Investigating the effect of the combination of nano-clay and reed ash (Phragmites australis (Cav.) Trin. ex Steud.) on stabilization of the fine aggregate earthy bed of forest roads

Today, the use of the biological stabilizers of soil such as ashes and nano-particles has been concerned to accelerate and improve the stabilizing process of the swelling soil of road bed. In this study the swell soil was brought from the routes of recommended forest road in district two of Bahramnia forest management plan in Golestan province according to the appearance and performance properties of soil. At first, for preparing the soil stabilization treatments the mixtures of 0.5% montmorillonite nano clay and 2% reed ash (Phragmites australis (Cav.) Trin. ex Steud.), 1% nano clay and 4% ash, 1.5% nano clay and 6% ash and 2% nano clay and 8% ash were added to soil and then mixed for 5 minute to access homogenous mixture without lump. After the curing time of 7, 14 and 28 days from the stabilization time, the Atterberg limit, standard proctor, unconfined compressive strength and Californian bearing ratio tests were done for 4 replications on mixtures of soil and control sample. Results showed that adding reed ash and nano clay increased the plastic limit and decreased the liquid limit and plastic index. Moreover, with increasing the amount of additive materials in the soil, the maximum dry density of the mixture decreased and optimum moisture content increased. The CBR and unconfined compressive strength of the mixture increased considerably until adding 1.5% nano clay and 6% ash and then adding more additive materials didn’t change the soil strength. In this study increasing the curing time, caused that the maximum dry density and soil strength to increase, whereas the plastic index of the mixture decrease. So, the optimal treatment of 1.5% nano clay and 6% ash and curing time of 28 day is recommended for stabilization of clay soil in study area