The wastes from polyethylene terephthalate (PET) packaging can be turned into armatures for concrete used in the transports infrastructure (roads with rigid concrete structure, pedestrian and concrete pavements and borders), as well as in the construction of safety elements (support walls, bulwark foundations). This experimental research was meant to create dispersed reinforced concrete with armatures from polyethylene waste, originated from the recycling programmes of PET-type packaging. The experimental programme was aimed at constructing some samples of dispersed reinforced concrete from recycled material coming from polyethylene terephthalate (PET) packaging wastes, their testing to the compressive strength and the comparison of results with the characteristics of the standardised samples of concrete (class C30/37). All the reinforcements used in this work to consolidate the dispersed reinforced concrete type were made from a mix of polyethylene terephthalate (PET) packages, of different types and characteristics, which are found daily in supermarkets and which then reach waste. The choice of a mix of polyethylene terephthalate (PET) packaging was chosen in order to render the general recycling of these types of materials as good as possible.

Woven fiber reinforced concrete is a material, which contains various quantities of polymer materials in composition, in addition to the conventional components of an ordinary concrete (mineral binder - cement, aggregates, water and additives). The present work refers to the concrete in which the reinforcement is made of polymeric materials (polyethylene terephthalate), originated from the recycling programs of PET-type packaging. The experimental program was aimed at constructing some samples of woven fiber reinforced concrete from recycled material coming from PET packaging wastes, their testing to the compression demands and the comparison of results with the characteristics of the standardized samples of concrete (class C30/37). Based on a sufficient number of determinations, certain correlations can be established between the compressive strength of the concrete at 28 days depending on the dosage of components (aggregate, binder, and reinforcement), water / cement ratio, reinforcement volume, etc., essential parameters from a compositional point of view. These correlations, customized by cement type and strength class, are very important to determine - with approximation - to what dosage of components (aggregate, binder, reinforcement) the respective level of compressive strength of concrete is obtained.

Fibre-reinforced concrete cannot replace the ordinary reinforced concrete. However, there are areas of use in which fibre-reinforced concrete can be used alternatively or in addition to the ordinary reinforced concrete, offering several advantages, some of that being presented in this study. The basic idea is that reinforcements create a multi-directional �mesh� within the cementitious matrix that will make concrete stronger. In fact, adding the fibrous material to concrete will increase the strength. In this sense, the micro-fibres primarily work to prevent micro- or shrinkage cracking, which mostly occurs during the initial curing process of the concrete, or those critical first 28 days. By contrast, the macro-fibres provide load-bearing strength after the concrete cracks. But, in fact, the subject is more complex. The types and size of fibres, their distribution and orientation are a hugely complex topic. Fibres, of whatever nature, have been found to improve the properties of concrete. Fibre-reinforced concrete provides an alternative to conventional reinforcement, with the advantage of time and reduced costs of performing maintenance work. The complexity of various fibre use presents challenges for the construction sectors that may be beyond current levels of expertise. In this study, particularities of concrete reinforced with polymer fibres are presented. Also, a comparative study is presented, based on our previous works in area of the concrete reinforcing with recycled polyethylene terephthalate (PET).

Selective Laser Melting is an Additive Manufacturing technology based on 3D scanning of successive layers of metal powder. Three distinct values were determined for each of the three technological parameters (P – the power of the laser, Vscan – scanning speed and te – exposure time), therefore resulting nine sets for the “layer by layer” processing. After SLM processing, the samples were sandblasted simply (1S), sandblasted successively (2S), or left unsandblasted (NS). The roughness (Ra) of the outer surfaces was measured for all the samples, and there was found a decrease in the height of the micro-irregularities and the uniformization of the roughness profile along with the intensification of the sandblasting process. For some samples, there were found uncertainties regarding the accuracy of the experimental results’ values, determined by the presence of the adherent particles identified by the SEM analysis of the outer surfaces. The number and size of these particles have affected the manner in which the samples were placed on the roughness tester’s plate, as well as the accuracy of the measurements. Under these conditions, the tip of the roughness tester’s diamond stylus has recorded the specific values of the surface’s secondary profile, which is affected by the existence of the formations adhering to the primary profile of the SLM processed samples.

Modern technologies of Additive Manufacturing type allow for the obtaining of the metal components specific to medical prosthetics in the best conditions. Selective Laser Melting (SLM) method is frequently used in dental medicine since there is an obvious trend to replace the classical casting techniques especially for non-noble Co-Cr alloys. According to the values of processing parameters (SLM) there will be parts having different roughness of the exterior surfaces. The conducted studies analysed the influences exercised by three process parameters (laser power – P, scan speed – vscan and exposure time – te) on roughness amplitude expressed by value (Ra). By combining the three distinct values adopted for each parameter we made nine sets of lamellar samples on whose non sandblasted surface, surface sandblasted once and surface sandblasted in two successive stages we carried out roughness measurements. Based on the results obtained for (Ra) parameter we formulated some recommendations for the technological parameter values that may provide surface roughness adequate to the subsequent destination of the processed parts (SLM).