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A series of tests were carried out to evaluate crack resistance and mechanical properties of polyvinyl alcohol fiber-reinforced cement-stabilized macadam, which is widely used as pavement base or subbase composite material. Three series of cement-stabilized macadam mixtures with cement content of 3.2%, 3.6%, and 4.0% were prepared by incorporating...
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This report represents a detailed works on utilization of refined Saccharum officinarum bagasse ash (SOBA) as partially mixed with the cement content for the preparation of normal concrete. This experiment reveals SOBA result on cement replacement material (CRM). The CRM properties of SOBA were used because of its chemical properties, fine grained...
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... And then fiber could receive and bear the stress through the bridge and transmission effects between the concrete and fiber, herein, the mechanical properties of concrete is significantly enhance [22][23][24][25][26]. At the same time, the fiber brings about plastic deformation to absorb a large amount of energy, which can delay the development of non-structural cracks and the formation of structural cracks in concrete, this could validly improve the anti-crack performance of concrete [27][28][29]. ...
... Despite that there are vast research on high-strength and high-modulus fine PVA fiber currently, for instance, Zhao et al. [27] fabricated a series of FRC by adding fine PVA fiber (diameter ~ 15 μm) to investigate the influence of the fine PVA fiber doping (0 ~ 1.2 kg/m 3 ) on mechanical properties and crack resistance properties of the concrete. As a result, when the addition of the fine PVA fiber was 0.9 kg/ m 3 , the split strength and compressive strength of FRC increased by 12.5% and 19.5% than that of the pure concrete, and the dry shrinkage coefficient was reduced by 44.4%, which demonstrated that fine PVA fiber can effectively improve the mechanical properties and anti-cracking properties of cement concrete, but the optimal doping of fine PVA fibers is only 0.9 kg/m 3 . ...
Large-diameter polyvinyl alcohol (PVA) fiber has a broad application prospect in the field of reinforcing geomorphic building materials owing to its large diameter and excellent mechanical properties. In this work, PVA2499 polymer was used as the raw material, DMSO/H2O as the hybrid solvent, and the staged heating approach was adopted to obtain high solid content of spinning solutions, and then a series of large-diameter medium-strength PVA fibers with different solid contents of spinning solutions (SCS) were prepared by dry-wet spinning, and the Fourier transform infrared spectroscopy (FTIR), scan electron microscope (SEM), differential scanning calorimetry (DSC), thermal analysis (TGA), X-ray diffractometer (XRD) and electronic universal testing machine were performed to explore the effect of the SCS on the structure and performance of PVA fiber. The results displayed that with the increase of the SCS, the -OH stretching vibration absorption peak of PVA fiber moved from 3276 cm−1 to 3262 cm−1; The tensile strength, initial modulus, the crystallization and orientation of PVA fibers all increased first and then decreased. Especially, when the SCS was 23.5wt%, the diameter of the PVA fiber was 110.6 ± 6.0 μm (124.8 ± 6.2 dtex), the tensile strength was 7.0 ± 0.3 cN/dtex, the initial modulus was 106.2 ± 10.3 cN/dtex, the crystallization and the orientation were 49.6% and 96.8%, respectively.
... Yu et al. analyzed the fatigue performance of PVA fiber cement-stabilized macadam and established a cumulative fatigue life damage model [16]. Zhao et al. prepared PVA fiber cement-stabilized macadam with different PVA fiber lengths, doping amounts, and different cement contents and studied their shrinkage characteristics [17]. In summary, the current research on the durability of PVA fiber cement-based materials is mainly focused on PVA fiber cement concrete. ...
... The fatigue life of cement-stabilized macadam under different stress intensity ratios was calculated by linear regression, as shown in Figure 8. (17) where i is the ith specimen number, and k is the number of specimens with the same stress level. ...
To further improve the durability of cement-stabilized macadam and guarantee the use quality and sustainability of a semi-rigid base, the current study was carried out. With the help of a dry shrinkage test, temperature shrinkage test, freeze–thaw bending test, and fatigue test, the effect of incorporating PVA fiber on the deformation characteristics of cement-stabilized macadam was analyzed, and the changes in low-temperature residual toughness of the mixture before and after modification were compared. The low-temperature toughness of PVA fiber cement-stabilized macadam was evaluated with the help of the standard toughness evaluation method. The fatigue life prediction equation of PVA fiber cement-stabilized macadam was established based on the Weibull distribution. The results showed that PVA fiber can effectively improve the deformation characteristics, low-temperature toughness, and fatigue performance of cement-stabilized macadam. The low-temperature residual flexural tensile strength and low-temperature bearing capacity were increased by 10.3% and 55.3%, respectively. The residual toughness indices were increased by 58.6%, 88.1%, and 98.3% and the residual strength index was increased by more than 100%. The fatigue life was improved by 178~368% under different stress intensity ratios. The fatigue life values obeyed the two-parameter Weibull distribution, and the correlation between the fatigue life prediction equation and the measured data was significant. The fatigue life prediction error was between 0.03 and 4.9% under different stress intensity ratios.
