Chemical Diffusion Through Concrete_822

8/6/2019 Chemical Diffusion Through Concrete_822

1/10

CHEMICAL DIFFUSION THROUGH

CONCRETE

A Study Showing That Concrete Is Highly

Porous, Allowing the Penetration and

Diffusion of Chemicals

by Murray Thompson (BAppSci Environmental

Health 1998, University of Western Sydney,

Hawkesbury)

June 2004

[email protected]

Preamble

This study has been created in order to demonstrate

clearly that available and reputable scientific studies and

industry experience highlight the fact that concrete slabsupon which residences are situated are extremely

porous, and to the extent that almost any chemical

situated under or next to the slab will be absorbed by the

slab.

I have produced this study to specifically emphasize that

it is much more than probable that the synthetic

pyrethroid termiticide that was applied around, and

immediately next to, the concrete slab under my

Department of Housing (DOH) unit located at Unit 15, 30

Sirius Road BLIGH PARK NSW 2756, on the 7 th December

2000, diffused through that slab and outgassed into my

unit as vapor for at least 1 years after application,
mailto:[email protected]:[email protected]


2/10

Murray Thompson August 2004 CHEMICAL DIFFUSION

THROUGH CONCRETE_822.doc

resulting in the production of a series of extremely

distressing poisoning symptoms over that period of time

and beyond in both myself and my child, and also in my

neighbour (whose unit shares the same concrete slab as

mine).

Discussion

1. First, what is concrete?

Concrete is a heterogeneous material constituted of a rigid skeleton with sand

and aggregates embedded into a porous hydraulic binder. A hydraulic binder

as Portland cement is a finely ground material which is first in a plastic and

workable state on mixing with water and then reacts with water to form

hydrates responsible for the rigidity. The concrete behavior is linked to the

evolution of the cementitious matrix which can be considered as permanently

aging material. Concrete is therefore the site of chemical, mechanical and

physical events like hydration, moisture transfer or shrinkage that can cause

premature cracking before any external loading occurs (Lamour, Haouas &

Moranville [online]).

Also:

Concrete is a porous material. Therefore, moisture movement can occur by

flow, diffusion, or sorption (Advanced Cement Technologies [online]).

Concrete structures are thus highlighted as porous,

ageing, and the site of mechanical and chemical events .

2. How open or consistently spread are the

pores or spaces inside concrete, and do these

pores affect the concrete in any way?

Concrete contains two types of pore: capillary and gel pores.

2


3/10



Capillary pores (approx) 1,3 um in size are the largest and form an

interconnected system, randomly distributed throughout the binder, which

provides a fairly direct path for aggressive ions. Gel pores on the other hand

comprise some 28% of the gel, but are much smaller than capillary pores,

and do not play a significant role in the permeability of the paste. However,

they do have an impact on time dependent movements in concrete, such as

shrinkage and creep (Eagle Cement (Natal Portland Cement) [online]).

Also:The presence of capillary pores and air voids influence concrete permeability

to a large extent. The ingress of aggressive agents into the pore structure is

responsible for various durability problems in concrete structure. The

deterioration of concrete in a structure is a result of several degradation

mechanisms that caused a decreased in the integrity of the structure. The

state of deterioration is often invisible and is only evident when there is a

significant reduction in the load carrying capacity ( Sutan, Hamdan and

Jin, 2002 [online] ).

So, concrete, by its very nature, is porous. As well,

concrete may then deteriorate with chemical reactions

of unhydrated cement and water, C 3 A and chloride ions,

carbonic ions and calcium silicate hydrates (Watanabe

[online]).

Further: Slab failures from caustic attack, in particular,

can reduce the service life of slabs down to as little as

five years, with most slabs providing an average life of only ten years, even though some predict a service life of

40 years with the application of current best practice

(CSIRO 2001 [online]).

There exist products designed specifically to take

advantage of the porosity of concrete. One such product

is named Xypex, which is designed to penetrate and

3


4/10



react with the mineral constituents of cement-based

materials. It can be applied on concrete, concrete-block,

cement stucco or the mortar between bricks (Xypex

Chemical Corporation 2002a [online]).

What is Xypex?

