scholarly journals Investigation on the Influences of Curing Time on the Cracking Resistance of Semiflexible Pavement Mixture

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Hua Tan ◽  
Zijia Xiong ◽  
Minghui Gong ◽  
Jie Chen ◽  
Jinxiang Hong
Keyword(s):  
Failure Mechanism ◽  
Energy Dispersive Spectrum ◽  
Bending Test ◽  
Strength Development ◽  
Curing Time ◽  
Cracking Resistance ◽  
Weak Zone ◽  
Grouting Material ◽  
Scb Test ◽  
Grouting Materials

Semiflexible pavement (SFP) is constructed by pouring grouting material into porous asphalt (PA) mixture. SFP has been widely used to address the rutting distress issues across China in recent years. However, studies on its cracking resistance are limited and the failure mechanism of the SFP mixture has not been fully explored nor understood in a comprehensive way. Moreover, the influences of the curing time on the cracking property of the SFP mixture are still not clear. To this end, the strength development and shrinkage properties of grouting materials are determined by utilizing the three-point beam bending test and the shrinkage test. The semicircular bending (SCB) test and the scanning electron microscope-energy-dispersive spectrum (SEM-EDS) are conducted in this study to investigate the cracking resistance and failure mechanism of SFP mixtures with different curing days. Results show that both the strength and shrinkage of grouting materials would develop as the curing time was extended from 0 days to 14 days. SCB test results show that SFP mixtures have higher tensile strength but a lower flexibility index (FI) than PA mixture. It is found that the cracking resistance of SFP mixture is influenced by both the grouting materials’ strength and shrinkage. SEM-EDS analysis demonstrates that the cement-asphalt interface is a stress concentration site and therefore is the weak zone where cracks would initially develop. The microcracks found in the interface zone with different curing days may contribute to the decline of the SFP mixture’s anticracking ability. This study sheds light on the further application of SFP in practical projects.

scholarly journals Fatigue Cracking Resistance of Engineered Cementitious Composites (ECC) under Working Condition of Orthotropic Steel Bridge Decks Pavement

2019 ◽  
Vol 9 (17) ◽  
pp. 3577 ◽  
Author(s):  
Yanjing Zhao ◽  
Jiwang Jiang ◽  
Fujian Ni ◽  
Lan Zhou
Keyword(s):  
Digital Image ◽  
Working Condition ◽  
Fatigue Cracking ◽  
Surface Strain ◽  
Internal Crack ◽  
Cementitious Composites ◽  
Cracking Resistance ◽  
Engineered Cementitious Composites ◽  
Crack Distribution ◽  
Scb Test

In order to investigate the fatigue cracking resistance of engineered cementitious composites (ECC) used in in total life pavement, the semi-circular bending (SCB) test and improved three-point bending fatigue test (ITBF) were utilized in this study. The digital image correlation (DIC) method was also utilized to track the surface strain fields of specimens during the SCB test. X-ray computed tomography (CT) and digital image processing (DIP) technologies were applied to measure the internal-crack distribution of the ITBF specimen. The results of the SCB test showed that the fatigue cracking damage process of ECC can be divided into three stages and that the cracking stable propagating stages occupied the main part, which indicates that ECC has excellent ductility and toughness and could work very well with existing cracks. The ITBF results showed that the fatigue cracking resistance of ECC was better than epoxy asphalt concrete (EAC). In addition, the internal-crack distribution along the depth direction of the ITBF specimen could be presented well by the image pixel statistical (IPS) method based on CT scanning of image slices. It could be found that multiple cracks propagate simultaneously in ECC, instead of a single crack, under the OSBD pavement working condition.

