Avaliação da influência do tempo de cura na estabilização de solos lateríticos com adição de cal e cimento

Abstract

With the intention of seek alternative solutions in the Brazilian Highway System, this study aims to better understand the lateritic soils for use in bases and sub-bases pavements, improving its properties with the additions of lime and cement. For the materials used in this research, the soil comes from the town of Candido Godoi-RS, the lime is hydrated of the class CH-II Dolomite and the cement is of the Portland type and the class is CP-IV. As a first step, the caracterization of the soil was realized, qualifying it for three types of diferent classifications: in the MTC metodology, the soil showed to be a argillaceous laterite type; in the Unified Classification it belongs to the MH group; and for the TRB classification it belongs to the A 7-5 group. Besides the characterization tests, Physical-Chemical tests were performed to estimate the amount of lime required to be used in the mixture. For the cement content to be used the ASTM D 3282 recommendations was followed. To determine the density, and the optimum moisture of the mixture, Mini Proctor compression tests were performed. The molding of the samples (CPs) were performed using a mixtures of soil + lime and soil + cement as well as pure soil samples. The proportion of lime addition was 6% and the addition of cement was 10%. Twenty eight cylindrical CPs were molded with the dimensions of 5 x 10 cm and each composition was allowed to cure at controlled temperature for 7, 28, 56, 90, 120, 180 and 270 days. After each cure age, the samples of each mixture were subjected to simple compression test. At the end of the compression test, it was noted that the addition of soil + lime did not showed a substantial gain in strength, unlike the mixture of soil + cement, hitting 2.1 Mpa of resistence within the first seven days of cure. Another important fact is that in all mixtures there was an increase in the stiffness of the samples, thus reducing the deformations found in the final coating layer. Therefore it is concluded that there was an improvement in soil properties with lime and cement additions, with an increase of both the resistance and stiffness in all the studied soils.