XYPEX is a non-toxic, chemical treatment for waterproofing, repair and

protection of concrete from a range of aggressive media, uniquely generating

a non-soluble crystalline formation deep within the pores and capillary tracts

of concrete (Xypex Chemical Corporation 2002b [online]).

Xypex is therefore designed to penetrate concrete in

order to prevent the concrete from allowing such

penetration of fluids .

3. By what process does Xypex penetrate

concrete?

Why must the concrete be wet prior to a XYPEX application?

The active ingredients in XYPEX penetrate the concrete by a process of

chemical diffusion in which chemicals in a highly concentrated solution (the

XYPEX slurry mixture) will spread through a solution of lower density (water

in the pores and capillaries of the concrete) until the two are equalized (Xypex

Chemical Corporation 2002a [online]).

The above quote implies that water may be found inside

a concrete slab, and that this water offers a transmission

route for chemicals to move via the agency of chemical

diffusion . Note:

Baroghel-Bouny (1994) among others showed that water transport occurs in

porous cementitious materials through different modes: vapor diffusion, liquid

4


5/10


6/10



coating (and to a lesser extent a sealer) greatly reduces diffusion and is a

primary defence against durability problems.

* Vapour moves by diffusion as mentioned above. Even seemingly dry

concrete may have significant vapour flow by diffusion" (McGrath 2000

[online]).

It is therefore clear that chemicals can be transported

through concrete in either a liquid or vapor form .

4. Can pesticide, specifically, enter a

residence via a concrete slab?

Pores in concrete naturally draw in water from the surrounding soil by

capillary action, just like a wick. The moisture usually evaporates as invisible

dampness, while it releases dissolved contaminants, such as minerals and

radon. The average basement absorbs 18 gallons of water each day.

Soil gas, rich in moisture, pesticide, radon and biological decomposition

gases, collects in the gravel and disturbed soil around foundations, and is

drawn into homes by the lower air pressure indoors through openings and

pores in concrete.

Pesticide moisture flow upwards through the concrete slabs by vapor diffusion

and capillary transmission passes through the top surface of the concrete

slabs as well as through floor surface treatments (carpet, tile, wood floors)

and leads to un-healthy contamination problems.

Today's almost airtight buildings let in little fresh air and draw from the ground

more "soil gas", rich in moisture and vapors from pesticides below ground.

Pores in concrete draw in water by capillary action. The average (slab) lets in

over (10) gallons of water each day, several times more than showering and

cooking combined! (Healthy Home Association 2003 [online]).

So readily does the building industry accept that

pesticides can penetrate concrete slabs, that the product

features brochure entitled: Underseal TM XT 750 Positive

Side Vertical Waterproofing Membrane with Built-in

Protection Board , lists its products property, test

6


7/10



method, and results (English and Metric) as:

Resistance to Penetration by Pesticides , ASTM

F- 2130 percentage of penetration , and 0.0 %

0.0% , respectively (Polyguard Products Inc. 2003

[online]) (my emphasis).

If cautions regarding the use of mildewcides in buildings

are advocated in United States product literature, then

why are they not advocated by government

bureaucracies that deal directly and intimately withdwellings and tenants, such as the DOH in Australia?

Where does the DOH tenant fit into what should be an

ethical discussion in terms of chemical applications in

and around a tenants home? Are they worthy of

consultation at all, especially, as in my case, I had

already made it patently obvious to the DOH prior to

moving into my DOH unit that I suffered from chemical

sensitive asthma? Note:

Safe Encasement Systems believes that the use of a coating that contains a

potentially harmful or poisonous substance such as an EPA-registered

pesticide (mildewcide) is a step that should be taken only after extensive

consideration and discussion with all parties involved (Safe Encasement

Systems Midwest 2001).

Concrete slabs are well known to soak up water and

chemicals from their surrounds readily.

5. Can organic chemicals enter a residence

any other way?

Recent investigations have found that organic chemicals may contaminate

drinking water by permeating buried plastic pipes and gasket materials...

