| Summary: |
Geosynthetics (GSs) are polymeric materials widely applied in civil engineering structures. However, various agents (such as weathering, oxidation, chemical species and microorganisms) may affect their durability and consequently their useful lifetime. For the right application of these materials we must take into account the degradation that GSs will suffer during time and we must assure that they will maintain minimum required values of certain properties over that time. So, it is extremely important to study their resistance against physical and chemical agents. Despite of such importance, there are not many systematic studies about the durability of GSs and a relative lack of knowledge is still found in this area. In Portugal, the only study available about the durability of GSs was performed by part of this research team as a task of a previous investigation project (POCTI/ECM/42822/2001).
In this project, degradation studies will be performed for GSs with different structures (geotextiles and geonets), made with different polymers (polyethylene and polypropylene) and stabilised with different chemical additives (chimassorb 944 and tinuvin 783) and pigments (black, green). More GSs with other structures, made of different polymers and stabilised with other additives, may also be studied.
GSs will be immersed in several acid and alkaline solutions, sea water and leachates from municipal waste landfills, will be exposed to thermo-oxidation and will be subjected to laboratorial accelerated weathering tests. Beyond that, GSs will be also exposed outdoors to natural weathering (in order to try to establish a correlation between natural and artificial weathering), will be subjected to microbiological attack and will be buried in municipal waste from a landfill. A successive exposition to two or more of these conditions will allow evaluating the existence of synergetic effects on the degradation suffered by GSs.
After the degradation tests, the properties  |
Summary
Geosynthetics (GSs) are polymeric materials widely applied in civil engineering structures. However, various agents (such as weathering, oxidation, chemical species and microorganisms) may affect their durability and consequently their useful lifetime. For the right application of these materials we must take into account the degradation that GSs will suffer during time and we must assure that they will maintain minimum required values of certain properties over that time. So, it is extremely important to study their resistance against physical and chemical agents. Despite of such importance, there are not many systematic studies about the durability of GSs and a relative lack of knowledge is still found in this area. In Portugal, the only study available about the durability of GSs was performed by part of this research team as a task of a previous investigation project (POCTI/ECM/42822/2001).
In this project, degradation studies will be performed for GSs with different structures (geotextiles and geonets), made with different polymers (polyethylene and polypropylene) and stabilised with different chemical additives (chimassorb 944 and tinuvin 783) and pigments (black, green). More GSs with other structures, made of different polymers and stabilised with other additives, may also be studied.
GSs will be immersed in several acid and alkaline solutions, sea water and leachates from municipal waste landfills, will be exposed to thermo-oxidation and will be subjected to laboratorial accelerated weathering tests. Beyond that, GSs will be also exposed outdoors to natural weathering (in order to try to establish a correlation between natural and artificial weathering), will be subjected to microbiological attack and will be buried in municipal waste from a landfill. A successive exposition to two or more of these conditions will allow evaluating the existence of synergetic effects on the degradation suffered by GSs.
After the degradation tests, the properties (physical, mechanic and hydraulic) of the GSs will be analysed and compared with those obtained for unexposed materials. Microscopic changes occurred in the polymeric structure of the GSs will be characterised by scanning electron microscopy. The development of an analytical method (inexistent at this date) for the determination of the level of additives present in GSs will also be started in this project.
A relation between the GSs composition (main polymer, type and concentration of additives) and the durability of the GSs will be established. Safety factors for the right application of GSs will be proposed taking into account the damage that these materials will suffer during time. |