Mechanical Strengths of Modified PET Mortar Composites in Aggressive MgSO4 Medium: ACI & B.S Predictions

Composites mortars based on plastic aggregates are often considered as an innovative materials of the future because of their potential and the advantages they present. In this paper, a comparative study was carried out on the effect of magnesium sulfate MgSO4 (5%) attack on the durability of composite mortars modified by recycled polyethylene terephthalate (PET). Laboratory tests were accomplished on limestone sand and cement mortars where the blended Portland cement was partially replaced by various volume fractions of PET plastic aggregates. Mechanical properties measured on specimens were used to assess the changes in the compressive strengths of PET-mortar composites exposed to MgSO4 attack at different ages, mainly the Young modulus of elasticity. Based on experimental compressive tests on selected specimens and there densities, the evolution of static Young modulus of elasticity has been discussed in accordance to predicted models proposed by (ACI-318) and (BS-8110) codes of practice. In addition, a comparative analysis has been carried out for corrosion resistance coefficients K of referenced mortar to those modified with plastic aggregates. It can be noted that, the corrosion resistance coefficients decrease as much as composite specimens are exposed to MgSO4 corrosive medium. For the case of modified composites, the values of K based on predicted Young modulus before and after immersion are better than the ones calculated for the unmodified mortar. Therefore, ACI 318 prediction model is recommended code for design and investigation works related to reparation mortars, screeds, pavements…etc. Also, it can be concluded that adding PET plastic aggregates by volume to blend Portland cement act to improve the corrosive resistance of this cement against MgSO4 aggressive medium

Development of Materials Based on PET-Siliceous Sand Composite Aggregates

Plastic waste recycling for the development of new building materials, such as cementitious composites, appears to be one of the best solutions to get rid of this type of waste. This operation has many economic and ecological advantages. The present study proposes some solutions for the recovery of plastic waste from PET (polyethylene terephthalate) bottles in order to obtain, after heat treatment at 290 °C followed by step cooling, a light composite material (PET-siliceous sand) with a hardness close to that of natural rock. The structure of the material obtained is characterized first; then the effect of this composite, with different substitution rates of natural aggregate, on the behavior of an industrial screed is studied. Afterwards, some specific recommendations for the uses of this screed, and possibly of the composite itself, are given. Although the main effects of certain polymeric additives on the mechanical properties of mortars are known, the mechanisms that are responsible for these effects are not yet well understood. Techniques such FTIR, XRD, SEM and differential scanning calorimetry (DSC) are analytical tools that can be used for the characterization and expertise of this type of composites, particularly the industrial composite screeds. Results from the present article enabled us to state that the composition of the materials obtained remains qualitatively unchanged and that no chemical interaction was observed between the mineral species and the waste PET lightweight aggregate (WPLA) or the composite itself; in fact, no new compounds were formed. In addition, the differential scanning calorimetry (DSC) technique allowed us to conclude that the addition of WPLA has an influence on cement hydration. The thermo-mechanical characterization of WPLA made it possible to observe an excellent arrangement between the PET and siliceous sand. Therefore, the development of WPLA may be another solution for a number of applications in the field of eco-materials for construction and building

The thermal properties of mortars modified by the effect of combining polymers and SCMs

The thermal performance of the building materials is relevant to any use of composite materials, especially in relation to constructions where it is desirable to have high specific heat, low thermal conductivity and slight or no decrease of stiffness upon heating. The thermal coefficients of composite mortars made up of mixtures of combining styrene polyacrylic SPA Latex and supplementary cementitious materials SCMs were measured at different ages (7, 14, 28, 60, 90 and 120 days). So, in order to determine the thermal conductivity, the calorific capacity and thermal diffusivity of SCM-modified mortars, it seemed interesting to evaluate the influence of adding the SPA Latex (0.5%, 1% and 2%w) on the properties of these mortars when exposed to a quick thermal conductivity meter based on standard ISO 8302-91. The highest thermal conductivity of 1.51 W.m-1.K-1 was observed with the samples containing only plain cement. It decreased with the increase of SPA latex percentages. The lowest values of thermal coefficients were obtained with the samples prepared with SPA polymer at 2% and SCMs. In this way, the results obtained highlight the beneficial effect of combining SPA polymer and SCM materials as thermal insulation in comparison with other insulation materials. In fact, using SCMs as cement substitutes reduces the energy consumption. These composite mortars address problems related to environmental pollution by CO2 emissions, and can be recommended as materials for energy efficiency in buildings

Structural Characteristics of Composite Mortars and their Evolution with PET Substitution Level for Several Specimens’ Ages

