The aim of this article – to determine short term and long term strengthening of clay soil, by strengthening it with fly ash obtained during the production of mineral wool. This article introduces research which is used to determine the optimal ratio of fly ash in cement suspension for strengthening of clay soil. Samples which were investigated in this research work prepared by mixing Portland cement, mineral wool fly ash, clay powder, sand and water. All investigated samples compressive strength after 6 months exceeded 1.7 MPa. It is enough of such strength in geotechnics to conduct strengthening of soil and it is possible to argue that soil is strengthened.

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Abstract. Just as other structural elements, ground slabs are an important unit of a building. It is especially true in the case of buildings, such as logistic centres, for which the primary purpose is storage of various goods. In this kind of buildings, floor slabs usually have high loads. For buildings where truck lifts are used, there are special requirements for flatness tolerance across and along the driving track of truck lifts. Therefore, the floor settlement differences in selected distances are limited. In localities where the soils under the floor slab are weak, they should be replaced or compacted. If these solutions are not possible or economically inappropriate, the slabs have to be supported on piles that must be based on strong deep soils. During the design process, it is very important to assign a proper value of rigidity of the piles. Pile stiffness has an enormous influence on the settlement of the slab as well as on the reinforcement intensity of the slab or even on the slab thickness. This paper presents the methodology for the evaluation of pile stiffness. In addition, it provides recommendations for the calculation of the floor slab on the piles. Calculations and obtained results confirmed the importance of certain design stages.

Abstract. This article studies technological, physical and technical properties and corrosion resistance of cement-sand slurry. Comparative data of the strength of test samples made on mortars of equal mobility with a composition of 1:1 (C: S) using river sand with fineness moduli (Mf): 1.50; 1.35; 1.25, showed the best results in the latter case. The use of the "Mylonaft M1" plasticizer in the solution in an amount of 0.5 % of the mass of the cementing with sand with Mf = 1.25 allowed to keep the mobility of 200 mm at W/C ratio = 0.6 without loss of the mixture homogeneity. Investigation of the corrosion resistance of sample mortars with the introduction of 1 % Na2SO4 into it during the process of its preparation made it possible to achieve stability in aggressive sulfate media at low (T = 20 °C) and normal temperatures (T = 5 ° C). In order to mechanize the work on strengthening the loess soils with cementing slurry the traditional equipment used in the production (stationary solution station with a compressor and a pump) has been compared with the advanced mobile unit UNB-125 × 50 SO on the basis of KamAZ 363501.

The ground floors of buildings usually have high loads from racks and other storage equipment in industrial buildings and logistics centers. Such types of buildings commonly require lift trucks. Therefore, there are special requirements for flatness tolerance across and along the driving track of truck lifts. Structural design solutions must be optimized and sustainable. The article reviews the behavior of soils and the importance of the actual behavior assessment of soils during the design of the ground floor on the elastic subgrade. The behavior of the ground floor’s areas above pile foundations that support the building’s columns is essential. Calculation results show the impact of subgrade stiffness on the behavior of reinforced concrete (RC) floor slab, especially in areas above pile foundations, where the stiffness of subgrade is much higher. The research provides a solution to achieve the required level of settlement dissimilarity in areas where there are piles underneath a building slab under the columns. The paper proposes a new integrated method for the evaluation of the subgrade reaction coefficient above the pile cap. The proposed method optimizes design time and eliminates the need for specialized geotechnical software. Obtained results confirmed the efficiency of the proposed design method.