... The single scraper spiral blade can achieve higher compressive strength than the double scraper spiral blade and spade shape blade in a two-shaft mixer (Zhang & Feng, 2011). Mixing speed varies with different mixed materials, such high mixing speed is beneficial to disperse the fine powder or mix the mixture without coarse aggregate (Abd EI-Motaal et al., 2020), whereas the mixture with coarse aggregate usually needs a lower mixing speed (≤ 100 rpm) (Zhao et al., 2020). Besides, as an increase of requirement of cement-base materials, more components (silica fume, limestone filler, etc.) and admixture (water reducer, etc.) are added to the mixture to improve the properties, leading to longer mixing time needed (Chopin et al., 2004;Vandanjon et al., 2003). ...
The technology of vibratory mixing has been applied to improve the compressive strength of cement-stabilized macadam (CSM). The aim of this study is to investigate the effect of vibration acceleration and cement dosage on the unconfined compressive strength and density of CSM. The mixtures with four cement dosages (2%, 3%, 4%, and 5%) were prepared by conventional mixing (0 g) and vibratory mixing (1 g, 2 g, and 3.5 g). The unconfined compressive strength was tested under different mixing methods. And the microstructure of CSM was analyzed by scanning electron microscope. The results indicate that samples using vibratory mixing have higher strengths, lower coefficient of variation, and denser microstructures, compared with the conventional compulsory mixing. Compared with 15% in conventional mixing, the strength variable coefficient of CSM is less than 10% in the vibratory mixing method. As the cement dosage and the vibration acceleration increase, the unconfined compressive strength increases. However, cement dosage has a more significant influence on improving the unconfined compressive strength than the mixing method. With the increase of every 1% in cement dosage, the 7-day strength of conventional mixing and in vibratory mixing average increased by 59% and 38%, respectively. However, the maximum improvement rate of the UCS value is 20–56.7% when vibration acceleration increased from 0 to 1 g. Especially when cement dosage is high, the effect of vibratory mixing on improving strength is limited. Besides, vibratory mixing reduces the original cement dosage by over 1.6% with the qualified unconfined compressive strength at vibration acceleration of 2 g, which is recommended in construction practice.
... However, in fact, the deterioration mechanism of microcrack pores inside the semirigid base material is often promoted by the mechanical behavior, so the macroscopic mechanical behavior performance must have some inevitable connection with the microfine pore development characteristics; an in-depth study of their relationship can help to reveal the intrinsic cracking mechanism of the material [22][23][24]. Most focus mainly on the study of thermodynamic parameters and properties of semirigid base material [5,[30][31][32][33][34][35]. Lv et al. [36] found that the strength and frost resistance of cement-stabilized gravel material increase with increasing curing time and cement content through unconfined compressive test, flexural test, and freeze-thaw test studies. ...
Understanding the evolution of mechanical properties and pore structure of semirigid base under large temperature difference is of great significance for evaluating the durability and safety of semirigid base structure and studying the damage cracking mechanism and prevention technology of semirigid base induced by large temperature difference climate. This paper studies the variation law of peak stress and dynamic modulus, the evolution characteristics of pore structure, and the pore size distribution of semirigid base after different cycles at different temperature intervals. Based on the analysis of peak stress and dynamic modulus test results, the degradation effect of freeze-thaw environment (−20°C∼20°C) on semirigid base is far greater than that of high-temperature environment (20°C∼60°C) and low-temperature environment (−5°C∼−30°C). There are significant decreases in peak stress and dynamic modulus of semirigid base in the late cycle (12 to 15 cycles). Under low-temperature and freeze-thaw environments, the axial load resistance of semirigid base is significantly correlated with the deformation resistance, and the correlation between the two is not significant under high-temperature environment. The variability of the thermal expansion and contraction characteristics of the internal microscopic phases of the semirigid base and the force characteristics of the pore interface phases are the root causes of the damage and cracking of the pavement base in a large temperature difference climate.
... PVA fibers affect cement's strength, setting time, and morphology by increasing fracture resistance and decreasing compressive strength and setting time [13]. The addition of PVA fibers improves the specimens' resistance to dry shrinkage and temperature shrinkage [14]. The mechanical performance of cementitious materials is strengthened by incorporating the additive of metal and polypropylene fibers [15]. ...
