scholarly journals Laboratory Investigation of Compaction Characteristics of Plant Recycled Hot-Mix Asphalt Mixture

2021 ◽  
Vol 13 (6) ◽  
pp. 3005
Author(s):  
Jiangang Yang ◽  
Chen Sun ◽  
Wenjie Tao ◽  
Jie Gao ◽  
Bocheng Huang ◽  
...  
Keyword(s):  
Regression Model ◽  
Hot Mix Asphalt ◽  
Orthogonal Experiment ◽  
Asphalt Mixture ◽  
Material Design ◽  
Void Content ◽  
Range Analysis ◽  
Aggregate Gradation ◽  
Compaction Characteristics ◽  
Compaction Energy

In this study, the compaction characteristics of recycled hot-mix asphalt (RHMA) were evaluated using the void content (VV), compaction energy index (CEI), slope of accumulated compaction energy (K), and lock point (LP). Then, the effects of the compaction parameters, including the gradation of the RHMA, reclaimed asphalt pavement (RAP) content, temperature of gyrations, and number of gyrations, on the compaction characteristics of RHMA were investigated. An orthogonal experiment was designed and the data collected were analyzed via range analysis; then, a regression model was generated relying on a quadratic polynomial. Furthermore, the regression model was used for the comparison and prediction of the mixture’s compactability during the material design. Finally, the compaction mechanism of RHMA was discussed from the perspective of the void content of RAP particles. The results showed that a finer aggregate gradation, a higher gyration temperature, a greater number of gyrations, and a higher RAP content were effective for increasing the compactability of RHMA. The range analysis results suggest that the gradation of RHMA has the greatest influence on compactability, followed by the RAP content. The RAP aggregate cannot diffuse to a new mixture completely, so the remained RAP particle reduces the void content of RHMA. Therefore, a higher RAP content up to 50% can help RHMA to achieve the designed void content with higher efficiency.

Prediction of Asphalt Cement Content of Compacted Hot-Mix Asphalt Specimens Using Nuclear Gauges

1996 ◽  
Vol 1545 (1) ◽  
pp. 169-177
Author(s):  
Iyad A. Alattar ◽  
Imad L. Al-Qadi
Keyword(s):  
Moisture Content ◽  
Hot Mix Asphalt ◽  
Extraction Methods ◽  
Void Content ◽  
Study Program ◽  
Aggregate Gradation ◽  
Air Voids ◽  
Asphalt Cement ◽  
Specimen Weight ◽  
A New Technique

Determining asphalt cement (AC) content of hot-mix asphalt (HMA) for quality control/quality assurance using extraction methods is a lengthy, time-consuming, and hazardous process. A demand for a faster and safer method led to the development of different nuclear gauges capable of predicting the AC content of HMA samples. Measuring the AC content of compacted specimens by nuclear gauges is a new technique whose feasibility was evaluated. A total of 216 Marshall compacted specimens were cast and tested in an attempt to develop correction models. The study program investigated the effect of various HMA parameters on the measured AC content, including aggregate gradation and type, air void content, moisture content, AC content, and specimen weight. Specimens were prepared at two different mix design formulas using AC-30 and compacted at two different compaction efforts to investigate the effect of air voids. Specimens (1200 g each) used for calibration were prepared at 3 to 7 percent AC content, whereas specimens prepared for measurements were prepared at 4 to 6 percent. Quartzite and diabase aggregate were used as open and dense graded in prepared mixes. Three levels of moisture content in HMA were evaluated. Different calibration models were developed for different asphaltic mixtures. The evaluated nuclear gauge for measuring AC content for compacted HMA specimens produced satisfactory results when the parameters of tested and calibration parameters were the same. The study found that specimen weight is the most significant factor. Other parameters have different degrees of influence on the measured AC content. Statistical models were developed to correct for the evaluated parameters.

