Plastic Shrinkage
Plastic Shrinkage - Related Videos
01:27
Shrinkage in Concrete
0 Views •
2024
Shrinkage in concrete is primarily due to water loss from evaporation, hydration of cement, or carbonation, leading to a reduction in volume. The volumetric contraction results in volumetric strain in concrete. However, in practice, shrinkage is measured as linear strain, which is one-third of the volumetric strain. When concrete is still in its plastic state, it can undergo a decrease in volume by about 1% of its absolute volume. This decrease is known as plastic shrinkage. It arises either...
01:21
Drying Shrinkage
0 Views •
2024
When hardened concrete is exposed to air with a relative humidity of less than 100 percent, it begins to lose the free water within its capillaries. As this water evaporates, the water initially adsorbed onto the calcium silicate hydrates migrates towards these now empty spaces and eventually evaporates as well. Over time, as more water leaves, the volume of the concrete decreases, a phenomenon known as drying shrinkage. A portion of this drying shrinkage can be reversed; if the concrete is...
01:24
Carbonation Shrinkage
0 Views •
2024
Atmospheric CO2 penetrates the concrete's pores and, in the presence of moisture, forms carbonic acid, which then reacts with calcium hydroxide in the hydrated cement, forming calcium carbonate. This process reduces the concrete's volume and is termed carbonation shrinkage. The concrete's permeability is slightly reduced as calcium carbonate produced during the reaction fills its pores. Furthermore, its strength is slightly enhanced as the water released during the reaction facilitates the...
08:45
Shrinkage of Dental Composite in Simulated Cavity Measured with Digital Image Correlation
0 Views •
Cited by 12 •
2014
In order to understand the spatial development of polymerization shrinkage stress in dental resin-composite restorations, Digital Image Correlation was used to provide full-field displacement/strain measurement of restored model glass cavities by correlating images of the restoration taken before and after polymerization.
01:25
Shrinkage, Obsolescence, and Holding Costs
0 Views •
2025
In inventory-based businesses, profitability often depends on more than just sales volume or procurement efficiency. Hidden costs tied to inventory management—specifically shrinkage, obsolescence, and holding costs—can significantly erode margins if left unmanaged.Shrinkage occurs when inventory is lost due to theft, damage, or administrative errors. Even with advanced tracking systems, discrepancies remain a persistent issue, especially in retail. Regular audits, employee training, and...
FAQs
The critical imbalance occurs when surface water evaporates faster than water can rise through bleeding. As the exposed cement paste loses water, it contracts while the surrounding fresh concrete still offers resistance. That restraint converts volume reduction into tensile stress, and cracking begins when this stress exceeds the early-age strength of the material.
These conditions increase the likelihood that water will leave the concrete surface faster than bleeding can replace it. The resulting imbalance accelerates contraction before the concrete has hardened sufficiently to resist tension. Wind can intensify surface drying, while heat and low moisture conditions make environmental exposure an important part of engineering risk assessment.
The cracks are generally shallow and irregular, reflecting localized contraction at the exposed surface rather than a uniform structural movement. Although they form early, they can reduce durability and compromise surface quality. Their occurrence therefore matters both for the long-term condition of the concrete and for the acceptability of the finished surface.
Risk assessment should consider both environmental exposure and concrete mixture characteristics. Engineers examine whether hot, dry, or windy conditions may promote rapid surface evaporation, then evaluate whether the mixture and placement circumstances provide adequate resistance during the weak, fresh stage. This assessment supports selecting preventive measures before cracking develops.
Practical controls include windbreaks, sunshades, evaporation barriers, and timely curing. Windbreaks and sunshades reduce the severity of environmental exposure, while evaporation barriers help limit water loss from the surface. Timely curing is important because it addresses the vulnerable early period when evaporation can outpace bleeding and promote tensile cracking.
Appropriate concrete mixture design is one of the controls engineers can select alongside environmental protection and curing. Its role is considered during evaluation of material-related risk, rather than as a substitute for managing hot, dry, or windy exposure. Combining mixture decisions with site controls provides a broader strategy for protecting durability and surface quality.