Effect of Curing Temperature on the Strength of Sand, Coal Fly Ash, and Lime Blends

The present research aims to quantify the influence of curing temperature ($T$), amount of lime ($L$), porosity ($\eta$), and porosity/lime ratio ($\eta /L_{iv}$) on the assessment of splitting tensile strength ($q_t$) and unconfined compressive strength ($q_u$) of sand–coal fly ash–lime blends. A series of splitting tensile and unconfined compression tests were carried out in the present work. The results show that increasing curing temperature in the blend, for the whole range of lime studied, increases $q_t$ and $q_u$. A power function fits well as the relation between $q_t$ and $q_u$ with $\eta$, and a linear function fits well the relation between $q_t$ and $q_u$ with L for all curing temperatures of the specimens. It was also shown that the porosity/lime ratio ($\eta /L_{iv}$) is a good parameter in the evaluation of $q_t$ and $q_u$ of the studied blends for the whole range of lime, porosities and temperature studied, at specific amount of coal fly ash (25%) and curing time period (28 days). The volumetric cementitious material content ($L_{iv}$) is adjusted by an exponent (0.30 for all curing temperatures blends) to end in unique correlations for each temperature. For the sand, coal fly ash, lime, moisture content, curing time period and curing temperatures, a unique relationship was achieved linking $q_t$ as well $q_u$ to $\eta ,L_{iv}$ and $T$. For a given curing time period (28 days), the relations $q_t\text{-}\eta /L_{iv}$ and $q_t\text{-}\eta /L_{iv}$ versus $T$ are shown to vary linearly up to a threshold, when asymptotes occur. Finally, the relation between $q_t/q_u$ is a constant for the whole range of $L$, $\eta$ and $T$ studied.