The Effect of Compaction Temperatures and Numbers on the Air Void Level of Porous Asphalt Pavements

2021 ◽  
Author(s):  
Ahmet Buğra İbiş ◽  
Burak Şengöz ◽  
Ali Topal ◽  
Derya Kaya Özdemir
Keyword(s):  
Heavy Traffic ◽  
Experimental Studies ◽  
Asphalt Mixture ◽  
Hollow Structure ◽  
Asphalt Pavements ◽  
Void Content ◽  
Porous Asphalt ◽  
Compaction Energy ◽  
Air Void ◽  
Air Void Content

Porous asphalt pavement is defined as an asphalt concrete that is designed with open gradation aggregate which helps in removing the water with an air void content of about 20% by creating drainage channels. Open gradation consists of large amounts of coarse aggregates and small amounts of fine aggregates. The water is drained due to this hollow structure, this air void content in the porous asphalt mixture which inevitably decreases with time is the main parameter affecting the service life as well as the structural and functional performance. Moreover, the reduction in air void content is one of the main reasons for the loss of permeability in porous asphalt pavements and this lead to the increase in pavement density under heavy traffic conditions. Each country has its own technical asphalt specification involving the required compaction energy and temperature. This study involves the effect of compaction temperatures and numbers on the air void in porous asphalt pavements prepared with 50/70 penetration grade bitumen. As a result of experimental studies, it has been observed that the reduced compaction temperature and the number of compaction (energy) increase the air void level in porous asphalt pavements.

Effects of Mixture and Aggregate Type on Over-Compaction in Hot Mix Asphalt in Tennessee

2021 ◽  
pp. 036119812110615
Author(s):  
Pawel Polaczyk ◽  
Yuetan Ma ◽  
Wei Hu ◽  
Rui Xiao ◽  
Xi Jiang ◽  
...  
Keyword(s):  
Service Life ◽  
Hot Mix Asphalt ◽  
Asphalt Mixture ◽  
Aggregate Structure ◽  
Mixture Density ◽  
Coarse Aggregates ◽  
Mastic Asphalt ◽  
Stone Mastic Asphalt ◽  
Compaction Energy ◽  
The Moment

Correct compaction is vital for asphalt mixture service life. An adequately compacted mixture with inferior properties can achieve better performance than a mixture with excellent properties but poorly compacted. This study investigated resistance to damage caused by over-compaction by utilizing the locking point concept. Over-compaction might cause damage to the aggregate structure and decrease service life. The locking point is defined as the moment during mixture compaction at which an aggregate skeleton is developed and becomes stable. Beyond the locking point, more compaction energy does not significantly increase mixture density and can damage aggregate particles. A total of 15 mixtures was utilized and evaluated using the gyratory compactor. Among them, five dense-graded plant mixtures contained different aggregates and binders, and 10 laboratory mixtures (three types: the surface, the base, and stone mastic asphalt [SMA]) were designed with the most popular coarse aggregates in Tennessee: hard limestone, soft limestone, gravel, and granite. The results of this study show that the highest locking point was reached by the mixtures containing gravel. The SMA mixtures have, on average, lower locking points than the dense-graded mixtures. Most of the dense-graded mixtures made with crushed stones failed in the range of +20 to +30 gyrations, whereas the samples made with gravels failed in the range of +30 to +40 gyrations, indicating that gravel seems to be the most resistant to damage.

scholarly journals Multi-Objective Optimization Design and Test of Compound Diatomite and Basalt Fiber Asphalt Mixture

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1461 ◽  
Author(s):  
Yongchun Cheng ◽  
Liding Li ◽  
Peilei Zhou ◽  
Yuwei Zhang ◽  
Hanbing Liu
Keyword(s):  
Optimization Design ◽  
Orthogonal Experiment ◽  
Asphalt Mixture ◽  
Basalt Fiber ◽  
Asphalt Mixtures ◽  
Orthogonal Experimental Design ◽  
Basalt Fibers ◽  
Contributing Factors ◽  
Range Analysis ◽  
Four Levels

