EFFECTS OF THE GRADATION CURVE OF SUB-MM-SIZED PARTICLES ON THE PROPERTIES OF SELF-COMPACTING CONCRETE

摘要

The results of a research project to be presented in this paper is focused on the production technology, mix design, and the mechanical and workability properties of self-compacting concretes. The derived statistical mix design models were construed from the results of 101 laboratory test concretes having the spread values between 600 and 850 mm and the T_(50)-time between 2 and 15 seconds in the slump-flow test. The studied concretes were produced using a cement amount of 200—420 kg/m~3, water content 155—170 kg/m~3, a superplasticizer dosage between 2 and 10 kg/m~3, and the fly ash and calcium carbonate filler amounts were less than 200 kg/m~3. The compressive strength values of the test concretes ranged from 33. 6 to 82. 8 MPa. Air content of fresh concrete was between 0. 9 and 9%. In the laboratory tests it was noticed that, in addition to water binder ratio and superplasticizer dosage, the gradation curve and properties of the dry concrete ingredients having particle dimensions below # 0.125 mm had a remarkable effect on the properties of self-compacting concretes. Therefore, new variables taking into consideration the form of the gradation curve and particle fineness modulus between 1 and 125 μm were introduced. Three spread sheet programs were produced based on the developed statistical mix design theory.