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.