, including workability, strength, density, abrasion resistance, seawater exposure and microstructure.

How tyre rubber changes concrete

Concrete is strong under compression but comparatively brittle when subjected to sudden impact. Recycled tyre rubber offers a different characteristic because it is more flexible than conventional mineral aggregate. When incorporated into concrete, it can give the material more flexibility and help it hold together longer under impact.


The study found that impact resistance increased as the proportion of crumb rubber rose. At the highest replacement level tested, 30%, impact resistance was reported to be as much as 83% higher than that of the conventional concrete mix. However, this improvement came with a trade-off. The researchers also recorded reductions in compressive, tensile and flexural strength as the rubber content increased.

The microstructural analysis provided further information about the interaction between the rubber particles and cement paste. Rather than treating the improved impact resistance as evidence that rubber strengthens concrete overall, the findings show that the rubber changes the material's behaviour, improving its ability to withstand impact while reducing conventional strength measures.

The trade-off behind rubberised concrete

As impact resistance increased, both compressive strength and tensile strength decreased as more rubber was added. Compressive strength refers to concrete's ability to resist crushing loads, making it an important consideration when assessing whether a particular mix can carry structural loads.

That trade-off means rubberised concrete is not simply a stronger version of conventional concrete. Its value lies in applications where resistance to impact is an important consideration and the reduction in conventional strength can be accommodated by the design. The study's findings therefore need to be considered in relation to the specific requirements of each application rather than treated as evidence that the 30% mix is suitable for all types of construction.

There is also a waste-management benefit to consider. Scrap tyres are difficult to dispose of, and using them as a source of crumb rubber creates another potential route for diverting tyre material from disposal. Incorporating processed tyre rubber into concrete could therefore connect two waste streams with a potential construction application.

The research provides evidence that increasing the rubber content can produce a substantial improvement in impact resistance, but it also shows why the material requires careful selection for its intended use. Where compressive and tensile strength are critical, the loss in strength may outweigh the benefit of greater impact resistance. Where impact performance is more important, however, the balance could be different.

The study therefore points to recycled tyre rubber as a material worth investigating for specialised concrete applications rather than as a universal replacement for conventional fine aggregate. Its findings show that changing the aggregate can significantly alter how concrete responds to different types of loading, while also offering a potential use for material that would otherwise be difficult to manage as waste.