scholarly journals Design of pH-responsive SAP polymer for pore solution chemistry regulation and crack sealing in cementitious materials

2020 ◽  
Vol 199 ◽  
pp. 108262 ◽  
Author(s):  
Shuaicheng Guo ◽  
Pegah Kord Forooshani ◽  
Qingli Dai ◽  
Bruce P. Lee ◽  
Ruizhe Si ◽  
...  
Keyword(s):  
Pore Solution ◽  
Cementitious Materials ◽  
Solution Chemistry ◽  
Ph Responsive ◽  
Crack Sealing

scholarly journals Physical, chemical, and mineralogical characteristics of blast furnace slag on durability of concrete

2018 ◽  
Vol 147 ◽  
pp. 01007
Author(s):  
Elakneswaran Yogarajah ◽  
Toyoharu Nawa ◽  
Toshifumi Igarashi
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Pore Solution ◽  
Cementitious Materials ◽  
Solution Chemistry ◽  
Partial Replacement ◽  
Phase Assemblage ◽  
Chloride Ingress ◽  
Furnace Slag ◽  
Durability Of Concrete

A partial replacement of Portland cement (PC) by ground granulated blast furnace slag (GGBFS) is an effective method to improve the durability of concrete due to its lower diffusivity and higher chemical resistance compared to PC. Further, the microstructure of GGBFS blended cementitious materials controls the physicochemical properties and performance of the materials in concrete. Therefore, understanding of cement hydration and cementing behavior of GGBFS is essential to establish microstructure property relationship for predicting performance. In this study, hydration, microstructure development, and chloride ingress into GGBFS-blended cement have been investigated. Solid-phase assemblage and pore solution chemistry of hydrating PC and cement blended with GGBFS were predicted using thermodynamic model and compared with experimental data. A mathematical model integrating PC hydration, GGBFS reaction, thermodynamic equilibrium between hydration products and pore solution, ionic adsorption on C-S-H, multi-component diffusion, and microstructural changes was developed to predict chloride ingress into GGBFS blended cementitious materials. The simulation results on chloride profiles for hydrated slag cement paste, which was prepared with 50% of replacement of PC with GGBFS, were compared with experimental results. The model quantitively predicts the states of chloride such as free, adsorbed on C-S-H, and chemically bound as Friedel’s salt.

scholarly journals Hydration, Microstructure and Compressive Strength Development of Seawater-mixed Calcium Sulphoaluminate Cement-based Systems

2021 ◽  
pp. X
Author(s):  
Ting ZHANG ◽  
Ditao NIU ◽  
Chaofei LI
Keyword(s):  
Pore Solution ◽  
Ph Value ◽  
Cost Effective ◽  
Cementitious Materials ◽  
Solution Chemistry ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Strength Development ◽  
Engineering Practice ◽  
Calcium Sulphoaluminate

In-depth understanding of the calcium sulphoaluminate (CSA) cement, a type of environment-friendly cement, is essential for its wide application in engineering practice. Partial replacement of CSA by alternative alumina-rich powders has significant potential in the production of cost-effective CSA cement. In this work various supplementary cementitious materials (SCMs) including slag, metakaolin and silica fume with different replacement levels were added into CSA cement, and mixing with seawater, to prepare paste and concrete specimens. The development of hydration products in the paste specimens was characterized by X-ray diffraction and Thermogravimetric analysis. The pore structures of the seawater-mixed paste specimens obtained from mercury intrusion porosimetry tests, along with the pH value and free chloride content in the pore solution, were analyzed. Results show that various SCMs have significantly different effects on the pore solution chemistry, hydration and microstructural formation of the seawater-mixed CSA cement, resulting in different mechanical behavior and durability properties. The results of this work are helpful for the development of cost-effective CSA cement-based concrete used in marine constructions.

scholarly journals Stabilizing effect of methylcellulose on the dispersion of multi-walled carbon nanotubes in cementitious composites

2020 ◽  
Vol 9 (1) ◽  
pp. 93-104
Author(s):  
Mingrui Du ◽  
Yuan Gao ◽  
Guansheng Han ◽  
Luan Li ◽  
Hongwen Jing
Keyword(s):  
Carbon Nanotubes ◽  
Pore Solution ◽  
Cementitious Materials ◽  
High Ionic Strength ◽  
Cementitious Composites ◽  
Uniform Distributions ◽  
Stabilizing Effect ◽  
Multi Walled Carbon Nanotubes ◽  
The Stability ◽  
Walled Carbon Nanotubes

AbstractMulti-walled carbon nanotubes (MWCNTs) have been added in the plain cementitious materials to manufacture composites with the higher mechanical properties and smart behavior. The uniform distributions of MWCNTs is critical to obtain the desired enhancing effect, which, however, is challenged by the high ionic strength of the cement pore solution. Here, the effects of methylcellulose (MC) on stabilizing the dispersion of MWCNTs in the simulated cement pore solution and the viscosity of MWCNT suspensions werestudied. Further observations on the distributions of MWCNTs in the ternary cementitious composites were conducted. The results showed that MC forms a membranous envelope surrounding MWCNTs, which inhibits the adsorption of cations and maintains the steric repulsion between MWCNTs; thus, the stability of MWCNT dispersion in cement-based composites is improved. MC can also work as a viscosity adjuster that retards the Brownian mobility of MWCNTs, reducing their re-agglomerate within a period. MC with an addition ratio of 0.018 wt.% is suggested to achieve the optimum dispersion stabilizing effect. The findings here provide a way for stabilizing the other dispersed nano-additives in the cementitious composites.

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