In recent years, there have been some studies into and experiments performed regarding the use of iron ore tailings in concrete as aggregates.
One study performed in western Australia, where there is a significant amount of iron ore, has been of particular interest to concrete contractors, manufacturers and rock contractors in Lufkin, TX and beyond. The team conducting the experiment used the standard process for making concrete, with several tests conducted to measure some of the concrete’s physical properties at different ages. The results were then compared with those produced by normal concrete with conventional aggregates.
Let’s take a brief look at the experiment.
For the normal, “control” concrete in the experiment, there were conventional materials used, such as cement, granite and sand. Iron ore tailings were added to the experimental concrete along with the cement.
The tailings were split up according to particle size. Those that were 4.75 mm in diameter and below were used as fine aggregates, and those that were 10 to 20 mm in diameter were used as coarse aggregates. The concrete mix design featured a ratio of 1:2:3 (cement, fine aggregates, coarse aggregates). It was prepared in a laboratory setting. The use of the iron ore resulted in the tailings concrete having a reddish-brown hue.
There were several tests performed on the concrete after it hardened: a compressive strength test, an acid resistance and alkalinity test and an indirect tensile strength test. The acid resistance and alkalinity test was only performed on the tailings aggregate concrete, but the other tests were conducted on both concrete samples. Compressive strength was determined by dividing the maximum load observed from the compression machine by the area of the cross-section of the tested specimen, and then measured in megapascals (MPa).
The compressive strength testing results showed higher compressive strength in the iron ore tailings aggregates concrete than in the normal concrete. There was an 11.56 percent difference in strength after 28 days of curing. Iron compounds have been shown to potentially accelerate cement hydration, which could be a factor in this result.
The indirect tensile strength increases with aging for both types of concrete. After one day the indirect tensile strength was higher in the tailings concrete, but after 28 days the control mix had achieved a higher indirect tensile strength. Tensile strength is important, because it measures how well the aggregates bond to the other materials in the concrete. Higher tensile strength means less of a likelihood of tensile cracking.
The pH values for the ages of concrete ranged from 11.8 to 12.5. This means there were high alkaline conditions in the tailings concrete, which make for a low potential for corrosion and acid attack, meaning it’s a good sign for long-term durability.
Overall, the researchers concluded normal concrete could feasibly be replaced with iron ore tailings concrete. While the tensile strength was not the same as that of normal concrete, it was continuing to improve throughout the course of the study.
For more information about how a rock contractor in Lufkin, TX can assist with your project, reach out to Brown’s Paving and Excavation today.
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This post was written by Writer