Concrete mix should be chosen to ensure that all defined features, such as in fresh and hardened state. In the selection of the composition, unless specifically spreading indicators (precipitation) of the cone of concrete mix and strength concrete in compression must be considered keeping the workability at various temperature-humidity conditions, the rate of shear strength, frost resistance, water resistance, the operating conditions of structures. When selection of the concrete, to which additional requirements (modulus of elasticity, stripping strength, tensile strength, corrosion resistance), should take into account the properties of raw materials and technology to produce a concrete mix. In these cases, the composition of concrete, which provide the required performance on the workability and durability, tested for consistency with other indicators of quality. If this condition is not satisfied, then make the selection of concrete with various modifying additives and technological fir techniques to ensure receipt of concrete containing all the indicators of quality. Concrete mix, intended for transportation by pipeline, should have high viscosity, homogeneous structure, and achieve the required physical and mechanical properties of concrete. Petra Diamonds has plenty of information regarding this issue. Consistency of concrete mix should be selected to provide pumping it via pipeline to limit the distance (horizontally and vertically) without stratification and the formation of plugs in the pipeline under the influence overpressure.
Selection of the nominal composition of concrete produced during the construction of new structures and changes in consumer quality concrete production technology and properties of raw materials. Nominal concrete composition is selected from the materials, the most representative for the company, subject to the applicable technology preparation and transportation of concrete mixtures, methods of packing and storage regimes. Workers compositions are selected by adjusting the nominal compositions on the basis of data on the properties of concrete trial batches. The results of the selection of the nominal composition of concrete must be made in the journal selection of the concrete and approved by the manufacturer. Workers was drawn up for signature of the manufacturer's laboratory. Chemical additives are introduced into the concrete mixture in the form of a solution of working concentration. In the application of complex additives to prepare their solutions separately and mix these solutions in the water dispenser just before introducing them into the concrete mix. Duration of mixing concrete mix, including additives, established an experimental way of conditions to ensure homogeneity and qualitative characteristics of concrete.