Incorporation of Crushed Sands and Tunisian Desert Sands in the Composition of Self Compacting Concretes Part II

Abdelhamid Rmili,Mongi Ben Ouezdou,Mhamed Added,Elhem Ghorbel 한국콘크리트학회 2009 International Journal of Concrete Structures and M Vol.3 No.1

This paper is interested in the incorporation of crushed sand and desert sand in the composition the self compacting concretes (SCC). Desert dune sand, which has a fine extra granulometry, and the crushed sand, which contains an important content of fines, can constitute interesting components for SCC. Part II consists in studying the behaviour of SCC containing various sands with different origins. These sands, with different sizes, consist of several combinations of rolled sand (RS), crushed sand (CS) and desert sand (DS). The study examines the influence of the granular combination of sands on the characteristics in the fresh and the hardened state of SCC. The results of the experimental tests showed an improvement of the workability of the fresh SCC by combining sands of varied granulometry. The addition of the DS to CS or to RS allowed the increase of the mixture viscosity but decreased the mechanical strengths. Furthermore, the CS-RS combinations increased the compressive and the tensile strengths of the studied SCC. The optimized formulations of sands gave the highest performances of the SCC.

Incorporation of CrusHed Sands and Tunisian Desert Sands in the Composition of Self Compacting Concretes

Abdelhamid Rmili,Mongi Ben Ouezdou,Mhamed Added,Elhem Ghorbel 한국콘크리트학회 2009 International Journal of Concrete Structures and M Vol.3 No.1

This paper examines the incorporation of the crushed sand (CS) and desert sand (DS) in the formation of self compacting concrete (SCC). These sands have been substituted for the rolled sand (RS), which is currently the only sand used in concretes and which is likely to run out in our country. DS, which comes from the Tunisian Sahara in the south, is characterized by a tight distribution of grains size. CS, a by-product of careers containing a significant amount of fines up to 15%, is characterized by a spread out granulometry having a maximum diameter of around 5mm. These two sands are considered as aggregates for the SCC. This first part of the study consists in analyzing the influence of the type of sand on the parameters of composition of the SCC. These sands consist of several combinations of 3 sands (DS, CS and RS). The method of formulation of the adopted SCC is based on the filling of the granular void by the paste. The CS substitution to the RS made it possible, for all the proportions, to decrease the granular voids, to increase the compactness of the mixture and to decrease the water and adding fillers proportioning. These results were also obtained for a moderate substitution of DS/CS (< 40%) and a weak ratio of DS/RS (20%). For higher proportions, the addition of DS to CS or RS did not improve the physical characteristics of the SCC granular mixture.

Incorporation of Crushed Sands and Tunisian Desert Sands in the Composition of Self Compacting Concretes Part Ⅱ: SCC Fresh and Hardened States Characteristics

Abdelhamid Rmili,Mongi Ben Ouezdou,Mhamed Added,Elhem Ghorbel 한국콘크리트학회 2009 International Journal of Concrete Structures and M Vol.3 No.1

This paper is interested in the incorporation of crushed sand and desert sand in the composition the Self Compacting Concretes (SCC). Desert Dune Sand, which has a fine extra granulometry, and the crushed sand, which contains an important content of fines, can constitute interesting components for SCC. Part II consists in studying the behaviour of SCC containing various sands with different origins. These sands, with different sizes, consist of several combinations of Rolled Sand (RS), crushed sand (CS) and Desert Sand (DS). The study examines the influence of the granular combination of sands on the characteristics in the fresh and the hardened state of SCC. The results of the experimental tests showed an improvement of the workability of the fresh SCC by combining sands of varied granulometry. The addition of the DS to CS or to RS allowed the increase of the mixture viscosity but decreased the mechanical strengths. Furthermore, the CS-RS combinations increased the compressive and the tensile strengths of the studied SCC. The optimized formulations of sands gave the highest performances of the SCC.

