Voids In The Mineral Aggregate Research Articles

Medical Waste Incineration Fly Ash as a Mineral Filler in Dense Bituminous Course in Flexible Pavements.

Medical waste incineration fly ash (MWIFA) contains heavy metals that are toxic by nature and pose numerous health risks. The paper deals with the suitability of MWIFA as a mineral filler in the bituminous layer as an alternative to conventional stone dust (SD) through an appropriate combination of engineering and environmental assessments. Engineering parameters, such as Marshall stability, stability loss, flow, unit weight, air voids (Va), voids filled with asphalt (VFA), and voids in the mineral aggregate (VMA) of the asphalt mixtures, were evaluated with varying filler ratios, from 2% to 10%. All parameters for both fillers at optimum bitumen content satisfied the Marshall Mix Design criteria. The optimum bitumen contents of all filler ratios were within the standard limit recommended by the Bangladesh Roads and Highways Department. It was found that mixes prepared with MWIFA can resist moisture effects, making them durable in the monsoon. The mixes with 5.5% MWIFA as mineral filler performed the best, whereas 9% SD filler was required to achieve similar performance. The environmental test results show no environmental restriction on stabilizing the MWIFA into paving mixtures. The mobility of heavy metals (As, Pb, Cu, Cr, Ni, Cd, Hg, and Zn) from the asphalt-MWIFA mix was insignificant. The cumulative concentrations of heavy metals (Cd, Ni, Zn, Cu, and Pb) from long-term leaching tests were far below the Dutch regulatory limit (U1). MWIFA can be considered an eco-friendly and sustainable mineral filler for the dense bituminous pavement layer.

Study on the influence mechanism of recycled concrete aggregate on strength of asphalt mixtures

Recycled concrete aggregate (RCA) has great potential use in pavement. However, unclear characteristics of RCA and its relationship with the properties of asphalt mixture hinder severely its promotion. The objective of this study is to characterize the microscopic morphology and structure of RCA, further investigate its impact on the strength of asphalt mixture and associated mechanisms, by means of various test method. Results showed that cement mortar was the vital factor to affect the properties of RCA. Hence, the asphalt mixtures with RCA had characteristics of higher air voids (VV) and voids in the mineral aggregate (VMA), lower asphalt saturation (VFA), compared with conventional asphalt mixtures (CAM). In addition, according to the results of Micro-Scratch (MS) test, the compression depths of aggregate, interfacial transition zone (ITZ) and asphalt mortar in RAM are larger than that in CAM. Therefore, the influence of RCA on the performance of asphalt mixture is mainly in the following two aspects: reducing the strength of asphalt mortar; decreasing the skeleton strength of asphalt mixtures.

Review and Evaluation of the Prediction Methods for Voids in the Mineral Aggregate in Asphalt Mixtures

The percentage of voids in mineral aggregates (VMA) is an important consideration in the design of asphalt mixtures. Accurate and precise prediction of VMA is critical in pavement engineering. This study reviewed and evaluated current VMA prediction methods. From the perspective of treating aggregate gradation, the methods were classified into four categories: the overall gradation prediction method (OGPM), gradual gradation prediction method (GGPM), indirect parameter prediction method (IPPM), and theoretical derivation method (TDM). Fifty-four groups of published test data from previous studies were used to evaluate the prediction results of the models, and the precision and accuracy of the prediction results were compared. From the perspective of the completeness of the modeling parameters and the theoretical foundation, the reasons for the differences in prediction results with different methods were analyzed. It was concluded that the TMD has a solid theoretical basis, especially the Yu method in TMD exhibited the best prediction precision and accuracy. Some modifications to the current methods were suggested, such as incorporating other factors affecting VMA and optimizing the particle shape indicators.

Mineralogical and Elemental Characterization of Conventional Asphalt of Peruvian Roadways by X-Ray Diffraction and Energy Dispersive X-ray Fluorescence

This research deals with the characterization of a sample of conventional asphalt, which is used for the manufacture of roadways in the city of Trujillo, Peru. The sample has been designed by using the Marshall method, through which the optimal content of the asphalt mixture was determined for an adequate combination of the aggregates. This method includes the determination of the optimum content of asphalt cement, stability, unit weight, air voids, flow, voids in the mineral aggregate, and flow stability. The Marshall test was carried out after dosing for the traditional mixture. We have used two techniques: energy dispersive X-ray fluorescence and X-ray diffractometry. The identification and quantification of the chemical elements present was carried out by using energy dispersive X-ray fluorescence, and the mineralogical analysis, by using X-ray diffractometry. This work is useful as a source of reference information. Subsequently, it will allow the implementation of procedures for modifying asphalt mixtures to optimize their performance.

