A recent study commissioned by the European Paper Sack Research Group has shown that paper sacks for cement offer equivalent protection to polyethylene FFS sacks over an 18-month storage period under identical conditions.
The study was conducted by the Norwegian Research organisation SINTEF on behalf of the European Paper Sack Research Group (ESG) a co-operation between CEPI Eurokraft and Eurosac.
„Cement hardens on contact with water. In order to maintain its quality and material properties even during longer storage periods, perfect protection of the product by the packaging is crucial,“ emphasises Catherine Kerninon, Secretary General of Eurosac. „To ensure that our industry meets the needs of cement manufacturers and can compete in the cement packaging market, we have analysed the shelf life of the two most commonly used bag types: paper and plastic.“
A typical pack of each variety was selected for the study: a standard paper valve bag for cement, consisting of two paper layers of 80 and 70 g and a 12 μm thick protective layer of high-density polyethylene (HDPE), and a standard plastic bag, The film consists of three COEX PE film layers (LDPE, HDPE and LLDPE) with a total thickness of 120 µm.
Study design
Three sacks of each type were filled with the same type of cement and istored in an external warehouse in Norway, where they were exposed to the prevailing weather conditions throughout the test period. The bags were stacked on a wooden pallet and with covered with a plastic stretch bonnet - a typical warehouse situation.
„Although the average storage period for bagged cement in Europe is estimated to be a maximum of two to three months, we wanted to investigate how the bags perform over a longer storage period of up to 18 months as part of our study,“ explains Catherine Kerninon. „For this reason, one bag of each type was removed from the warehouse after three periods of different lengths.“
The results show a High storage stability of both bag typesWhether total weight, degree of hydration, mortar strength, initial flow behaviour or 28-day compressive strength - the Quality and product features of the cement samples periodically taken from both types of bags fully met the requirements of the cement industry.
The study proves it: Paper sacks offer good storage stability and are characterised by their High environmental compatibility off: Your CO2-The carbon footprint is 2.5 times smaller than that of plastic bags. This is the result of another recent study by the Swedish research institute RISE.
Source: Eurosac
