| abstract |
Method of producing monolithic mainly cementbound concrete in the density range of 650-1300 kg/m3, preferably of 800-1200 kg m3 with substantially good placing properties both for building in situ and prefabrication. The concrete consists of cement mortar with an air-void volume of 7-18% of the total concrete volume and aggregate consisting of lightweight organic or inorganic material. The smaller particles of the aggregate should be spherical, exceptionally lightweight, hydrophobic and durable against deformation in order to reduce the water content without changing the consistency of the concrete. The production of concrete is based on the aggregate having a continuous distribution of particle size within which the particle density decreases with decreased particle size, that during mixing small as well as big air-voids are created with strengthened and thickened bubble walls, that the thixotropy of the cement paste is strengthened and that air bubbles are replaced with an equivalent volume of sand particles in excess of those which are needed for the creation of air bubbles. The effects are achieved with multifunctional polymer microparticles on which different surfactant systems have been adsorbed. Air bubbles with their thickened walls as well as the most lightweight aggregate particles reduce the difference in density between the continuous medium and the air bubbles - aggregate particles. |