This study focuses on improving the performance of asphalt mixture at low- and high- temperature and analyzing the effect of diatomite and basalt fiber on the performance of the asphalt mixture. Based on the L16(45) orthogonal experimental design (OED), the content of diatomite (D) and basalt fiber (B) and the asphalt-aggregate (A) ratio were selected as contributing factors, and each contributing factor corresponded to four levels. Bulk volume density (γf), volume of air voids (VV), voids filled with asphalt (VFA), Marshall stability (MS) and splitting strength at −10 °C (Sb) were taken as the evaluation indexes. According to the results of the orthogonal experiment, the range analysis and variance analysis were used to study the effect of the diatomite content, basalt fiber content and asphalt-aggregate ratio on the performance of the asphalt mixture, and the grey correlation grade analysis (GCGA) was used to obtain the optimal mixing scheme. Furthermore, the performance tests were conducted to evaluate the performance improvement of asphalt mixtures with diatomite and basalt fibers, and the scanning electron microscopy (SEM) tests were carried out to analyze the mechanism of diatomite and basalt fibers in asphalt mixtures. The results revealed that the addition of diatomite and basalt fiber can significantly increase the VV of asphalt mixture, and reduce γf and VFA; the optimal performance of the asphalt mixture at high- and low-temperature are achieved with 14% diatomite, 0.32% basalt fibers and 5.45% asphalt-aggregate ratio. Moreover, the porous structure of diatomite and the overlapping network of basalt fibers are the main reasons for improving the performance of asphalt mixture.

Fabrication of highly stable and durable furfurylated wood materials. Part I: process optimization

Holzforschung ◽  
2020 ◽  
Vol 74 (12) ◽  
pp. 1135-1146
Author(s):  
Wanju Li ◽  
Minghui Liu ◽  
Hankun Wang ◽  
Yan Yu
Keyword(s):  
Orthogonal Experiment ◽  
Weight Percent Gain ◽  
Weight Percent ◽  
Chinese Fir ◽  
Curing Temperature ◽  
Modulus Of Rupture ◽  
Scale Production ◽  
Range Analysis ◽  
Decay Fungi ◽  
Mold Resistance

AbstractIn order to improve dimensional stability and durability of wood, furfurylation of poplar and Chinese fir wood using newly developed furfuryl alcohol (FA) formulation combined with a common vacuum and pressure impregnation process was studied. An orthogonal experiment was designed to optimize the furfurylation process for the two wood species. The weight percent gain (WPG), equilibrium moisture content (EMC), anti-swelling efficiency (ASE), modulus of rupture (MOR), modulus of elasticity (MOE), as well as resistance to mold, decay fungi, and termites were evaluated. The results showed that nearly all the properties of the furfurylated wood could be improved to various extents. The average ASE of the furfurylated Chinese fir and poplar could reach as high as 80, 71, 92% and 79, 90, 75% in tangential and radial directions, and by volume, respectively, higher than most previously reported wood modification processes. Furthermore, the modified wood had excellent biological durability, with nearly 100% mold resistance, strong decay and termite resistance. Finally, processing parameters with 50% FA, 105–115 °C curing temperature, and 5–8 h curing time were therefore recommended for pilot-scale production of furfurylated poplar and Chinese fir wood based on range analysis.

scholarly journals Study of High-Temperature Properties of Asphalt Mixtures Used for Bridge Pavement with Concrete Deck

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4238
Author(s):  
Piotr Pokorski ◽  
Piotr Radziszewski ◽  
Michał Sarnowski
Keyword(s):  
Permanent Deformation ◽  
Asphalt Mixture ◽  
Binder Content ◽  
Void Content ◽  
Concrete Bridge ◽  
Asphalt Mixes ◽  
Protective Layers ◽  
Concrete Bridge Decks ◽  
Air Void ◽  
Air Void Content

The paper presents the issue of resistance to permanent deformations of bridge pavements placed upon concrete bridge decks. In Europe, bridge asphalt pavement usually consists of a wearing course and a protective layer, which are placed over the insulation (waterproofing). Protective layers of bridge pavement are commonly constructed using low air void content asphalt mixes as this provides the suitable tightness of such layers. Due to increased binder content, asphalt mixes for bridge pavement may have reduced resistance to permanent deformations. The article presents test results of resistance to permanent deformations of asphalt mixes for the protective layers. In order to determine the composition of mixtures with low air void content and resistance to permanent deformation, an experimental design was applied using a new concept of asphalt mix composition. Twenty-seven different asphalt mixture compositions were analyzed. The mixtures varied in terms of binder content, sand content and grit ratio. Resistance to permanent deformation was tested using the laboratory uniaxial cyclic compression method (dynamic load creep). On the basis of experimental results and statistical analysis, the functions of asphalt mixture permanent deformation resistance were established. This enabled a determination of suitable mixture compositions for protective layers for concrete bridge decks.

