New approach to design concrete mix proportions by coating thickness of aggregates

Total paste volume of concrete consists of the void between aggregates(VV) and the lubricating paste for workability i.e. the surface area of aggregates(S) multiplied by coating thickness(t). So the total paste volume of concrete can be described as VP=VV+St. This study presents a new approach to design concrete mix proportions by coating thickness of aggregates. This approach is on the basis of densified mixture design algorithm (DMDA) and adopts the Fuller's curve to deduce a new method to design concrete mix proportions. There are three main processes in this approach: (1)use least squares method to draw near Fuller's curve and calculate the proportions of blended aggregates; (2)estimate the surface area of blended aggregates and coating thickness and calculate the total paste volume in accordance with the above estimated results; (3)according to the calculated total paste volume and DMDA the amount of constituted materials in concrete is calculated. This new approach will modify the design method i.e. the packing test and enlarging paste amount (VP=nVV) of original DMDA. The properties of concrete will be made more quantitative through this approach.