Numerical Simulation of Internal Relative Humidity of Concrete Exposed to Drying

2020 ◽  
Vol 117 (6) ◽  
Keyword(s):  
Numerical Simulation ◽  
Relative Humidity ◽  
Internal Relative Humidity

scholarly journals Autogenous Shrinkage, Strength, and Hydration Heat of Ultra-High-Strength Paste Incorporating Nano-Zirconium Dioxide

2020 ◽  
Vol 12 (22) ◽  
pp. 9372
Author(s):  
Guang-Zhu Zhang ◽  
Han-Seung Lee ◽  
Xiao-Yong Wang
Keyword(s):  
Relative Humidity ◽  
Room Temperature ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Hydration Heat ◽  
Experimental Device ◽  
Hydration Reaction ◽  
Hydration Products ◽  
Internal Relative Humidity ◽  
Two Stages

Ultra-high-strength paste (UHSP) combined with nanomaterials has been extensively studied. However, the research on nano-ZrO2 is limited. In this study, UHSP with various nano-ZrO2 contents is analyzed. The motivation of this study is to clarify the effects of nano-ZrO2 on the hydration products, strength, autogenous shrinkage, and hydration heat of UHSPs. The water-to-binder ratio (w/b) of the specimens is 0.2. The nano-ZrO2 content is 0, 1.5, and 3 wt.%. The strength is measured at the age of 3, 7, and 28 days. The hydration heat is measured from the mixing stage to 3 days. The hydration products are analyzed by X-ray diffraction (XRD) and thermogravimetric analysis (TG). The autogenous shrinkage is measured from the mixing stage for 7 days using a new experimental device. The new experimental device can measure autogenous shrinkage, internal relative humidity, and internal temperature simultaneously. The following conclusions can be drawn based on the experimental studies: (1) Two stages were noticed in the autogenous shrinkage of UHSPs: a variable-temperature stage and a room-temperature stage. The cut-off point of these two stages occurred in roughly 1.5 days. Furthermore, in the room-temperature stage, there was a straight-line relationship between the autogenous shrinkage and internal relative humidity. (2) With the increase of the nano-ZrO2 amount, the compressive strength at 3 days, 7 days, and 4 weeks increased. (3) With the nano-ZrO2 increasing, the flow decreased. (4) With the nano-ZrO2 increasing, the hydration heat increased due to the physical nucleation effect of the nano-ZrO2. Furthermore, the nano-ZrO2 used in this study was chemically inert and did not take part in the cement hydration reaction based on the XRD, differential thermal, and TG data. This paper is of great significance for the development of high-strength cementitious materials doped with nano-ZrO2.

Effect of Ceramsite Prewetting Degree on the Internal Relative Humidity of Ceramsite Concrete

2011 ◽  
Vol 94-96 ◽  
pp. 1451-1455
Author(s):  
Cai Yi Chen ◽  
Tao Ji ◽  
Yong Bo Chen ◽  
Yong Ning Liang
Keyword(s):  
Relative Humidity ◽  
Water Absorption ◽  
Pressure Measurement ◽  
Humidity Sensors ◽  
Measurement Device ◽  
Desorption Process ◽  
Reservoir Function ◽  
Internal Relative Humidity

The water absorption and desorption process of different prewetting degree ceramsites embedded in ceramsite concrete was obtained by a U-tube micro pressure measurement device. The internal relative humidities of ceramsite concrete using different prewetting degree ceramsites were monitored by humidity sensors. The study reveals that, with the increase of ceramsite prewetting degree, the internal relative humidity of ceramsite concrete increases because the reservoir function of ceramsite is more obvious.

Internal relative humidity and drying stress gradients in concrete

2006 ◽  
Vol 39 (9) ◽  
pp. 901-909 ◽  
Author(s):  
Zachary C. Grasley ◽  
David A. Lange ◽  
Matthew D. D'Ambrosia
Keyword(s):  
Relative Humidity ◽  
Stress Gradients ◽  
Internal Relative Humidity

Research on Self-Desiccation at early Age of High Performance Concrete with Polypropylene Fiber

2011 ◽  
Vol 374-377 ◽  
pp. 1827-1830
Author(s):  
Wei Wei Yu ◽  
Qing Xiong ◽  
Yun Yu ◽  
Hang Lin
Keyword(s):  
Relative Humidity ◽  
High Performance ◽  
High Performance Concrete ◽  
Polypropylene Fiber ◽  
The Self ◽  
Experimental Results ◽  
Early Age ◽  
Experimental Conditions ◽  
Internal Relative Humidity ◽  
The Impact

This paper focuses on the impact which polypropylene fiber (PF) has on the self-desiccation effect at early age of high performance concrete (HPC). The experimental results indicate that PF has little influence on the Internal Relative Humidity (IRH) caused by self-desiccation effect of concrete, but can reduce early aged self-desiccation shrinkage of concrete. With the PF dosage increasing, the values of early self-desiccation shrinkage of HPC decrease first and then increase. In the experimental conditions, the value of self-desiccation shrinkage of concrete with 0.6Kg/m3 PF is the lowest one.

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