Technical Properties of Concrete Mix

When performing products made of reinforced concrete or pouring monolithic structures, perhaps the most important property of a concrete mixture is called workability or as it is also called formability - it is the ability of a concrete mixture to fill the mold with the chosen sealing method and at the same time maintain its uniformity. When evaluating this property, the following characteristics are used:
• Mobility of the mixture - strength structural characteristic;
• Stiffness is a characteristic of the dynamic viscosity of a mixture;
• Coherence - shows the ability of water separation of the mixture in the settling process.
The mobility of the resulting "liquid stone" is determined by measuring its build-up of the cone made from the test mixture. The precipitation is determined as the average of two values of the cone measurements, made from one sample of the composition. In the case where the cone sludge is zero, the workability of the mixture is characterized by its rigidity.
The stiffness of concrete, or more precisely of its mixture, is determined by the vibrating time required to make it smooth and compacted with a pre-poured concrete cone embedded in the stiffener. The device has an internal cylindrical ring with a diameter of 240 mm and a height of 200 mm. In this ring, place the standard cone and fill it with a mixture, after which the cone is removed. The instrument disk is lowered onto the surface of the formed cone from the test mixture using a tripod. After that, the stopwatch and the vibration pad are simultaneously turned on. The vibrating platform works until the release of the cement mixture through the five-millimeter hole of the disk begins. At this moment, the time is fixed. This is the time of vibration compaction and it is a characteristic of the stiffness of the concrete mixture. Two measurements are made for the same composition, and the final time is defined as the averaging of the two measured values.
Such a property as connectivity characterizes the homogeneity of the concrete mixture and the general properties of concrete. Preservation of uniformity of a concrete mix at its transportation, filling in the form and consolidation is the extremely important and difficult task. In the process of compaction, the components of the mixture of grains converge and a certain amount of water is released, which is pressed upwards.
One of the main ways to combat the stratification of a concrete product is to reduce the amount of water in the preparation of the initial composition of concrete, the use of various plasticizing constituents, and also to improve the water-retaining capacity of the mixture by means of a more careful selection of the original grain components.