309 - What a brick

Following on from Essay 283 on concrete, I wondered recently if there is progress in, for example, making a more eco-virtuous brick. The building industry is remarkably conservative, not helped in any way by the reluctance of government to encourage innovation and the slowness of supportive regulation.

We make bricks from clay, which is abundantly available. The clay is shaped and baked in kilns at temperatures from 1000ºC up to 1,250°C. The majority of brick kilns are heated by fossil fuels, which contribute to climate change. [1] The brickworks is usually immediately adjacent to the clay source and transport of bricks to site is an obvious issue. Bricks would be a more sustainable product if we could reuse them, but the process of cleaning, generally done by hand, makes this as yet too labour intensive for anything more than recovering bricks for repair of existing buildings, where the need to match the existing brick makes the recovery worthwhile. We also make bricks from concrete (which I'd generally call blockwork, myself) and calcium silicate, sometimes called sand-lime bricks.¹  

There is a growing range of products that offer themselves as alternatives, but one of the great advantages of bricks are that they are sufficiently ubiquitous that transportation both is and is not an issue. Bricks do need to be transported, but there is probably a supplier not too far away, and quite possibly a brickworks surprisingly close. ²

Map from Brick.org.uk. I took these barcharts from the linked document at [4]. It seems to me that this 2017 report shows we are not far from 2020 compliance, needing around a 5% change, say around 2% per year.  [And 6/10 for the diagram, 8/10 in 2019 reportThe target for 2020 is 706 kWh/t.  We make under 2 billion bricks a year (Statista and [5]) but need quite a bit more, perhaps by 20%. So there is scope to develop and include alternatives. Clay bricks last about 150 years but we must explore ways to recycle brick successfully. Clay is a resource we are not able to renew so we should be looking at alternatives. The BDA [5] talks about sustainable manufacturing, but I didn't find content explaining the availability of future sources of suitable clay.

Properties required of substitute materials need to match the thermal mass, acoustic insulation, durability, non-combustibility, lack of maintenance, resilience to flooding, perhaps also adaptability. ³ 

Some materials are available from recycling, which seems immediately attractive. Fly ash and Bottom ash (FA, from coal combustion and BA, from waste incinerators) are mixed with concrete to make bricks. The mix is determined by the required compressive strength for the resulting brick. The obvious advantage is that this diverts what would otherwise be a non-trivial volume of waste material from being dumped. Similarly, recycled aggregates can be used; additional work here is the crushing of the recovered stonework and, not unlike the recycled plastic problems, the quality of recyclate is a crucial factor. Sea sand is another possibility; in Britain the determination to not have salt in concrete serves as a disincentive. That's my salty comment, unsubstantiated.


But these suggestions go no further than the essay on concrete and I want very much more than that. I'd like to discuss products that are not forms of concrete with substitutes for the clinker part.

Source [1] discusses Kenoteq K-Briqs, which is construction and demolition waste including bricks, gravel, sand and plasterboard is crushed and mixed with water and a binder. The bricks are then pressed in customized molds. Tinted with recycled pigments, they can be made in any color. Spellings; this from CNN. So what is the binder, if it isn't concrete? K-Briqs claim 10% of the energy and CO₂ of conventional (UK) bricks. Zero waste is claimed; this is not true, since the BDA includes the mortar in their waste calculations, though Kenoteq could make bricks in shapes that might not need mortar.

Source [8] describes a zero-waste building material made with human urine, which hardens at room temperature, as an alternative to environmentally taxing kiln-fired bricks.  .... Human urine, loose sand and a bacteria that produces the enzyme urease are combined in a brick-shaped mould. The urease triggers a chemical reaction, breaking down the urea in urine, while producing calcium carbonate — aka limestone, the main component of cement. This solidifies the bricks, and the longer they're left in their moulds, the stronger they get.  "Made with urine" means urine is but one component; with, not from. Urine does not harden at room temperature; medicine—and human biology—would be quite different if it did.

Source [3] describes Polycare's  Polymer concrete is a fairly impenetrable material designed for long term use. It is: 3-5 times stronger than ordinary concrete; 6 times more resistant and completely waterproof; Impervious to grease, acid and frost; Can be shaped in ways that do not need cementing together. [3]
I think this suggests that with a little ingenuity, we could do construction with material very close by supplemented with surprisingly little in terms of structure and binding element, but this product is more nearly concrete than brickwork.

