Effects of low-dosage lime treatment on beneficial reuse of pond ash as Secondary Cementitious Materials (SCMs)

Howard Fitzgerald, Lhoist
Utsa Rashique, Lhoist
Karen Slade, Lhoist
Ian Saratovsky, Lhoist

Description

Lime treatment is an effective way to dehydrate and solidify ponded coal ash, facilitating easier handling and transportation to, and compaction in a landfill. However, questions arise regarding the impact of low lime dosage on the future beneficial reuse of the treated pond ash. One such potential beneficial reuse case is its application as a Secondary Cementitious Material (SCM), especially as a pozzolan grade fly ash for mortars and for ready mixed concrete production. Given the retirement of coal fired power plants and the resulting reduction in fresh, as-produced fly ash, exploring alternatives like reclamation and beneficial reuse of ponded ash is crucial. This study investigates the feasibility of lime-treated pond ash as a pozzolan grade fly ash. The physical and chemical properties of the treated pond ash are compared to ASTM C618 standards, showing a good match. The study involved replacing various percentages of Portland Cement in a type S masonry mortar mix with the treated pond ash sample. Testing revealed satisfactory short- and long-term strength performance, along with excellent results in various other parameters like water retention, water demand, setting time, and other properties. Overall, lime-treated pond ash proved to be a potentially effective SCM in a standard mortar mix. This is a strong indicator that low dosage lime treatment of ponded ash will not adversely impact its beneficial use as an SCM in the future.

 
May 14th, 1:30 PM May 14th, 2:00 PM

Effects of low-dosage lime treatment on beneficial reuse of pond ash as Secondary Cementitious Materials (SCMs)

Grand Rapids, Michigan

Lime treatment is an effective way to dehydrate and solidify ponded coal ash, facilitating easier handling and transportation to, and compaction in a landfill. However, questions arise regarding the impact of low lime dosage on the future beneficial reuse of the treated pond ash. One such potential beneficial reuse case is its application as a Secondary Cementitious Material (SCM), especially as a pozzolan grade fly ash for mortars and for ready mixed concrete production. Given the retirement of coal fired power plants and the resulting reduction in fresh, as-produced fly ash, exploring alternatives like reclamation and beneficial reuse of ponded ash is crucial. This study investigates the feasibility of lime-treated pond ash as a pozzolan grade fly ash. The physical and chemical properties of the treated pond ash are compared to ASTM C618 standards, showing a good match. The study involved replacing various percentages of Portland Cement in a type S masonry mortar mix with the treated pond ash sample. Testing revealed satisfactory short- and long-term strength performance, along with excellent results in various other parameters like water retention, water demand, setting time, and other properties. Overall, lime-treated pond ash proved to be a potentially effective SCM in a standard mortar mix. This is a strong indicator that low dosage lime treatment of ponded ash will not adversely impact its beneficial use as an SCM in the future.