Concrete made with old tires proves itself in real-world setting

https://newatlas.com ^ | March 30, 2022 | By Nick Lavars & University of South Australia

[Red Badger]

With a notoriously large carbon footprint, concrete is a prime target for researchers developing greener materials for the future of construction. A number of studies have shown how old rubber tires can be used to make versions that are stronger, more heat-resistant and flexible enough for use as a road material. A new study has assessed its value in real-world settings by using concrete containing old tires as a residential slab and monitoring its performance over several years, where it outshone conventional concrete in a number of ways.

The type of concrete at the center of this study is known as crumb rubber concrete, and its production involves grinding rubber tire down into crumbs of a similar consistency to sand. These crumbs can then be used to replace a certain proportion of the sand typically mixed in with the cement, water and other ingredients to form concrete, lessening the reliance on the natural material and giving the discarded rubber a second life.

Scientists at the University of South Australia and Melbourne's RMIT University have sought to take this material from the "lab to the slab," noting that while it has shown a lot of promise in laboratory testing, its reliability in real-world construction requires further exploration.

To investigate its practical application in residential settings, the scientists poured two crumb rubber-reinforced concrete slabs at the University of South Australia campus in 2018, along with two conventional concrete slabs. These formed the entrances to a civil engineering laboratory that sees a lot of foot traffic, with the team closely monitoring the materials' performance over time.

[Red Badger]

Crumb rubber concrete made by grinding down discarded tires has stood up well in real-world testing

https://www.sciencedirect.com/science/article/abs/pii/S2352012421011802?via=ihub

Abstract While there is extensive data now available for the performance of crumb rubber concrete (CRC) in laboratory mixes, it is essential to understand whether satisfactory performance can be replicated in real-world structures.

This is particularly the case for the area of residential construction, which is a sector that is sometimes characterised by fairly average outcomes due to a sometimes-low skilled workforce operating with minimal supervision.

To replicate a real-world situation, CRC research has been moved from “the lab to the slab” in this paper. Two large-scale (4 × 8 m each) reinforced concrete residential footing slabs were constructed. One was cast with CRC and the other with a standard residential mix of conventional concrete (CC).

In addition, two reinforced concrete residential ground slabs of different dimensions were constructed out of CRC and CC mixes to assess abrasion resistance. These ground slabs were poured in high traffic entrances of a civil engineering laboratory. All mixes were provided by a commercial ready-mix company and the construction was undertaken by an experienced footing contractor. A large range of factors have been investigated and compared. Those related to construction requirements, included the effect of using rubber on concrete mixing, delivery, workability, pumpability, ease of surface finishing, and curing.

The contractors reported easy screeding and less physical effort to do so, with no difference reported when finishing the concrete surface when using a concrete power trowel for footing slabs.

Other factors that were investigated included: fresh and hardened density, compressive strength, modulus of elasticity, shrinkage, carbonation, chloride ingress, abrasion resistance, rising damp, and corrosion. The results show that CRC is a potentially viable and promising alternative to conventional concrete in the residential concrete market.

[HighSierra5]

So if I fall on this new concrete, I’ll bounce back up?

[nascarnation]

Interesting.
I wonder what the economics of this are?

Wikipedia says 43% of scrap tires are burned as fuel, and 25% ground into material for products like running tracks.

[\/\/ayne]

Yes. Yes, you will.

[Don W]

30 years ago they tried this with asphalt.

It did not work very well.

[4yearlurker]

I remember that. The roads started burning and smoking.

[dead]

It’d be nice if it’s economical and works well. Not so nice if it sucks and it’s rammed down society’s throat anyway to appease the green screechers.

[ProtectOurFreedom]

“crumb rubber concrete”

After a couple of years in service, it will be “crumbling rubber concrete.”

“Rubberized asphalt” has been a total disaster in California. Roads crumble in a fraction of the time of virgin asphalt.

[mcshot]

Only to get run over by a beer truck.

[Bob434]

TE rub thiugh is that you have to use wither 1 tire or 3 or more, not 2 because if you do, the concentrate will be 2 tired to hold together

[Repeal The 17th]

“...concrete is a prime target for researchers developing greener materials...
...crumbs can then be used to replace a certain proportion of the sand in the mix...
...lessening the reliance on the natural material...”
-
Is there a shortage of sand that I am unaware of?

[Red Badger]

Yes, the deserts are shrinking and the seas are rising................

[Sequoyah101]

Adding a ductile material to the matrix of a material whose hallmark is compressive strength and rigidity seems not very smart. Seems to be a lot of not very smart going around these days.

Asphalt would not survive unreinforced if it were not somewhat ductile.

I wonder what those “rubber” inclusions do for spalling, freeze resistance, permeability, bonding, development length of steel and other things we always were concerned about with concrete.

The whole experiment sounds like reinventing the wheel by a bunch of somewhat educated fools and tools.

[Wally_Kalbacken]

It is the amount of CO2 released in the production of concrete that environmentalists seem to have as a target.

[nh1]

Well, take the sand from the ocean and solve both problems. :^)

[StAntKnee]

Shortage of sand. My thought precisely. Sand, I would imagine, is a LOT more eco friendly when you consider the energy expended turn tires into crumbs. Did you hear that, Greenies? A hell of a lot more energy than sifting and washing gravel to get sand. Having said that, the crumbs sound like a heckuva concept. Done a bit of concrete work. Watched a pour last year, a slab with no rebar. Fiberglass threads instead. Said to be every bit as durable as rebar reinforced. Seems to have lasted without fractures over the winter. Pretty impressive. I’d use the rubber crumbs if it were economical. And if it didn’t look like crap.

[dangus]

This is so unbelievably stupid! It’s like an alcoholic “cutting down on his drinking” by drinking ten shots of vodka instead of eight cans of beer. Sand isn’t the issue. Replacing sand with immortal rubber will only make the problem worse.

Incidentally, they tried doing this with roadways to reduce the use of petroleum products in asphalt back in the 1980s. They stopped after it was shown that the rubber-asphalt was slick as hell after it rained. It’s probably why the Thunderbird I bought as my first car slipped like crazy and was utterly destroyed on rainy afternoon, but try proving that five years later.

[dangus]

I think most of the remaining 22% are in enormous, miles-long heaps outside Scranton, PA, until the inevitable environmental disaster happens someday.

[nascarnation]

When they catch on fire, it’s bad news.
That huge WalMart warehouse fire here in Indiana this month had a LOT of new tires on the shelves.

[punchamullah]

Good sand is becoming rather scarce, in my part of the world, anyway. Desert sand and beach sand are useless for concrete and mortar, as they do not have the requisite sharpness and angularity.

I did many offshore sand searches for dredging and reclamation projects in the ‘80s and ‘90s. Most were for projects in Singapore, and the greatest part of the sand dredged came from Indonesian waters. After some snit between Indonesia and Singapore, Indonesia banned the export of sand, and now most of the sand consumed in Singapore for concrete and reclamation is dredged offshore Thailand and carried all the way to S’pore, ~500 miles.

I still do a lot of concrete and cement work in Jakarta, and the price of good sand has risen 250% in the last ten years. Most of the good sand is taken from rivers and quarries and the distances get further all the time. Construction in Jakarta alone consumes some 20 000 tonnes of sand daily.