The study of strength of sandy soils reinforced with cement with the addition of «DorZem Ds-1», for use in the construction of foundations of roads

Abstract

Currently, road organizations are faced with the problem of increasing the bearing capacity of the layers of road pavement. This problem can be solved by using new design solutions, technologies and materials. The use of local road construction materials, industrial waste, stabilization and strengthening of soils in the foundations of the pavement will increase the bearing capacity of the pavement, reduce transportation costs for the delivery of materials and reduce the cost of construction. Strengthening of soils – a set of measures to improve their strength and water resistance. In the process of strengthening the soils for use in the foundations of the pavement the main task is to obtain a new building material with the desired structural and mechanical properties. The process of strengthening is a process of structure formation, new connections are created by influencing the soil structure-forming binders (cement, lime, organic binders, etc.). When stabilizing the properties of soils, mainly the content of water in the soil, use stabilizers. They usually are water-repellent additives. When strengthening the soil can use different types of modifiers: Russian and foreign. We used the modifier «Dorzem DS-1». It is a powdery substance. The use of «Dorzem DS-1» fundamentally changes the process of crystallization. The mechanism of binding of soil particles changes from «bonding» to the «plexus» – when hitting the «Dorzem DS-1» in the ground begin to form crystalline dlinnorylye of communication, which «envelop» all the elements. On the strength of they, like Kevlar thread (strong, flexible). Due to this, strong, wear-resistant structures are obtained (cement, lime, organic binders, etc.). Several years in a row on the instructions of road construction organizations of the city of Bryansk employees of the Department «Roads» BGITU conducted research to strengthen clay soils. Recently, road organizations began to prefer sandy soils. They are enough in the Bryansk region, but they are mostly fine-grained and dusty. Performing the task of LLC «Bryansk road construction company №1», we have previously been installed grain composition of sandy soil. Its density and humidity were determined. From the silty sand specimens have been fabricated reinforced soil using Portland cement grade 400, modifiers the «Palace area DS-1» and water for mixing, tested. The samples had cuboid shape with dimensions: 10х10х10 cm and 7х7х7 cm. The compressive strength was determined as the average value of four samples in a series made from a mixture of one composition. The Age of the samples during the tests was 28 days, which corresponds to the brand strength of the main mineral binder of the 1st type (Portland cement) – GOST23558-94 p. 6.1. Laboratory tests of samples from the soil treated with cement and cement plus the additive «Dorzem DS-1» showed that the greatest strength can be achieved by adding to the soil 12 % of the cement over the weight of the soil and 3 % of the additive. The strength obtained in this case is 4,882 MPa, i.e. about 5 MPa. In the manufacture of samples of hardened soil cement with one (12 % in excess of the weight of the clay) strength is much lower 3,712 MPa. This pattern is observed in other formulations of recipes. The use of additives «Dorzem DS-1» in strengthening the soil can improve the performance of water resistance and frost resistance, eliminate the formation of cracks.