An Experimental Study on the Rheological Properties of the Combined Self-Compacting Concrete by Quality Variations

Abstract

The purpose of this study is to investigate experimentally the variation factors range having influence on the rheological properties of the combined self-compacting concrete according to materials quality, weighting error and site conditions. Two types cement (blast-furnace slag cement and belite cement), lime stone powder as binder and the optimum mix proportions in the preceded study are selected for this study. Also, variations for sensitivity test are as followings; (1) Concrete temperature 3 cases (2) Surface moisture of sand 5cases (3) Fineness modulus of sand 5cases (4) Specific surface of lime stone powder 3cases (5) Dosage of chemical admixture 5cases. Slump flow (650±50 mm), 500 mm reaching time ((7±3 sec), V-type flowing time (15±5 sec) and U-box height (min. 300 mm) are tested for sensitivity. As test results, the variations range for quality control are as followings. (1) Concrete temperature; 10∼20℃(below 30℃) (2) Surface moisture of sand; base±0.6% (3) Fineness modulus of sand; 2.6±0.2 (4) Dosage of chemical admixture; base±0.2% (5) Specific surface of lime stone powder 6000 cm 2 /g. Compared with two types cement including based belite cement (binary type) and based slag cement (ternary type), the combined self-compacting concrete used belite cement type is most stable in the quality control because of high contents for lime stone powder and C 2 S. It is to propose a control scheme of the combined self-compacting concrete in the actual construction work.