No abstract

The main objective of this study is the recovery of dune sands and rubber waste (powders). The latter constitutes a potential source of several environmental and economic problems. The objective of this present work is to examine the ability to use dune sand for the preparation of mortars with sufficient physico-mechanical properties to allow them to be used in various building construction applications. The formulation of the mixtures is based on replacing dune sand with powders, at different weight contents: 10 %, 20 %, and 30 %. The quantity of cement is set at 450 g. The results obtained show in the first place that the particle size of the mixture tends to be spread out with a remarkable increase in the fineness modulus, and in the second place the density of the mixture decreases by 6.5 % (for the apparent) and by 10 % (for the absolute), which means the calculation of loads for the resulting mortar must decrease. Porosity has decreased to 20 % and absorption has increased to 30%. The strengths have decreased over 40 % for compressive strength and over 30 % for tensile strength, with an improvement in the relationship between the two strengths.

In this study, rubberized cementitious materials are produced with recycled rubber waste as an alternative to fine aggregate. Mixtures with different additions to rubber wastes (RW), silica fume (SF), and blast furnace slag (BFS) have been designed and characterized. Hardened properties including compressive and bond strength, shrinkage, water-accessible porosity, rapid chloride migration, and microstructure were investigated. The results show that the addition of SF and BFS improves the performances of rubberized mortars and reduces shrinkage. The incorporation of 5% RW with 20% BFS increases compressive strength and reduces water-accessible porosity. Ion chloride resistance was enhanced by a combination of 15% RW, 8% SF, and 20% BFS. The addition of SF and BFS as cement replacement improves the performance of mortars due to their filling effect and a pozzolanic reaction, which has been verified by a microstructural analysis.

The granulated blast furnace slag exhibits pozzolanic reactivity when combined with appropriate activator and can be used in a wide range as cement replacement. The aim of this study is to investigate the effect on the mechanical and microstructure properties of incorporating admixture composed by granulated blast furnace slag (GBFS), calcined eggshell (CES), and brick waste (BW), as replacement of cement in the formulation of mortar. Ten different mixes of mortar prismatic specimens were tested with different replacement levels of raw materials (50, 75, and 100%). The results show that the increase in the proportion of raw materials decreases significantly drying shrinkage, dry unit weight and strengths of mixtures mortar compared to control mortar at early age. The decrease in strengths is less important in the long term due the development of pozzolanic reaction. Moreover, the water absorption and open porosity were increased for all cases. The microscopic analysis by Scanning Electron Microscopy (SEM) shows that the proportion of 15% of calcined eggshell powder in admixture, provides more Calcium Silicate Hydrate gel (C-S-H) in the internal cementitious matrix of the mortar, which explains the best mechanical strength provided by this mixture.