7


8/10



Many lipophilic compounds tested were found to permeate to a detectable

level in consumers tap water within a month at one third of their aqueous

solubilities. It was also found that PB [polybutylene] was more permeable

than low-density polyethylene to toluene and that chlorinated hydrocarbons

permeated PB faster than unchlorinated hydrocarbons. Gasoline

compositions such as benzene, toluene, ethyl benzene, and xylenes

appeared to be highly permeable to PB and gasket material (Park, Bontoux,

Holsen, Jenkins & Selleck 1991).

The Pesticides Act (1999) obviously needs a significant

overhaul in order for it to take into account the duel

imperatives of the concept of Chemical Trespass andbasic human rights (the right to be notified of a chemical

application). This is, in fact, currently a task being

undertaken by the Australian Chemical Trauma Alliance

(ACTA) in South Australia, which is making a submission

to the DEC (old EPA) in respect to prior notification rights

for pesticide applications under the NSW Pesticide Act

(Personal email, Mr. Don Want, 16 th May 2004).

As well, given that the reliability of concrete slabs is

essentially an unknown factor when chemical pesticide

barriers are applied around a residence, building codes

also need to be seriously addressed. Slab integrity needs

to be tested for porosity before any decision to introducea toxic nerve agent to a human habitation is made.

REFERENCES

Advanced Cement Technologies [online], Technical Bulletin 10.106 CONCRETE PERMEABILITY High Reactivity Metakaolin (HRM) Engineered Mineral Admixturefor Use With Portland Cement , http://metakaolin.com/member/10.106%20Concrete%20Permeability.htm , accessed: July 04, 2004)

8
http://metakaolin.com/member/10.106%20Concrete%20Permeability.htmhttp://metakaolin.com/member/10.106%20Concrete%20Permeability.htmhttp://metakaolin.com/member/10.106%20Concrete%20Permeability.htmhttp://metakaolin.com/member/10.106%20Concrete%20Permeability.htm


9/10



Baroghel-Bouny V. (1994), Caractrisation microstructurale et hydrique des ptes deciment et des btons ordinaires et trs hautes performances, Ph. D. thesis, EcoleNationale des Ponts et Chausses, LCPC Paris, pp. 467.

CSIRO 2001 [online], New Solution to Costly Alumina Industry

Concrete Failure, http://www.cmit.csiro.au/innovation/2001-08/concrete.htm , accessed: July 27, 2004.

Eagle Cement (Natal Portland Cement) [online], ConcreteDurability , http://www.npc-eagle.co.za/site/awdep.asp?dealer=5011&depnum=2145 , accessed: June 26, 2004)

Healthy Home Association 2003 [online],http://www.healthyhomeassociation.com/1/hhmoisture.htm ,accessed: June 25, 2004.

Lamour, V., Haouas, A. & Moranville, M. [online], Chemo-hydro-mechanical behavior of concrete at early ages, LMT Cachan 61,Avenue du Pdt Wilson 94235 Cachan Cedex France, http://arw-bled2004.scix.net/Files/acceptedpapers/Accepted/NATOVL.pdf ,accessed: June 25, 2004.

McGrath, Patrick F. Ph.D., 2000 [online], Water Permeability vsWaterproof -- ASCE Met Section Construction Group, Cooper UnionStudent Chapter, May 25, 2000 ,Xypex Chemical Corporation, Richmond, B.C., Canada; 45 UnionRoad, PO BOX 255 Lavington NSW 2641, Australia,http://www.xypex.com.au/support/papers/200211121471.htm ,

accessed: May 15, 2004.Park, J.K., Bontoux, L., Holsen, T.M., Jenkins, D. and Selleck, R.E.1991 [online], Permeation of Polybutylene Pipe and Gasket Materialby Organic Chemicals, Journal of the American Water Works

Association (October), AWWA Bookstore Download Center,http://www.techstreet.com/cgi-bin/detail?product_id=883493 ),accessed: June 2004.

Safe Encasement Systems Midwest 2001, Technical Bulletin No. 01-5 December 2001; revised June 5, 2003, Encasement For Mold AndMildew Situations, http://www.safeencasement.com/articles/MOLD%20and%20COATINGS-TB-01-5-Rev.6.pdf , accessed: June 26, 2004.

