Recycled Concrete in Alaska Availability and Uses Shane Durand Kauai Alpha

Recent study by the CMRA construction material recycling association shows AK lagging behind other states in the acceptance of RCA

Recycling concrete relatively new in AK traditionally been buried on site or near by property. New operations allow this material to be recycled at fixed site recyclers or on site

Source of Concrete and type of material important to final product

Source typically determines Size, quality

Curb and gutter, sidewalk etc. makes up the gravy of recycled concrete Very consistent, sized well

Another overlooked portion of the recycled concrete waste stream is brick and material recovered from C&D Facilities. 5% by weight or more of a roll off is brick, rock, mortar etc.

Brick in a straight demo is often found to be painted or coated and thrown away. Try not to crush full loads of brick.

More than half of concrete recycled is structural from demolition such as buildings bridges and

Airport hard stands

Typical Recycle Facility accepts 2 categories of rubble Typical Recycle Facility accepts 2 categories of rubble. Everyone seems to have some what different requirements but generally it is what will fit directly into crusher and materials that require further processing.

Nonconforming, vaults, pole bases, lots of embedded metals

Nonconforming, vaults, pole bases, Bollards are the bane of the recycler

These require further processing on site or at the recycle facility prior to crushing These are the same large nonconforming materials being on site pulverized. This material could be used as fill on site or crushed into a spec product.

Coatings on concrete Paint, waterproofing, fireproofing, insulation, vapor barrier. Besides the debris and contamination health and environmental issues. Lead paint and Asbestos containing materials Lead paint studies by the USACE indicate this may not be of concern in final product but issues during processing. ACM can not be processed and has to be removed or landfilled Recycle facilities require paperwork on demolition debris.

Lead coating USACE Pubs

Debris such as vapor barrier, insulation pex tubing

Here at fixed plant picker on the screen removing debris

Need picture of air lift separator Air density separation started using in 2012 Works at fixed plant not so well on site Is deleterious material overblown?

Here are results from Kulis 20 different structures demolished Here are results from Kulis 20 different structures demolished. Average of results and outliers. Hi Deleterious .6% on 6” minus average .1% all in the field

3” minus hi .2% average .1%

So we have discussed sources, considerations and requirements so lets talk about more hows and tools of the trade. Prior to crushing most all concrete requires some sort of demolition. Saw cutting both structural and flat work

Hydraulic Hammers are main tool for demolition and size reduction. Does not efficiently liberate all of the steel or size well under 24”

Good for primary reduction

Example of concrete demolition with hammer Lots of steel but sized well for crusher

Pulverizes many different kinds but used for demolition and well suited for secondary size reduction and making a 6” minus product Can make a spec subbase on site with a pulverizer. Liberates a lot of the metal. Some pulverizers use magnet

Does the material need to be sized further 3” minus subbase, 1” minus base course etc. On site a portable crusher can be used or an excavator mounted crusher jaw or horizontal impactor Jaws make 1” minus impactors 3” minus

Mobile on site crushers same feed requirements as fixed facility

Fixed facilities use multiple types of crusher and screen combinations can make different products in Anchorage the typical material is a 1” minus RCA that meets the gradations specifications etc. for Base Course.

Whichever method of processing you end up with a lot of rebar.

Processing on site this can become troublesome to handle

Fixed site process rebar down or bale it for recycling

What are uses of RCA. Before recent development of specs by ADOT private use.

Besides use as base or subbase RCA can be used for Gabbion fill material On the left is basket with crushed concrete and the right is alluvial virgin rock

Questions? Shane Durand (907)748-7400 CRS@CRS-Alaska.com A lot of different uses. Depends on source, location, qnty value