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.

scholarly journals The Hydration, Mechanical, Autogenous Shrinkage, Durability, and Sustainability Properties of Cement–Limestone–Slag Ternary Composites

2021 ◽  
Vol 13 (4) ◽  
pp. 1881
Author(s):  
Mei-Yu Xuan ◽  
Yi Han ◽  
Xiao-Yong Wang
Keyword(s):  
Compressive Strength ◽  
Electrical Resistivity ◽  
Experimental Studies ◽  
Autogenous Shrinkage ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Hydration Heat ◽  
Granulated Blast Furnace Slag ◽  
Binder Ratio

This study examines the hydration–mechanical–autogenous shrinkage–durability–sustainability properties of ternary composites with limestone filler (LF) and ground-granulated blast furnace slag (BFS). Four mixtures were prepared with a water/binder ratio of 0.3 and different replacement ratios varying from 0 to 45%. Multiple experimental studies were performed at various ages. The experimental results are summarized as follows: (1) As the replacement levels increased, compressive strength and autogenous shrinkage (AS) decreased, and this relationship was linear. (2) As the replacement levels increased, cumulative hydration heat decreased. At the age of 3 and 7 days, there was a linear relationship between compressive strength and cumulative hydration heat. (3) Out of all mixtures, the ultrasonic pulse velocity (UPV) and electrical resistivity exhibited a rapid increase in the early stages and tended to slow down in the latter stages. There was a crossover of UPV among various specimens. In the later stages, the electrical resistivity of ternary composite specimens was higher than plain specimens. (4) X-ray diffraction (XRD) results showed that LF and BFS have a synergistic effect. (5) With increasing replacement ratios, the CO2 emissions per unit strength reduced, indicating the sustainability of ternary composites.

scholarly journals The Influence of Superabsorbent Polymers and Nanosilica on the Hydration Process and Microstructure of Cementitious Mixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5194
Author(s):  
Gerlinde Lefever ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Marc Raes ◽  
Tom Hauffman ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Isothermal Calorimetry ◽  
Autogenous Shrinkage ◽  
Hydration Process ◽  
Microstructural Development ◽  
Self Healing ◽  
Hydration Kinetics ◽  
Superabsorbent Polymers ◽  
Water To Cement Ratio ◽  
Supplementary Material

Superabsorbent polymers (SAPs) are known to mitigate the development of autogenous shrinkage in cementitious mixtures with a low water-to-cement ratio. Moreover, the addition of SAPs promotes the self-healing ability of cracks. A drawback of using SAPs lies in the formation of macropores when the polymers release their absorbed water, leading to a reduction of the mechanical properties. Therefore, a supplementary material was introduced together with SAPs, being nanosilica, in order to obtain an identical compressive strength with respect to the reference material without additives. The exact cause of the similar compressive behaviour lies in the modification of the hydration process and subsequent microstructural development by both SAPs and nanosilica. Within the present study, the effect of SAPs and nanosilica on the hydration progress and the hardened properties is assessed. By means of isothermal calorimetry, the hydration kinetics were monitored. Subsequently, the quantity of hydration products formed was determined by thermogravimetric analysis and scanning electron microscopy, revealing an increased amount of hydrates for both SAP and nanosilica blends. An assessment of the pore size distribution was made using mercury intrusion porosimetry and demonstrated the increased porosity for SAP mixtures. A correlation between microstructure and the compressive strength displayed its influence on the mechanical behaviour.

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.

The Research of Green High Performance Recycled Construct Materials

2011 ◽  
Vol 71-78 ◽  
pp. 4471-4475
Author(s):  
Xiao Xiong Zha ◽  
Kai Zhang
Keyword(s):  
Compressive Strength ◽  
High Performance ◽  
Experimental Studies ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Large Water

Recycled concrete aggregates have large porosity, large water absorption and high crush index. Mechanical properties of recycled concrete aggregates could be improved by adding activated water instead of ordinary water. On the basis of the experimental studies, this paper analyzes the influences on recycled concrete compression strength when using activated water. There are many different factors such as the kinds and amounts of alkali and the water slag ratio affecting the compressive strength of recycle geopolymer. The results show that activated water has a high enhancement on compressive strength of recycled aggregate concrete, and the highest compressive strength of recycled geopolymer is 57.3MPa.

