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.

Effect of Gypsum on Hydration Degree and Structure of Hardened Paste of Alite-Strontium Calcium Sulphoaluminate Cement

2011 ◽  
Vol 306-307 ◽  
pp. 1024-1028
Author(s):  
Qiu Ying Li ◽  
Ling Chao Lu ◽  
Shou De Wang
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Cement Clinker ◽  
Hardened Cement ◽  
Hydration Degree ◽  
Synthesis Conditions ◽  
Sulphoaluminate Cement ◽  
Calcium Sulphoaluminate ◽  
Calcium Sulphoaluminate Cement ◽  
Curing Age

Synthesis conditions and performance of alite-strontium calcium sulphoaluminate cement have been studied by introducing strontium calcium sulphoaluminate into Portland cement clinker. The effects of gypsum on compressive strength, hydration degree and structure of hardened alite-strontium calcium sulphoaluminate cement paste were studied in this paper. Composition and structure of the hardened cement paste were analyzed by XRD and SEM. Results show that appropriate content of gypsum could contribute to the hydration of alite-strontium calcium sulphoaluminate cement. When gypsum content is 9%, the compressive strengths for 1d, 3d and 28d curing age are 30.7MPa, 59.5MPa and 105.5MPa, and the corresponding hydration degree are 40.4%, 57.5% and 85.8%, respectively. The hydration products of alite-strontium calcium sulphoaluminate cement are mainly ettringite (AFt), Ca(OH)2, C-S-H gel. Large amount of AFt formed at early curing age provides a sound basis for early compressive strength, and a lot of C-S-H gel generated at later curing age increases the density of the hardened paste.

scholarly journals Microstructural Evolution and Strengthening Mechanism of SiC/Al Composites Fabricated by a Liquid-Pressing Process and Heat Treatment

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3374 ◽  
Author(s):  
Sangmin Shin ◽  
Seungchan Cho ◽  
Donghyun Lee ◽  
Yangdo Kim ◽  
Sang-Bok Lee ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Microstructural Evolution ◽  
Load Transfer ◽  
Volume Fraction ◽  
High Volume ◽  
Strengthening Mechanism ◽  
Spherical Particles ◽  
Pressing Process ◽  
Liquid Pressing Process

Aluminum alloy (Al7075) composites reinforced with a high volume fraction of silicon carbide (SiC) were produced by a liquid-pressing process. The characterization of their microstructure showed that SiC particles corresponding to a volume fraction greater than 60% were uniformly distributed in the composite, and Mg2Si precipitates were present at the interface between the matrix and the reinforcement. A superior compressive strength (1130 MPa) was obtained by an effective load transfer to the hard ceramic particles. After solution heat treatment and artificial aging, the Mg2Si precipitates decomposed from rod-shaped large particles to smaller spherical particles, which led to an increase of the compressive strength by more than 200 MPa. The strengthening mechanism is discussed on the basis of the observed microstructural evolution.

scholarly journals INFLUENCE OF RELATIVE HUMIDITY ON COMPRESSIVE STRENGTH OF FLY ASH CEMENT PASTE

2008 ◽  
Vol 73 (631) ◽  
pp. 1433-1441 ◽  
Author(s):  
Warangkana SAENGSOY ◽  
Toyoharu NAWA ◽  
Pipat TERMKHAJORNKIT
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Relative Humidity ◽  
Cement Paste

Effect of Steel Slag on Shrinkage Characteristics of Calcium Sulfoaluminate Cement

2021 ◽  
Vol 1036 ◽  
pp. 263-276
Author(s):  
Hao Ran Huang ◽  
Yi Shun Liao ◽  
Siraj Ai Qunaynah ◽  
Guo Xi Jiang ◽  
Da Wei Guo ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Relative Humidity ◽  
Cement Paste ◽  
Steel Slag ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Chemical Shrinkage ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Slag Content

The effects of steel slag with 0, 10%, 20 % and 40% content on the chemical shrinkage, autogenous shrinkage, internal relative humidity, and drying shrinkage of calcium sulfoaluminate cement paste were studied. The results show that the compressive strength of calcium sulfoaluminate cement paste at an early stage decreases gradually when the content of steel slag increases. When the steel slag content is 0 and 10%, the compressive strength of hardened cement pastes gradually decreases at 90 and 180 days, but the samples with steel slag content of 20% and 40% maintain the compressive strength growth within 180 d. With the extension of curing period, the gap of compressive strength is gradually narrowed. The autogenous shrinkage decreases with the increase of steel slag content and has a good linear relationship with the relative humidity inside the paste. The proportion of autogenous shrinkage to chemical shrinkage is deficient, and most chemical shrinkage occurs in the form of the pore volume. Although the trends of drying shrinkage and autogenous are consistent, the former is more severe than the latter.

scholarly journals Effect of Nano-Silica on the Autogenous Shrinkage, Strength, and Hydration Heat of Ultra-High Strength Concrete

2020 ◽  
Vol 10 (15) ◽  
pp. 5202 ◽  
Author(s):  
Guang-Zhu Zhang ◽  
Hyeong-Kyu Cho ◽  
Xiao-Yong Wang
Keyword(s):  
Compressive Strength ◽  
Relative Humidity ◽  
High Strength Concrete ◽  
Room Temperature ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Silica Content ◽  
Nano Silica ◽  
Internal Relative Humidity ◽  
Two Stages

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.

scholarly journals Effect of Cement Types and Superabsorbent Polymers on the Properties of Sustainable Ultra-High-Performance Paste

Materials ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1497
Author(s):  
Mei-Yu Xuan ◽  
Yi-Sheng Wang ◽  
Xiao-Yong Wang ◽  
Han-Seung Lee ◽  
Seung-Jun Kwon
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Relative Humidity ◽  
Portland Cement ◽  
High Performance ◽  
Isothermal Calorimetry ◽  
Experimental Studies ◽  
High Rate ◽  
Superabsorbent Polymers ◽  
Internal Relative Humidity

This study focuses on the effects of superabsorbent polymers (SAP) and belite-rich Portland cement (BPC) on the compressive strength, autogenous shrinkage (AS), and micro- and macroscopic performance of sustainable, ultra-high-performance paste (SUHPP). Several experimental studies were conducted, including compressive strength, AS, isothermal calorimetry, X-ray diffraction (XRD), thermogravimetric analysis (TGA), attenuated total reflectance (ATR)–Fourier-transform infrared spectroscopy (FTIR), ultra-sonic pulse velocity (UPV), and electrical resistivity. The following conclusions can be made based on the experimental results: (1) a small amount of SAP has a strength promotion effect during the first 3 days, while BPC can significantly improve the strength over the following 28 days. (2) SAP slows down the internal relative humidity reduction and effectively reduces the development of AS. BPC specimens show a lower AS than other specimens. The AS shows a linear relationship with the internal relative humidity. (3) Specimens with SAP possess higher cumulative hydration heat than control specimens. The slow hydration rate in the BPC effectively reduces the exothermic heat. (4) With the increase in SAP, the calcium hydroxide (CH) and combined water content increases, and SAP thus improves the effect on cement hydration. The contents of CH and combined water in BPC specimens are lower than those in the ordinary Portland cement (OPC) specimen. (5) All samples display rapid hydration of the cement in the first 3 days, with a high rate of UPV development. Strength is an exponential function of UPVs. (6) The electrical resistivity is reduced due to the increase in porosity caused by the release of water from SAP. From 3 to 28 days, BPC specimens show a greater increment in electrical resistivity than other specimens.

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