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The development of a single pan-European freeze / thaw test for clay roofing tiles

Objective

The objective of this study is to develop a draft standard for a single pan-European freeze/thaw test, using sensible laboratory conditions, to provide in a short period of time results, which are consistent with the behaviour of tiles on-site.
State of progress:
Data collected from the experimental roofs during the second winter have been analysed and compared to these collected during the first winter. According these results, it has been set that when frost cycles occur:
- The most frequent highest water content corresponds to a progressive imbibition of 5 days completed with 2 days soaking. Once a winter the water content can reach 100 % of the saturation level.
- The most frequent highest difference of temperature between the two faces of the tile is 1°C.
- The most frequent highest cooling rate is 2°C/h. Sometimes it reaches 10°C/h.
The study lab dealt with:
- The influence of the cooling rate. Quicker is the cooling rate, severer is the test.
- The influence of the difference of temperature between the two faces of the tiles. It has been shown that it is not the difference of temperature which is the most important point, but the fact that the backside of the tile is protected from the ventilation when freezing. Without any protection resistant tiles show damages and non-resistant tiles do not show any damages, but with a protection, the results become as expected.
The followings will consist on testing 10 types of tiles known as frost and non-frost resistant to test the effect of a protection placed on the backside.
Background:
In the context of European standardization, the durability of clay roofing tiles will be assessed. According to the differences in climates and codes of practice in Europe, the development of a single pan-European test can only be successfully accomplished with the aid of several European partners with a wide experience in the field. Currently, a draft standard exists, which describes four test methods for four different geographical areas. Nevertheless, the tests yield unsatisfactory frost test results. Therefore, it has been recognised that it is important to measure the fundamental parameters connected to the behaviour of frost on clay roofing tiles in order to use the collected data in the laboratory environment.

Work programme:
The study is divided into two parts :
Part 1:- A practical study involving the examination of the frost behaviour of tiles placed on five experimental roofs in five European countries. The roofs are specially constructed for the study. During exposure, on-site parameters such as temperature, rate of variation of temperature, water content etc. will be recorded.
Part 2:- With the date collected from Part 1, a test method will be developed. The influence of the parameters involved in the frost phenomenon will be checked in order to ensure the highest correlation between on-site and laboratory conditions.

Coordinator

Centre Technique des Tuiles et Briques
Address
17,Rue Letellier
75015 Paris
France

Participants (5)

Centro Technológico da Cerâmica e do Vidro
Portugal
Address
Rua Cornel Veiga Simao
3020 Coimbra
Cunial Antonio Ilca SpA
Italy
Address
Via Molinetto 46
31054 Possagno Treviso
Dakpannenfabriek Pottelberg N.V.
Belgium
Address
86,Kapel Ter Bede
8500 Kortrijk
QsM Gesellschaft für Qualitätssicherung und Materialprüfung mbH
Germany
Address
197-203,Am Zehnthof
45307 Essen
Verband Schweizerische Ziegelindustrie
Switzerland
Address

6210 Sursee