Indices relation and statistical probability analysis of physical and mechanical performance of asphalt mixtures

Rutting deformation is one of the most prominent diseases in asphalt pavement’s early damage. In this paper, it analyzes the relation and their distribution law between Marshall stability and the physical and mechanical indices of asphalt mixtures based upon a correlation analysis and statistical principles, which is to find the reasonable range of rutting performance design parameters of asphalt pavement. The results showed that the asphalt mixture’s stability increased with the increase in bulk volume relative density and asphalt saturation, but decreased with the increase in the percent of air-voids and the voids in the mineral aggregate. The optimal fitting function of bulk volume relative density and asphalt saturation for AC-13 asphalt mixture follows a Weibull distribution, that of Marshall stability and air-voids follows a Gamma distribution, and that of percent voids in the mineral aggregate and flow value follows a Lognormal distribution. For a GAM-16 asphalt mixture, the optimal fitting function of bulk volume relative density and Marshall stability follows the Weibull distribution, the optimal fitting function of air-voids follows a Gamma distribution, that of flow value and percent voids in the mineral aggregate follows a Lognormal distribution, and asphalt saturation follows a Normal distribution. It is recommended that AC-13 asphalt mixtures’bulk volume relative density ranges from 2.27～2.38 g·cm3, the air-voids ranges from 3.4～6.0%, and GAM-16 asphalt mixtures’bulk volume relative density ranges from 2.29～2.37 g·cm3, the voids in mineral aggregate ranges from 17～18.17%, the asphalt saturation ranges from 75～82.13%, which can provide a reference for in-depth understanding of the deformation characteristics and construction of highways’ pavement in similar areas.

Dynamic Characteristic Master Curve and Parameters of Different Asphalt Mixtures

Using an AMPT tester and based on laboratory tests, this paper performed a comparative study on the dynamic characteristics of different asphalt mixtures, analyzed the influence of different asphalt binders on the characteristic parameters of the dynamic modulus master curve and the phase angle master curve of asphalt mixture, and expounds the evaluation function of the phase angle master curve for mixture relaxation characteristics. The results show that the modulus master curve parameters of the asphalt mixture are closely related to voids in the mineral aggregate, mixture density, and asphalt content of the asphalt mixture. For the same kind of asphalt mixture, because the gradation of mineral aggregate is fixed and the volume parameters are almost the same, the ultimate modulus of the mixture at different temperatures is unique; when the temperature changes or the asphalt changes, the shape parameter β of the modulus master curve changes regularly, which brings different dynamic responses, and the lower β will show the characteristics of a higher modulus. Asphalt is the source of the viscoelasticity of the asphalt mixture. Although the influence of particle gradation of the mixture will bring about the change of modulus, the phase angle of the mixture depends on the viscoelastic properties of asphalt, and the initial phase angle in the main curve is positively correlated with asphalt penetration and negatively correlated with the softening point and viscosity, while the peak phase angle A is negatively correlated with penetration, and the softening point viscosity is positively correlated. The viscoelastic interval, represented by ω, is negatively correlated with penetration but positively correlated with the softening point and viscosity. The peak position, parameter ωc, of the phase angle master curve can evaluate the relaxation characteristics of the mixture, and the crack resistance of different mixtures can be compared without complex model calculation. In the comparison of the relaxation time of asphalt mixture, the relaxation time of foam cold-recycled mixture is the largest, which is significantly higher than that of other forms of cement mixture; the emulsified asphalt cold-recycled mixture is equivalent to AC20 and LSPM30 mixtures; the SBS-modified asphalt mixture has the best relaxation characteristics.

