Research work on outside sprayed-on cellulose insulation covered with plastering

Status

finished

Summary

The sustainable use of resources in common is probably the most difficult challenge mankind has to face in future. Containment of global warming and the reduction of CO2 emission is one of the aims to go for in this concern. From this point of view research work on new and more effective ways of thermal insulation application are highly focusing on an up to date problem. At the present in Austria cellulose insulation materials are mainly used in wooden framework wall-constructions. They are commonly blown into residential attic and wall cavities providing a seamless blanket for thermal insulation.

This research work was done to expand knowledge about outside sprayed-on cellulose insulation application focusing on mechanical and physical properties respectively. The basic investigation has shown that only very little systematic research work has been done on sprayed-on insulation layers so far. Most of the research and development work was done in the United Sates and Finland caused by the long tradition of using cellulose for insulation matters in these countries.

Various spraying equipment was used for applying cellulose layers onto brick walls. These spraying experiments indicated that the general performance of the widespread common spraying methods or techniques is rather poor as far as achievable shear stress parameters are concerned. In the testing also glue or bonding agents were used to improve the mechanical properties. Different sorts of problems occurred during the spraying experiments. The most difficult problem was to mix water or bounding agents homogeneously with cellulose in the spraying process. Several adaptations and improvements of the used equipment were necessary to improve the spraying process to an acceptable standard. Material tests were performed using a tensile testing machine to gain mechanical parameters of spray-applied cellulose insulation layers. The involved parameters were shear stress, tensile resistance (in as well as normal to layer direction) compression strength and thermal conductivity. The different investigated probes had densities between 70 to 150 kg/m3. Just after the spraying the water content of the cellulose layers was mostly between 60 - 75 %. For the comparison of various binders (mineral and organic binders in different concentrations) a number of 17 sprayed-on probes were involved in a tensile resistance measurement sequence. The results indicate clearly that tensile resistance of binder reinforced spray-applied cellulose insulation can achieve and even overtop threshold values required for mineral-wool insulation boards (MW-PT). If a more homogeneous mixture between binding and cellulose can be achieved the properties may even be increased distinctly.

Finally sprayed-on cellulose insulations were covered with different sorts of plastering. The basic experiments have proved that plastering can directly be applied on top of binder reinforced cellulose layers. Additionally pull-off experiments were performed to gain information concerning resistance and strengths of the complete insulation system (wall - cellulose insulation - plastering). The results indicate that more comprehensive testing is required to gain reliable and clear data. In the future further research work in this field should be done in order to expand and to improve the state of the art of spray-applied cellulose insulation.

Contact

Dipl.-Ing. Michael Mandl
Regionale Innovations- und Forschungsstelle Hartberg, JOANNEUM RESEARCH
Am Oekopark 7
A 8230 Hartberg
Tel.: +43 (0)3332 65085
Fax: +43 (0)3332 65085-2955
E-Mail: michael.mandl@joanneum.at