Source [14] looks at alternative bricks with additives organic (ABO) and inorganic (ABI). If your chief concern is to replace the firing process, look instead for stabilisation, and you may well find reports from France and Belgium. It seems to me that the attraction here is to divert waste material—of any description, including plastic waste— into construction volume. Provided this is non-toxic, meaning not a bio-hazard in any way, this is good use and to be encouraged at a national level, with the objective of sustainable development. There is quite clearly room for a lot more development and that this needs to be encouraged at a state level, for otherwise there is little incentive to invest. It seems to me that the energy demands alone are enough to provide incentive to explore rapidly. The drag against this progress—in Britain certainly—is our extraordinary conservatism, made obvious by a long-lasting preference for brickwork, confirmed every time a building changes hands. If you want a list of the materials that have been tested and reported on, this, [14], is the best I have found yet.

What we need right now is a way of making bricks form waste plastics, enough to cause 'mining' of plastics.

Looking to see if anyone has announced any progress on using plastic waste to make a brick equivalent, I came across [15] a report of an Ivory Coast use of bricks based on plastic waste (but the bricks were moulded in Colombia, which doesn't strike me as clever). Fundamentally, the plastic waste is melted and poured into man-sized Lego bricks. The result is lighter, cheaper and will last longer than conventional bricks. Obviously waterproof, I wonder how they perform under load.

If we take plastic (presumably sorted and perhaps cleaned to an extent) and then shred it into small enough pieces, these can be fused together with sufficient heat. [17] describes one such, where the heat is superheated water (and so under compression). Simply pressing the softened material into shape while hot and fluid is sufficient. Like the K-Briqs at [1], these need stiffening from something like rebar, but in the same way do not need a mortar equivalent. These will make good wall filler, but will not be structural; sound and thermal insulation very good. Look up ByBlocks and RePlast. I can see them simply replacing blockwork used non-structurally.

Even closer to adult Lego is [18], shown here. This is a 3D printed brick made from plastic waste. Extremely good thermally (clay brick, around 3W/m²K; this brick, 0.25W/m²K). What was not explained was how much work went into the plastic before it could go through a printer. I suspect that there is a lot of quality control required. Again, I found nothing indicating it would act as a structural component, so one would be looking for timber, steel, concrete and the like for the structural components and using these plastic-based bricks as infill.


In Australia [19] a rubber polymer made from sulfur and canola oil, can be compressed and heated with fillers to create construction materials. The article suggests that green' types of bricks and construction materials could be made from recycled PVC, waste plant fibres or sand. [19] is dated May 2020, so we will need to wait to see if this progresses.


Having cycled through the hunting process, it is clear that we could quite easily replace non-structural blockwork with materials largely made from waste we need to get rid of. The plastic wastes won't form high quality structural material but will perform well as insulation. The inorganic wastes will do that once we find a suitable binder and the challenge then is to find ways to do this in ways that consume considerably less energy than is required by a brickworks. Certainly, we could repurpose current brickwork designs to accommodate different materials. The disincentive to using current brickworks is the transport of material to the works, which is only worthwhile if this transport is replacing some other movement such as to landfill. 

We need political encouragement (some of that nudging discussed in essay 302) to fund the exploration and then to permit the experimentation of these alternative materials. I think that would be better action than abandoning good regulation (such as green belts, ludicrous when we have so much brown belt space available). If we were to solve our British plastic waste problem, that just on its own would be a wonderful piece of progress.


DJS 20200716

top pic from BDA

   ⁴  ⁵  ⁶  ⁷  ⁸  ⁹ footnote spares

1 sand-lime bricks are extensively used by contractors in industrialised countries such as Europe, Russia, Australia and United States, the main reason is because the suitable siliceous sands are more readily available compare to clay in their country, in fact it has been broadly manufactured and produces in United States in the early year of 1900s. [7]

2 For example Lancashire has three brickworks in operation, at Accrington, Claughton and Hesketh (I think; I didn't find a confirmation of this).

