Effect and mechanism of colloidal silica sol on properties and microstructure of the hardened cement-based materials as compared to nano-silica powder with agglomerates in micron-scale

Kong, Deyu; Pan, Haiwen; Wang, Linhai; Corr, David J.; Yang, Yang; Shah, Surendra P.; Sheng, Jiansong

doi:10.1016/j.cemconcomp.2019.02.015

Cited by 59 publications

(18 citation statements)

References 42 publications

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“…In addition, on the basis of the through-solution mechanism, it was generally proposed that sucrose retards cement hydration by adsorbing onto anhydrous or (more likely) the partially hydrated mineral surfaces, preventing further nucleation and growth through poisoning nucleation sites for C-S-H gels [42][43][44][45][46][47], and the addition of nucleation sites in the form of C-S-H seed can reduce or eliminate the retarding effect by providing an alternate pathway for the hydration process [18]. However, our previous studies argued whether nanoparticles incorporated in the cement-based materials could act as nucleation sites or not for C-S-H growth during cement hydration [49][50][51][52][53]. Through modeling experiments, no nucleus function can be observed for C-S-H growth in the hydrating system with nano-silica and nano-TiO 2 addition [53].…”

Section: Introductionmentioning

confidence: 99%

Influences and Mechanisms of Nano-C-S-H Gel Addition on Fresh Properties of the Cement-Based Materials with Sucrose as Retarder

Kong

Pan

et al. 2020

Materials

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Influences and mechanisms of chemically synthesized nano-C-S-H gel addition on fresh properties of the cement-based materials with sucrose as a retarder were investigated in this study. The results showed that the flow value of the fresh cement paste was gradually but slightly reduced with increasing nano-C-S-H gel addition due to its fibrous but well-dispersed characteristic in both water and cement paste. The semi-adiabatic calorimetry testing results verified that incorporation of nano-C-S-H gel could greatly mitigate the retarding effect of sucrose on cement hydration. The total organic carbon (TOC) indicated that the addition of the nano-C-S-H gel helps to reduce adsorption of the sucrose molecules into the protective layer, thus the semi-permeability of the protective layer was less reduced and that is why the addition of the nano-C-S-H gel can mitigate the retardation caused by the sucrose. Through XRD analysis, it was found that the CH crystals are more prone to grow along the (0001) plane with larger size in the paste with nano-C-S-H addition before the induction period starts, because the C-S-H nanoparticles can form 3D network to slow down the diffusion rate of the released ions and eliminate the convection in the paste, thus suppress the 3D nucleation and growth of the CH crystals. The XRD analysis also indicated a refinement of the ettringite crystals in the paste with sucrose addition, but introduction of nano-C-S-H gel did not show further refinement, which was also verified by the SEM observation.

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Section: Introductionmentioning

confidence: 99%

Influences and Mechanisms of Nano-C-S-H Gel Addition on Fresh Properties of the Cement-Based Materials with Sucrose as Retarder

Kong

Pan

et al. 2020

Materials

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“…The effects of NS powder and SS on the hydration of cement were compared. It was found that compared with NS powder, SS could significantly accelerate the process of hydration and further improve the mechanical properties of cement [27][28][29][30]. GO also has similar problems, due to the strong Van der Waals self-attraction and ionization interference, GO is prone to agglomeration in the alkaline environment of cement paste, limiting its strengthening effect on cement.…”

