BSE‐IA reveals retardation mechanisms of polymer powders on cement hydration

Background: Concrete is a common material used in the construction of marine structures, such as bridges, water treatment plants, jetties, etc. The use of concrete in these environment exposes it to attack from chemicals like sulphates, chlorides and alkaline, thereby causing it to deteriorate, and unable to perform satisfactorily within its service life. Hence, the need to investigate the durability properties of concrete has become necessary especially when admixtures are used to modify some of its properties. Objective: This research work investigates the effect of Cassava Starch (CS) on the durability characteristics of concrete. Methods: The durability properties investigated in this work are water absorption, sorptivity, resistance to sulphates, sodium hydroxides and chloride penetration. The specimens were prepared by adding CS by weight of cement at 0.4, 0.8, 1.2, 1.6 and 2.0% respectively. The concrete specimens were cured for 28 days, tested for compressive strength before ponding in ionic solutions of sodium hydroxide, sulphuric acid and sodium chloride. Six (6) concrete mixes were prepared, five of which were used to evaluate the effect of CS on the durability characteristics of concrete. Results: The slump values reduced with the increasing dosage of CS due to the viscous nature of the CS paste. Generally, the addition of CS in concrete tends to improve the resistance of concrete to sulphate and chloride attack due to the ability of the muddy-like starch gel to block the pore spaces of hardened concrete, hence, reduces the rate at which water and other aggressive chemicals penetrate the concrete. In addition, the retarding ability of CS impedes the formation of mono-sulphate aluminates during cement hydration, thereby making the concrete less susceptible to sulphate attack. Conclusion: The addition of CS to concrete by weight of cement generally improved the durability characteristics of concrete, while the relative performances of the concrete mixes showed that CS 2.0 gave a better resistance to chloride penetration and sulphate attack.

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A review on the properties, reinforcing effects, and commercialization of nanomaterials for cement-based materials

Nanotechnology Reviews ◽

10.1515/ntrev-2020-0023 ◽

2020 ◽

Vol 9 (1) ◽

pp. 303-322 ◽

Cited By ~ 3

Author(s):

Zhifang Zhao ◽

Tianqi Qi ◽

Wei Zhou ◽

David Hui ◽

Cong Xiao ◽

...

Keyword(s):

Cement Hydration ◽

State Of The Art ◽

Research Progress ◽

Market Survey ◽

Future Perspectives ◽

Nano Silica ◽

Physical Processes ◽

Existing Problems ◽

Cement Based Materials ◽

The Cost

AbstractThe behavior of cement-based materials is manipulated by chemical and physical processes at the nanolevel. Therefore, the application of nanomaterials in civil engineering to develop nano-modified cement-based materials is a promising research. In recent decades, a large number of researchers have tried to improve the properties of cement-based materials by employing various nanomaterials and to characterize the mechanism of nano-strengthening. In this study, the state of the art progress of nano-modified cement-based materials is systematically reviewed and summarized. First, this study reviews the basic properties and dispersion methods of nanomaterials commonly used in cement-based materials, including carbon nanotubes, carbon nanofibers, graphene, graphene oxide, nano-silica, nano-calcium carbonate, nano-calcium silicate hydrate, etc. Then the research progress on nano-engineered cementitious composites is reviewed from the view of accelerating cement hydration, reinforcing mechanical properties, and improving durability. In addition, the market and applications of nanomaterials for cement-based materials are briefly discussed, and the cost is creatively summarized through market survey. Finally, this study also summarizes the existing problems in current research and provides future perspectives accordingly.

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The impact of Fe dosage on the ettringite formation during high ferrite cement hydration

Journal of the American Ceramic Society ◽

10.1111/jace.17640 ◽

2020 ◽

Author(s):

Dawei Wan ◽

Wenqin Zhang ◽

Yong Tao ◽

Zonghua Wan ◽

Fazhou Wang ◽

...

Keyword(s):

Cement Hydration ◽

Ettringite Formation ◽

The Impact

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Effect of Morphologically Controlled Hematite Nanoparticles on the Properties of Fly Ash Blended Cement

Nanomaterials ◽

10.3390/nano11041003 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1003

Author(s):

Pantharee Kongsat ◽

Sakprayut Sinthupinyo ◽

Edgar A. O’Rear ◽

Thirawudh Pongprayoon

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Size Distribution ◽

Cement Hydration ◽

Blended Cement ◽

Spherical Shape ◽

Particle Sizes ◽

Fe2o3 Nanoparticles ◽

Structure And Properties ◽

Hematite Nanoparticles

Several types of hematite nanoparticles (α-Fe2O3) have been investigated for their effects on the structure and properties of fly ash (FA) blended cement. All synthesized nanoparticles were found to be of spherical shape, but of different particle sizes ranging from 10 to 195 nm depending on the surfactant used in their preparation. The cement hydration with time showed 1.0% α-Fe2O3 nanoparticles are effective accelerators for FA blended cement. Moreover, adding α-Fe2O3 nanoparticles in FA blended cement enhanced the compressive strength and workability of cement. Nanoparticle size and size distribution were important for optimal filling of various size of pores within the cement structure.

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Impact of limestone fineness on cement hydration at early age

Cement and Concrete Research ◽

10.1016/j.cemconres.2021.106515 ◽

2021 ◽

Vol 147 ◽

pp. 106515

Author(s):

Yosra Briki ◽

Maciej Zajac ◽

Mohsen Ben Haha ◽

Karen Scrivener

Keyword(s):

Cement Hydration ◽

Early Age

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Surface modification of YS-20 with polydopamine for improving the tribological properties of polyimide composites

Friction ◽

10.1007/s40544-020-0473-1 ◽

2021 ◽

Author(s):

Liangfei Wu ◽

Zhaozhu Zhang ◽

Mingming Yang ◽

Junya Yuan ◽

Peilong Li ◽

...

Keyword(s):

Polymer Composites ◽

Tribological Properties ◽

Metallic Copper ◽

Great Effort ◽

Modified Polymer ◽

Milling Method ◽

Multi Walled Carbon Nanotubes ◽

Mixing Method ◽

Walled Carbon Nanotubes ◽

Polymer Powders

AbstractRecently, great effort has been devoted to prepare various reinforce fillers to improve polymer performances, but ignoring the importance of raw polymer powders which are indispensable parts of hot-pressed polymer composites. Herein, we engineer raw polyimide (PI) powders with the assistance of polydopamine (PDA) in aqueous solutions. After the modification, polymer powders change from hydrophobic to hydrophilic, which makes it is possible to further modification of polymer powders in liquid phase. During the curing process of modified polymer powders, the partial dehydration of the catechol groups and crosslinking of PDA via C-O-C bonds are confirmed. Based on the features of PDA, a non-destructive mixing method is utilized to realize homogeneous dispersion of multi-walled carbon nanotubes (MWCNTs) in polymer matrix. In comparison with ball milling method, this way can preserve the integrated innate structure of MWCNTs effectively. Besides, by taking full advantage of the reducing and metal-coordination capability of PDA, Cu2+ is successfully loaded onto the surfaces of polymer powders. The related characterizations demonstrate that Cu2+in situ converts to metallic copper rather than copper oxide during the hot pressing process. The tribological properties of corresponding polymer composites are also studied. These results indicate that modifying polymer powders with PDA is multi-profit and presents practical application prospect.

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