Conceptualization of Three-Stage Fatigue Failure in Asphalt-Rubber Gap-Graded Mixtures using Dynamic Semi-Circular Bending Test

2020 ◽  
Vol 2674 (7) ◽  
pp. 44-55
Author(s):  
Veena Venudharan ◽  
Krishna Prapoorna Biligiri
Keyword(s):  
Failure Process ◽  
Mouth Opening ◽  
Fatigue Performance ◽  
Bending Test ◽  
Crack Mouth Opening Displacement ◽  
Fatigue Process ◽  
Structural Deterioration ◽  
Asphalt Rubber ◽  
Scb Test ◽  
Cracking Mechanism

The objective of this study was to qualitatively measure the cracking mechanism of asphalt-rubber gap-graded (AR-Gap) mixtures and compare the methodical approach proposed in this research with the conventional fatigue process. As part of experimentation plan, dynamic a semi-circular bending (SCB) test was conducted on 27 AR-Gap mixtures with varying mix parameters, including, binder type, binder content, and aggregate gradation. Fatigue life ( Nf) obtained from the dynamic SCB test was analyzed from a statistical viewpoint, and key relationships that potentially contribute to fatigue performance were identified. Later, crack mouth opening displacement (CMOD) was used to study the cracking mechanism of AR-Gap mixtures. CMOD data were analyzed using the Francken model that theorizes the accumulated damage as a three-stage failure. Further, fatigue tertiary life ( Nft) was determined on the premise of structural deterioration obtained from the three-stage failure process. The fatigue disparity factor (ξ), the ratio of Nf to Nft for each asphalt mix was estimated to compare fatigue performance indices. The score of ξ for all the mixtures exceeded 50%, which was indicative of longer crack initiation and crack propagation phase over the third stage of the fatigue cracking mechanism. Overall, the fatigue mechanism was explained through the conceptualization of the three-stage fatigue process through various intrinsic properties of AR-Gap mixtures.

Study of Rheological Properties of Carbon Nanotube-Reinforced Ultrafine Cement Grouting Materials

2021 ◽  
pp. 1-44
Author(s):  
Yunxiao Liu ◽  
Jiahang Zhang ◽  
Yinyin Chi
Keyword(s):  
Carbon Nanotubes ◽  
Rheological Properties ◽  
Polyvinyl Pyrrolidone ◽  
Cement Grouting ◽  
Grouting Material ◽  
Multi Walled Carbon Nanotubes ◽  
Different Diameters ◽  
Grouting Materials ◽  
Walled Carbon Nanotubes ◽  
Ultrafine Cement

In this study, three different diameters of multi-walled carbon nanotubes (MWCNTs) dispersed by polyvinyl pyrrolidone (PVP) were used to reinforce superfine cement grouting materials. The effect of MWCNTs and polyvinyl pyrrolidone (PVP) on the rheological properties of grouting material were accordingly studied. It was found that the yield stress (τ0) and plastic viscosity (η) were slightly decreased when PVP content was low and increased when the PVP content increased. The effect of MWCNT diameter on τ0 was not found to be clear but was more significant on η. The smaller MWCNT diameter was, the more quickly η increase. It was also found that the thixotropic ring area was increased as the MWCNTs content increased. The addition of PVP and MWCNTs caused an increase in the number of entanglement points in different scales, which was the main reason for the viscosity and thixotropy increase. Therefore, the rheological properties of superfine cement grouting material should be adjusted when MWCNTs were added as a reinforcing component. Due to the wrapping of PVP on cement particles which isolates the contacting part between the water and the cement particles, it slows down the cement's hydration rate thus slows down the fluidity loss of the slurry.

scholarly journals Polyurethane/Red Mud Composites with Flexibility, Stretchability, and Flame Retardancy for Grouting

Polymers ◽  
2018 ◽  
Vol 10 (8) ◽  
pp. 906 ◽  
Author(s):  
Chunjing Zhang ◽  
Bo Shuai ◽  
Xuefeng Zhang ◽  
Xinxin Hu ◽  
Hui Zhang ◽  
...  
Keyword(s):  
Polyethylene Glycol ◽  
Flame Retardancy ◽  
Red Mud ◽  
Three Dimensional ◽  
Engineering Application ◽  
Synergistic Interactions ◽  
Grouting Material ◽  
Dimensional Network ◽  
Grouting Materials ◽  
Inorganic Composite