Palm Kernel Shell as Partial Coarse Aggregate Replacement in Asphalt Mixture: Optimum Binder Content and Volumetric Properties Investigation

2021 ◽  
Vol 1047 ◽  
pp. 179-185
Author(s):  
Siti Zubaidah Mohd Asri ◽  
Faridah Hanim Khairuddin ◽  
Choy Peng Ng ◽  
Noor Aina Misnon ◽  
Nur Izzi Md Yusoff ◽  
...  
Keyword(s):  
Coarse Aggregate ◽  
Asphalt Mixture ◽  
Control Sample ◽  
Palm Kernel ◽  
Binder Content ◽  
Partial Replacement ◽  
Volumetric Properties ◽  
Aggregate Gradation ◽  
Palm Kernel Shell ◽  
Mixture Samples

Pavement failures such as fatigue, rutting, cracking, bleeding, and stripping are typical pavement deterioration. Researchers have been experimenting with pavement modification to overcome these problems. This study determines the optimum binder content (OBC) for modifying an asphalt mixture with a partial replacement of coarse aggregate (5mm-14mm sieve size) with palm kernel shell (PKS). A 60/70 penetration grade bitumen was mixed with 10, 20 and 30% PKS at selected aggregate gradation following the Public Work Department of Malaysia (JKR/SPJ/2008-S4) specification. The preparation of 60 samples of unmodified and modified asphalt mixture employed the Marshall Method compacted with 75 blows. The OBC was determined based on five volumetric properties of asphalt mixture namely stability, flow, bulk density, void filled with asphalt, and void in total mix. The OBC and volumetric properties of the modified PKS asphalt mixture samples were compared with unmodified asphalt mixture samples in accordance to the specification. Results showed that the OBC sample with 30% aggregate replacement produced the highest OBC value of 5.53% relative to the control sample with 5.40% OBC. The trend for OBC with PKS replacement begins with 10% PKS with 5.30% OBC, 20% PKS with 5.32% OBC and 30% PKS. All volumetric properties of the PKS samples are within the specification limit. Thus, PKS has a promising potential as a coarse aggregate replacement in asphalt mixture.

scholarly journals Development of Back-calculation Model for Aggregate Gradation Determination Using Fractal Theory

2018 ◽  
Vol 159 ◽  
pp. 01006
Author(s):  
Bagus Hario Setiadji ◽  
Supriyono ◽  
Djoko Purwanto
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Asphalt Mixture ◽  
Fractal Dimensions ◽  
Calculation Model ◽  
Careful Consideration ◽  
Upper And Lower Bounds ◽  
Aggregate Gradation ◽  
Fractal Characteristic ◽  
Fractal Characteristics

Several studies have shown that fractal theory can be used to analyze the morphology of aggregate materials in designing the gradation. However, the question arises whether a fractal dimension can actually represent a single aggregate gradation. This study, which is a part of a grand research to determine aggregate gradation based on known asphalt mixture specifications, is performed to clarify the aforementioned question. To do so, two steps of methodology were proposed in this study, that is, step 1 is to determine the fractal characteristics using 3 aggregate gradations (i.e. gradations near upper and lower bounds, and middle gradation); and step 2 is to back-calculate aggregate gradation based on fractal characteristics obtained using 2 scenarios, one-and multi-fractal dimension scenarios. The results of this study indicate that the multi-fractal dimension scenario provides a better prediction of aggregate gradation due to the ability of this scenario to better represent the shape of the original aggregate gradation. However, careful consideration must be observed when using more than two fractal dimensions in predicting aggregate gradation as it will increase the difficulty in developing the fractal characteristic equations.

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