Improvement of subgrade California Bearing Ratio (CBR) using recycled concrete aggregate and fly ash

The study aims to understand the effect of different admixtures on improving the quality of flexible pavement subgrades. In this paper, recycled concrete aggregates (RCA) and Fly Ash were used as the admixtures in improving the maximum dry density (MDD), swelling potential, and California bearing ratio (CBR) of subgrade soil. The percentages of RCA and fly Ash used were 5%, 10%, and 15%. With the upscaling in fly ash dosage, the optimum moisture content and the California bearing ratio increased. However, the MDD of soil decreased for higher fly ash contents. On the contrary, the optimum moisture content (OMC) of the soil decreased and the MDD and California Bearing Ratio increased with an increase in RCA content. Both RCA and fly ash-treated soil demonstrated lower values of swelling. At 5% dosage, both RCA and fly ash admixtures were found to improve CBR. However, at higher percentages (10% and 15%) of fly ash, the CBR values decreased while in comparison, soil samples performed significantly better in the CBR test with the increasing dosage of RCA. The findings of this research can be used to examine the suitability and effects of recycled aggregate and fly ash on the performance of soil in terms of CBR, particularly when the soil is planned to be used as a subgrade in highways

Temperature and humidity effects on salt crystallization in burnt clay bricks

This study offers an idea of investigating the temperature and humidity effect on salt crystallization in burned clay brick when it is subjected to a saline environment. It has been investigated that salt may be carried into masonry pores structures by moisture. As moisture production and movement are affected by temperature and humidity, the mechanism of salt crystallization is affected as well. Uniaxial Salt crystallization in burned clay bricks at different temperatures (20 °C, 30 °C, and 40 °C) and humidity (70%, 80%, and 90%) has been investigated, considering all other parameters to be constant. Analyzing the data derived from the experiment, two equations have been developed (one for temperature effect analysis and another for humidity effect analysis). Results indicate that the salt crystallization in burned clay bricks increases when the temperature of samples and sodium sulfate (Na2SO4) solution increases. However, the salt crystallization in burned clay bricks goes down when the relative humidity of the surrounding environment of samples decreases