The hydraulic transport of sediments in circular ducts that work under pressure is subject to changes in flow conditions that basically affect the pressure losses due to friction and therefore the hydraulic gradient of the flow which depends on the concentration of sediments in suspension. In this sense, in the present work the dependence of the sediment concentration of the water-fine sediment mixture on the hydraulic gradient of the flow was analyzed, for this experimental laboratory tests were carried out, in Polyvinyl Chloride (PVC) pipes with nominal diameters of 1/2", 1" and 1 1/2" for water-sediment mixtures of the ML type (clay silts), with concentrations by weight (Cw) of 1%, 3%, 5% and 7%,taking as a baseline the flow for clear waters (Cw=0%). In this sense, it is evident that there is a positive linear correlation between the flow rate of the water-sediment mixture and the hydraulic gradient (Sf) for all the concentrations studied, also fulfilling that for the same flow rate at the highest concentration of fine sediment in the mixture greater is the hydraulic gradient and vice versa. While for the same system of conduction under pressure at a higher concentration of sediments, the flow rate is lower and therefore the hydraulic gradient is also lower. On average the increase in the hydraulic gradient generated by the flow of water mixtures with fine sediment clay silt with concentrations of 1%, 3%, 5% and 7% for flow rates between 0.9 m/s to 1.8 m/s in PVC pipes, is met: for diameter 1/2" goes from 14% to 128%, for pipe diameter 1" goes from 37% to 373% and for pipe diameter 1 1/2" goes from 14% to 1" diameter pipe from 68% to 811%, increments measured over the baseline of hydraulic flow gradients with clear water.
