scholarly journals Nanofibrillated celluloses for the performance improvement of ultra-high ductility cementitious composites

2021 ◽  
Author(s):  
Long Liang ◽  
Xin Zhang ◽  
Qiaoling Liu ◽  
Xiurong Li
Keyword(s):  
Isothermal Calorimetry ◽  
Peak Stress ◽  
Rheological Parameters ◽  
Cementitious Composites ◽  
High Ductility ◽  
Hydration Kinetics ◽  
Early Hydration ◽  
Degree Of Hydration ◽  
Low Field ◽  
Flexural Tests

Abstract This study explored the effect of nanofibrillated celluloses (CNF), namely 0%, 0.05%, 0.1%, and 0.15% of binders weight, on the hydration, rheology, pore structure, and mechanical properties of ultra-high ductility cementitious composites (UHDCC). The hydration kinetics were conducted with different CNF contents using isothermal calorimetry (IC), showing a retardation effect of CNF on the early hydration of UHDCC matrices at 70 h due to the absorption of CNF on the surface of cement particles. Then, thermogravimetric analysis (TGA) demonstrated that CNF improved the degree of hydration at 28 days due to the formation of the CNF transport of water into unhydrated cement cores. The two rheological parameters, namely the yield stress and plastic viscosity, of the fresh UHDCC matrices increased with the increasing CNF contents. Low-field nuclear magnetic resonance (LF-NMR) analysis, as a non-destructive method, proved that the addition of CNF could reduce the porosity of UHDCC and refine its pore size distribution, and the 8.9–46.1% enhancement in the compressive strength of corresponding specimens was found. Notably, CNF could increase the tensile initial cracking stress by 91.2% and tensile stress by 30.8% of UHDCC, and maintain or increase its over 8% of tensile strain-hardening capacity. The flexural tests also were found a 54.6% increase in the initial stress and a 14.8% increase in the peak stress. As a preliminary, CNF shows crucial promising as a greener nanomaterial to improve the strength and ductility of UHDCC.

scholarly journals Comparison of the Hydration Characteristics of Ultra-High-Performance and Normal Cementitious Materials

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2594
Author(s):  
Haiyun Zhou ◽  
Hongbo Zhu ◽  
Hongxiang Gou ◽  
Zhenghong Yang
Keyword(s):  
High Performance ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Hydration Process ◽  
Chemical Shrinkage ◽  
Hydration Kinetics ◽  
Degree Of Hydration ◽  
Phase Development ◽  
Hydration Characteristics ◽  
Development Tendency

The hydration mechanism of ultra-high-performance cementitious materials (UHPC) departs considerably from that of normal cementitious materials (NC). In this study, the strength, isothermal calorimetry, chemical shrinkage, X-ray diffraction (XRD), and thermogravimetry (TG) methods are used to determine the hydration characteristics of UHPC and NC that contain silica fume (SF). A simple device was modified to test the chemical shrinkage for long-term growth, and the ultimate chemical shrinkage is obtained by semi-empirical formula fitting. It is found that the degree of hydration of UHPC is significantly lower than that of NC. The hydration kinetics analyzed using the Krstulovic-Dabic model shows that the hydration process of NC is type NG-I-D, which is characterized by gentle and prolonged hydration. However, the hydration of UHPC is type NG-D with the distinguishing features of early sufficiency and later stagnation. The growth of the strength, exothermic evolution, and phase development of UHPC is decelerated as the hydration process proceeds, which confirms the weak development tendency of hydration at the later stage. In addition, the effect of SF on the hydration of UHPC is minor, and the higher content of SF is beneficial to the hydration at the later stage.

scholarly journals Influence of Ultrasonication of Functionalized Carbon Nanotubes on the Rheology, Hydration, and Compressive Strength of Portland Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5248
Author(s):  
Laura Silvestro ◽  
Artur Ruviaro ◽  
Geannina Lima ◽  
Paulo de Matos ◽  
Afonso R. G. de Azevedo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Portland Cement ◽  
Mechanical Performance ◽  
Isothermal Calorimetry ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Degree Of Hydration ◽  
Vis Spectroscopy ◽  
Localized Defects

The functionalization process usually increases the localized defects of carbon nanotubes (CNT). Thus, the ultrasonication parameters used for dispersing non-functionalized CNT should be carefully evaluated to verify if they are adequate in dispersing functionalized CNT. Although ultrasonication is widely used for non-functionalized CNT, the effect of this dispersing process of functionalized CNT has not been thoroughly investigated. Thus, this work investigated the effect of ultrasonication on functionalized CNT + superplasticizer (SP) aqueous dispersions by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). Furthermore, Portland cement pastes with additions of 0.05% and 0.1% CNT by cement weight and ultrasonication amplitudes of 0%, 50% and 80% were evaluated through rheometry, isothermal calorimetry, compressive strength at 1, 7 and 28 days, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). FTIR results from CNT + SP dispersions indicated that ultrasonication may negatively affect SP molecules and CNT graphene structure. The increase in CNT content and amplitude of ultrasonication gradually increased the static and dynamic yield stress of paste but did not significantly affect its hydration kinetics. Compressive strength results indicated that the optimum CNT content was 0.05% by cement weight, which increased the strength of composite by up to 15.8% compared with the plain paste. CNT ultrasonication neither increases the degree of hydration of cement nor the mechanical performance of composite when compared with mixes containing unsonicated CNT. Overall, ultrasonication of functionalized CNT is not efficient in improving the fresh and hardened performance of cementitious composites.

