Restrained shrinkage cracking: the role of shrinkage reducing admixtures and specimen geometry

10.1617/13799 ◽  
2002 ◽  
Vol 35 (246) ◽  
pp. 85-91 ◽  
Author(s):  
W. J. Weiss
Keyword(s):  
Specimen Geometry ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Restrained Shrinkage Cracking ◽  
Shrinkage Reducing Admixtures

Control of Cracking with Shrinkage-Reducing Admixtures

1997 ◽  
Vol 1574 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Surendra P. Shah ◽  
Shashidhara Marikunte ◽  
Wei Yang ◽  
Corina Aldea
Keyword(s):  
Drying Shrinkage ◽  
Plain Concrete ◽  
Type Specimen ◽  
Wire Mesh ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Restrained Shrinkage Cracking ◽  
Tensile Forces ◽  
Parking Garages ◽  
Shrinkage Reducing Admixtures

Shrinkage cracking can be a critical problem in concrete construction, especially for flat structures such as highway pavements, slabs for parking garages, and bridge decks. One way to reduce the shrinkage cracking is to provide reinforcement in the form of wire mesh to resist tensile forces. In recent years, short, randomly distributed fibers have been used to control shrinkage cracking. The efficiency of shrinkage-reducing admixtures (SRAs) in controlling restrained shrinkage cracking of concrete is reviewed. A ring-type specimen was used for restrained shrinkage cracking tests. The SRA selected for this investigation was a propylene glycol derivative, which was used at 1 and 2 percent by weight of cement. Free (unrestrained) shrinkage, weight loss, compressive strength, and fracture toughness were also investigated. The results of SRA concretes were compared with that of plain concrete with the same water-to-cement ratio. A theoretical model based on nonlinear fracture mechanics was developed for predicting transverse cracking of the concrete ring specimen caused by drying shrinkage. The model prediction of time to cracking compared well with the experimental data. The model can be extended to different geometries and dimensions than those considered in this research.

Strengthening of a Bridge Pier with HPC: Modeling of Restrained Shrinkage Cracking

2016 ◽  
Vol 711 ◽  
pp. 1027-1034 ◽  
Author(s):  
Adriano Reggia ◽  
Sara Sgobba ◽  
Fabio Macobatti ◽  
Cristina Zanotti ◽  
Fausto Minelli ◽  
...  
Keyword(s):  
High Performance ◽  
Mechanical Performance ◽  
High Performance Concrete ◽  
Numerical Models ◽  
Experimental Tests ◽  
Concrete Bridges ◽  
Restrained Shrinkage ◽  
Shrinkage Cracking ◽  
Rc Structures ◽  
Restrained Shrinkage Cracking

After more than fifty years from the opening of the largely discussed “Autostrada del Sole” Highway in 1964, the infrastructure system in Italy appears marked by the passing of time, similarly to what observed in several other countries worldwide. The great heterogeneity of the Italian landscape has determined a great variety of construction types, such as large span concrete bridges over the northern rivers and large arch concrete bridges over the valleys of the central region. Increment of vehicle traffic and new seismic regulations are setting new requirements to adapt the existing infrastructure, which should be otherwise replaced. Moreover, reinforced concrete (RC) aging and deterioration have led to structural and material degradation, including severe cracking and corrosion. Specialized materials such as High Performance Concrete (HPC) could represent a viable convenient solution for repairing, strengthening and retrofitting of RC structures as both structural capacity and durability can be refurbished. However, alongside high mechanical performance, HPC is characterized by a high cracking sensitivity at very early age, due to its high stiffness and shrinkage. Restrained shrinkage cracking, particularly significant in repaired structures where the existing concrete generates a considerable restraint against the free movement of the repair material, may represent a limit to the effective application of these materials. For this reason, shrinkage compatibility of HPC with the existing concrete substrate needs to be experimentally and numerically assessed. A study is herein presented where, based on experimental tests, different numerical models are developed and compared to assess and eventually minimize the risk of shrinkage cracking in bridge piers strengthened with HPC.

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