Flexibility, stretchability, and flame retardancy are of ever increasing importance in constructing grouting materials. Herein, a simple and effective strategy to make organic-inorganic composite grouting material in a “flexible, stretchable, and flame retardant” way was based on the excellent synergistic interactions among polyurethane prepolymer, red mud, polyethylene glycol, and trimethylolpropane. The resultant polyurethane/red mud composite grouting material with three-dimensional network structure presented a favorable flexibility, desirable compressive strength of 29.2 MPa at 50% compression state, and a good elongation at 15.1%. The grouting material was mainly composed of amorphous polyurethane and crystalline red mud, and its probable formation mechanism was reaction of prepolymer with H2O, polyethylene glycol and trimethylolpropane under vigorous stirring in the presence of catalyst. Furthermore, the grouting material possessed favorable thermal stability, flame retardancy and repairment performance for roadway cracks. This work may open a simple and convenient avenue for the massive engineering application of red mud and preparation of flexible organic-inorganic hybrid grouting material.

Study on Microfine Cement Grouting Material for Silty Fine Sand Stratum

2013 ◽  
Vol 838-841 ◽  
pp. 1457-1462
Author(s):  
Chun Lei Xia ◽  
Ying Ye ◽  
Guan Ming Wang ◽  
Li Cui
Keyword(s):  
Portland Cement ◽  
Particle Diameter ◽  
Fine Sand ◽  
Cement Grouting ◽  
Grouting Material ◽  
Soluble Glass ◽  
Microfine Cement ◽  
Sand Flow ◽  
Sand Stratum ◽  
Grouting Materials

Silty fine sand is the second smallest sand with a particle diameter ranging from 0.0625 to 0.120 mm.This kind of sand exists in a large amount in Beijing subway excavation project. Due to the poor self-stabilization of this stratum,seeping , sand flow and collapse take place frequently. Grouting materials such as Portland cement and soluble glass (also called sodium silicate) are employed in most of excavation projects to reinforce this sand stratum. However, the reinforcement is not effective, leading to a large amount of accidents in the process of construction. The reason may be attributed to the fact that Portland cement is unable to penetrate into the stratum and the strength of soluble glass (0.6MPa) is too weak to resist the stratum pressure. To solve this problem, a modified microfine cement grouting material able to penetrate into silty fine sand stratum is developed in this paper. A combination of suspension and diluent is used to increase the penetration extension of the grouts,and the experimental results reveal that the addition of the mixture of suspension and diluent in microfine cement grouting materials improves the penetration property substantially.

scholarly journals Fracture Behavior Analysis of Semi-Circular Bending Test

2019 ◽  
Vol 271 ◽  
pp. 03007
Author(s):  
David Renteria ◽  
Shadi Saadeh ◽  
Enad Mahmoud
Keyword(s):  
Fracture Behavior ◽  
Asphalt Mixture ◽  
Asphalt Mixtures ◽  
Bending Test ◽  
Random Generation ◽  
Crack Initiation And Propagation ◽  
Air Voids ◽  
Generation Technique ◽  
Initiation And Propagation ◽  
Scb Test

The objective of this paper is to investigate the effect of air voids on the fracture properties of asphalt mixtures using SCB test in Discrete Element Method (DEM). Superpave and Coarse Matrix High Binder (CMHB) mixtures gradation were used to generate the percentages of aggregate, mastic, and air voids within the specimens. Aggregates and air voids were randomly generated for each asphalt mixture case. Model results illustrate that the crack initiation and propagation is controlled by the location of the aggregate particles and air voids in the mixture. Additionally, the absence of air voids above the tip of the notch increases the stiffness of the sample and increase its resistance to failure. The novelty of using DEM and the random generation technique for generating numerical specimens proved to be a useful approach in investigating the properties of the mastic, aggregate and interface as they relate to fracture of asphalt mixtures.

scholarly journals Strengthening of Concrete Element with Precast Textile Reinforced Concrete Panel and Grouting Material

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3856
Author(s):  
Young-Jun You ◽  
Hyeong-Yeol Kim ◽  
Gum-Sung Ryu ◽  
Kyung-Taek Koh ◽  
Gi-Hong Ahn ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bending Test ◽  
Strengthening Effect ◽  
Textile Reinforced Concrete ◽  
Concrete Element ◽  
Rc Structures ◽  
Flexural Strengthening ◽  
Grouting Material ◽  
Rc Slab ◽  
Rc Slabs

