Hydration process and microstructure evolution of low exothermic concrete produced with urea

Wang, Liguo; Ju, Siyi; Chu, Hsin; Liu, Zhiyong; Yang, Zhiqiang; Wang, Fengjuan; Jiang, Jiuchuan

doi:10.1016/j.conbuildmat.2020.118640

Cited by 40 publications

(8 citation statements)

References 29 publications

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“…After the curing treatment, the porosities of U0.20F3.0, U0.18F3.0, and U0.16F3.0 were 3.07%, 2.53%, and 1.92%, respectively, which followed the sequence U0.20F3.0 > U0.18F3.0 > U0.16F3.0, as shown in Figure 3a. The porosity of UHPC was lower than that of high-strength concrete [45], and this was similar to the findings of Yu et al [27], Wang et al [46], and Jiang et al [47]. The porosities of U0.18F3.0 and U0.16F3.0 were invariably lower than that of U0.20F3.0, which suggested that the porosity of UHPC diminished when the water/binder ratio of UHPC was reduced.…”

Section: Microstructuresupporting

confidence: 87%

Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand

Chu

Wang

et al. 2020

Materials

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Ultra-high-performance concrete (UHPC) has received increasing attention in recent years due to its remarkable ductility, durability, and mechanical properties. However, the manufacture of UHPC can cause serious environmental issues. This work addresses the feasibility of using aeolian sand to produce UHPC, and the mix design, environmental impact, and mechanical characterization of UHPC are investigated. We designed the mix proportions of the UHPC according to the modified Andreasen and Andersen particle packing model. We studied the workability, microstructure, porosity, mechanical performance, and environmental impact of UHPC with three different water/binder ratios. The following findings were noted: (1) the compressive strength, flexural strength, and Young’s modulus of the designed UHPC samples were in the ranges of 163.9–207.0 MPa, 18.0–32.2 MPa, and 49.3–58.9 GPa, respectively; (2) the compressive strength, flexural strength, and Young’s modulus of the UHPC increased with a decrease in water/binder ratio and an increase in the steel fibre content; (3) the compressive strength–Young’s modulus correlation of the UHPC could be described by an exponential formula; (4) the environmental impact of UHPC can be improved by decreasing its water/binder ratio. These findings suggest that it is possible to use aeolian sand to manufacture UHPC, and this study promotes the application of aeolian sand for this purpose.

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Section: Microstructuresupporting

confidence: 87%

Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand

Chu

Wang

et al. 2020

Materials

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“…These values indicate that an increasing GO content leads to a nonlinear reduction in the porosity of RS-UHPC. The porosity of the RS-UHPC prepared in this study was lower than those of low-heat concrete [ 46 ], sacrificial concrete [ 47 , 48 ], and UHPC mixed with coarse aggregates [ 49 ]. The lowest porosity of RS-UHPC was observed when the GO concentration was 0.05 wt.% Therefore, from the perspective of the porosity, the optimum GO concentration to be mixed in RS-UHPC is 0.05 wt.%.…”

Section: Resultsmentioning

confidence: 99%

Effect of Graphene Oxide on Mechanical Properties and Durability of Ultra-High-Performance Concrete Prepared from Recycled Sand

et al. 2020

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Ultra-high-performance concrete (UHPC) has been used as an advanced construction material in civil engineering because of its excellent mechanical properties and durability. However, with the depletion of the raw material (river sand) used for preparing UHPC, it is imperative to find a replacement material. Recycled sand is an alternative raw material for preparing UHPC, but it degrades the performance. In this study, we investigated the use of graphene oxide (GO) as an additive for enhancing the properties of UHPC prepared from recycled sand. The primary objective was to investigate the effects of GO on the mechanical properties and durability of the UHPC at different concentrations. Additionally, the impact of the GO additive on the microstructure of the UHPC prepared from recycled sand was analysed at different mixing concentrations. The addition of GO resulted in the following: (1) The porosity of the UHPC prepared from recycled sand was reduced by 4.45–11.35%; (2) the compressive strength, flexural strength, splitting tensile strength, and elastic modulus of the UHPC prepared from recycled sand were enhanced by 8.24–16.83%, 11.26–26.62%, 15.63–29.54%, and 5.84–12.25%, respectively; (3) the resistance of the UHPC to penetration of chloride ions increased, and the freeze–thaw resistance improved; (4) the optimum mixing concentration of GO in the UHPC was determined to be 0.05 wt.%, according to a comprehensive analysis of its effects on the microstructure, mechanical properties, and durability of the UHPC. The findings of this study provide important guidance for the utilisation of recycled sand resources.

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“…It can also be seen from Figure 12 that the temperatures recorded at the same depth are different on different dates. This is because a great deal of heat is produced by the concrete during the hydration process which causes the temperature to change over time [ 31 , 32 , 33 , 34 ]. This will affect the temperature increment produced by the heating belt in the joint area.…”

Section: Resultsmentioning

confidence: 99%

Application of Fiber Bragg Grating Sensor Technology to Leak Detection and Monitoring in Diaphragm Wall Joints: A Field Study

Zhang

Chen

Zheng

et al. 2021

Sensors

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Joints between diaphragm wall panels are weak spots in wall construction. It is essential that potential leak sites are detected prior to excavation. In this study, a novel leak detection and monitoring system is presented that is based on fiber Bragg grating (FBG) sensing technology. A field study was performed in a deep excavation supported by diaphragm walls (in Hohhot, China) to validate the feasibility and effectiveness of the proposed method. Two schemes were trialed; one using pipes made of stainless steel, and one used a pipeless method. The results of the field study are presented and discussed. They show that potential leak sites in the wall joints could be determined prior to excavation using the proposed detection method. Stainless steel is a good material to use to make the detection tube because it can protect the FBG sensors and heating belts from damage and is more sensitive to water leakage. The field study provides good evidence for the feasibility of the new detection system. It also provides valuable experience for the field application of the system and has generated useful data to use in follow-up work.

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Hydration process and microstructure evolution of low exothermic concrete produced with urea

Cited by 40 publications

References 29 publications

Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand

Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand

Effect of Graphene Oxide on Mechanical Properties and Durability of Ultra-High-Performance Concrete Prepared from Recycled Sand

Application of Fiber Bragg Grating Sensor Technology to Leak Detection and Monitoring in Diaphragm Wall Joints: A Field Study

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