Profile of internal relative humidity and depth of drying in cementitious materials containing superabsorbent polymer and nano-silica particles

In this paper, the effect of nano-silica on the autogenous shrinkage, hydration heat, compressive strength hydration products of Ultra-High Strength Concrete (UHSC) is studied. The water/binder ratio (w/b) of UHSC is 0.2. The nano-silica replaces 2% and 4% of the mass fraction of the cement in UHSCs, respectively. A new instrument was developed to simultaneously measure the autogenous shrinkage, internal relative humidity, and internal temperature of UHSC. The following results were obtained from the analysis of the experimental data: (1) The trends in the autogenous shrinking of UHSC can be divided into two stages, which are the variable temperature stage and the room temperature stage. The dividing point between the two stages occurs at the age of approximately 2 days. During the room temperature stage, the internal relative humidity and autogenous shrinkage showed a good linear relationship. (2) The compressive strength of UHSC increased significantly with the increase of nano-silica content at 3 days, 7 days, and 28 days. (3) The total accumulated heat of UHSC increased during the 72 h, with the increasing of nano-silica content. (4) The XRD data at the age of 28 days showed that the Ca(OH)2 peaks of nS2 and nS4 have a tendency to weaken due to the pozzolanic reaction, compared with the peak of nS0.

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Relationship between Internal Relative Humidity and Autogenous Shrinkage of Cement Paste with Supplementary Cementitious Materials (SCM)

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.539.35 ◽

2013 ◽

Vol 539 ◽

pp. 35-39 ◽

Cited By ~ 1

Author(s):

Yue Li ◽

Qian Qian Yan

Keyword(s):

Fly Ash ◽

Relative Humidity ◽

Autogenous Shrinkage ◽

Cementitious Materials ◽

Supplementary Cementitious Materials ◽

Cement Pastes ◽

Different Types ◽

Influence Of Water ◽

Internal Relative Humidity ◽

Main Factor

The influence of water to binder (W/B), types and dosage of supplementary cementitious materials (SCM) on the internal relative humidity (IRH) and autogenous shrinkage (AS) of cement pastes caused by self-desiccation were investigated, and their relationship was discussed. The results show that, W/B is a main factor that affects IRH change and AS of cement pastes with SCM. With the decrease of W/B, IRH of cement pastes decreases, but AS of cement pastes increases. Different types and dosages of SCM affect the IRH differently; fly ash (FA) reduces AS, silica fume (SF) increases AS, and the effect of GBFS on AS is between FA and GBFS. The linear correlation between the change of IRH and AS of cement pastes with SCM is established.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1129.315 ◽

2015 ◽

Vol 1129 ◽

pp. 315-322 ◽

Cited By ~ 2

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.

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