In this paper, an experimental study was carried out in order to provide more data on the effects of expanded perlite aggregate (EPA) dosage on the compressive strength and thermophysical properties of lightweight concrete at different ages. The first part of this experimental study was devoted to the choice of the proper mixing procedure for expanded perlite concrete (EPC). Thereafter, six sets of cubic specimens and six sets of parallelepiped specimens were prepared at a water-to-cement ratio of 0.70 with varying replacement percentages of sand by EPA ranging from 0% to 80% by volume of sand. Compressive strength, thermal conductivity and thermal diffusivity were determined over curing age. Unit weights for the mixtures prepared varied between 560 and 1510 kg/mP 3 P. Compressive strength was decreased when perlite content was increased. The test results indicated that replacing natural aggregate by EPA increased the thermal resistance of the lightweight concrete and consequently, improved thermal insulation.

The purpose of the present study is to recover marble waste and expanded perlite aggregate (EPA) for use as an additive to cementitious matrix building materials. The main goal is to produce a new insulation block floor from lightweight concrete (LC) by mixing sand from the waste marble crushing process (SWM), natural sand, and EPA. First, optimal mixture of natural sand, SWM, and EPA was determined for a given insulation LC. To this end, plate and cubic specimens were prepared by varying the volume proportion of SWM to natural sand in percentages of 0, 20, 40, 60, 80, and 100. Mechanical and physical properties such as the compressive strength, thermal conductivity, thermal diffusivity, specific heat capacity, and sound reduction index at different frequencies were investigated. Finally, a prototype of a new insulation lightweight block floor was manufactured from the optimal mixture of the studied LC. The results showed that the incorporation of SWM significantly improved the mechanical properties and the thermal insulation of LC compared to those of the natural sand. These results are promising and give the present insulation block floor the opportunity to be used in composite slabs.

The durability of reinforced concrete structures depends on their behavior in relation to the climatic and environmental conditions that exist in the environments in which they are built. These structures are often subject to a permanent process of physical and chemical degradation as a result of external aggression. In this context, this paper presents the different chemical causes of concrete degradation such as carbonation, alkali-reaction and sulphate reactions. The diagnosis and repair techniques of the infected concrete have also been developed.

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