This present study aims to investigate the evolution of structural response of PET-Mortar composite test with a short-beam specimen in three-point bending tests, with composite mortar ages and volumetric polymer rate and this, based on compression strength tests. The ultimate PET-mortar composite structural responses are calculated at the mid span of the short-beam by the mean of mechanics-of-materials theory basis. According to this theory, the distribution of bending moments and shear forces at any point of the composite short-beam specimen doesn’t depend on material mechanical properties especially the young modulus of modified mortar composite; so, the structural response analysis has been limited to investigate the evolution of ultimate deflection with several volumetric PET rates and composite mortar ages. In the other hand, we present a comparative study between experimental test results of splitting tensile and compressive strengths with the ones predicted by codale previsions (ACI-363 and B.S) codes in terms of PET mortar ages and volumetric PET rates in order to recommend the most suitable design code for PET-mortar composite applications in construction industries

Influence of natural pozzolan, silica fume and limestone fine on strength, acid resistance and microstructure of mortar

International audienceBased on an ongoing experimental programme, this research focuses on the effect of various supplementary cementitious materials (SCMs) (natural pozzolan (NP)/silica fume (SF)/limestone fine (LF) at various substitution levels) on the microstructure and mechano-chemical resistance of blended mortar. The paper primarily considers the characteristics of these materials, including their strength and the effects of aggressive chemical environments, by using sulphuric acid and nitric acid. The porosity and pore size distribution of the mortars are also examined using mercury intrusion porosimetry (MIP).The microstructural changes in pastes caused by SCMs and the acid attack of the solution are analysed and related to the phase composition found by X-ray diffraction (XRD). Microstructural investigations, such as scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), were also used to support the explanation for these mechanisms.The results, according to ASTM C267, showed that the addition of natural pozzolan or limestone fine would improve the acid resistance of mortar, but at different rates depending on the proportion of SCMs. On the other hand, mortars with silica fume are severely damaged in the sulphuric acid environment

Evaluation of natural pozzolan for use as supplementary cementitious material

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Chemical, mechanical and thermal properties of mortar composites containing waste PET

International audienceThe main objective of this study was to investigate the potential utilization of polyethylene terephthalate PET waste incementitious matrix, as substituent to cement, to develop lightweight construction materials and for preventing chemical attacksor repairing various reinforced concrete structures. Composites containing different amounts of PET particles, as partialreplacement to cement by weight, were characterized by destructive and non-destructive testing. So, the thermal conductivity,ultrasonic pulse velocity (UPV) and sorptivity coefficients of composite made up of mixtures of PET polymer were measured;the adverse environmental conditions are simulated by using various acid solutions. The corrosion process was monitored bymeasuring the mass loss and compressive strength for different periods. The experimental investigation revealed that the additionof PET particles reduces the UPV; furthermore, thermal conductivity and sorptivity of the composites have been decreased. So,the decrease of the sorptivity-value is favorable to the durability of the specimen structures. On behalf of the resistance toaggressive environments, it was found that the course of action of acid attack is dependent on the type of acid and solubility ofthe calcium salt formed. The presence of PET was found to lower the detrimental effect of acids on composite. Scanning electronmicroscope (SEM), X-ray diffraction and FT-IR analyses were used to better understand the cement hydration products of thedeteriorated mortars. In this way, the obtained PET-mortar composites would appear to be low-cost materials which wouldcontribute to resolving some of the solid waste problems in addition to conserving energy

Physical, mechanical and thermal properties of lightweight composite mortars containing recycled polyvinyl chloride

International audienceThis paper presents an experimental investigation into the use of waste recycled polyvinyl chloride (PVC) as an alternative fine aggregate in eco-friendly mortars. The aim is to improve the brittle behavior of cementitious materials in strong acid environments as well as the improvement of the thermal insulation performance of the developed material. Mortars incorporating 0, 10, 30, 50 and 70% PVC as a replacement for natural sand were studied. Density, compressive and flexural strengths, ultrasonic pulse velocity, and thermal conductivity tests were performed to evaluate the properties of PVC-mortar composites. The resistance of different mixes to strong acids was examined based on 5 weeks’ of immersion in 5% sulfuric acid (H2SO4), 5% hydrochloric acid (HCl), and 5% nitric acid (HNO3) solutions.The results showed that the incorporation of up to 70% PVC into lightweight ductile mortars is possible, though values of compressive and flexural strengths and ultrasonic pulse velocity decreased with increase in PVC content. In addition, the use of PVC aggregates by natural sand replacement caused the resistance of mortars against strong acids to increase considerably.Based on the thermal conductivity results, mortars with higher PVC aggregates rates improved the thermal insulation of composite mortars