scholarly journals Internal Relative Humidity, Autogenous Shrinkage, and Strength of Cement Mortar Modified with Superabsorbent Polymers

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1074 ◽  
Author(s):  
Girum Urgessa ◽  
Ki-Bong Choi ◽  
Jung Yeon
Keyword(s):  
Relative Humidity ◽  
Coefficient Of Thermal Expansion ◽  
Autogenous Shrinkage ◽  
Thermal Characteristics ◽  
Cross Linking ◽  
Superabsorbent Polymers ◽  
Cracking Potential ◽  
Linear Relationships ◽  
Internal Relative Humidity ◽  
Compressive And Flexural Strengths

Laboratory evaluations were performed to investigate the effect of internal curing (IC) by superabsorbent polymers (SAP) on the internal relative humidity (IRH), autogenous shrinkage, coefficient of thermal expansion (CTE), and strength characteristics of low water-cement ratio (w/c) mortars. Four types of SAP with different cross-linking densities and particle sizes were used. Test results showed that the SAP inclusion effectively mitigated the IRH drops due to self-desiccation and corresponding autogenous shrinkage, and the IC effectiveness tended to increase with an increased SAP dosage. The greater the cross-linking density and particle size of SAP, the less the IRH drop and autogenous shrinkage. The trend of autogenous shrinkage developments was in good agreement with that of IRH changes, with nearly linear relationships between them. Both immediate deformation (ID)-based and full response-based CTEs were rarely affected by SAP inclusions. There were no substantial losses in compressive and flexural strengths of SAP-modified mortar compared to reference plain mortar. The findings revealed that SAPs can be effectively used to reduce the shrinkage cracking potential of low w/c cement-based materials at early ages, without compromising mechanical and thermal characteristics.

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.

Effect of Porosity on Mechanical and Hygric Properties of Concrete with Natural Pozzolan Addition

2014 ◽  
Vol 982 ◽  
pp. 22-26 ◽  
Author(s):  
Tereza Kulovaná ◽  
Pavla Rovnaníková ◽  
Zbyšek Pavlík ◽  
Robert Černý
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Moisture Transport ◽  
High Performance ◽  
High Performance Concrete ◽  
Moisture Diffusivity ◽  
Natural Pozzolan ◽  
Cement Replacement ◽  
Hygric Properties ◽  
Partial Cement Replacement

Effect of porosity on mechanical and hygric properties of high performance concrete (HPC) with natural pozzolan as partial Portland cement replacement up to 40% is studied in the paper. The reference HPC mixture is researched as well in order to evaluate the influence of pozzolan usage on concrete performance. For the studied materials, measurement of compressive strength, sorptivity, apparent moisture diffusivity, and water vapor diffusion permeability is done. The obtained data shows that application of the pozzolan as partial cement replacement leads to increase of concrete porosity that is related to the lower mechanical strength and higher moisture transport properties. Therefore, the applied natural pozzolan has a potential to replace a part of Portland cement in concrete manufacturing but its content in concrete mixture has strict limitations.

The Influence of Zinc on the Hydration and Compressive Strength of Portland Cement

2014 ◽  
Vol 1000 ◽  
pp. 43-46
Author(s):  
Iva Kolářová ◽  
Pavel Šiler ◽  
František Šoukal
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Hazardous Waste ◽  
Ordinary Portland Cement ◽  
Raw Materials ◽  
Isothermal Calorimetry ◽  
Weight Percent ◽  
Tricalcium Silicate ◽  
Hydraulic Activity ◽  
Interesting Object

The aim of this work was to investigate the effect of addition of elements present in secondary raw materials on the hydration and compressive strength of Portland cement. Ordinary Portland cement (OPC) has been used to solidify hazardous waste for about 25 years and the effect of waste components on the hydraulic activity is an interesting object for the research. In this study Zn nitrate, chloride and oxide were added to Portland cement. The concentrations of 0.1 and 1.0 weight percent of zinc in cement were tested. After 1, 7 and 28 days the compressive strength was reduced or similar by the addition of zinc in comparison with pure cement. This difference is probably due to a delay in tricalcium silicate hydration as shown by isothermal calorimetry.

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