The application of Impact-echo acoustic method to evaluate the degradation and the composition of mortar composites modified with rubber aggregates and EVA polymer binder degraded at high temperatures was studied. Specimens were prepared by using a type CEM I Portland cement and siliceous sand, as well as by substituting 25% of sand with shredded automobile tires and by adding of EVA polymer binder (10% w/w to cement mass). The samples were subjected to high-temperature treatment in the temperature range of 200-400 °C. The results of non-destructive testing of such samples by acoustic methods confirmed the differences in the structure of mortar specimens. Addition of rubber aggregates in samples caused absorption of lower frequency as compared to reference specimens. A significant decrease of the absorbed frequencies was observed depending on the temperature. The largest decrease happened after exposure of samples at 200-300 °C. It indicates that the effect of heat treatment was reduced when the EVA binder was added.

The paper deals with the study of dominant frequencies of an Impact-Echo method response signal obtained from a reinforced concrete beam with a steel rod diameter of 8 mm. Tension pulse was produced in axis of the rod at one end and detected in axis at opposite end of rod. Dominant frequencies of the response signal will be the main criterions for the reinforced concrete rebar corrosion progress. The article presents the results of measurements obtained after 12 months controlled degradation in aqueous NaCl solution. The results were compared with measurements of electrical resistance of reinforcing steel by using the Thomson double bridge.

The present paper deals with the applicability of Impact-echo acoustic method to testing of cement-based composites prepared from a mix of cement mortar and quartz sand, which were intentionally degraded by high-temperature treatment (in the temperatures range from 200°C to 1200°C). Changes in the the bulk density and the flexural tensile strength were monitored during the degradation for comparison.

The aim of this paper is to evaluate the corrosion of reinforced concrete structure. To assess the state of corrosion we used frequency signal analysis, where we observed the changes in dominant frequencies and growth of damping factor λ. Tension pulse was produced in axis of the rod at one end and detected in axis at opposite end of rod. Diameter of steel rod was 8 mm. The article presents the results of measurements obtained during 24 months controlled degradation in aqueous NaCl solution.

The paper deals with testing of CO2 diffusivity through poly (vinyl butyral) (PVB) layers and their efficiency to serve as barriers against cement mortar carbonation. Two different types of PVB were tested; PVB sheet made from original extruded PVB polymer and PVB sheet made from PVB dispersion obtained from recycled windshields. The first part of the work was focused on testing CO2 diffusion when polymer sheets were exposed to a CO2 atmosphere (10% v/v CO2) with 0% RH. The excellent barrier capability against CO2 permeability of both types of polymer layers was observed. In the second part, mortar specimens were exposed for 23 days to two different carbonation regimes (laboratory conditions and chamber with CO2 atmosphere (1% v/v CO2) and 60% RH), having been coated or not with recycled PVB dispersion. Compressive strength tests, carbonation depth measurements and acoustic measurements (impact-echo method) were performed. The results showed the alternation of the compressive strength values depending on whether PVB coating was used or not. Both phenolphthalein test and impact-echo method confirmed the protective effect of PVB layer against mortar carbonation.