Low Energy Compaction of Aggregate Packing Mechanism

2014 ◽  
Vol 567 ◽  
pp. 422-427
Author(s):  
Yasreen G. Suliman ◽  
Napiah Madzlan ◽  
Ibrahim Kamaruddin ◽  
Johnson A. Olufemi

Aggregate packing mechanism and its properties are always significant in the compaction, density and consequential strength and resistance of the bituminous mixture. Realizing that aggregate interlocking contributes to the strength, the packing of aggregate would increase the force of intact between aggregates. This work is focused on improving the compaction energy, engineering properties and rutting resistance of bituminous mixture by using the aggregate packing concept. After obtaining the optimum proportions for developed mixture via packing test, hot-mix asphalt samples are prepared and compacted with 50 and 75 blows, while well graded hot-mix asphalt samples are compacted with 75 blows. The Marshall Test result showed that developed mixture at lower compaction energy meets all the requirements of asphaltic concrete for heavy traffic and also exhibit higher density, stability, and lower air voids and voids in mineral aggregate compared to the well graded mixture. Developed mixture also demonstrated higher mixture stiffness and lower rut depth compared to the well graded one. This is due to the optimal distribution of the various aggregates sizes of developed mixture, which gives the interlocking necessary and stone to stone contact to improve the mixture density, stiffness and rutting resistance.

Author(s):  
Pawel Polaczyk ◽  
Yuetan Ma ◽  
Wei Hu ◽  
Rui Xiao ◽  
Xi Jiang ◽  
...  

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.


2021 ◽  
Vol 13 (6) ◽  
pp. 3005
Author(s):  
Jiangang Yang ◽  
Chen Sun ◽  
Wenjie Tao ◽  
Jie Gao ◽  
Bocheng Huang ◽  
...  

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.


2018 ◽  
Vol 158 ◽  
pp. 1055-1064 ◽  
Author(s):  
Zhen Leng ◽  
Zeyu Zhang ◽  
Yuan Zhang ◽  
Yangyang Wang ◽  
Huayang Yu ◽  
...  

Author(s):  
Stephen Sebesta ◽  
Tom Scullion

Segregation is a serious problem in hot-mix asphalt and typically results in poor performance, poor durability, a shorter life, and higher maintenance costs for the pavement. A summary of the results and recommendations from three projects in Texas in which infrared imaging and ground-penetrating radar were used to examine the uniformity of the pavement mat is presented. Both techniques have significant advantages over currently used nuclear density techniques in that they provide virtually 100% coverage of the new surface. The effectiveness of both the infrared and radar techniques was evaluated by taking measurements on new overlays at the time of placement, coring, and then identifying relationships between changes in the infrared and radar data with changes in the measured volumetric and engineering properties of the cores. Analyses of the results showed that changes in both infrared and radar data are significantly related to changes in hot-mix asphalt properties such as air void content and gradation. On the basis of current Texas Department of Transportation specifications, significant changes in the hot-mix asphalt are expected if temperature differentials of greater than 25°F (13.9°C) are measured after placement but before rolling. If the surface dielectric of the in-place mat changes by more than 0.8 for coarse-graded mixes and 0.4 for dense-graded materials, significant changes in mix properties are expected. Given the promising results from this work, agencies should consider implementing both the infrared and ground-penetrating radar technologies.


2010 ◽  
Vol 113-116 ◽  
pp. 1560-1564
Author(s):  
Xi Zhong Yuan ◽  
Fei Liu ◽  
Wei Cui ◽  
Cheng Cheng Liu

