Many types of the corrosion of Portland cement stone immersed into inorganic liquid media are conditioned by chemical exchange reactions between the substances dissolved in them and cement hydration products. To prevent the corrosion formation in corrosive media it is necessary to form cement clinker hydration products that do not enter into ion exchange reactions in the solutions. The concrete structure defines the penetration rate of corrosive ions and that of the removal of corrosion products, in other words the behavior of corrosive processes. The investigations that were carried out showed that the presence of finely dispersed organogenic calcite (chalk) in the cement stone composition results in a change of the phase composition of the hydrates of new formations, i.e. it results in a decreased content of the free calcium hydroxide and the binding of aluminate phases to form stable hydration products. The use of this additive contributes also to the compaction of the microstructure of cement stone due to the occupation by additive grains of the vacancies in the gaps between the cement grains and due to an increased dispersion of hydration products for which calcite particles serve as crystallization centers. All these factors contribute to an increased corrosion resistance of the cement stone and the concrete exposed to the action of corrosive solutions.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

In modern construction, a large variety of small architectural forms are used, for the production of which cement concrete is traditionally used, which should have improved physical and mechanical properties and decorative properties, while having a low cost. Improvement of these properties is achieved through the use of carbonate additives - highly dispersed chalk. Experimental results show that the addition of highly dispersed chalk affects the structure of cement stone, which is represented by low-base hydrosilicates, calcium hydrocarbonate and complex compounds that create a dense structure, which reduces the permeability of the material for corrosive media. It is assumed that the addition of highly dispersed chalk improves the elastic-plastic properties, increases the crack resistance, which provides high performance properties of concrete.

The concretes used for transport infrastructure facilities are exposed to the active impact of corrosive environment; therefore, such concretes face raised demands as for water repellency, frost resistance and corrosion resistance. These properties can be improved due to the use of additives that have a different kind of effect. This research paper gives consideration to the influence of added highly-dispersed chalk on the physical and mechanical properties of concrete, in particular, water repellency and frost resistance. Experimental data show that the doping of highly-dispersed chalk results in a reduced water repellency and an increased frost-resistance of concrete. The basic physical and mechanical properties of concretes depend on the structure with a special particle packing of the matrix in the interlayers between the structure –forming elements of each level. Assumingly, the influence of added highly-dispersedchalk on the water-repellency and frost-resistance of pavement concrete is conditioned by the optimal arrangement of chalk particles (matrix particles) in the interlayers between the cement particles and the filler (structure-forming elements).

The influence of the alkaline component on the physico-mechanical properties and the structure of the clinkerless waterproof composition on the basis of Kryvyi Rih blast furnace slag and an alkaline component – sodium hydroxide – have been investigated. High and very high correlation between the compressive strength f of the composition and the alkali – sodium hydroxide – strength A/S has been established. The dependence f on A/S has an extreme wave-like pattern with maxima at A/S = 1.5% and 15-20%, which is explained by the formation of one and two series of hydration products between slag particles similarly to Portland cement-based compositions. It has been established that the hydration products of the composition are predominantly gel-like one, such as hydrosilicate gel and zeolite-like sodium calcium hydroalumosilicates; fewer crystalline hydration products include prismatic and needle-like crystals of complex salts of aluminate phases. The pore size in the composition structure mostly does not exceed 2 microns, although single pores up to 10 microns in size also occur.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry