Improving Mortar Crack Resistance with Hardwood Pulp Fiber as an Internal Curing Agent
Presenter Status
Undergraduate Student
Session
F-4
Location
CSH Room 108
Start Date
9-5-2014 3:30 PM
End Date
9-5-2014 4:00 PM
Presentation Abstract
Early-age crack development in cementitious materials often poses concerns over the long-term durability of the structure in which they are employed. When restrained, cracks develop in a concrete or mortar specimen as a result of tensile stresses. Tensile stresses result from shrinkage attributed to water loss. Efforts contributing to a reduction of water loss can be made via a process known as curing. Although external curing can help prevent water loss by continuously depositing water on the surface of the cementitious material, internal curing allows for interior distribution of water with the aid of the constituents of the concrete/mortar itself. The objective of this research was to observe and assess the effects of hardwood pulp fiber in cement mortar as a potential internal curing agent. Two similar volumes of mortar were cast on the same day: one with fiber and another as a control-cast without fiber. With various ASTM standards (C1581/ C1581M-09A, C157/C157M-08, C596-09, C215-08, and C496-04) as guide during the experiments, comparisons of the two types of mortar mixes indicated that the hardwood pulp fiber not only facilitated in a reduction of autogenous shrinkage in the tested mortar bar specimens, but also a three to four day delay of the visible cracking of the restrained mortar specimens.
Improving Mortar Crack Resistance with Hardwood Pulp Fiber as an Internal Curing Agent
CSH Room 108
Early-age crack development in cementitious materials often poses concerns over the long-term durability of the structure in which they are employed. When restrained, cracks develop in a concrete or mortar specimen as a result of tensile stresses. Tensile stresses result from shrinkage attributed to water loss. Efforts contributing to a reduction of water loss can be made via a process known as curing. Although external curing can help prevent water loss by continuously depositing water on the surface of the cementitious material, internal curing allows for interior distribution of water with the aid of the constituents of the concrete/mortar itself. The objective of this research was to observe and assess the effects of hardwood pulp fiber in cement mortar as a potential internal curing agent. Two similar volumes of mortar were cast on the same day: one with fiber and another as a control-cast without fiber. With various ASTM standards (C1581/ C1581M-09A, C157/C157M-08, C596-09, C215-08, and C496-04) as guide during the experiments, comparisons of the two types of mortar mixes indicated that the hardwood pulp fiber not only facilitated in a reduction of autogenous shrinkage in the tested mortar bar specimens, but also a three to four day delay of the visible cracking of the restrained mortar specimens.