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.

Sand–bentonite mixtures are used in road embankments as a protective material for protecting underground high-voltage cables and utility pipelines supplying water and gas etc. The sand–bentonite mixtures provide benefits while laying high-voltage cables. The purpose of this study is to determine the proportions as well as mechanical and thermal properties of a dry-mixed sand–bentonite mixture and to investigate the suitability of such mixtures for installation around high-voltage underground power lines in road embankments. When selecting a sand–bentonite mixture, the following requirements must be ensured: the compressive strength must be greater than 0.5 MPa after 24 h; the thermal resistivity must be greater than 1.2 K m/W (thermal conductivity 0,833 W/(K m)); and the moisture content of the sand–bentonite mixture must be less than 13%. The following materials were used when selecting the bentonite mixture: bentonite, 0–4.0 mm fraction sand, cement (CEM I 42.5R), and water. In this study, six groups of samples were formed, in which the parts of concrete, sand, cement, and water were added in different proportions. The strength and thermal conductivity of the samples were analyzed. Studies about the use of bentonite around high-voltage cables have revealed the need for wet mixing of bentonite suspensions. The required thermal conductivity properties of the soil were not achieved by dry mixing. This method of mixing can be useful only in cases when the thermal conductivity of the mixed soil is not relevant, because the work can be continued after a day.

Straipsnyje yra apžvelgtos grunto liekamosios deformacijos ir įvertintas liekamasis grunto deformacijų modulis esant skirtingam grunto apkrovimų ciklų kiekiui. Šie tyrimai leidžia prognozuoti inžinerinio geologinio pagrindo, kuris perima apkrovas, elgseną esant skirtingam apkrovimo ciklų kiekiui (intensyvumui). Bandymai atlikti su triašio slėgio aparatu, imituojant automobilių kelių sukeliamas ir perduodamas apkrovas pagrindams. Gruntas ištirtas esant skirtingiems apkrovų intensyvumams ir grunto gyliams. Gauti rezultatai parodė, kad liekamasis grunto deformacijų modulis labai priklauso nuo grunto bandinio apkrovimo ciklų kiekio ir apkrovų intensyvumo. Nustatyta, kad bendrosios tirto grunto deformacijos nebuvo didesnės nei 2,0 %. Matuojant bandinio vertikalias deformacijas ties bandinio viduriu, liekamosios deformacijos nebuvo didesnės nei 0,5 %. Gauti rezultatai yra labai vertingi prognozuojant / modeliuojant inžinerinio geologinio pagrindo elgseną esant skirtingam apkrovų ciklų kiekiui ir intensyvumui. Rezultatus galima lengvai pritaikyti tokio paties grunto sluoksnio skirtingiems gyliams (įvertinti liekamąjį grunto sustiprėjimą).

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This article represents traffic loads on the road structure distribution and evaluation of the vertical and horizontal stresses formation in the soil embankment. This evaluation allows to predict the depth and intensity of the propagation of additional stresses resulting from traffic loads. The calculations were performed in accordance with four normative documents applied in Lithuania, which define the loads on the road structure. The obtained results showed that the area to which the load is distributed has the greatest influence on the intensity of stresses and the distance of propagation. The maximum horizontal stress in the embankment was found to be no more than 70 kPa and the maximum stress propagation depth did not exceed 0.9 m. The results can be applied to a triaxial test apparatus to restore horizontal stresses in the embankment. It is recommended to select a lateral pressure from 20 kPa to 70 kPa for tests provided with triaxial test device. The mechanical properties of the soil determined with triaxial test device and recommended lateral pressure would be representative of the test results obtained in the field of embankment.