The Effects of Water-Reducer on Early-Age Plastic Shrinkage of Concrete

Qin, Hong Gen; Fei, Zhi Hua; Guo, Weinong; Tian, Qinghua

doi:10.4028/www.scientific.net/amm.174-177.1113

Cited by 5 publications

(3 citation statements)

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“…Further, the air content after spraying (AS) showed no relationship (r = −0.031); however, this indicator can be related to the yield stress obtained after spraying [69], which ultimately affects the mixture stiffness. The AEWR factor shows a strong negative correlation with the crack width (r = −0.863) at 1% significance, owing to the capillary pressure-reducing properties of AEWR [56]. Moreover, the compressive strength exhibited a high negative correlation (r = −0.711) at a significance level of 5%, which is consistent with Section 3.3.…”

Section: Rheological Propertiessupporting

confidence: 81%

“…In this study, the cone slump was maintained at 120 ± 30 mm, while the entrained air content was controlled within the limit of 7 ± 2% to ensure similar plastic conditions for all test series by using AEWR. AEWR possesses the ability to reduce capillary pressure in the meniscus by reducing the rate of evaporation [56]; therefore, the indicator of its content can be used to characterize the ability of a mixture to resist cracks in the plastic phase. Another important indicator for shotcrete is the air content after spraying.…”

Section: Slump and Air Content Testsmentioning

confidence: 99%

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Prediction of Plastic Shrinkage Cracking of Supplementary Cementitious Material-Modified Shotcrete Using Rheological and Mechanical Indicators

Yun,

Panov,

Han

2023

Materials

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Plastic shrinkage cracking is a complex and multifaceted process that occurs in the period between placement and the final setting. During this period, the mixture is viscoplastic in nature and therefore possesses rheological properties. The investigation of the relationship between rheological behavior and its propensity to undergo cracking during the plastic phase presents an intriguing subject of study. However, many factors influence plastic cracking, and the corresponding interaction of its effects is complex in nature. This study aimed to evaluate the impact of rheological and physicomechanical properties on the occurrence of plastic cracking in high-performance shotcrete containing various supplementary cementitious materials. To achieve this, plastic cracking was evaluated employing the ASTM C 1579 standard and a smart crack viewer FCV-30, and the rheological parameters were controlled using an ICAR rheometer. In addition, a study was conducted to assess the strength development and fresh properties. Further, a relationship was established via statistical evaluation, and the best predicting models were selected. According to the study results, it can be concluded that high-yield stress and low plastic viscosity for colloidal silica mixtures are indicators of plastic cracking resistance owing to improved fresh microstructure and accelerated hydration reaction. However, earlier strength development and the presence of a water-reducing admixture allowed mixtures containing silica fume to achieve crack reduction. A higher indicator of yield stress is an indicator of the capillary pressure development of these mixtures. In addition, a series containing ultrafine fly ash (having high flow resistance and torque viscosity) exhibited a risk of early capillary pressure build-up and a decrease in strength characteristics, which could be stabilized with the addition of colloidal silica. Consequently, the mixture containing both silica fume and colloidal silica exhibited the best performance. Thus, the results indicated that rheological characteristics, compressive strength, and water-reducer content can be used to control the plastic shrinkage cracking of shotcrete.

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Section: Rheological Propertiessupporting

confidence: 81%

Section: Slump and Air Content Testsmentioning

confidence: 99%

Prediction of Plastic Shrinkage Cracking of Supplementary Cementitious Material-Modified Shotcrete Using Rheological and Mechanical Indicators

Yun,

Panov,

Han

2023

Materials

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“…Indeed, different water reducers were tested in terms of their influence on the resistance to plastic shrinkage, and all types of water reducer exhibited satisfactory performance. The polycarboxylate water reducer provided the best performance in comparison to wood calcium and naphthalene [66].…”

Section: Plain Concrete With Admixturesmentioning

confidence: 99%

Shrinkage Behavior of Conventional and Nonconventional Concrete: A Review

et al. 2020

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Concrete is indeed one of the most consumed construction materials all over the world. In spite of that, its behavior towards absolute volume change is still faced with uncertainties in terms of chemical and physical reactions at different stages of its life span, starting from the early time of hydration process, which depends on various factors including water/cement ratio, concrete proportioning and surrounding environmental conditions. This interest in understanding and defining the different types of shrinkage and the factors impacting each one is driven by the importance of these volumetric variations in determining the concrete permeability, which ultimately controls its durability. Many studies have shown that the total prevention of concrete from undergoing shrinkage is impractical. However, different practices have been used to control various types of shrinkage in concrete and limit its magnitude. This paper provides a detailed review of the major and latest findings regarding concrete shrinkage types, influencing parameters, and their impacts on concrete properties. Also, it discusses the efficiency of the available chemical and mineral admixtures in controlling the shrinkage of concrete.

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