The Examination of Heavy Metals Leaching from Fly Ash Concrete: An Extension

Overview

Purpose: The purpose of this project is to 1) examine the leaching of heavy metals from fly ash concrete by testing water samples for metals (found in fly ash) from concrete that is frozen, sitting in salt water, acid rain, river water, and distilled water. 2) to see if the various weathering(s) impact the amount of leaching of heavy metals and 3) to see if the results are dose-dependent, meaning that the greater the proportion of fly ash in the concrete, the more the fly ash metals will leach into the water. Hypothesis: It is hypothesized that 1) heavy metals will leach out of fly ash concrete. 2) It is hypothesized that the greatest amount of leaching will come from the concrete that is frozen and sitting in acid rain and less leaching from the concrete that is sitting in distilled water. In addition, 3) the results will be dose-dependent, meaning that the greater the proportion of fly ash in the concrete, the more the fly ash metals will leach into water. Procedure: Three types of concrete were made including: a control concrete sample with 0% fly ash, a 30% fly ash sample, and a 50% fly ash sample. For each type of concrete, five samples were made. The concrete was poured tubular molds. The concrete samples were put into fifteen glass containers with 600 milliliters of water in each container. Distilled water was used for the freezing samples. After a month of weathering (from, freezing, salt water, distilled water, river water and acid rain) the water samples in which the concrete was weathered were tested for heavy metals with a Sensafe heavy metals testing kit. Data: The data indicates that the metals in fly ash are leaching out of the concrete in small amounts the largest being the 50% fly ash concentration weathered by freezing with 600 ppb. The second greatest amount for the heavy metals being 50% fly ash soaked in river water with 220 ppb. The smallest amount of leaching for any sample was the salt water sampling with the greatest amount of leaching only reaching 20 ppb. Conclusion: Hypothesis 1 can be accepted because heavy metals did leach out of the concrete samples. Hypothesis 2 is strongly supported by the data showing that the results are weather dependent due to the massive amounts of leaching from the frozen sample. Hypothesis 3 is also strongly supported by the data. The 50% samples have the greatest amount of leaching across all samples the only sample that comes close except for the frozen sample which reaches 550 parts per billion close to the largest amount of 600 parts per billion.

Competition history

• AJAS 2019 Category not listed

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