Influence du durcissement à la vapeur initiale par l'énergie solaire et de l'addition du sable de dune broyé au ciment sur les propriétés mécaniques et la durabilité des bétons

UNSPECIFIED (2022) Influence du durcissement à la vapeur initiale par l'énergie solaire et de l'addition du sable de dune broyé au ciment sur les propriétés mécaniques et la durabilité des bétons. Doctoral thesis, Faculté des Sciences et de la technologie.

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Abstract

The manufacture of Portland cement consumes a considerable amount of energy and natural resources. The introduction of the addition of powdered dune sand (PDS) in the cement production allows, in addition to the economic and ecological gain, an improvement in the performance of concretes. This improvement essentially results from three effects which act simultaneously in a complementary manner (granular, physico-chemical and chemical effect). On the other hand, in recent years, public and political awareness of environmental and energy security issues have led to the promotion of renewable energy sources and the use of renewable energy to carry out projects in a short period of time. The production rate of concrete elements plays an important role. Therefore, initial steam curing by solar energy is very necessary to achieve considerable early strength so that the molds can be reused for another casting. This is why the objective of this research work is to experimentally evaluate the combined effect of initial steam curing by solar energy and powdered dune sand (PDS) on the mechanical properties and durability of concretes. First, the effect of different PDS rates on workability was investigated. Subsequently, the effect of (PDS) content on the mechanical strengths at different ages of concrete in water-curing was studied, as well as the effects of curing modes on the mechanical strengths of specimens incorporating PDS were examined. Finally, particular attention was paid to the combined effect of (PDS) levels and curing regimes on durability parameters such as capillary absorption and resistance to chemical attack by acids (HCl) and sulphates (H2SO4). Five curing regimes were examined: water curing, solar steam curing at 42°C, solar steam curing at 26°C, subsequent water-curing for one day after three days of steam curing at 42°C and subsequent water-curing for three days three days of steam curing at 42°C. The results reveal that the partial substitution of cement by (PDS) plays a beneficial role on workability. Good mechanical strength of concrete made with 10%(PDS) was obtained after 28 and 60 days of curing. Steam curing at 42°C is more useful than at 26°C, as the pozzolanic activity of (PDS) begins to be significant by the third day. Irrespective of (PDS) rate and steam curing method the flexural strength was very similar to that of compressive. The results also show the beneficial effect of the technique of subsequent water-curing for three days after three days of steam curing at 42°C on the physical and mechanical properties and on the resistance against chemical attack of HCl and H2SO4 acids on concrete containing 10% PDS.

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