Date on Master's Thesis/Doctoral Dissertation
8-2024
Document Type
Master's Thesis
Degree Name
M. Eng.
Department
Civil and Environmental Engineering
Degree Program
JB Speed School of Engineering
Committee Chair
Sun, Zhihui
Committee Member
Robinson, Brian
Committee Member
Kim, Young Hoon
Author's Keywords
internal curing; lightweight aggregate; biochar; curing
Abstract
Curing is a critical step in concrete construction. When a concrete specimen is properly cured, its shrinkage and early age curling/warping can be reduced, and the concrete strength can be increased. Curing methods can be divided into two categories: traditional external curing and emerging internal curing methods. Internal curing has similar benefits to external curing, such as reduced early-age cracking and shrinkage risk, and increased durability and strength. The purpose of this research is to investigate internal curing additives and their impact on length change, weight change, compressive strength, autogenous shrinkage, and internal relative humidity. Mortar mixtures with lightweight aggregate (LWA), biochar, and E5 internal cure were created to compare to a control mix and a mix with fly ash in each testing method. SEM imaging was additionally used to identify hydration reactions occurring in air and moisture cured specimens.
The research from this study found lightweight aggregate was an effective internal curing additive which reduced length change and allowed the internal relative humidity to remain constant. Due to its porous nature, the compressive strength of the specimens was reduced. Additives like E5 works differently from LWA. It reduced length and weight changes by floating up to the specimen surface to prevent moisture evaporation. The mortar specimen with biochar showed a similar compressive strength to the control specimens, but it caused the greatest shrinkage and expansion during the length change test.
SEM imaging concluded there were abundant hydration products around LWA, indicating its effectiveness in internal curing. The images also showed that the biochar powder used in the specimens was cut too fine and the pore structure was compromised.
Recommended Citation
Scott, Payton, "The impact of internal curing additives on compressive strength, shrinkage, and internal relative humidity of mortars." (2024). Electronic Theses and Dissertations. Paper 4409.
Retrieved from https://ir.library.louisville.edu/etd/4409
