Kinetics of destruction of nanomodified sulfir composites

As the service load on structures is constantly growing, modern construction industry needs new materials which could provide more capabilities and meet special requirements for operational performance. One of such materials is the so-called sulfur composite. When producing this composite the sulfur is used as a binder and different powders, fibers and grains can be used as the disperse phases. There are many advantages of sulfur composites: cheap binder, quick structure forming, high chemical resistance etc. For some operational conditions, however, the sulfur composites show the lack of required compressive strength. But recently developed method — nanomodification — addresses mentioned drawback of sulfur composites. Nanomodification is the formation of intermediate nanoscale layer on fine filler by means of addition of selected precursor. Moreover, taking into account the necessity to characterize the material not only by one scalar parameter — the compressive strength — but also by kinetics of fracture, we can decide that experimental methods of fracture mechanics should be used during examination of sulfur composite. One of the most promising is the acoustic emission (AE) method, which is often designated as a method of non-destructive testing. Nevertheless, acoustic emission occurs — and can be measured — during the process of destructive testing too. The successful application of the acoustic emission method for studying kinetics of fracture imposes some requirements to testing machine characteristics; thus, all measurements were carried out with the device that had been developed for this purpose. It was shown that nanomodified sulfur composites demonstrate the reduction of AE energy to the final stage of load. Because of this, we propose to describe the fracture kinetics by «median stress» — stress corresponding to the half-release of all AE energy during fracture. It was shown that offered scalar parameter is in strong correlation with compressive strength.