scholarly journals Blended cement hydration assessment by thermogravimetric analysis and isothermal calorimetry

2018 ◽  
Vol 149 ◽  
pp. 01062
Author(s):  
Meriem Meziani ◽  
Nasser Chelouah ◽  
Ouali Amiri ◽  
Nordine Leklou
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermogravimetric Analysis ◽  
Isothermal Calorimetry ◽  
Blended Cement ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hydration Kinetics ◽  
Scanning Calorimetry ◽  
Cement Pastes ◽  
Degree Of Hydration

In the present study, the hydration of Portland cement pastes containing 5%, 10%, 15% and 20% tuff, limestone filler and granodiorite was investigated by thermogravimetric analysis coupled with differential scanning calorimetry and microcalorimetry isotherm. The monitoring of the hydration kinetics by thermogravimetric analysis made it possible to quantify the quantity of water combined with the cement (nonevaporable water) and the degree of hydration. By coupling this technique to the differential scanning calorimetry, it was also possible to measure the energy absorbed or released by the material during its decomposition. The results showed that the non-evaporable water content and the degree of hydration of the mixtures containing various mineral admixtures were relatively lower with respect to the reference mixture when as the content of mineral admixture increased. The effect of the evolution of the hydration process on the mechanical properties of mortars was also monitored. The relative variation of the compressive strength to that of the flexural strength was evaluated at 7, 28 and 90 days. Results showed that all the mixtures have a greater contribution in flexion than in compression.

scholarly journals Surface-Functionalized Nanocelluloses as Viscosity-Modifying Agents in Engineered Cementitious Composites

2021 ◽  
Vol 8 ◽  
Author(s):  
Long Liang ◽  
Junlei Yang ◽  
Guowei Lv ◽  
Zhen Lei ◽  
Xiurong Li ◽  
...  
Keyword(s):  
Surface Oxidation ◽  
Attenuated Total Reflection ◽  
No Oxidation ◽  
Rheological Parameters ◽  
Cementitious Composites ◽  
Gravimetric Analysis ◽  
Oxidation Degree ◽  
Engineered Cementitious Composites ◽  
Degree Of Hydration ◽  
Polyethylene Fiber

This study investigated the feasibility of using nanofibrilliated celluloses (CNF) (0.1% by weight of binder materials) with three oxidation degrees, no oxidation (NCNF), low oxidation (LCNF), and high oxidation (HCNF), as a viscosity-modifying agent (VMA) to develop polyethylene fiber (PE)-engineered cementitious composites (ECC). Attenuated total reflection-Fourier transform infrared (ATR-FTIR), dynamic light scattering (DLS), and zeta potential were performed to characterize the properties of the CNF with different oxidation degrees. More stable CNF suspensions could be obtained due to the increasing oxidation degree. Rheology tests showed that CNF replacing VMA could modify the plastic viscosity and yield stress of the fresh matrices. With increasing the oxidation degree of CNF, a significant enhancement was seen for the rheological parameters. It was conducted that CNF could increase the compressive strength, the tensile stress, the nominal flexural strength, and the fracture toughness compared with ECC using VMA, and much higher oxidation degrees yielded higher enhancements (HCNF > LCNF > NCNF). ECC using CNF to replace VMA also achieved ultra-high ductility behavior with the tensile strain of over 8% and the saturated multiple cracking pattern. These finds were supplemented by thermal gravimetric analysis (TGA), which showed that the degree of hydration increased with increasing CNF surface oxidation degree. Additionally, the morphology images of PE fibers were observed by scanning electron microscope (SEM).

scholarly journals Tensile Performance of High Ductility Cementitious Composites With Recycled Powder From C&D Waste

2021 ◽  
Vol 8 ◽  
Author(s):  
Jing Ji ◽  
Huayu Song ◽  
Liangqin Jiang ◽  
Hongguo Ren ◽  
Yunfeng Zhang ◽  
...  
Keyword(s):  
Tensile Properties ◽  
Sem Analysis ◽  
Cementitious Composites ◽  
Environmental Scanning ◽  
Gravimetric Analysis ◽  
High Ductility ◽  
Hydration Kinetics ◽  
Phase Development ◽  
Polyethylene Fiber ◽  
Micro Structures

The effects of recycled powder (RP) on hydration, micro-structures, compressive strength and tensile properties of high-ductility cementitious composites (HDCC) were studied. Three mass ratios of RP ranging from 10, 30 to 60% were employed to partially replace the cement. The hydration kinetics of RP-amended matrix was measured to investigate the influence of RP on the cementitious hydration process and the phase development was quantified by the thermal gravimetric analysis. Mechanical properties, including the compressive and tensile properties of HDCCs were obtained at 28 days. The morphology of reinforced polyethylene fiber at the fracture surface was obtained by the environmental scanning electron microscope (SEM) analysis.

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