Cementitious materials can be reinforced by adding different fibers. However, the effect of different fiber reinforcements on the mechanical properties of cement-based materials remains to be further studied. This paper studies the influencing factors of different fiber cement-based materials by combining experimental and theoretical methods. The tests used carbon fiber, glass fiber, and polyvinyl alcohol (PVA) fiber-reinforced cement-based materials. The addition ratios of fibers are 0%, 0.5%, and 1% by volume respectively. The compressive strength, bending strength, and drying shrinkage are studied for 3 to 28 d. The relationship between bending strength, compressive strength, dosage, and shrinkage is analyzed. The test results show that carbon fiber cement-based materials’ bending, and compressive strength increase the fastest, followed by glass and PVA fibers. The presented mathematical model accurately predicted the strength of the three fiber cement-based materials at different curing times. Compared to glass fiber and PVA fiber, carbon fiber shrinks less. It can be shown that the fiber significantly affects the early strength change of the fiber cement-based material by changing the shrinkage size of the fiber-cement-based material. The bending strength of carbon fiber, glass fiber, and PVA fiber increases with the increase of fiber volume fraction. On the other hand, the compressive strength increases and then decreases. Mechanical tests show that carbon fiber has the best reinforcement effect. The number of fibers, center spacing, and ultimate tensile length are all important factors that affect the strength of different fiber cement-based materials. Moreover, applied ABAQUS software established compression and bending finite element models of fiber-cement composites. It can predict the mechanical performance concerning fiber cement-based materials’ different types and volume fractions.
This study investigates the shrinkage performance of cement-stabilized gravel (CSG) compacted using vertical vibrations. The reliability of the vertical vibration compaction method (VVCM) for preparing CSG was confirmed by comparing the mechanical properties of different laboratory compaction specimens with field core samples. The factors influencing shrinkage deformations of CSG were investigated. Based on fracture mechanics, a pair of shrinkage cracking coefficients were proposed to represent the shrinkage cracking of CSG, and the shrinkage cracking performance of CSG was quantified to assess the effect of gradation and cement content on shrinkage cracking. The mechanical strength of VVCM-compacted CSGs was found to exhibit a correlation of 91% with the field core samples. Most of the drying-shrinkage deformation of CSG occurs within the first 15 d (> 85% of the total), during which it increased linearly with the amount of water loss. The resistance of a skeleton dense gradation to drying- and temperature-shrinkage deformations was superior to that of a suspended dense gradation. Moreover, increasing dust and cement contents exacerbated the shrinkage deformation of CSG. The skeleton dense gradation had the best shrinkage cracking resistance, and an excess dust content worsened the shrinkage cracking of CSG. Increasing cement content resulted in higher drying-shrinkage deformation but did not considerably affect shrinkage cracking.
Based on the orthogonal test method, the mixture proportion design of cement-stabilized macadam (CSM) modified with rubber powder and fiber is studied. With strength and dry-shrinkage as key indices, the influence of length of polyvinyl alcohol (PVA) fiber, fiber content, particle size of rubber powder, and rubber powder content on the performance of CSM is analyzed, and the optimum mixing proportion is determined. Based on this, the modification mechanism of CSM by rubber powder and fiber is further studied from a micro perspective. The results show that the 7-day unconfined compressive strength of CSM gradually increases with the increase of fiber length. With the increase of fiber content, the compressive strength shows a trend of first increasing and then decreasing. The 7-day unconfined compressive strength of CSM gradually increases with the increase of rubber powder mesh size and linearly decreases with the increase of rubber powder content. The 28-day average dry-shrinkage coefficient of CSM shows a trend of first decreasing and then increasing with the increase of fiber length and fiber content, and gradually increasing with the increase of rubber powder mesh number and rubber powder content. Considering the strength and shrinkage characteristics, the optimum mixing parameters are 40 mesh rubber powder, 0.5 % rubber powder, 18-mm fiber length, and 1.2-kg/m3 fiber content. Scanning electron microscopy results show that there is a gap between the rubber powder and the cement matrix, and the interface between the two is discontinuous, with weak bonding, resulting in a decrease in the compressive strength of CSM. PVA fiber can improve the toughness of CSM. It has good adhesion with cement matrix. It forms a three-dimensional network support structure in the CSM mixture and can restrain water loss in the cement matrix, thus greatly improving the cracking resistance of CSM.
Poly(vinyl alcohol) is one of the most attractive polymers with a wide range of uses because of its water solubility, biocompatibility, low toxicity, good mechanical properties, and relatively low cost. This review article focuses on recent advances in poly(vinyl alcohol) electrospinning and summarizes parameters of the process (voltage, distance, flow rate, and collector), solution (molecular weight and concentration), and ambient (humidity and temperature) in order to comprehend the influence on the structural, mechanical, and chemical properties of poly(vinyl alcohol)-based electrospun matrices. The importance of poly(vinyl alcohol) electrospinning in biomedical applications is emphasized by exploring a literature review on biomedical applications including wound dressings, drug delivery, tissue engineering, and biosensors. The study also highlights a new promising area of particles formation through the electrospraying of poly(vinyl alcohol). The limitations and advantages of working with different poly(vinyl alcohol) matrices are reviewed, and some recommendations for the future are made to advance this field of study.
