scholarly journals Mechanisms and Critical Technologies of Transport Inhibitor Agent (TIA) throughout C-S-H Nano-Channels

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 515
Author(s):  
Qi Luo ◽  
Jiale Huang

The critical issue of the durability of marine concrete lies in the continuous penetration and rapid enrichment of corrosive ions. Here a new ion transfer inhibitor, as TIA, with calcium silicate hydrate (C-S-H) interfacial affinity and hydrophobicity is proposed through insights from molecular dynamics into the percolation behavior of the ion solution in C-S-H nano-channels and combined with molecular design concepts. One side of the TIA can be adsorbed on the surface of the cement matrix and can form clusters of corrosive ions to block the gel pores so as to resist the ion solution percolation process. Its other side is structured as a hydrophobic carbon chain, similar to a door hinge, which can stick to the matrix surface smoothly before the erosion solution is percolated. It can then change into a perpendicular chain shape to reduce the percolation channel’s diameter and thereby inhibit the percolation when ions meet the inhibitor. Therefore, once the erosion solution contacts TIA, it can quickly chelate with calcium ions and erosion ions at the interface to form clusters and compact pores. In addition, the water absorption, chloride migration coefficient, and chloride content of concrete samples decreased significantly after adding TIA, proving that TIA can effectively enhance the durability of cement-based materials. The structure–activity relationship of ion transfer that is proposed can provide new ideas for solving the critical problems of durability of cement-based materials and polymer molecular design.

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Fakhim Babak ◽  
Hassani Abolfazl ◽  
Rashidi Alimorad ◽  
Ghodousi Parviz

We investigate the performance of graphene oxide (GO) in improving mechanical properties of cement composites. A polycarboxylate superplasticizer was used to improve the dispersion of GO flakes in the cement. The mechanical strength of graphene-cement nanocomposites containing 0.1–2 wt% GO and 0.5 wt% superplasticizer was measured and compared with that of cement prepared without GO. We found that the tensile strength of the cement mortar increased with GO content, reaching 1.5%, a 48% increase in tensile strength. Ultra high-resolution field emission scanning electron microscopy (FE-SEM) used to observe the fracture surface of samples containing 1.5 wt% GO indicated that the nano-GO flakes were well dispersed in the matrix, and no aggregates were observed. FE-SEM observation also revealed good bonding between the GO surfaces and the surrounding cement matrix. In addition, XRD diffraction data showed growth of the calcium silicate hydrates (C-S-H) gels in GO cement mortar compared with the normal cement mortar.


1987 ◽  
Vol 114 ◽  
Author(s):  
Sean Wise ◽  
Kevan Jones ◽  
Claudio Herzfeld ◽  
David D. Double

ABSTRACTVery high strength castable chemically bonded ceramic (CBC) materials have been prepared which consist of finely chopped steel fibers and steel aggregate in a silica modified portland cement matrix. This paper examines the effect of metal fiber addition on compressive and flexural strengths. The overall chemistry of the matrix is held constant but the morphological form of silica used and the cure conditions are altered to examine their effect. Compressive strengths in excess of 500 MPa and flexural strengths in excess of 80 MPa can be obtained.It is found that flexural strength increases proportionally with fiber content over the range of 0 to 10% by volume. Compressive strengths are not affected. Use of silica fume in the mixes produces higher strengths at low temperatures than mixes which contain only crystalline silica. High temperature curing/drying (400°C), which produces the highest strengths, produces equivalent properties for formulations with and without silica fume. Higher water/cement ratios are found to reduce compressive strengths but have relatively little effect on the flexural properties.


2016 ◽  
Vol 04 (01) ◽  
pp. 1640001 ◽  
Author(s):  
Ying Wan ◽  
Xing Li ◽  
Shenqi Wang

Biohybrid materials play an important role in tissue engineering, artificial organs and regenerative medicine due to their regulation of cell function through specific cell–matrix interactions involving integrins, mostly those of fibroblasts and myofibroblasts, and ligands on the matrix surface, which have become current research focus. In this paper, recent progress of biohybrid materials, mainly including main types of biohybrid materials, rapid prototype (RP) technique for construction of 3D biohybrid materials, was reviewed in detail; moreover, their applications in tissue engineering, artificial organs and regenerative medicine were also reviewed in detail. At last, we address the challenges biohybrid materials may face.


2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira

Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide (CO2) in the atmosphere due to increased industrial emission is deleterious to hydrated cement materials due to carbonation. Recent research has shown that blended cements are more susceptible to degradation due to carbonation than OPC. The ingress of CO2 within the porous mortar matrix is a diffusion controlled process. Subsequent chemical reaction between CO2 and cement hydration products (mostly calcium hydroxide [CH] and calcium silicate hydrate [CSH]) results in degradation of cement based materials. CH offers the buffering capacity against carbonation in hydrated cements. Partial substitution of OPC with pozzolanic materials however decreases the amount of CH in hydrated blended cements. Therefore, low amounts of CH in hydrated blended cements make them more susceptible to degradation as a result of carbonation compared to OPC. The magnitude of carbonation affects the service life of cement based structures significantly. It is therefore apparent that sufficient attention is given to carbonation process in order to ensure resilient cementitious structures. In this paper, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed. In conclusion, carbonation process is influenced by internal and external factors, and it has also been found to have both beneficial and deleterious effects on hardened cement matrix.


