Porosity of building materials used in construction

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Porosity of building materials used in construction

Postby RouterAl » 10 months 3 weeks ago (Sat Sep 14, 2019 2:46 am)


This is an interesting video just posted on the porosity of rocks, ( Fluorspar used ) and how much air is present even in something you would not assume to have air spaces within them. One of the lies used to discredit Fred Leuchter and others is that bricks were not porous beyond 1 micron, hence no Prussian Blue formations in the alleged gas chambers etc etc. Any one involved in building or restoration of existing buildings knows that is nonsense, bricks are fully porous as is sandstone and schist's. This video is a great demonstration of the amount of air in all materials, it would be interesting to see it repeated with a brick and a piece of sandstone.
This man has produced many video's on timber framed buildings and how to keep them dry and restore the damage caused by using modern materials in these old buildings. I should emphasise he does not hold revisionist views and I use his video only as an illustration.

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Re: Porosity of building materials used in construction

Postby Lamprecht » 10 months 3 weeks ago (Sat Sep 14, 2019 10:17 am)

From a previous thread: viewtopic.php?t=12720
Lamprecht wrote:From The Rudolf Report:
"DIN 4108, part 3 to 5, deals with diffusion of steam into building materials. The most important coefficient for building materials is the so-called coefficient of diffusion resistance; this is a dimensionless number indicating, how much longer the diffusion of steam takes to penetrate a layer of certain materials compared to the time it takes to diffuse through the same layer of still air. This coefficient is valid not only for water vapor, but also for gaseous hydrogen cyanide as well as for any other gas. In the list of 100 different building materials compiled in DIN 4108 part 4, one can find lime and cement mortar with diffusion resistances from 15 to 35, in which case the resistance grows with increasing cement content, for gypsum plaster, the coefficient is 10, for brick walls 5 to 10, for glass wool mats it is 1. That means, if a gas diffuses through a layer of still air with a speed of 1 cm per second, it does take 15 to 35 seconds to diffuse through a 1 cm thick layer of lime or cement mortar and 5 to 10 seconds to diffuse just as deep into a brick wall. (I am grateful to Mr. C.H. Christmann for this reference.) In this regard, compare also the analysis about the porosity of masonry, graph 7, p. 183."

Graph 7:

And from of your other post in the thread on Myles Power & the Leuchter report (I added the link and indented the quoted portion): viewtopic.php?t=12438
RouterAl wrote:Slightly off subject but I recently read the David Irving's 2000 court case judgment, all of it. That's where I first heard of this nonsense of the human hairs width penetration of HCN vapour's and the attempt to rubbish the Leuchter report. Unfortunately Mr Irving was obviously not an expert on building techniques or perhaps failed to realised the damage that this utter nonsense caused to his and the revisionist case.

Any one involved in the construction industry who does not understand material porosity and water transport by building materials and constructing barriers to water penetration and the drying effects of different mortar types , in the construction of structures using bricks , sand stone, granite , schist stone and concrete is really is a no expert. Any building text book should show up the utter nonsense of the source of this "hairs width" nonsense.

I copied this from a brick manufacturers web site.
Porosity is an important characteristic of brick. In contrast to other moulded or pre-cast building materials, the porosity of brick is attributed to its fine capillaries. By virtue of the capillary effect, the rate of moisture transport in the brick is ten times faster than in other building materials. Moisture is released during day-time and re-absorbed during night-time. The ability to release and re-absorb moisture (a "breathing" process) by capillary effect is one of the most useful properties of brick that helps to regulate the temperature and humidity of atmosphere in a house. This distinctive property makes brick an admirable building material, particularly suitable for houses in the tropics. On the other hand, all porous materials are susceptible to chemical attacks and liable to contamination from weathering agents like rain, running water and polluted air. Porosity of building material is an important factor to consider in respect its performance and applications.

Experiment results show that bricks with water absorption rate at 8% is 10 times more durable in resisting salt attack than that with water absorption rate at 20%. Well burnt brick has a normal water absorption rate less than 10% in contrast to that of concrete block and cement mortar exceeding 15%. This explains why brick walls require comparatively minimum maintenance in the course of time.

To mitigate the adverse effects but at the same time retain the advantages associated with porosity, the rate of water absorption of facing bricks for masonry brickwork should preferable be maintained around 10%.

[ source: https://archive.is/yyptI ]

When you factor in the action of the mortar , which I will assume is lime mortar, which is the best media for ensuring no matter what material it bonds, that water can pass from within the structure to the external air and that penetrating wind driven rain can dry out from inside the structure easily via the mortar capillary action. Even if the building inside walls are plastered , especially with lime based plaster this effect still works, it's why you have dry rooms in buildings , water enters the plaster and gets drawn through the brick work or mortar and then evaporates to the air. It's why Gore-tex works , water vapour passes through the pores of the Teflon material, which is proof against the entry of large water droplets.

That's why the bricks are blue because water vapour and the HCN gas pass out of the brick via the capillary pore based drying process caused by the temperature differences between day and night. The building inside can dry out and external water will not last long in the structure , particularly wind driven rain , the biggest enemy to all buildings . There are libraries full of information on the porosity of building materials, evidently all the people involved in discrediting the work of Leuchter have never worked in construction or construction academia. If you want a simple example next time you see a brick-wall covered in white efflorescences that's the action of capillary porosity moving salts in the building and brick to the surface where it disfigures the brick work.

In that same thread, the cyanide penetration claim is debunked by Germar Rudolf.

Much more can be read in chapter 6 of the Rudolf Report, "Formation and Stability of Iron Blue":
"There is a principal which is a bar against all information, which is proof against all arguments, and which cannot fail to keep a man in everlasting ignorance -- that principal is contempt prior to investigation."
-- Herbert Spencer

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