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Concrete surfaces may present surface defects, such as compaction voids. Mechanisms and parameters conditioning the concrete surface's texture have been little investigated in the scientific literature. This experimental study aims to assess the influence of the paste volume, the water/cement ratio (W/C), and the rheological properties of concrete on the compaction voids. Five series of concrete mixtures were tested in order to study the formation and the behaviour of compaction voids. All the concrete mixtures were based on an identical optimized granular skeleton made of 50% of sand and 50% of coarse aggregate. In the first two series of mixtures, all the parameters were kept constant except the paste volume and the W/C. In the third and fourth series of mixtures, all the parameters were kept constant except the dosage of the superplasticizer. In the fifth series, all the parameters were kept constant except the dosage of the viscosity-modifying agent. The rheological properties and surface area of compaction voids were measured for all concrete mixtures. The results obtained show that the amount of compaction voids decreases with an increase of the mortar volume. They also point out the existence of a threshold value of slump and yield stress below or beyond which, the amount of compaction voids becomes significant.

Influencia del filler calizo en morteros de cemento portland The efect of calcareous filler on Portland cement mortars M.' JOSE ESCORIHUELA, IGNACIO MENÉNDEZ y FERNANDO TRIVIÑO ICCET/CSIC FRANCISCO HERNÁNDEZ, NORBERTO HURTADO y M.' ANTONIA MARTÍN ICCP ESPAÑA Fecha de recepción: 12-11-93. RESUMEN Se estudia la influencia que la adición de "filler" calizo a un cemento portland ejerce sobre las resistencias mecánicas de sus morteros. A partir de un cemento portland al que se le añade "filler" calizo, desde O al 50 %, se prepararon probetas de mortero normalizado. Las probetas una vez curadas a las edades de 7, 28 y 90 días, se sometieron a roturas por flexotracción y compresión, se determinaron las resistencias mecánicas y se estableció la correlación entre éstas y el contenido en "filler" calizo. Asimismo, sobre los morteros obtenidos se realizó un estudio por difracción de rayos X. SU M MAR Y The present paper deals with the influence that the addition of calcareous "fillers" to a Portland cement has on the mechanical resistances of its mortars.