2019 ◽  
Vol 298 ◽  
pp. 00053 ◽  
Author(s):  
Ekaterina Potapova ◽  
Ivan Korchunov

The results of chloride ions with aqueous solution penetrating into the cement structure were determined with the colorimetric method. Some tendencies of chloride solutions migration in different conditions were established. The article suggests the possible ways of the prevention of destructive processes occur during the excessive pore solution saturation in cement matrix with chloride ions.


2017 ◽  
Vol 79 (5-3) ◽  
Author(s):  
Mimi Hani Abu Bakar ◽  
Neil F Pasco ◽  
Ravi Gooneratne ◽  
Kim Byung Hong

Properties such as electrical conductivity, low resistivity, chemicals and corrosion resistance are mostly found in carbon based materials. Epoxy resin is excellent for electrical insulation and can be used as a conductor with the addition of conductive filler. Combinations of carbon and epoxy show qualities of a conductive electrode, mechanically strong with design flexibility and thus makes them suitable as electrodes in microbial fuel cell (MFC). In this study, graphite-epoxy composites were fabricated with multi-walled carbon nanotube (MWCNT) embedded in the matrix surface. 9,10-Anthraquinone-2,6-disulfonic acid disodium salt/polypyrrole (PPy/AQDS) was used as mediator, covalently electrografted on electrode’s surface. Electrochemical stability of anodes during continuous operation were measured in air-cathode MFCs. It appears that maximum power in MFC could be increased up to 42% with surface modification using PPy/AQDS. Internal resistance (Rint) could be reduced up to 66% with the inclusion of MWCNT. These findings show that a one-day fabrication of a-ready-to-use conductive electrode is possible for graphite content between 70-80% (w/w).


2001 ◽  
Vol 702 ◽  
Author(s):  
Xiaoping Shui ◽  
Xuli Fu ◽  
Martin Segiet ◽  
D.D.L. Chung

ABSTRACTPolymer-matrix and cement-matrix structural composites containing discontinuous carbon filaments (diameter = 0.1 μm) that were made catalytically from methane were developed for structural and electromagnetic functions. The composites were particularly attractive for electromagnetic interference shielding and radio wave reflection, due to the skin effect and the small diameter of the filaments. Coating the filaments with nickel by electroplating further enhanced the electromagnetic performance. However, the composites were not attractive for structural functions other than vibration damping, due to the large amount of interface between the filaments and the matrix. An effective configuration for the damping function involved using the filaments as an additive between the laminae of continuous conventional carbon fibers in a polymer-matrix structural composite.


2011 ◽  
Vol 284-286 ◽  
pp. 2414-2419 ◽  
Author(s):  
Jun Cai Zhang ◽  
Cheng Chang Jia

In this paper, nano-Ti3SiC2/MoSi2 composite, whose second phase was 20-150nm, was in situ prepared by mechanical activation (MA) and SPS process with the quaternary powers of Mo, Si, Ti, and C. The results showed that: (1) matrix MoSi2 has strong repulsion to other elements, which leads to more second-phase particles inside the matrix rather than on the matrix surface; (2) matrix MoSi2 has strong restriction on the growing of the second phase, which makes the particle diameter of the second phase inside the matrix only in 200 nm around, while that over the surface reaches to 800 nm around.


2016 ◽  
Vol 113 (11) ◽  
pp. 2862-2867 ◽  
Author(s):  
Zheng Liang ◽  
Dingchang Lin ◽  
Jie Zhao ◽  
Zhenda Lu ◽  
Yayuan Liu ◽  
...  

Lithium metal-based battery is considered one of the best energy storage systems due to its high theoretical capacity and lowest anode potential of all. However, dendritic growth and virtually relative infinity volume change during long-term cycling often lead to severe safety hazards and catastrophic failure. Here, a stable lithium–scaffold composite electrode is developed by lithium melt infusion into a 3D porous carbon matrix with “lithiophilic” coating. Lithium is uniformly entrapped on the matrix surface and in the 3D structure. The resulting composite electrode possesses a high conductive surface area and excellent structural stability upon galvanostatic cycling. We showed stable cycling of this composite electrode with small Li plating/stripping overpotential (<90 mV) at a high current density of 3 mA/cm2 over 80 cycles.


1975 ◽  
Vol 97 (2) ◽  
pp. 217-220 ◽  
Author(s):  
E. Rabinowicz

An experimental and analytical study has been carried out to discover the factors which determine the friction and wear coefficients of composites consisting of a hard metal matrix and a softer filler. To be effective the filler should have a lower metallurgical compatibility than the matrix against the other sliding surface. The concentration of the filler should be at least a few percent so that it can be smeared out over the matrix surface, and there is an upper limit to filler concentration associated with loss of bulk strength of the composite. A simple calculation suggests that large particles of filler material are better than fine particles with 20 micrometer particles being the smallest that are fully effective.


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