Incorporation of CrusHed Sands and Tunisian Desert Sands in the Composition of Self Compacting Concretes Part I: Study of Formulation

Rmili, Abdelhamid,Ouezdou, Mongi Ben,Added, Mhamed,Ghorbel, Elhem Korea Concrete Institute 2009 International Journal of Concrete Structures and M Vol.3 No.1

This paper examines the incorporation of the crushed sand (CS) and desert sand (DS) in the formation of self compacting concrete (SCC). These sands have been substituted for the rolled sand (RS), which is currently the only sand used in concretes and which is likely to run out in our country. DS, which comes from the Tunisian Sahara in the south, is characterized by a tight distribution of grains size. CS, a by-product of careers containing a significant amount of fines up to 15%, is characterized by a spread out granulometry having a maximum diameter of around 5mm. These two sands are considered as aggregates for the SCC. This first part of the study consists in analyzing the influence of the type of sand on the parameters of composition of the SCC. These sands consist of several combinations of 3 sands (DS, CS and RS). The method of formulation of the adopted SCC is based on the filling of the granular void by the paste. The CS substitution to the RS made it possible, for all the proportions, to decrease the granular voids, to increase the compactness of the mixture and to decrease the water and adding fillers proportioning. These results were also obtained for a moderate substitution of DS/CS (< 40%) and a weak ratio of DS/RS (20%). For higher proportions, the addition of DS to CS or RS did not improve the physical characteristics of the SCC granular mixture.

Incorporation of Crushed Sands and Tunisian Desert Sands in the Composition of Self Compacting Concretes Part II: SCC Fresh and Hardened States Characteristics

Rmili, Abdelhamid,Ouezdou, Mongi Ben,Added, Mhamed,Ghorbel, Elhem Korea Concrete Institute 2009 International Journal of Concrete Structures and M Vol.3 No.1

This paper is interested in the incorporation of crushed sand and desert sand in the composition the self compacting concretes (SCC). Desert dune sand, which has a fine extra granulometry, and the crushed sand, which contains an important content of fines, can constitute interesting components for SCC. Part II consists in studying the behaviour of SCC containing various sands with different origins. These sands, with different sizes, consist of several combinations of rolled sand (RS), crushed sand (CS) and desert sand (DS). The study examines the influence of the granular combination of sands on the characteristics in the fresh and the hardened state of SCC. The results of the experimental tests showed an improvement of the workability of the fresh SCC by combining sands of varied granulometry. The addition of the DS to CS or to RS allowed the increase of the mixture viscosity but decreased the mechanical strengths. Furthermore, the CS-RS combinations increased the compressive and the tensile strengths of the studied SCC. The optimized formulations of sands gave the highest performances of the SCC.

New MoO3-CeO2-ZrO2 and WO3-CeO2-ZrO2 nanostructured mesoporous aerogel catalysts for the NH3-SCR of NO from diesel engine exhaust

Jihene Arfaoui,Abdelhamid Ghorbel,Carolina Petitto,Gerard Delahay 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.95 No.-

New MoO3 or WO3 modified CeO2-ZrO2 aerogel catalysts were elaborated using the sol gel methodcombined to supercritical drying for the NO-SCR by NH3 in excess of O2. XRD, N2-Physisorption, NH3-TPD,H2-TPR and DRUV-Vis spectroscopy were used to analyse the samples. The results reveal that all theaerogel powders (ZrO2, CeO2-ZrO2, MoO3-ZrO2, WO3-ZrO2, MoO3-CeO2-ZrO2 and WO3-CeO2-ZrO2),calcined at 500 C, are nanostructured and mesoporous materials, developing essentially the diffractionpeaks of the ZrO2 tetragonal phase, which was stabilized by the presence of cerium. Ce, Mo and W specieswere found highly dispersed on the zirconia surface, their nature and the diverse interactions developedbetween them affect the crystallites size of ZrO2, acidity, reducibility, surface oxygen mobility of catalystsand influence extremely their SCR activity. Higher NO-SCR performances are obtained, between 200 and500 C, over the new ternary MoO3-CeO2-ZrO2 and WO3-CeO2-ZrO2 catalysts compared to correspondingbinary systems (CeO2-ZrO2, MoO3-ZrO2 and WO3-ZrO2). This discloses a synergism in the NO-SCR relatedto the existence of strong interactions Ce$Mo and Ce$W. Interestingly, above 90 % NO conversions intoessentially N2 (97 %) are achieved between 350 and 500 C over the most efficient MoO3-CeO2-ZrO2ternary catalyst.