3 My house is approaching the upper age limit for bricks and I've owned older. The Brick Development Association, BDA, declares brickwork to be maintenance free. I disagree, for the pointing needs renewing, perhaps every 50 years, certainly every 100 years. I have seen building where the bricks are decaying and I hope we have improved manufacture across the centuries so that we can rely upon bricks lasting a good deal longer. We have grown a habit of using blockwork in association with brick, which is a sort of blown concrete; lighter, larger and so quicker to erect, similarly strong but not quite so weather proof or pretty, which is why we use blockwork for the inner leaf of combination construction, these days with further insulation in the sandwich.

The 2019 report is much better written than the 2017 report.


[1] https://edition.cnn.com/style/article/going-green-kbriq-sustainable-brick-spc-intl/index.html   https://www.dezeen.com/2020/03/02/kenoteq-k-briq-brick-construction-waste/

[2] https://www.youtube.com/watch?v=GEvoXuFKSA0

[3] https://biomarketinsights.com/how-could-a-sustainable-alternative-to-bricks-revolutionise-the-construction-world/

[4] https://www.brick.org.uk/about/our-members,  https://www.brick.org.uk/admin/resources/2018-bsr.pdf

[5] https://www.brick.org.uk/admin/resources/brick-sustainability-report-2016-1.pdf  Well worth a read, but I thought it could be a far more adventurous document; it read to me as if produced with a modicum of reluctance, "We've got to do this".

[6] https://www.brick.org.uk/admin/resources/2019-bsr.pdf

[7] https://www.ukessays.com/essays/construction/alternative-recycling-materials-for-bricks-production-construction-essay.php A good overview of bricks.  Essays, UK. (November 2018). Alternative Recycling Materials For Bricks Production Construction Essay. Retrieved from https://www.ukessays.com/essays/construction/alternative-recycling-materials-for-bricks-production-construction-essay.php?vref=1

[8] https://www.dezeen.com/2018/11/06/bio-bricks-human-urine-environmentally-friendly-university-cape-town/

[9] https://www.enviromate.co.uk/blog/eleven-green-building-materials-way-better-concrete a collection of extreme samples also 

[10] https://www.quora.com/What-are-the-substitute-of-bricks-that-can-be-used-in-construction Better than you might expect, with pictures.

[11] https://biomarketinsights.com/how-could-a-sustainable-alternative-to-bricks-revolutionise-the-construction-world/

[12] https://poly-care.de/en/polycare-en Really light on detail, I thought. 

[13]  https://www.youtube.com/watch?v=XfcbtZcpWrA How to Make Mud Bricks

[14] https://www.sciencedirect.com/science/article/pii/S0195925519301374  

Very good, in that it supplies many possible alternative materials, if a bit dry and heavy in jargon – probably an insider's paper. For example, cradle to gate and cradle to grave as applied to a brick equivalent: these two diagrams shows cradle to grave—the complete life cycle for traditional bricks (TB, top) and Alternative bricks. Cradle to gate means that the study of the partial product life cycle of the alternative bricks often ends at the gate, meaning the factory gate. This is a regulatory matter related to environmental product declarations. 

Similarly LCA is Life Cycle Assessment, which come in five stages: materials extraction, processing and manufacturing, product use, and product disposal. Wiki. Of course, [14] has a proper reference list.

[15] https://www.plasticstoday.com/recycling/bricks-made-plastic-waste-build-much-needed-classrooms-west-africa

[16] https://www.citymetric.com/skylines/9-building-materials-made-entirely-waste-products-932  I loved the idea that we make bottles so that they will tessellate (Brit spelling) so they can later be used; again, not load bearing. Also the idea that plastic grains replace the sand equivalent in concrete and asphalt (hence plasphalt).

[17] https://www.expertskiphire.co.uk/plastic-bricks   and  https://www.designindaba.com/articles/creative-work/eco-friendly-construction-blocks-made-plastic-waste and https://www.plasticstoday.com/recycling/byfusion-promises-reduce-plastic-ocean-making-building-blocks

[18] https://www.pbctoday.co.uk/news/construction-technology-news/plastic-waste-bricks/68131/

[19] https://www.sciencedaily.com/releases/2020/05/200526111255.htm


https://www.youtube.com/watch?v=H8efNdG7au4   on the use of hempcrete and lime. Very much carbon negative, so a house can quite easily be carbon neutral when conplete. Unbelievably fireproof.  Search hempcrete on youtube for other demo videos.




Related pages

242 - Plastic Waste Revisited

283 - C0₂, Cement and Concrete 



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