Mechanical properties of structural concrete containing very fine aggregates from marble cutting sludge

The marble extraction industry has a significant impact on Portugal's economy, but it is also responsible for important environmental impacts. Large amounts of waste are produced every year that can be as much as 80-90% of all the materials extracted. Therefore, solutions must be found that will satisfy the increasing production of this waste. The aim of this research is to evaluate the mechanical performance of concrete with various incorporation ratios of sludge from the marble extraction industry as cement replacement (0%, 5%, 10% and 20% of the total volume of cement), as well as with plasticizers. Workability and bulk density tests were carried out on fresh concrete, while compressive strength, splitting tensile strength, modulus of elasticity, ultrasonic pulse velocity and abrasion resistance tests were performed to evaluate the relevant properties of concrete in the hardened state. It was found that the mechanical properties of concrete containing sludge from the marble extraction industry tend to decline. However, satisfactory results were obtained for replacement ratios of up to 10%, thereby validating the use of this concrete in the construction sector. Regarding the use of plasticizers, it was observed that they improve the mechanical performance of concrete with marble sludge by offsetting the decline of its properties relative to conventional concrete. (C) 2015 Elsevier Ltd. All rights reserved.