Transortprocesser och Reaktioner i Belagda Betonggolv - Olika faktorers inverkan på emission från golvkonstruktioner

Licentiate thesis, 1999

The objective has been to increase the knowledge on one of the sources of
hydrocarbons (VOCs) in indoor air: combinations of PVC-sheets and adhesives
on concrete floor slabs. The studies included investigations of four parameters:
surface moisture, distribution of alkali, hydrocarbons in concrete and emissions of hydrocarbons.
Where measuring methods were lacking, new methods were developed.
A small number of materials were part of a standard systems that
were the base for the development of a model. These systems included various
PVC-sheets and linoleum flooring, with and without adhesives. A limited
number of water-borne adhesives and concretes with different properties was
used. In a few cases levelling compounds were used in-between the flooring
material and the concrete floor.
Decisive reactants are alkaline moisture and an alkali-sensitive organic material.
The critical limit is between pH 11 and 13. When applying a water-borne
adhesive the concrete surface receives a small contribution of moisture that
increases the RH some 10 % at the surface. With a new measuring method this
distribution of moisture could be measured close to the surface. The results from
the investigations of the distributions of alkali showed a rise in alkali content
close to the concrete surface due to the drying process.
The hydrocarbons penetrate deep into the concrete floor slab and remains there
for a long time. Different hydrocarbons penetrate differently during a certain
time. The course of emissions is also different for different hydrocarbons. Some
are emitted earlier than others, probably because the flooring material has
different tightness for different hydrocarbons.
Levelling compounds and linoleum flooring are two examples of products that
give low rates of emission. Two other important parameters are the drying time
for the concrete floor slab and the waiting-period when applying a water-borne
adhesive.
A qualitative model containing all relevant processes has been established based
on a physical understanding of the processes that interact in various
combinations of flooring materials on concrete. The model is able to describe the
performance of a number of applications: normal concrete floors and self-
desiccating concrete floors, with and without levelling compounds.