J.M.L. Reis

Effect of Textile Waste on the Mechanical Properties of Polymer Concrete

The mechanical behavior of polymer concrete reinforced with textile trimming waste was investigated. Two series of polymer concrete formulations were studied, with different resin/sand (i.e. binder/fine aggregate) weight ratios. In each series, recycled textile chopped fibers at 1 and 2% of the total weight was used. Flexural and compressive tests were performed at room temperature and load vs. displacement curves were plotted up to failure. In the study, both the influence of fiber content and resin/sand weight ratio were considered relative to the behavior of polymer concrete reinforced with textile fibers. A decrease in properties was observed as function of textile fibers content. When specific properties were considered, this tendency was kept. However, higher textile fibers content lead to a smoother failure, unlike brittleness failure behavior of unreinforced polymer concrete.

Mechanical characterization of fiber reinforced Polymer Concrete

A comparative study between epoxy Polymer Concrete plain, reinforced with carbon and glass fibers and commercial concrete mixes was made. The fibers are 6 mm long and the fiber content was 2% and 1%, respectively, in mass. Compressive tests were performed at room temperature and load vs. displacement curves were plotted up to failure. The carbon and glass fibers reinforcement were randomly dispersed into the matrix of polymer concrete. An increase in compressive properties was observed as function of reinforcement. The comparison also showed that Polymer Concrete, plain and reinforced, has a better performance than regular market concrete, suggesting that PC is a reliable alternative for construction industry.

Effect of temperature on the mechanical properties of polymer mortars

This paper presents the results of an experimental program to investigate the effect of temperature on the performance of epoxy and unsaturated polyester polymer mortars (PM). PM is a composite material in which polymeric materials are used to bond the aggregates in a fashion similar to that used in the preparation of Portland cement concrete. For this purpose, prismatic and cylindrical specimens were prepared for flexural and compressive tests, respectively, at different temperatures. Measurements of the temperature-dependent elastic modulus and the compressive and flexural strength were conducted using a thermostatic chamber attached to a universal test machine for a range of temperatures varying from room temperature to 90 oC. The flexural and compressive strength decreases as temperature increases, especially after matrix HDT. Epoxy polymer mortars are more sensitive to temperature variation than unsaturated polyester ones.

Experimental investigation on the effects of recycled aggregate on fracture behavior of polymer concrete

The sustainable management of solid wastes stimulates metallurgic and metal mechanics industries to look for safety applications for these wastes. The present paper examines the fracture behavior of polymer concrete (PC) manufactured with recycled foundry waste in substitution of fresh one. The recycled foundry sand is contaminated with polymer resin from the mold making process. Epoxy and unsaturated polyester resins were used as binder as cement substitute. The fracture results are analyzed by fracture energy; Gf, fracture toughness, KIc, and the crack tip opening displacement, CTOD. It is found that the use of recycled foundry sand significantly influences the fracture properties. The use of recycled sand increase fracture toughness and similar fracture energy is observed. These results show that recycled sand is an excellent alternative as raw material.

Mechanical characterization of sisal fiber-reinforced recycled HDPE composites

The increasing awareness of the environment protection has contributed to concerns regarding alternative procedures for recycling of plastic wastes. Since chemical processes are high cost, energy and often environment harmful, thermo-mechanical techniques of recycling rises as a good alternative. This research deals with mechanical characterization of thermo-mechanical recycling of composites based on recycled high density polyethylene (HDPE) from post-consumed motor-oil plastic containers as matrix and natural fibers (sisal) as reinforcement. The composites were made by extrusion and then melt blended in a compression mold. The sisal fibers do not contribute to increase tensile strength. As fiber content increases loss of ductility is observed.

