Étude des propriétés mécaniques des sables traités au ciment dans le cas de sables contaminés par une argile kaolinique

Résumé

Dans le cadre d'une étude des possibilités d'utilisation des gisements de sables argileux pour la construction des chaussées, ce travail, basé sur les conclusions d'une précédente note concernat l'aptitude au compactage des mélanges sable-argile-ciment, porte sur la détermination des propriétés mécaniques de ces matériaux ternaires tassés à leur densité sèche maximum.

On donne une description du dispositif expérimental; on étudie les variations de la résistance à la comprresion en fonction de la teneur en argile, de la densité sèche, du dosage en ciment et du temps de cure ainsi que l'effet d'une insuffisance de compactage ou d'une immersion. On propose une interprétation structurale des résultats.

Summary

The authors examine the mechanical properties of clayey sand test specimens treated with cement, previously brought to a state of maximum compactness by static compaction. The dry density and the water content are obtained by packing the material mass in a given volume. The quantity of material needed is calculated from dynamic test results. A description is given of the test device designed and buit for this work.

The test pieces are then subjected to compression test up to failure. The influence of clay content, dry density, cement content and curing time on the strength and the shape of the stress-strain curves is then discussed. This emphasizes the fact that deformability and strength increase with the clay content, as long as this material only constitutes a pore phase. A structural interpretation of the whole mechanical behaviour is proposed.

The study is completed by mechanical tests on specimens which are purposely insufficiently compacted and on test specimens after immersion: the presence of clay increases the sensitivity to compaction and the loss of strength after immersion, but in this case the relative loss of strength compared with clean sand shows an acceptable limit as long as the clay content does not exceed20%, a value which can be considered as presenting the real possibilities of practical application.