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2 Bulletin of the Polish Academy of Sciences. Technical Sciences

2 2016

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Scientific basis and rules of thumb in civil engineering: conflict or harmony?

Czarnecki L., Gemert D.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2016

Vol. 64, nr 4

665-–673

Science and engineering intermingle in the area of construction. Engineering works, often of great dimensions and design life cycle of many decades, have to be designed on a scientific basis since the safety of hundreds of users depends on their design. The task of scientific institutions is to define the construction performance within categories that correspond to the contemporary level of knowledge and technology. A construction appraiser who speaks out in a way that ensures unquestionable competence about the performance of elements and buildings (existing and under construction), should be convinced of the scientific basis of his opinions. A comparison of construction sections vs. basic requirements presents an archetype of the science of construction. A matrix of the science of construction reveals its multi-faceted nature; if related to time – the issue of durability has to be considered, and if related to the scale – the complexity. Defining the construction performance in terms of technical features is a constant search for a relationship between the material model and the usability model of a building. The construction industry uses a lot of “rules of thumb”, more than any other sector of technology. In the era of computer-aided design, CAD, and building information modelling (BIM), those rules of thumb remain invaluable verification tools.

Combustability of building products versus fire safety

Fangrat J.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2016

Vol. 64, nr 4

709--717

The combustion process is described and analysed based on the experimental results in the context of building fire safety. Data are obtained by means of five standard methods: ISO 5657 ignitability test, ISO 5657 cone calorimeter, ISO 9705 room corner test, EN ISO 1716 small calorimeter, and EN ISO 1182 small furnace. Various categories of building products were tested: cellulose based products (particle boards, plywoods), solid wood, floor coverings, concrete, ceramics, insulations (thermal and/or acoustic), boards (wall/ceiling), mortars, adhesives, and thin coatings. The studied products exhibited very different fire properties from non-combustible to easily combustible. In order to more effectively differentiate non-combustibles and combustibles within building products, the modified heat of combustion was calculated using all test results according to EN ISO 1716 and EN ISO 1182. The revision of criteria for Euro class A1 and A2 is proposed to obtain more realistic reaction-to-fire evaluation. In conclusion, it is advised to use single limit for heat of combustion for A1 and A2 Euro class. The proposed approach for modified heat of combustion is a convenient tool for the fast and cost-effective initial test method for non-combustibility evaluation and seems to be the proper method for distinguishing between non-combustibles and combustibles within building products. It is a better reflection of the real physical process of combustion than the current one. The third A1 criterion is questionable, regarding time to auto-ignition in EN ISO 1182 cylindrical furnace. The measurement for gross heat of combustion by EN ISO 1716 method is proposed for all Euro classes of building products with different limit values.