Why are we still having problems with moisture and concrete floor slabs?

(after Howard Kanare)

Water is an essential ingredient in concrete, but uncontrolled excessive moisture can create a whole host of problems with concrete floor slabs. Some of the modes of distress include:

· Adhesive breakdown of adhered finish floor coverings

· Debonding of coatings

· Osmotic blisters of epoxy systems including coatings and epoxy terrazzo

· High pH (alkalai) attack of floor finishes

· Microbial growths

· Flooring expansion, such as cupping of wood strips or planks

· Reactions between incompatible floor patching/ leveling materials.

Despite the development of many excellent, longstanding practices, there are still a large number of moisture-related problems. Some contributing factors include: design professionals specify a blotter/ cushion/ subbase layer over a vapour retarder; vapor retarders are not carefully protected during construction; concrete floor slab mixes often are made with smaller than desirable aggregate and mixes are not optimized for minimum shrinkage; inappropriate moisture tests still are specified; moisture resting is not always done correctly; some unreasonably moisture-sensitive adhesives are still on the market; there is no performance specification or test method for moisture resistance of adhesives or floor coatings; and failures of some moisture-suppression products occur because there are no performance specifications for moisture suppression products.

(CONCRETE CONSTRUCION, November 15, 2007)

b) Find additional information on distresses listed and speculate on the remediation. Use the linking words/phrases from Appendix 1:

21 Read the information below and discuss it with your partner:

BAMBOO FLOORING

There are many types of flooring available for people to choose from when they’re considering redoing their floors. Some of the more popular flooring options include carpeting, tiles, laminate, or traditional hardwood. Most professionals agree that bamboo flooring is some of the best flooring out there.

Bamboo is an incredibly strong wood. It is naturally tough when it grows wild no matter what soil it is grown in. The fact that the bamboo always undergoes further strengthening usually in a company's factory before it is shipped out to be used as flooring ensures that you have a very strong, durable wood. It is even stronger than oak.

Bamboo is technically a grass and grows extremely quickly compared to any other type of wood. In fact, it takes a bamboo tree only 3 years to reach full maturity while with most other trees, it is twice as or three times as long. It means that bamboo can be replaced much more easily, making its use better for the environment.

Unfortunately, there are currently no official certification standards for bamboo flooring. That means that quality or hardness of the bamboo flooring can actually vary, depending on the producing company.

Bamboo floors can be easy to scratch or dent if they are damaged by heavy furniture that is moved or jolted. Many people with rowdy children choose not to get bamboo flooring because children tend to be hard on floors.

Under direct sunlight, bamboo loses its colour easily especially if it is in naturally-lit rooms. That means it is better to use it in darker rooms where direct exposure to sunlight is kept at a minimum, which may not be an option for some people.

22 Topics for projects and presentations:

1. Types of subfloor construction.

2. Floating floor.

3. Floor vibration.

4. Underfloor heating.

5. Modern tendency: glass floor.

APPENDIX 1

COMMUNICATION CLICHÉS

Introducing the topic I’d like to outline… I’m going to tell you…		Asking for clarification Are you saying that…? I’m not sure I understand. Can you explain it a bit more clearly? I don’t understand what you are driving at, can you say it another way? Would you please clarify your last statement? What exactly do you mean?
Presenting an opinion It seems to me (that…) There is no doubt that… It strikes me that …	Clarifying/rephrasing In other words... To put it another way… In particular…
Giving an opinion I really think we need… There is no doubt that… I feel… is the best way to… Shouldn’t we have more information?	Making contrasting points However… Nevertheless….
Agreeing I agree entirely. I take your point. I think so too. I have the same opinion about … You are absolutely right.	Interrupting Can I just say something here? Hang on.
Disagreeing I can’t accept that. (I’m afraid)I disagree entirely. Point taken, but surely … is an important factor? I really can’t agree with you here.	Resisting interruption No, let me finish, please. Can I finish the point? Just a moment, please.
Making general statements In general… On the whole…	Giving examples For instance For example In particular
Asking for reaction How do you feel about? What do you think?	Speeding up I think we should move on now. Can we come back to that?
Keeping to the point I’m not sure that’s relevant. Perhaps we could get back to the point. Let’s leave that aside for a moment.	Slowing down Hold on, we need to look at this in more detail. I think we should discuss this a bit more.