Textile reinforced concrete (TRC) has widely been used for strengthening work for deteriorated reinforced concrete (RC) structures. The structural strengthening often requires accelerated construction with the aid of precast or prefabricated elements. This study presents an innovative method to strengthen an RC slab-type element in flexure using a precast panel made of carbon TRC. A total of five RC slabs were fabricated to examine the flexural strengthening effect. Two of them were strengthened with the precast panel and grouting material and another set of two slabs was additionally strengthened by tensile steel reinforcement. The full-scale slab specimens were tested by a three-point bending test and the test results were compared with the theoretical solutions. The results revealed that the ultimate load of the specimens strengthened with the TRC panel increased by at least 1.5 times compared to that of the unstrengthened specimen. The application of the precast TRC panel and grouting material for the strengthening of a prototype RC structure verified its outstanding constructability.

Effect of Curing Regimes on Metakaolin Geopolymer Pastes Produced from Geopolymer Powder

2012 ◽  
Vol 626 ◽  
pp. 931-936 ◽  
Author(s):  
Liew Yun Ming ◽  
Kamarudin Hussin ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Mohammed Binhussain ◽  
Luqman Musa ◽  
...  
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Solidification Process ◽  
Curing Temperature ◽  
Alkali Concentration ◽  
Strength Development ◽  
Curing Time ◽  
Curing Conditions ◽  
Metakaolin Geopolymer ◽  
Geopolymer Paste

The properties of metakaolin geopolymer paste are affected by the alkali concentration, the initial raw materials, solidification process, and amount of mixing water as well as the curing conditions. This study aimed to investigate the effect of curing temperature (room temperature, 40°C, 60°C, 80°C and 100°C) and curing time (6h, 12h, 24h, 48h and 72h) on the geopolymer pastes produced from geopolymer powder. The results showed that curing at room temperature was unfeasible. Heat was required for the geopolymerization process, where strength increased as the curing temperature was increased. Moderate elevated curing temperature favored the strength development of geopolymer pastes in comparison with those treated with extreme elevated curing temperature. When geopolymer paste was subjected to extreme elevated curing temperature, shorter curing time should be used to avoid deterioration in strength gain. Similarly, longer curing time was recommended for moderate elevated curing temperature. The microstructure of geopolymer paste cured at moderate curing temperature showed obvious densification of structure. In contrast, the structure formed was weak and less compact at very high elevated curing temperature.

Development of Superfine Spherical Silica Grout as an Alternative Grouting Material for the Geological Disposal of Long-Lived Radioactive Waste

2010 ◽  
Author(s):  
Morimasa Naito ◽  
Hirokazu Kishi ◽  
Naomi Fukuoka ◽  
Tsutomu Yamada ◽  
Hideaki Ishida
Keyword(s):  
Radioactive Waste ◽  
Calcium Hydroxide ◽  
Cementitious Materials ◽  
Geological Disposal ◽  
Grouting Material ◽  
Spherical Silica ◽  
Geological Repository ◽  
Binder Ratio ◽  
Grouting Materials ◽  
Term Performance

As an alternative grouting material for the geological repository of long-lived radioactive waste, the “Superfine Spherical silica Grout” (SFSG) material is developed using a fine spherical silica and a fine calcium hydroxide. The developed SFSG material takes an advantage of its smaller particle size distribution (max. ∼1 micron or less) than those of the cementitious materials, and also provides a low alkaline environment so as to reduce unfavorable effects on the long-term performance of geological disposal system. The SFSG is a mixture of the “super fine silica powder”, the superfine calcium hydroxide and additives such as superplasticizer. Presently, the mixture being investigated for grouting materials is focused on water/binder ratio (W/B) of 1.2. Some preliminary laboratory experiments were carried out to characterize its fundamental properties from the viewpoint of practical use for geological disposal, which is required to be equivalent with the conventional cementitious materials in terms of penetrability, strength, pH performance and workability. From a series of experiments, it was concluded that SFSG is expected to become an alternative grouting material for a geological repository.

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