ABSTRACT

Some roads have a gravel layer and most asphaltic roads have gravel shoulder and part of that sand is fine grained soil. Road dust increases in heavy traffic and affects safety, economy, quality and environment. Different stabilizers are used to control the dust in gravel topping roads. One of them is calcium chloride. One of its common uses is the dust control in gravel topping roads. In this research, in order to achieve the optimal mixture procedure after grading the gravel material of pavement surface layer, the effect of calcium chloride salt on the physical properties of the fine grained part was investigated in different percent of calcium chloride samples and different percent of moisture in two dry cases. Results show that increasing the calcium chloride percent in the dry case, the moisture absorption amount of the fine grained part of the gravel topping materials is increased, by contrast, uniaxial tensile and compressive strengths decrease with the increase of calcium chloride more than certain percent. The amount of calcium chloride has a reverse effect on liquid limit, plasticity limit and plastic index, conversely, uniaxial tensile and compressive strengths such that increasing the calcium chloride salt by 6% will increase the plastic limit by 6% and the liquid limit by 12% and plastic index by 25% and also the uniaxial tensile strength is increased by 11% and the uniaxial compressive strength is decreased by 36%.