Sutan, N. Mohamed, Hamdan, S. and Jin, E.C.C., 2002 [online],Faculty of Engineering, Universiti Malaysia Sarawak, 94300 KotaSamarahan, Sarawak, Malaysia,http://www.ndt.net/article/v07n11/sutan2/sutan2.htm , accessed:

July 04, 2004)

Polyguard Products Inc. [online] 2003,http://www.polyguardproducts.com/products/architectural/datasheets/750.pdf , Underseal TM XT 750 Positive Side Vertical WaterproofingMembrane with Built-in Protection Board , Ennis, TX, 75120-0755,accessed: June 25, 2004.

9
http://www.cmit.csiro.au/innovation/2001-08/concrete.htmhttp://www.cmit.csiro.au/innovation/2001-08/concrete.htmhttp://www.npc-eagle.co.za/site/awdep.asp?dealer=5011&depnum=2145http://www.npc-eagle.co.za/site/awdep.asp?dealer=5011&depnum=2145http://www.healthyhomeassociation.com/1/hhmoisture.htmhttp://arw-bled2004.scix.net/Files/acceptedpapers/Accepted/NATOVL.pdfhttp://arw-bled2004.scix.net/Files/acceptedpapers/Accepted/NATOVL.pdfhttp://www.xypex.com.au/support/papers/200211121471.htmhttp://www.techstreet.com/cgi-bin/detail?product_id=883493http://www.safeencasement.com/articles/MOLD%20and%20COATINGS-TB-01-5-Rev.6.pdfhttp://www.safeencasement.com/articles/MOLD%20and%20COATINGS-TB-01-5-Rev.6.pdfhttp://www.ndt.net/article/v07n11/sutan2/sutan2.htmhttp://www.polyguardproducts.com/products/architectural/datasheets/750.pdfhttp://www.polyguardproducts.com/products/architectural/datasheets/750.pdfhttp://www.cmit.csiro.au/innovation/2001-08/concrete.htmhttp://www.cmit.csiro.au/innovation/2001-08/concrete.htmhttp://www.npc-eagle.co.za/site/awdep.asp?dealer=5011&depnum=2145http://www.npc-eagle.co.za/site/awdep.asp?dealer=5011&depnum=2145http://www.healthyhomeassociation.com/1/hhmoisture.htmhttp://arw-bled2004.scix.net/Files/acceptedpapers/Accepted/NATOVL.pdfhttp://arw-bled2004.scix.net/Files/acceptedpapers/Accepted/NATOVL.pdfhttp://www.xypex.com.au/support/papers/200211121471.htmhttp://www.techstreet.com/cgi-bin/detail?product_id=883493http://www.safeencasement.com/articles/MOLD%20and%20COATINGS-TB-01-5-Rev.6.pdfhttp://www.safeencasement.com/articles/MOLD%20and%20COATINGS-TB-01-5-Rev.6.pdfhttp://www.ndt.net/article/v07n11/sutan2/sutan2.htmhttp://www.polyguardproducts.com/products/architectural/datasheets/750.pdfhttp://www.polyguardproducts.com/products/architectural/datasheets/750.pdf


10/10



Watanabe, GENERAL STRATEGIES FOR PREDICTING PHYSICALDURABILITY OF BUILDING AND BUILDING COMPONENTS , K. BuildingResearch Institute, Tsukuba, Japan,http://www.cmit.csiro.au/research/special/se_asia/harm_conf1/paper

_watanabe.pdf , accessed: July 27, 2004.

Xypex Chemical Corporation 2002a [online], Frequently Asked Questions , http://www.hi-dry.com/faq/ , accessed: June 19, 2004.

Xypex Chemical Corporation 2002b [online], (http://www.xypex.com.au/ ,accessed: June 25, 2004)

* * *

10
http://www.cmit.csiro.au/research/special/se_asia/harm_conf1/paper_watanabe.pdfhttp://www.cmit.csiro.au/research/special/se_asia/harm_conf1/paper_watanabe.pdfhttp://www.hi-dry.com/faq/http://www.xypex.com.au/http://www.cmit.csiro.au/research/special/se_asia/harm_conf1/paper_watanabe.pdfhttp://www.cmit.csiro.au/research/special/se_asia/harm_conf1/paper_watanabe.pdfhttp://www.hi-dry.com/faq/http://www.xypex.com.au/

Documents

Chemical Diffusion Through Concrete_822