Section: Introductionmentioning

confidence: 99%

Effects of Graphene Oxide Encapsulated Silica Fume and Its Mixing with Nano-Silica Sol on Properties of Fly Ash-Mixed Cement Composites

et al. 2022

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In the present research work, the ternary effects of varying dosages of graphene oxide encapsulated silica fume (GOSF), nano-silica sol (SS), and fly ash (FA) on the rheological properties, compressive strength, the content and crystal size of calcium hydroxide (CH), porosity, water absorption, and microstructure of cement were studied. The results showed that the incorporation of SF improved the dispersion of GO in the cement matrix. GOSF was prepared through electrostatic attraction between the positively charged SF and negatively charged GO. The ternary mixture of GOSF, SS, and FA had a synergistic effect that improved the performance of cement. When the curing age of cement reached 28 days, the compressive strength reached a peak of 86.5 MPa, the minimum values of content and crystal size of CH were 11.55% and 45.69 nm, respectively, and the minimum values of water absorption and porosity were 0.0011 cm/s0.5 and 13.56%, respectively. In terms of microstructure, the denser structure of C-S-H gel and the regular arrangement of CH were noticed.

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“…When the GO and NS content were 0.03% and 3%, respectively, increasing the SP dose from 0.6% to 1.2% resulted in a further reduction in the water sorptivity coefficient of the cement composites [26]. Kong et al [33,34] investigated the effects of colloidal silica sol (SS) and nanosilica powder (NS) on fresh and cured cement materials. In comparison to NS addition, the addition of SS had a clearly superior accelerating impact on cement hydration in early age and a better strength enhancement of the mortar in later age.…”

Section: Introductionmentioning

confidence: 99%

“…However, following the calcium leaching test, the strength of the mortar with SS addition decreased more than that of the mortar with NS addition, owing to the dissolution of bigger CH crystals in the coagulated gel network, which resulted in large pores in the mortar. Despite the fact that the flocculation impact of SS may lead to a more compact microstructure [33,34], cement paste flowability declined when the particle size of SS was reduced, owing to the fact that flocculation inhibited the pozzolanic activity and seeding effect of the nanomaterials [35]. In addition, it was discovered that SS had a greater impact on cement composites with a lower water-cement ratio [36].…”

Section: Introductionmentioning

confidence: 99%

Colloidal Nanosilica Effect on the Properties and Durability of Coir Reinforced Cement Brick

Shah

Lee

Zamzuri

et al. 2022

Advances in Materials Science and Engineering

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The impact of nanosilica on the properties and microstructure of cement-based products has lately attracted a lot of attention. The effects of colloidal nanosilica (CNS) at different concentrations on the hydration process and performance of cement-based composites reinforced with coconut coir were examined in this study. CNS was applied at concentrations of 0%, 2%, 4%, and 6% by weight of cement, respectively. The samples were evaluated in terms of flexural test, scanning electron microscopy (SEM), thermogravimetric analysis (TG-DTG), and X-ray Diffraction (XRD) after 7, 28, and 60 days of curing. Flexural strength improved by 13%, 11%, and 23% in the presence of CNS after 7, 28, and 60 days of hydration, respectively, as compared to the samples without CNS addition. The highest flexural strength was reported in samples containing 4% CNS. Beyond this, flexural strength decreases noticeably owing to the presence of too much nanosilica, which repressed the hydration process. The predominant causes of sample failure appear to be fiber breakage and fiber pull-out. In the sample containing 4% CNS, a dense structure was seen. The fibers had a strong bond with the matrix, showing that fiber/matrix bonding was improved. CNS served as a pozzolanic reaction promoter, converting CH to C-S-H, and a filler to improve cement microstructure. The CH content decreased when CNS was added, while the C-S-H gels increased.

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Effect and mechanism of colloidal silica sol on properties and microstructure of the hardened cement-based materials as compared to nano-silica powder with agglomerates in micron-scale

Cited by 59 publications

References 42 publications

Influences and Mechanisms of Nano-C-S-H Gel Addition on Fresh Properties of the Cement-Based Materials with Sucrose as Retarder

Influences and Mechanisms of Nano-C-S-H Gel Addition on Fresh Properties of the Cement-Based Materials with Sucrose as Retarder

Effects of Graphene Oxide Encapsulated Silica Fume and Its Mixing with Nano-Silica Sol on Properties of Fly Ash-Mixed Cement Composites

Colloidal Nanosilica Effect on the Properties and Durability of Coir Reinforced Cement Brick

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