What is the Difference Between Cementation and Compaction

The key difference between cementation and compaction is that cementation refers to the process of gluing together sediments by minerals that are coming out of supersaturated water, whereas compaction refers to the smooshing together of deposited sediments by the weight of water and the settlement of other sediments on top of it.

Cementation and compaction are important terms in soil sciences. Cementation is the hardening and welding of clastic sediments by the precipitation of mineral matter in the pore spaces. Compaction or soil compaction is the application of stress to a soil that can cause densification as air is displaced from the pores between the soil grains.

CONTENTS

1. Overview and Key Difference
2. What is Cementation 
3. What is Compaction
4. Cementation vs Compaction in Tabular Form
5. Summary – Cementation vs Compaction

What is Cementation?

Cementation is the hardening and welding of clastic sediments by the precipitation of mineral matter in the pore spaces. Clastic sediment in this context refers to sediments that are created from preexisting rock fragments. Cementation can be described as the last stage in the formation of sedimentary rock.

The process of cementation usually involves ions that are carried in groundwater chemically precipitating to form new crystalline materials between sedimentary grains. In this process, “bridges” are formed by the new minerals that fill the pores between original sediment grains and old ones. Therefore, they can bind them together. In this way, sand becomes sandstone, and gravel becomes conglomerates or breccia.

Furthermore, cementation occurs as a part of the diagenesis or lithification of sediments, and it takes place primarily below the water table without taking the sedimentary grain size into account. In addition, it requires a large amount of pore water to pass through sediment pores for new mineral cement to crystallize.

What is Compaction?

Compaction or soil compaction is the process of application of stress to a soil that can cause densification as air is displaced from the pores between the soil grains. In contrast, if the cause of densification is water or other liquid being displaced between soil grains, then we call it consolidation, not compaction. Typically, compaction occurs as a result of heavy machinery compressing the soil. However, it can also occur due to the passage of animal feet.

In the field of soil science, soil compaction can be described as a combination of both engineering compaction and consolidation. Therefore, it can take place due to a lack of water in the soil, applied stress that comes due to internal suction and water evaporation, due to passage of animal feet, etc.

Moreover, the soil that has undergone compaction is less able to absorb rainfall, which increases runoff and erosion effects. Since the mineral soil grains are pressed together, it is difficult for plants to survive in this type of soil.

What is the Difference Between Cementation and Compaction?

Cementation and compaction are important terms in soil sciences. The key difference between cementation and compaction is that cementation refers to the process of gluing together sediments by minerals that are coming out of supersaturated water, whereas compaction refers to the smooshing together of deposited sediments by the weight of water and the settlement of other sediments on top of it.

The below infographic presents the differences between cementation and compaction in tabular form for side by side comparison.

Summary – Cementation vs Compaction

Cementation is the hardening and welding of clastic sediments by the precipitation of mineral matter in the pore spaces. Compaction or soil compaction is the application of stress to a soil that can cause densification as air is displaced from the pores between the soil grains. The key difference between cementation and compaction is that cementation refers to the process of gluing together sediments by minerals that are coming out of supersaturated water, whereas compaction refers to the smooshing together of deposited sediments by the weight of water and the settlement of other sediments on top of it.

Reference:

1. “Soil Compaction: Methods, Meaning, and Effects.” Mintek Resources, 3 Mar. 2022.

Image Courtesy:

1. “CarmelOoids” By Photograph taken by Mark A. Wilson (Department of Geology, The College of Wooster). – English Wikipédia. (Public Domain) via Commons Wikimedia
2. “Seabees compactor roller” By United States Air Force, MSgt. Rickie D. Bickle – Navy News Stand Photo ID: 070606-F-8678B-011 (Public Domain) via Commons Wikimedia