Chemical admixtures — Chemistry, applications and their impact on concrete microstructure and durability

https://ciks.cbt.nist.gov/bentz/Earlyagereview.pdf

A review of early-age properties of cement-based materials

Autogenous shrinkage of high performance concrete: A review

Fluid ingress is a primary factor that influences freeze-thaw damage in concrete. This paper discusses the influence of fluid ingress on freeze-thaw damage development. Specifically, this paper examines the influence of entrained air content on the rate of water absorption, the degree of saturation, and the relationship between the saturation level and freeze-thaw damage. The results indicate that whereas air content delays the time it takes for concrete to reach a critical degree of saturation it will not prevent the freeze-thaw damage from occurring. The results of the experiments show that when the degree of saturation exceeds 86–88%, freeze-thaw damage is inevitable with or without entrained air even with very few freeze-thaw cycles.

Water Absorption and Critical Degree of Saturation Relating to Freeze-Thaw Damage in Concrete Pavement Joints

....................................................................................................................................................... iii List of Figures ............................................................................................................................................... vi List of Tables ................................................................................................................................................ ix

Internal Curing: A 2010 State-of-the-Art Review

Cracking that forms between concrete placement and concrete setting is generally described as plastic shrinkage cracking The authors discuss how concave menisci may form on fresh concrete surfaces due to water evaporation Potential development of plastic shrinkage cracks may occur when concrete surface tensile stress and concrete settlement develop because of the menisci The authors focus on how mortars containing a shrinkage-reducing admixture (SRA), which is commercially available, develop plastic shrinkage cracks When exposed to the same environmental conditions, fewer and narrower plastic shrinkage cracks are shown in SRA-containing mortar than plain mortar The authors propose that pore fluid of SRA-containing mortar has lower surface tension, which can result in lower crack-inducing stresses at the mortar's topmost layer, reduced capillary tension, reduced settlement, and less evaporation

Influence of Shrinkage-Reducing Admixtures on Development of Plastic Shrinkage Cracks

Early-age cracking has been found to occur in some concrete bridge decks, slabs, and pavements when the volumetric changes associated with drying, hydration, and temperature reduction are prevented. While free-shrinkage tests can quantify length change, they may not always be sufficient for detecting materials that are prone to cracking, since the potential for cracking is influenced by complex interactions of strength gain, stiffness development, creep, shrinkage, the degree of restraint, and toughness. The simplicity of the ring test enables it to be used as a comparative test to screen potential mixture designs. From the use of this test, AASHTO developed a provisional standard ring test that establishes specimen geometry; however, the provisional standard does not provide an approach for quantifying stress development or indicating how close a specimen may be to failure. Described is a simple stress solution for quantifying the results of the ring test. Issues related to ring and free-shrinkage specimen geometries are discussed to improve the fundamental understanding of the information provided by the ring test. Also described is how elastic stress and actual stress can be compared to measure the stress relaxation in a material. To better illustrate the microcracking and visible-crack development process, acoustic-emission testing was performed. These experiments indicated that specimens with a higher level of restraint exhibited more microcracking as a part of the stress relaxation process.

Quantifying Early-Age Stress Development and Cracking in Low Water-to-Cement Concrete: Restrained-Ring Test with Acoustic Emission:

While significant research has been performed to assess the transport properties of concrete, a vast majority of previous research has focused on behavior in undamaged concrete This paper 

Brad Pease

Papers

Influence of Shrinkage-Reducing Admixtures on Development of Plastic Shrinkage Cracks

Quantifying Early-Age Stress Development and Cracking in Low Water-to-Cement Concrete: Restrained-Ring Test with Acoustic Emission:

Influence of Mechanically Induced Cracking on Chloride Ingress in Concrete

Quantifying early-age stress development and cracking in low w/c concrete using the restrained ring test with acoustic emission