Volume 42, N. 1

January-April 2019

Maximum Tensile Strength of Sand - Coal Fly Ash - Lime Blends for Varying Curing Period and Temperature

Technical Notes

Volume 42, N. 1, January-April 2019 | PAPER (21 downloads)


The pozzolanic reactions, responsible for the resistance of soil-lime blends, are endothermic. As such, increasing the curing temperature in turn increases the strength of lime-stabilized soil. Recent research has shown that there is a maximum limit to the resistance of a specimen, based on its curing time. This study aims to predict the maximum tensile strength of sand-coal fly ash-lime blends for several curing times. To achieve that, a series of splitting tensile tests were carried out using cylindrical specimens with diameter and length equal to 50 mm and 100 mm, respectively. Lime content varied from 3% to 7%, dry unit weight ranged from 14 kN/m³ to 16 kN/m³, curing temperatures were 20, 35, 50, 65, 80 and 90 °C, curing periods were 1, 3 and 7 days and fly ash content was established as 25%. Results show that the increase in curing temperature boosts the tensile strength of sand-coal fly ash-lime blends up to a limit that varies with curing time. The porosity/lime index, defined as the ratio of the compacted mixture’s porosity and volumetric lime content adjusted by an exponent, proves to be an appropriate parameter to estimate the splitting tensile strength of the soil-coal fly ash-lime studied for all curing times and temperatures studied. Using this index, curves were obtained for the calculation of the maximum temperature that influences the resistance of the studied mixture for each curing time. An equation capable of determining the maximum resistance that can be reached in each curing time, independent of curing temperature, was also obtained through the index.

Keywords: coal fly ash, curing temperature, curing time, lime, maximum splitting tensile strength, sand, soil stabilization,

Submitted on November 30, 2017.
Final Acceptance on December 01, 2018.
Discussion open until August 30, 2019.
DOI: 10.28927/SR.421083