Deformation of excessively wet subgrade is often problematic during pavements construction as well as under regular vehicular traffic loads. In order to create a sturdy and stable platform for heavy traffic pavement, a “green materials” based entirely on industry byproduct of combination fly ash (FA) with carbide lime (CL) and flue gas desulfurization gypsum (FGDG) was proposed in this study. In order to investigate the effectiveness and improvement of engineering properties, solidification test and compaction test were carried out in laboratory, and Dynamic Cone Penetrometer (DCP) was conducted at the construction site. Investigation results showed significant improvement in drying rate, workability, and mechanical behavior. The addition of FA/CL/FDG stabilizer increases the solids content by “bulking” and reduces the free moisture through hydration reactions. The addition of FA/CL/FGDG leads to an increase of approximately 18% in the maximum allowable moisture content, which would largely facilitate the compaction of the excessively wet soils. Post construction evaluation using DCP indicates the stabilized soil can be utilized under high volume traffic condition.


2021 ◽  
Vol 12 (1) ◽  
pp. 1-14
Author(s):  
Levy Sang ◽  
Temitope Idowu ◽  
Victoria Okumu

As the construction industry continues to evolve globally, there is a need to develop best practices geared towards achieving sustainable construction. Asphalt concrete’s demand has been increasing steadily with an estimated global demand of 122.5 million tons in 2019. This is driven primarily by the growth in construction activities in developing countries as each country works towards enhancing its transportation facilities to cater to the ever-expanding population. Hence, there are needs to develop newer and more efficient means of asphalt consumption. One of such is identifying cheaper or waste materials for use in Asphalt production. This study, therefore, examined the viability of waste marble dust (WMD), an industrial waste produced during the shaping and polishing of marble blocks and also during its extraction from the mines, as a mineral filler in Hot-mix asphalt (HMA) concrete. Engineering properties such as Marshall stability and flow, Void characteristics, Indirect tensile strength and Tensile strength ratio properties were examined. It was observed that the addition of WMD steadily increased the Marshall Stability and indirect tensile strength values and lowered the voids percentages. The study’s major finding is that waste marble dust is highly suitable as a mineral filler in HMA and a 3% by volume addition of WMD in HMA at 4.5% binder content produced the most optimal mix for use in road pavements.


2017 ◽  
Vol 3 (8) ◽  
pp. 610 ◽  
Author(s):  
Sadam Hussain

Swelling of expansive clays is one of the great hazards, a foundation engineer encounters. Each year expansive soils cause severe damage to residences, buildings, highways, pipelines, and other civil engineering structures. Strength and deformation parameters of soils are normally related to soil type and moisture. However, surprisingly limited focus has been directed to the compaction energy applied to the soil. Study presented herein is proposed to examine the effect of varying compaction energy of the engineering properties i.e. compaction characteristics, unconfined compressive strength, California bearing ratio and swell percentage of soil. When compaction energy increased from 237 KJ/m3 to 1197 KJ/m3, MDD increased from 1.61 g/cm3 to 1.75 g/cm3, OMC reduced from 31.55 percent to 21.63 percent, UCS increased from 110.8 to 230.6 KPa, and CBR increased from mere 1 percent to 10.2 percent. Results indicate substantial improvement in these properties. So, compacting soil at higher compaction energy levels can provide an effective approach for stabilization of expansive soils up to a particular limit. But if the soil is compacted more than this limit, an increase in swell potential of soil is noticed due to the reduction in permeability of soil.


Author(s):  
John A. Hinrichsen ◽  
John Heggen

The use of voids in mineral aggregate (VMA) criteria for proper mix design of hot-mix asphalt is a time-honored and fairly successful tool. Recent developments in the field of asphalt mix design have encouraged the use of mixtures with a coarse aggregate structure to resist the effect of heavy traffic loads. By using the equations presented, which account for both aggregate gradation and the volumetric properties of the materials, the mix designer is able to judge the proper VMA requirement for each unique blend of materials. By applying the new equations, the most economical mix may be selected without great risk of reduced durability. Supporting data from field application are presented to illustrate the use of the equations.


2021 ◽  
Author(s):  
Ahmet Buğra İbiş ◽  
Burak Şengöz ◽  
Ali Topal ◽  
Derya Kaya Özdemir

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.


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