I am not a materials engineer, but it looks to me that bricks with more than 10% of polyethylene are likely to be flammable in the case of a house fire.
I don’t know whether the Grenfell tower cladding had filler, but it is common for the polyethylene core to be mixed with filler within the cladding to help protect against fire, for example the ALPOLIC A2 product mentioned in [1] has an image showing a table with:
ALPOLIC fr: Combustible ingredients < 30%. < 13 MJ/kg
ALPOLIC A2: Combustible ingredients < 10%. < 3 MJ/kg
And [1] says “Its calorific value is given as something less than 13 MJ/kg, more than four times the value considered to be of ‘limited combustibility’ in the UK”.
Above facts are why I think even a large percentage of sand might still leave flammable bricks (polyethylene is like solid petroleum, until it melts and behaves more like a liquid or wax with a viscosity depending on multiple factors).
[1] http://theriveroflife.com/2018/02/08/grenfell-tower-is-the-c...
You need space shuttle aerogel tiles not paint.
Sand has a lot of thermal mass, so with some insulation against surface fires (PE surface is easy to ignite) - say a proper coat of paint, or maybe some plaster - a lone kindling would not ignite the bricks. A proper fire will, but then you should be running away anyhow.
Still, if I were a firefighter, I would not approve of such building materials, unless the shoddy construction is well known, so noone dares go inside, mainly because it's likely to collapse and turn in to a bunch of hot burning goo. Luckily, they seem to use it for pavement.
again, far before a fire reaches a point where it's widespread the heat of the gasses created by a small fire are already 4x what these bricks can stand before the binder involves melt.
So long before you're worried about thermal mass, there would be nothing holding these bricks together and you have a mass of loose sand and melted plastic.
You could paint it with intumescent paint but I doubt it would be effective given the low melting temperature, and would probably end up costing as much or more as the brick.
If unconvinced, try the same with a piece of old sofa, fake leather or vinyl flooring (with or without paint).
I don't think you're listening to what I'm saying about the common air temperature around small fires (auto-ignition of hot gasses at ~600°C is common) and the melting temperature of the binder in these bricks (150°C max).
It's not about ignition of the PE, its about cohesion of the brick PE binder (and thus the sand) at higher temperatures. Your painting this brick that will lose cohesion will do exactly nothing for the performance of the brick.
I dare you to think about it critically, instead of making useless dares that don't address what the other person is saying.
I mean, yes, it's nowhere near western building codes, and if there is a non-trivial fire, you need to get out, fast. Much faster than with most typical building materials, though the bricks won't come loose instantly, and that has to do with thermal mass, conductivity, temperature and amount of heat.
Note, a match will not do, if painted. A blast furnace will, but I do not see the relevance.
Yes, I may have overestimated how much fire the bricks might survive, in my first comment, but I'm not saying the building would withstand a fire - the main point is, that it's more resistant than EPS cladding, couches and PVC flooring, so not as dangerous as it might seem.
A non-flammable coating would perhaps be a layer of plaster or paint?
I think you are seriously overestimating the flammability of the product. Have you seen rooms with vinyl floors, PVC windows, foam / fake leather couches? Each of those will burn more easily a viciously than the bricks.
My concern would be with possible structural failure at high temperatures and some fires may be able to pass through walls of these bricks. However, I don't think they are building apartment buildings from these bricks.