Diminishing natural sand resources have created a need for alternate materials for use as fine aggregate in portland cement concrete. Manufactured sands generally are more angular and contain a higher percentage of fines than natural sands, both of which can affect workability and water demand, and the properties of concrete. While manufactured sands have been used in a number of locations in North Carolina's interstate highways, only a few aggregate sources have a long service record, particularly under freezing conditions.
Much of the research on manufactured sand use in concrete has been conducted by the aggregate industry with conclusions based primarily on compressive strength. There is a general lack of information on frost durability, salt scaling resistance and permeability of concrete produced with manufactured sands, or on the effects of the higher water demands typical of manufactured sands on bleeding or segregation.
This study was conducted to analyze selected manufactured sand characteristics and to determine the effects of manufactured sands on the fresh and hardened properties emphasizing deicer salt scaling resistance of concrete. This report describes the effects of various manufactured sands on the durability of concrete, including the effects of w/c ratio and supplementary cementitious materials. A limited investigation was also conducted on the effects of overall aggregate grading and manufactured sand gradation.
