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.

Self-compacting concrete (SCC), which appeared in the 1980s in Japan, is a concrete that differs from others by its high fluidity. The constituents of SCC can be quite different from those of ordinary concretes. They can differ both in their proportions and in their choice. Given the method of installation of SCCs, particular attention is paid to the study of their physical and mechanical characteristics. In this context, experimental tests were conducted to assess the effect of high temperatures on the behavior of SCC. For this purpose, a SCC and ordinary concrete (OC) were tested at temperatures of 20, 150, 300, 450, and 600 ${}^{\circ }$C. Prismatic specimens of dimensions 100 × 100 × 400 mm³, cylindrical specimens of dimensions 160 × 320 mm, and parallelepiped specimens of dimensions 270 × 270 × 40 mm³ were prepared for physical (thermal conductivity) and mechanical (compressive strength, elastic modulus, flexural strength, and ultrasonic pulse velocity) tests. The results showed an increase in the compressive strength for SCC between 150 and 300 ${}^{\circ }$C following an additional hydration of the cementitious matrix. The residual flexural strength of the concretes decreases progressively with the increase in temperature. This reduction is about 90% from 450 ${}^{\circ }$C to 600 ${}^{\circ }$C. The results also showed that the thermal conductivity of concrete decreases as the temperature increases and can reach a value of 1.2 W/mK for the heating temperature of 600 ${}^{\circ }$C.

The present work focused on the experimental study of the mechanical, thermal and acoustic properties of cement composite reinforced using Posidonia oceanica (PO) fibers. For this purpose, parallelepipedic specimens of dimensions 270 mm × 270 mm × 40 mm and cubic specimens of dimensions 150 mm × 150 mm × 150 mm were prepared with a water-to-cement ratio of 0.50 by varying the volume of fibers (V_f) from 0% to 20%. Properties such as compressive strength, thermal conductivity, thermal diffusivity, standardized level difference and sound transmission class were examined. The compressive strength of the specimens was determined using the rebound hammer test, while the thermal measurements were performed with the steady-state box method. The results showed that the addition of PO fibers improved the compressive strength of the mixtures and produced a maximum value of 33.60 MPa for a 10% volume of fiber content. Thermal conductivity and thermal diffusivity decreased significantly with the addition of fibers for all the mixtures. The experimental investigation also showed that the sound transmission class of PO-fiber-reinforced cementitious composites decreased as the fiber volume increased due to an increase in air voids in the mixtures.

Concrete is a material whose properties depend on its initial formulation, its conditions of use, and its change over time depending on its environment and the different types of degradation that it is likely to undergo. Knowledge and monitoring of its various mechanical properties are therefore essential for the maintenance of civil engineering works. All of the concrete assessment methods, whether destructive or non-destructive, can then provide a valuable diagnosis to the operators of the structure. Depending on their precision, they can be used to easily detect an alteration in the characteristics of the materials, locate a damaged area, the extent of the damage, or even precisely quantify the evolution of this damage over time and predict future changes. This paper presents the Ultrasonic Pulse Velocity technique (UPV) which is used by many companies to assess the compressive strength of concrete in situ and which allows measuring the speed and attenuation of elastic waves. The influence of the reinforcements on the ultrasonic pulse velocity has been studied and this is in the case of reinforcement perpendicular and parallel to the direction of propagation. The influence of several factors affecting the UPV, whether related to the properties of concrete or otherwise, was mentioned. Indeed, the porosity, the water/Cement ratio, the micro-cracks, the state of saturation and the temperature of concrete are parameters which strongly influence the values of UPV.