The effect of internal relative humidity on the early age deformation of cement paste containing magnesia

2021 ◽  
Vol 283 ◽  
pp. 122604
Author(s):  
Jinyuan Lu ◽  
Pan Feng ◽  
Lijing Shao ◽  
Hua Li
Keyword(s):  
Relative Humidity ◽  
Cement Paste ◽  
Early Age ◽  
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.

Internal Relative Humidity and Drying Shrinkage of Lightweight Aggregate Concrete

2014 ◽  
Vol 629-630 ◽  
pp. 473-480
Author(s):  
Xiu Hua Zheng ◽  
Yu Feng Zhai ◽  
Shi Zuo Zhan ◽  
Shu Jie Song
Keyword(s):  
Relative Humidity ◽  
Early Stage ◽  
Drying Shrinkage ◽  
Lightweight Aggregate ◽  
Lightweight Aggregate Concrete ◽  
Early Age ◽  
Aggregate Concrete ◽  
Cement Ratio ◽  
Air Content ◽  
Internal Relative Humidity

In this paper, the influence of water cement ratio, prewetting degree of lightweight aggregate, flyash content and air content on the internal relative humidity (IRH) and drying shrinkage of lightweight aggregate concrete (LAC) were studied using a relative humidity sensor and drying shrinkage apparatus. Results showed that the IRH of concrete decreased rapidly at early age and slowed down at late age, and prewetting lightweight aggregate could compensate the loss of IRH. The effect of compensation could be enhanced with the increasing of prewetting degree of lightweight aggregate, and the addition of flyash retarded the decrease of IRH at early age. The drying shrinkage of LAC increased quickly at early stage and it slowed down to the even after 60 days or longer age. Furthermore, the drying shrinkage of LAC increased with increasing of water cement ratio. The effect of air content on the drying shrinkage of LAC was limited at early stage. However, at the late stage it grew at different level with increasing of air content. By raising the prewetting degree of lightweight aggregate, mixing with proper dosage of flyash, the shrinkage rate of LAC can be reduced markedly. Key words: lightweight aggregate concrete, internal relative humidity, drying shrinkage, prewetting degree, flyash.

Comparison of Ordinary Pores with Internal Cured Pores Produced by Superabsorbent Polymers

2015 ◽  
Vol 1129 ◽  
pp. 315-322 ◽  
Author(s):  
Jin Yang ◽  
Fa Zhou Wang ◽  
Yun Peng Liu
Keyword(s):  
Compressive Strength ◽  
Relative Humidity ◽  
Cement Paste ◽  
Volume Fraction ◽  
Expanded Polystyrene ◽  
Spherical Particles ◽  
Superabsorbent Polymer ◽  
Hydration Degree ◽  
Internal Relative Humidity ◽  
Transmission Velocity

Porous cementitious mixtures were prepared with two different spherical particles: expanded polystyrene (EPS) and superabsorbent polymer (SAP). The effect of EPS and SAP on the compressive strength, ultrasonic transmission, internal relative humidity and hydration degree under different volume fraction were studied. Results indicated that SAP matrix possessed much higher compressive strength (30-60%, 28d), ultrasonic transmission velocity, internal humidity (11-13%RH, 28d) and hydration degree (13-21%, 28d) than EPS matrix, which indicated that the desorption of SAP accelerated the hydration and increased the compactness of the surrounding cement paste. The internal cured pores left by SAP might have been strengthened which was different from ordinary pores produced by EPS.

scholarly journals Effect of Supplementary Materials on the Autogenous Shrinkage of Cement Paste

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3367 ◽  
Author(s):  
Tianshi Lu ◽  
Zhenming Li ◽  
Hao Huang
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Relative Humidity ◽  
Cement Paste ◽  
Blast Furnace Slag ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
Chemical Shrinkage ◽  
Internal Relative Humidity ◽  
Furnace Slag

In recent years more and more attention has been given to autogenous shrinkage due to the increasing use of high-performance concrete, which always contains supplementary materials. With the addition of supplementary materials—e.g., fly ash and blast furnace slag—internal relative humidity, chemical shrinkage and mechanical properties of cement paste will be affected. These properties significantly influence the autogenous shrinkage of cement paste. In this study, three supplementary materials—i.e., silica fume, fly ash and blast furnace slag—are investigated. Measurements of final setting time, internal relative humidity, chemical shrinkage, compressive strength and autogenous deformation of the cement pastes with and without supplementary materials are presented. Two water-binder ratios, 0.3 and 0.4, are considered. The effects of different supplementary materials on autogenous shrinkage of cement paste are discussed.

Prediction of internal relative humidity in concrete modified with super absorbent polymers at early age

2017 ◽  
Vol 149 ◽  
pp. 543-552 ◽  
Author(s):  
Dejian Shen ◽  
Mingliang Wang ◽  
Ying Chen ◽  
Wenting Wang ◽  
Jinyang Zhang
Keyword(s):  
Relative Humidity ◽  
Early Age ◽  
Internal Relative Humidity
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