ABSTRACT
Abstract This paper deals with a study, the purpose of which was to find out the factors affecting the workability of no-slump concrete. A new apparatus c a l l e d Intensive Compaction Tester has made t e s t s possible. Even small changes in workability can be observed by the t e s t e r . Investigations show that the workability i s improved by water, superp l a s t i c i z e r , s i l i c a fume, high-grade sand and round-shaped gravel. The workability i s deteriorated by poor sand, crushed aggregate, elevated temperature and a long delay before casting. Keywords: No-slump concrete, Workability, Testing, S i l i c a fume, Aggregate, Hollow-core slab, Superplasticizer
1 Introduction The workability of no-slump concrete has been investigated very l i t t l e . Lack of appropriate methods and equipment has been an obstacle to the research work. Presently almost a l l methods for testing workability are designed for more flowable concretes. Because of the d i f f i c u l t workability of no-slump concrete, the quality control of the concrete mix i s very important. The smallest changes i n the raw material cause so great changes in the workability that the quality of the finished products changes. I f the no-slump concrete i s properly compacted, the properties of the finished product are excellent. An example and perhaps the most common application for no-slump concrete i s prestressed, extruded hollow-core slabs. The valuable properties of no-slump concrete can a l l be u t i l i z e d in the manufacture of hollow-core slabs:
Good s t a b i l i t y before hardening. High early and grading strength by an appropriate amount of cement. The good durability and small deformations of hardened concrete.
