Physical Property and Heavy Metal Leaching Behavior of Concrete Mixed With Woody Ash

Abstract

In recent years, the woody biomass power generation has attracted a lot of attention since woody biomass is an alternative energy source to fossil fuels. In the future, further implementation of woody biomass power generation is expected, and a large amount of woody ash will be discharged. Several studies have been conducted on the effective use of woody ash for construction materials. However, woody ash has not been practically used because of concerns about the leaching of heavy metals from concrete mixed with woody ash. If the above problem can be solved, a large amount of woody ash is expected to be used. In this study, the fresh property and hardened properties, such as compressive strength and length change were measured to evaluate the feasibility of using concrete mixed with woody ash. Furthermore, a heavy metal leaching test was conducted to assess the environmental impact caused by concrete mixed with woody ash. As the result, the concrete mixed with woody ash has the slump and air content similar to that of normal concrete, the compressive strength meeting the standard durability design strength in Japan, and the shrinkage is similar to that of normal concrete. Additionally, the concentration of heavy metals exceeding the soil environmental quality standards in Japan was partially detected, but the leaching amount of heavy metals from the concrete mixed with woody ash was similar to that from normal concrete.

Leaching Potential and Effectiveness of Pervious Mortar Filters in Bacteria and Turbidity Removal from Surface Water

“…Calcium can be determined directly with EDTA, if the pH of the test sample is made high enough (12)(13), so that magnesium will precipitate as magnesium hydroxide and at the end point of the titration the Eriochrome Black T (EBT) indicator will only react with calcium to form a blue solution. From this method the calcium (Ca) concentration in the water can be obtained.…”

“…This means pervious mortar or concrete can dissolve or leach if exposed to specific water qualities for an extended period (11). Leaching is a significant degradation observed in cement-based composites, representing one of the primary factors responsible for their mechanical alteration (12)(13)(14)(15)(16). This process starts when cement paste comes into contact with pure or acidic water (low pH), causing hydrolysis (17).…”

The Leaching Behavior of Pervious Mortar Used as Water Filter in Rural Areas

“…Leaching is one of the degradation phenomena that occur in concrete or cement-based composites. Leaching is one of the main factors that change the mechanical properties of cement-based composites [15][16][17][18][19]. The deterioration process known as "leaching" in the cement paste occurs due to contact with pure water or water with a low pH, which encourages the hydrolysis of hydrates [20].…”