Tensile Strength Bearing Ratio and Slake Durability of Class F Fly Ash Stabilized with Lime and Gypsum

Suitability of Flyash-Lime-Phosphogypsum Composite in Road Pavements

“…The gain in strength with curing period for high calcium fly ash is very high compared to that of low calcium fly ash due to presence of reactive minerals and glassy phase [15]. Addition of small percentages of gypsum 0.5 or 1.0% to fly ash lime mix increased the strength of compacted specimens at lower curing period (7 days) compared to only lime stabilized mixes [16]. It was further mentioned in this study that the contribution of gypsum is significant for curing periods up to 45 days and increases with increase in gypsum content from 0.5 to 1.0%.…”

“…direct tensile, bending, and double punch tensile and Brazilian split tensile strength test. However, out of all these methods, the Brazilian split tensile test has been widely used for the determination of indirect tensile strength by different investigators [16,19] and [32].…”

“…The effect of temperature on the durability study on the fly ash mixed with fluorogypsum, hydrated lime sludge mixed with/ without Portland cement concluded a decrease in the durability with the increase in temperature [27]. The bearing ratio tests on fly ash-lime mixes and reported that the bearing ratio can be increased with the addition of small percentages of gypsum (0.5 and 1.0%) [16]. It was further mentioned in this study that the bearing ratio of the unsoaked specimens containing 10% lime and 1.0% gypsum and cured for 28 days was 172% in comparison to 34% for unstabilized fly ash at the same curing period.…”

“…Many investigators [24,25] studied the durability of stabilised materials through slake durability tests. The effects of lime content (4, 6, and 10%), gypsum content (0.5 and 1.0%), and curing period (up to 90 days) on the slake durability characteristics of class F fly ash reported that unstabilized fly ash samples and samples stabilized with 4% lime does not even last for first cycle at all the curing periods whereas, additions of small percentages of gypsum (0.5 and 1.0%) in fly ash-lime mixes improved the durability characteristics at 28 days of curing [16]. Slake durability test on the fly ash, lime and gypsum mixes in order to assess the resistance offered by a fly ash mix to weakening and disintegration when subjected to two standard cycles of drying and cooling on specimen cured for 28 and 56 days reported that slake durability index for fly ash mix without gypsum varied from 96% to 97% during the 1st cycle for 28 days cured specimen and increased marginally for 56 days cured specimen [2].…”

“…Generally a recycled construction material should satisfy the requirements of strength [21]. The tensile strength of a class F fly ash stabilized with lime (4, 6, and 10%) alone or in combination with gypsum (0.5 to 1.0%) varied between 309 and 1,084 kPa for 45 days curing [16]. One of the most important properties that the stabilized mixes should have is the ability to retain its strength over the year when exposed to the destructive forces of weather.…”