Fracture Mechanics of Polymer Mortar Made with Recycled Raw Materials

The aim of this work is to show that industrial residues could be used in construction applications so that production costs as well as environmental protection can be improved. The fracture properties of polymer mortar manufactured with recycled materials are investigated to evaluate the materials behaviour to crack propagation. The residues used in this work were spent sand from foundry industry as aggregate, unsaturated polyester resin from polyethylene terephthalate (PET) as matrix and polyester textile fibres from garment industry, producing an unique composite material fully from recycled components with low cost. The substitution of fresh by used foundry sand and the insertions of textile fibres contribute to a less brittle behaviour of polymer mortar.

A Thermomechanical and Adhesion Analysis of Epoxy/Al2O3 Nanocomposites

The thermomechanial properties of polymeric nanocomposites are related to the quality of the adhesion between matrix and nanoparticle. Since the adhesion is related to the nature of the materials and the surface available for chemical, electrostatic and mechanical interactions among these materials, weak bonding forces between alumina (inorganic) and polymer matrices (organic) were expected. Furthermore, using nanoparticles with greater diameters means that the specific surface area reduction will have an adverse impact on the adhesive process. For epoxy matrices reinforced with alumina nanoparticles, different volume fractions and sizes were observed by differential scanning calorimetry (DSC): a relation between the glass transition temperature (Tg) and the nanoparticle size. This observation was tested by dynamic mechanical analysis (DMA) and the cross-link density was calculated. In addition, the thermal stability enhanced by alumina addition to organic resins and the quality of the adhesion was observed by thermogravimetric analysis (TGA).

Mechanical Characterization Using Optical Fiber Sensors of Polyester Polymer Concrete Made with Recycled Aggregates

The sustainable management of solid wastes encourages metallurgic and metal-mechanic industries to look for safety applications for their wastes, thereby attenuating the environmental impact or lowering the costs. The study herein proposes strain monitoring the recycling of foundry sand with organic pollutants, as inert, in the manufacturing process of polymer concrete using optical fiber sensors. This work also analyzes the compressive strength of polyester polymer concrete made with foundry waste, i.e., recycled foundry sand and polyester polymer concrete made with fresh sand. The foundry sands are contaminated with Sodium Silicate from the mould-making process. Polymer Concrete (PC) is a composite material in which the binder consists entirely of a synthetic organic polymer. Optical fiber sensors present a great deal of potential in monitoring the structural health condition of materials. Experimental results show that the use of the embedded FBG sensor can accurately measure strain, providing information to the operator that the structure is subjected to failure. Multiplexed FBG strain sensors enable measuring strain in different locations by occupying only one tiny optical fiber.

Displacement rate effect on the flexural properties of glass fiber reinforced polyurethane

The object of this study was to evaluate the flexural strength of glass fiber reinforced polyurethane composites under variable displacement rates. Flexural tests have been conducted at a range of displacement rates included 0.2, 2, 20, 100, 200, 1000 mm/min. Specimens with identical geometry have been used in all the tests. This particular composite has viscoelastic behavior with both elasticity modulus and ultimate flexural strength being strongly dependent of the displacement rate. Results showed that, both the flexural modulus and the ultimate flexural strength are increased with the increasing in the displacement rate.

Influence of Al2O3 and CuO nanoparticles on the thermal properties of polyester- and epoxy-based nanocomposites

The modification of polymer properties through the addition of nanoparticles has lead to the development of the so-called nanocomposites. The purpose of this study was to investigate the effect of Al2O3 and CuO nanoparticles on the thermo-physical properties of epoxy- and polyester-based nanocomposites. Analysis was carried out for different volume fractions of nanoparticles, ranging from 2.5 to 10 %. The results showed that the glass transition temperature (Tg) varies differently on each matrix and nanoparticles sizes. However, the obtained Tg showed no significant change with nanoparticle concentration. The cross-link density studied by DMA for each nanocomposite shows that Al2O3 fillers are responsible for the decrease in cross-link density, while CuO nanoparticles contribute to improve this property. A significant improvement of thermal stability of epoxy and unsaturated polyester resins containing CuO nanoparticles was observed.