NATURAL CRUSHED ROCK AS AGGREGATE FOR ULTRA HIGH STRENGTH CEMENT CONCRETES

Abstract

Because of strong competition and new trends of concrete construction, cement industry is
starting to offer cement of high class in world markets (62.5; 72.5; 82.5) with whom production of
ultra hard concretes of 100 MPa up to 250 MPa of withstanding is possible. To achieve such
withstanding, not only cement of high class are needed but also rock aggregates of at least 30% higher
rigidity than the required rigidity of concrete. Technological solutions for this kind of concrete will be
highly demanded by the cement industry, civil engineering industry and industry for the exploitation of
raw mineral materials. Production of such crushed aggregates will find its use in the production of ultra
high rigidity concretes and will open new surroundings.
This paper offers the overview of tests in laboratories conducted on samples of aggregates made of
gabbro rock under Nero Zimbabwe’s name, as an initial phase of research. In later phases it
covers a larger number of above mentioned samples from various excavation sites, with a special
accent on these kinds of sites in former Yugoslavia. It is expected that these premises may have
reserves of rock aggregate resistant to pressures of 150 MPa to 330 MPa which would open
possibilities of constructing ultra high rigidity concretes.
In addition to analyzing the required production of ultra high strength concrete, the authors consciously
point out the problem of interpreting the mechanical characteristics of the material. The technical
profession does not consider the physical state of the investigated materials, where the compressive
strength of concrete is in the form of relative strength. From the aspect of legal sciences, the concept of
relative at the construction of large and small objects can cause legal consequences for the constructor
and its profession.