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In recent years, the durability of concrete has been the subject of a few research projects carried out by several scientific and technical centres. As a major cause of concrete degradation around the world, reinforcing steel corrosion requires our full attention. This article analyses one of the phenomena at the origin of these disorders, namely the carbonation of concrete, and proposes some provisions to guard against it. The article is divided into two parts; the first describes the causes and consequences of the chemical process of carbonation as well as the means to protect it. The second deals with the influence factors on carbonation such as the minimum cement dosage, the type of cement, the water-cement ratio (W/C) and the reinforcement coating. Indeed, prismatic specimens (15 x 15 x 60 cm3) and cubic specimens (15 x 15 x 15 cm3) were made for different mixtures and with a W/C ratio of 0.50, 0.55 and 0.60. The prismatic specimens were subjected to a carbonation test, while the cubic specimens were used to determine the compressive strength, the corresponding density and the immersion water absorption.

The formulation of self-compacting concrete (SCC) requires a large volume of additions to increase the volume of the paste and reduce the amount of cement. This paper presents the results of an experimental and theoretical study of the effect of particle size of limestone filler on the rheology of SCC in its fresh state. The first part is devoted to the experimental study of the influence of particle size of the limestone filler on the rheology of SCC in the fresh state. In the second part, a simple theoretical model was developed to determine the dosage of filler considering its particle size. Finally, the theoretical model was validated by experimental tests on differents SCC mixed with different quantities of filler predicted by the model. The results showed that all concretes have a similiar rheology and compressive strength.

An experimental study was conducted to investigate the potential of fired clay bricks containing sawdust as a construction material. Sawdust samples were obtained from wood shavings prepared in the laboratory; the clay was ground to a fine homogenous powder. Both materials were subjected to physical and chemical tests. Clay brick samples containing 4% and 8% sawdust by mass were produced in the laboratory, fired at temperatures ranging from 70 to 850 ?C, and compared with control clay brick samples containing 0% sawdust. The behavior of the bricks was studied during firing to determine the suitable firing temperature for clay–sawdust bricks. The fired clay–sawdust bricks were further tested for drying shrinkage, porosity, compressive strength, water absorption, and bulk density properties. The results showed that the firing time for clay bricks decreased by approximately 2 h when 4% sawdust was added, and by approximately 4 h when 8% sawdust was added. The results also show that the added sawdust produced lighter, more absorbent, and less resistant clay bricks.

Marble industries produce vast amounts of wastes, and this is detrimental to the environment. Accordingly, these waste materials require appropriate management to ensure a cleaner environment. Given that, the utilisation of recycled materials in construction is desirable, owing to the space saved from landfill purposes and reduction in carbon dioxide (CO2) as well as the lower cost related to the waste materials. Subsequently, this paper investigated the effects of adding waste marble powder (WMP) as filler on the strength performance of mortar, with different Blaine Specific Surface (BSS) on the precise class of resistance of the Artificial Cement Portland CEM I 42.5. The experimental investigation and statistical analysis were carried out on mortar mixes containing four different types of marble powder as the filler (F1, F2, F3, F4) with BSS values of 3860, 5640, 7620 and 9280 cm2/g, respectively. Substitution rates of 5, 15, and 25% were applied. In addition, the water/cement + filler ratios (W/(C + F)) or W/Ceq and the true class of resistance of the new cement were measured for each mix. Moreover, the theoretical models (termed as equivalence models), which enabled the determination of the precise class of resistance of the cement and W/Ceq ratios as a function of the BSS of the used marble fillers and substitution rate, were developed. The obtained results revealed that 5% substitution of cement by the marble powder provided compressive strength values similar to that of the control mix for all types of filler. However, with further increase in the substitution rate, the compressive strength reduced. Subsequently, both the experimental and theoretical results presented a good agreement. It was concluded that the proper use of waste marble powder as a partial replacement of cement would have environmental benefits, and simultaneously, increase the feasibility of marble stone industries.

Current research in the field of building materials is oriented towards the recovery of waste to ensure the lightening of certain building elements and energy saving. The objective of this study is to produce a new bricks by adding sawdust to clay mixtures. The first part of this experimental work consists on detremining the proper manufacturing process and cooking diagram for these new bricks. In the second part, the effect of the maximum cooking temperature, the firing phase time's of the bricks and the sawdust prportion on the physical and mechanical properties of the new bricks have been studied. The studied properties are the absorption ratio, the unit weight and the compressive strength. The results showed that the addition of an increasing amount of sawdust tends to modify the physical and mechanical properties of the cooked samples. The presence of sawdust reduces the number of connections between the clay grains and produces a lighter, more absorbent and less resistant material. Finally, the results showed that the manufacture of bricks based on sawdust is possible.

Currently, marble waste is valued by incorporating powders, obtained by drying and grinding sludge resulting from marble blocks cutting operation, or the aggregates, obtained by crushing the solid waste, on self-compacting concrete. These two procedures require a lot of energy. This experimental and theoretical work focuses on the direct incorporation of marble sludge in self-compacting concrete. The first part needs the study of the rheological behavior of the marble sludge grout (MSG) as a function of the added water amount. For this, different grouts were prepared and tested by varying the water/sludge ratio. In the second part, four self-compacting concretes (SCCs) were mixed with MSG having different water/sludge ratios in order to validate a new technique of gassing self-compacting concrete with MSG. The test results show that the marble grains of grout is totally dispersed when the water/sludge ratio was equal to 1.2. The results also show that the gassing with MSG allows us to obtain SCC having both self-compacting property and self-leveling property compared to SCC made by adding marble filler to the cementitious matrix.

The marble powder (MP), obtained from waste sludge marble processing, has a high specific surface area; this could mean that it can be used as filler added to self-compacting concrete (SCC). The aim of this experimental work is to study the effects of the cement-MP paste volume on the rheology in the fresh state and the hardened properties (compressive strength) of SCC by a microstructure analysis on paste samples with different amounts of MP. For all pastes, the morphological forms and the chemical composition of the main mineral components were analyzed by the scanning electron microscope (SEM) and X-ray diffraction (XRD). The hydration, microstructure, and mineralogical changes has been studied. Experimental results show that the cement-MP paste volume has significant effects on the self-compacting and the self-leveling properties in the fresh state of SCC. In addition, the paste volume has a significant contribution on the compressive strength of SCC. Results indicate also that the difference in chemical composition between MP and cement have not any contribution on the paste volume effects.