Mechanical strength model of engineered cementitious composites with freeze–thaw damage based on pore structure evolution

Lu, Shan; Yin, Liqiang; Yan, Changwang; Lu, Lihe; Zhou, Ji

doi:10.1016/j.cemconcomp.2022.104706

Cited by 30 publications

(4 citation statements)

References 37 publications

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“…According to the principle of the NMR, the distribution of the NMR T 2 spectrum is related to the aperture, and this process can be simplified as [ 44 , 45 ]:

where T 2 is the free relaxation time of the pore fluid, ms; ρ 2 is the transverse surface relaxation strength of T 2 , μm/ms; S is the stomata surface area, cm 2 ; V is the fluid volume in the pore, cm 3 . For samples that can be equivalent to spherical and cylindrical holes, Equation (9) can be further converted into the relationship between the T 2 relaxation time and aperture [ 46 ]:

where γ c is the radius of the hole; F s is the geometric factor, spherical hole F s = 3, and cylindrical hole F s = 2. Then, Formula (10) can be adjusted as:

where C = ρ 2 F s , C is the transformation coefficient.…”

Section: Experimental Designmentioning

confidence: 99%

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Investigation on the Mechanical Properties and Strengthening Mechanism of Solid-Waste–Sulfur-Based Cementitious Composites

Liu

Yan

et al. 2023

Materials

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This research used waste ceramic powder (CP) to replace aggregate, fly ash (FA) as filler, and combined them with sulfur to prepare composite cementitious materials. The variations of the mechanical properties with the aggregate proportions (aggregate mass/total mass) of 65%, 70%, and 75%, and the FA contents (FA mass/aggregate and filler mass) of 0%, 10%, 20%, 30%, 40%, and 50% were studied. The correlation evaluation model of sulfur content, CP content, FA content, and mechanical properties was established using the gray correlation theory, and the comprehensive mechanical property evaluation model was established as the foundation of the entropy method. Finally, the optimum proportion of the solid-waste–sulfur-based cementitious composites was determined. Results showed that, without FA, the CP increased from 65% to 75% and the comprehensive mechanical properties of the specimen increased by 60.53%. After FA was added, the peak point of the comprehensive mechanical properties appeared in group S75F10, which was 0.9210. During the hardening of the cementitious material, sulfur was mainly used as a binder, CP played the role of skeleton and part of the filler, whereas, as a crystal nucleus, the FA promoted the transformation of the sulfur crystals. Both the CP and FA can reduce the porosity of the specimen to a certain extent and have potential defect repair ability, thus densifying the matrix and improving the strength. When the proportion of sulfur: CP: FA is 1:2.7:0.3, the flexural (FS), compressive (CS), and splitting tensile (STS) strengths of the specimen are 14.8, 86.2, and 6.8 MPa, respectively. The flexural (FCR) and tensile (TCR) compression ratios are 0.172 and 0.079, respectively.

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“…According to the principle of the NMR, the distribution of the NMR T 2 spectrum is related to the aperture, and this process can be simplified as [ 44 , 45 ]:

where γ c is the radius of the hole; F s is the geometric factor, spherical hole F s = 3, and cylindrical hole F s = 2. Then, Formula (10) can be adjusted as:

where C = ρ 2 F s , C is the transformation coefficient.…”

Section: Experimental Designmentioning

confidence: 99%

“…For samples that can be equivalent to spherical and cylindrical holes, Equation (9) can be further converted into the relationship between the T 2 relaxation time and aperture [ 46 ]:

where γ c is the radius of the hole; F s is the geometric factor, spherical hole F s = 3, and cylindrical hole F s = 2.…”

Section: Experimental Designmentioning

confidence: 99%

Investigation on the Mechanical Properties and Strengthening Mechanism of Solid-Waste–Sulfur-Based Cementitious Composites

Liu

Yan

et al. 2023

Materials

Self Cite

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“…Before the low-field NMR test is performed, the low-field NMR instrument is calibrated. The excess water on the surface of the plastic film is wiped off, and the samples are carefully positioned in the low-field NMR system for testing [39]. The low-field NMR test equipment is shown in Figure 3, and the parameter settings are shown in Table 5.…”

Section: Low-field Nmr Testmentioning

confidence: 99%

“…On the one hand, the appropriate dosage of RCP (10%) effectively reduces the pore volume and increases the compactness of the concrete. This result is due to the secondary hydration reaction and micro-aggregate filling effect, in which the RCP occupies the tiny pores within the concrete [39]. On the other hand, excessive incorporation of RCP (30%) results in increased pore volume and decreased compactness.…”

Section: Porositymentioning

confidence: 99%

Gray Model Study of Strength and Pore Structure of Recycled Concrete Powder (RCP) Concrete Based on Low-Field NMR Technology

Hou,

Yu,

Zhang

et al. 2023

Materials

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In order to improve the resource utilization of recycled concrete powder (RCP), this study aimed to investigate the effect of RCP admixture, curing age, and alkali excitation on the strength of RCP concrete. In addition, the pore structure characteristics of RCP concrete were analyzed in combination with low-field NMR. Furthermore, a gray predictive GM (1, 4) model was established to predict the mechanical properties of the concrete based on the pore structure parameters, especially the compressive and flexural tensile strengths. The results of the study indicate that the mechanical properties, namely compressive strength and flexural strength, of RCP concrete exhibit an initial increase followed by a subsequent decrease with increasing RCP content at 3 d, 7 d, and 28 d curing ages. In particular, the concrete exhibits the highest mechanical properties when the RCP content reaches 10%. As the curing age increases, the RCP gradually achieves full hydration, resulting in further refinement of the concrete pores and a denser structure, which subsequently improves the mechanical properties. In addition, the strength growth rate of alkali-excited recycled concrete (ARC) showed a continuous increase, indicating that alkali excitation increasingly improved the mechanical properties of the concrete. Furthermore, the study accurately predicted the mechanical properties of RCP concrete by using GM (1, 4) prediction models for its compressive strength and flexural tensile strength using pore characteristic parameters.

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Evolution characteristics of engineered cementitious composite pore structure and its correlation with the tensile property under simulated traffic vibrations at an early age

Lu,

Liu,

Yin

et al. 2024

J Mater Sci

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Mechanical strength model of engineered cementitious composites with freeze–thaw damage based on pore structure evolution

Cited by 30 publications

References 37 publications

Investigation on the Mechanical Properties and Strengthening Mechanism of Solid-Waste–Sulfur-Based Cementitious Composites

Investigation on the Mechanical Properties and Strengthening Mechanism of Solid-Waste–Sulfur-Based Cementitious Composites

Gray Model Study of Strength and Pore Structure of Recycled Concrete Powder (RCP) Concrete Based on Low-Field NMR Technology

Evolution characteristics of engineered cementitious composite pore structure and its correlation with the tensile property under simulated traffic vibrations at an early age

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