No abstract

Builders in our country are not familiar with the practice of using mineral additives, as cement substitutes, in cast-in-place and in ready-mix concretes. It thus seemed important to study and evaluate the impact of these additives, as cement substitutes, on the properties of set concrete. The mineral additive used is natural pozzolan found in large quantities in Western Algeria (Béni-Saf); however, it must be beneficiated. To do so, we designed three pozzolan-based concretes (20, 25, and 30%). We measured compressive strengths at various times and produced a reference control concrete for comparison purposes.Key words: pozzolan, dosage, concrete, composition, substitution, compressive strength.[Journal translation]

Supplementary cementitious materials (SCMs) prove to be effective to meet most of the requirements of durable concrete and leads to a significant reduction in CO 2 emissions. This research studies the effect different SCMs (natural pozzolan (PN) / limestone fine (FC) at various replacement levels) on the physical and mechano-chemical resistance of blended mortar. The paper primarily deals with the characteristics of these materials, including heat of hydration, strength and effects of aggressive chemical environments (using sulphuric acid and nitric acid). Over 6 mixes were made and compared to the control mix. Tests were conducted at different ages up to 360 days. The experimental results in general showed that Algerian mineral admixtures (PN/FC) were less vulnerable to nitric and sulphuric acid attack and improved the properties of mortars, but at different rates depending on the quantity of binder.

Cement is a strategic commodity in the civil engineering for the construction of reinforced concrete structures. But its production generates around 5% of toxic gases such as CO 2 responsible for environmental degradation. Furthermore, cement industry is a consumer sector of non-renewable energy. The use in the cement of natural additions is a solution to reduce the CO 2 gas and the cost of production. The purpose of this work is the study of a sustainable building material: natural pozzolan Beni-saf (PNB) incorporated to mortars exposed to sulfate attack (5% Na 2 SO 4 ). The loss of mass, monitoring the pH reading of each attack solution as well as specimens dimensions are different tests to study the durability of mortars made with 10, 20 and 30% of natural pozzolan. The result derived from this research is that pozzolan improves mortars resistance to sodium sulfate environment.

Reinforcement corrosion is one of the main causes of concrete deterioration. The steel in concrete is naturally protected from corrosion by the presence of a passive film formed through the high alkalinity of concrete. A technique to improve the protection of steel in concrete is the inclusion of mineral additions. Natural pozzolan (NP) from Beni-Saf is a mineral addition that is abundant in western Algeria. The experiment was conducted on mortar specimens, containing steel bars and exposed to the aggressive solutions of Na2SO4 and MgSO4. The status of reinforcement is periodically monitored by measuring the electrochemical potentials and the corrosion rates by the technique of linear polarization resistance (LPR) and also the thermal conductivity was evaluated. The test results show that natural pozzolan significantly affects the physical properties of mortars, improves the corrosion resistance of mortars containing up to 20% of natural pozzolan and reduces the thermal conductivity.