Cross Laminated Timber - Concrete replacement

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peakbagger

Minister of Fire
Jul 11, 2008
8,697
Northern NH
Interesting article (No doubt sponsored by a Cross Laminated Timber Development Council)

https://www.archdaily.com/922980/is-cross-laminated-timber-clt-the-concrete-of-the-future

One of the big world wide carbon emitters is making the cement that goes into concrete. In order to make the cement it needs to be calcined. That takes a lot of energy as it needs 2700 deg F and also puts out a lot of CO2 not including the fuel used to heat it up that high.To date I think most carbon trading programs conveniently ignore concrete despite if being a major CO2 source. The Europeans have really been pushing CLT and other earlier wood systems to replace concrete and sequester carbon (for as long as the building lasts.

Structurally CLT makes a lot of sense but not so sure on building entire walls out of it. It looks to me like a major waste of wood unless the structure demands it. It also shifts local labor to a remote factory. I am aware of several attempts to build a CLT plant in Maine over the years and it has typically been chicken and egg situation when some entity wants a pile of subsidies to build a plant and hope the market then builds up fast enough to pay the bills. There was earlier version laminated hardwood beam plant that was actually built in Orono Maine, with lots of subsidies, that was around a couple of years until the economics drove them out of business. Everything I have read to date is CLT is fundamentally dependent on someone paying a subsidy for the structure to use CLT or a client decision that CLT is going to be used for other than economic reasons.

The other driver is Europe has shifted the vast majority of there forests to mechanized tree farms. Usually fast growing monocultures that have never seen a chainsaw. That yields a lot of fast growing wood with low ring count that tends to need laminating to deal with shrinkage and warpage. CLT can use up a higher percentage of the tree than regular boards and timber.

BTW, the glues used usually relegates these products to the solid waste landfill instead of the fuel pile. I have talked to folks who have burned structural laminated timber (looks like really thick plywood and they said it burned quite well and lot longer than they expected. They were not particularly worried about the emissions.
 
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