H. Taïbi

Resistance of Polymer (PET) - Mortar Composites to Aggressive Solutions

This paper describes an innovative use of plastic bottle waste as cement-substitution within composite materials for preventing chemical attacks or repairing various reinforced concrete structures. Various weight fractions of cement varying from 2.5% to 7.5% were substituted by the same weight of polyethylene terephthalate (PET). The specimens were tested in flexure and compressive strength and for chemical resistance to acid, basic solutions at 5% and for chloride ion permeability. From this study, it was found that the PET-modified mortars exposed to aggressive environments showed better resistance to chemical attack and higher resistance to chloride ion penetration than unmodified one without substantially affecting the mechanical strength in tap water. The addition of PET to the modified mortars, means reducing the penetration of aggressive agents. So, the mass loss of composites exposed to hydrochloric and acetic acid solutions is lower than those of unmodified mortar. The basic solutions are harmless for composite materials. The formations which appear such as different calcium salts were determined by X-ray diffraction and FT-IR.

Mineral-Based Composite Materials for Energy Efficiency in Buildings

Degradation of building materials is an important phenomenon influencing their design and utilization. Mineral-based polymer-mortar composites (PMC) are often used as inexpensive promising materials to prevent the deterioration of constructions or remedy various reinforced concrete structures and they are used as materials for energy efficiency in buildings. In repair applications, polymer addition allows improving the adhesion properties of materials used in coating. With the intention of improving the sustainability of these composites, the influence of latex polymer and supplementary cementitious materials (natural pozzolan and silica fume) additions on the characteristics of these composites was investigated in aggressive media, such as acids. Mortars made with local pozzolanic mineral admixtures, obtained by substituting cement by different proportions of polymer (0, 5, 7.5, 10, 12.5 and 15%) were conserved in acidic solutions for 56 days. The microstructural analysis of these mortars was performed, using the X-ray diffraction technique, after 56 days of exposure to acid attack. The obtained results enable to bring out the beneficial effect of adding a latex polymer and other pozzolanic additives into modified materials on resistance to acid attacks. So, these composite materials can be recommended as materials for energy efficiency in buildings.

Plastic Waste Particles in Mortar Composites: Sulfate Resistance and Thermal Coefficients

Plastic industry produces large amounts of waste polyethylene terephthalate (WPET), what causes environmental problems. An investigation was carried out on the effect of sulfate attack on the durability of composites produced with WPET. An attempt was also made to determine the thermal coefficients as well as the dynamic elastic moduli. Experiments were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced by various volume fractions of WPET particles. The test solutions used to supply the sulfate ions and cations were 5% sodium sulfate solution and 5% magnesium sulfate solution. Tap water was used as the reference solution. Mass changes, compressive and flexion strengths measured on specimens were used to assess the changes in the mechanical properties of composites exposed to sulfate attack at different times. X-ray diffraction, FT-IR spectroscopy, scanning electron microscope (SEM/EDS) and differential scanning calorimetry were used to evaluate the microstructural nature of the sulfate attack. The test results showed that the presence of WPET had a beneficial effect in the control of the strength loss due to sodium and magnesium sulfate attacks and gave better insulation properties. This study insures that reusing TWPET particles as cement substitutes in mortar gives a good approach to sulfate durability, insulation, mechanical properties and solves some of the solid waste problems posed by plastics. Therefore, WPET-mortar composites are often presented as the materials of the future because of their potential for innovation and the advantages they offer. In fact, using WPETs as cement substitutes reduces the energy consumption. These composites address problems related to environmental pollution by CO2 emissions, and are used to repair various reinforced concrete structures.

Destructive and Non-Destructive Testing of an Industrial Screed Mortar Made with Lightweight Composite Aggregates WPLA

Today, only a very small portion of plastic waste is recycled, while huge quantities remain untreated and are becoming increasingly worrying. The search for other alternatives is still an urgent necessity so that these wastes can be reduced to the maximum; their valorization may be the best solution. This study concerns a new technique for the valorization of polyethylene terephthalate (PET) plastic bottle wastes, in order to design a composite material, i.e. siliceous sand-PET, which then gives a Waste Plastic Lightweight Aggregate “WPLA”. Our hope is to provide solutions to specific and general applications in the field of construction. Some observations are noted on the effects of this composite on destructive and non-destructive testing, such as the physical properties and mechanical behaviors of an industrial composite screed, by substituting 0, 25, 50, 75 and 100% by weight of natural aggregate by this composite. Scanning electron microscope (SEM), FT-IR and X-ray diffraction analyses were used to better understand the cement hydration products of the composite mortars. Some possible uses of this screed, or even of the composite itself, can subsequently be recommended. Encouraging results were obtained regarding the usage of this composite aggregate as an eco-material in the field of construction for sustainable development. In addition, it provides environmental-friendly and cost-effective solutions in using recycled materials for concrete construction applications.

Testing of Composite Mortars Based on Supplementary Cementitious Materials: Estimating Durability and Thermal Properties

The growing need for building material resources, and the requirements to preserve the environment, in a vision of sustainable development, has become necessary to study reinforcement techniques, using composite materials. Using local organic or inorganic materials in construction fields and public works is particularly important. Polymer mortar composites (PMC) are usually employed in the building industry as finishing materials, tile adhesive (mortar-adhesive) or façade coating. In repair applications, the addition of soluble polymer (latex) allows improving the adhesion properties of the materials used as coating. The use of mineral additives as partial substitutes for cement, in construction sites as well as in ready-to-use mortars, is an unknown practice in our country. For this reason, we thought it is crucial to study and assess the influence of these additions on the properties of cured composite. Supplementary cementitious materials (SCM) used in this study are silica fume and natural pozzolan, which necessarily need to be valorized.The present research work aims to use a specific experimental methodology that is able to identify the relationship between the degree of substitution by the mineral additives, the polymer and the modifications to the properties of fresh and hardened cement mixtures. Therefore, five PMC combinations were formulated from different percentages of additions, i.e. natural pozzolan (NP: 25%w), silica fume (Sf: 5%w) and polymer latex (P: 0, 5, 7.5, 10, 12.5 and 15%w). Their durability factors, such as the porosity accessible to water and capillary absorption rate (sorptivity), were characterized, at different maturities. An attempt was also made to determine the thermal coefficients. The results obtained were compared with those of the reference mortars, made with Portland cement (CEMI). They showed that the decrease in porosity, sorptivity and thermal conductivity depends on the pair “SCMs/polymer”. But overall, the addition of polymer latex and pozzolanic additions have a beneficial effect on the durability and thermal properties of the composite materials.