Strength improvement of cement emulsified asphalt mixture through aggregate gradation design

Aggregate gradation greatly affects properties of cement emulsified asphalt mixture (CEAM). In this work, an aggregate design based on fractal theory method (FTM) was put forward and trial calculation method (TCM) was adopted to design aggregate gradation of the mixtures. Properties of the mixtures, Marshall stability and splitting strength, were adopted as indexes to evaluate effects of the two methods. In addition, other properties of the mixtures such as, voids in mineral aggregates, porosity and residual stability of the mixtures were carried out to verify effects of the two methods. Furthermore, the gradation obtained by the two methods was simulated based on partical flow code in two dimension (PFC2D). The results show that the aggregate with the optimum gradation possesses dense skeleton structure and excellent stability. Particle contact force is relatively uniform distribution. Besides, voids in the mineral aggregate, porosity and residual stability of the mixture designed by FTM were superior to that designed by TCM. It was confirmed that the aggregate gradation design method with fractal model established in this work is reasonable and effective to improve strength of cement emulsified asphalt mixture.

Evaluation of The Effect of Gradation on Mechanical properties of Stone Mastic Asphalt Mixtures

For stone mastic asphalt (SMA) mixtures, the aggregate gradation is the significant requirement to achieve the best structural design. In this research, an attempt to evaluate the effect of nominal maximum aggregate size (NMAS) and gradation on SMA volumetric and mechanical properties. Samples for each mixture were designed and fabricated according to NAPA specifications. A total of 9 SMA mixtures with three NMASs, each with three different aggregate gradations, one asphalt binder (styrene butadiene styrene SBS) modified binder were studied. Volumetric analysis of specimens revealed that the voids in the mineral aggregate (VMA), and voids filled with asphalt (VFA) rise with a reduction in NMAS. SMA samples with higher NMAS have lower optimum asphalt than those of lower NMAS. From the laboratory study, SMA mixes fabricated utilizing the upper limit of gradation showed the highest mechanical properties in terms of Marshall Stability and indirect tensile strength. It was recorded also that the SMA mixtures with larger NMAS had higher ITS and Marshall stability contrasted to the others. This improvement could be because of the larger portion of coarse aggregate in the SMA mixture.

Tinjauan Durabilitas Campuran Asphalt Concrete Wearing Course Menggunakan Aspal Tua Dengan Berbagai Bahan Peremaja

Asphalt concrete wearing course is laid on the top of road pavement so that directly exposed to ultra violet light and other environment impact. The higher temperature at the pavement surface and exposure to atmospheric oxygen accelerated aging cause asphalt to stiffen and become brittle. This aging result decrease the binding of asphalt and aggregate leads various damage of pavement. The aged asphalt rejuvenated and recycled with rejuvenating agent has been developed to reduce the use of virgin material for road maintenance. This article aims to review durability of asphalt concrete wearing course using waste cooking oil, epoxy resin, kerosene and waste engine oil as asphalt rejuvenators. Aging asphalt was prepared by heating in an oven at 85 oC for 120 hours (long term oven aging). Durability was assessed from the value of Marshall immersion which represent the resistance of asphalt mixture at water immersion. Relation between Marshall immersion and voids in mix (VIM), voids in the mineral aggregate (VMA), voids filled with bitumen (VFB) and density are also evaluated. From the analysis, it can be concluded that the use of waste cooking oil, epoxy resin, kerosene and waste engine oil as asphalt rejuvenators increase the durability of asphalt mixture containing the aged asphalt.

Evaluation of volumetric performance of asphalt mixtures containing recycled construction aggregate (RCA)

ABSTRACT High rate of construction and demolition waste materials results in a large amount of stockpiled waste materials. Pavement industry is now considering a sustainable approach for asphalt mixture design incorporating certain waste materials. This research investigates the feasibility of substitution of virgin aggregates in asphalt mixes with recycled construction aggregates (RCA) obtained from the construction and demolition sector. A preliminary experimental study including determination of flakiness index, particle shape, wet/dry strength variation, water absorption rate, particle density, crushing value, deleterious material and weak particles was conducted on blends of RCA and virgin aggregates to evaluate the engineering properties of aggregate blends. Different asphalt mixes incorporating RCA at different rates were prepared and evaluated using a gyratory compaction. The results of the regression analysis showed that the asphalt mixtures containing 20% to 22% RCA provide comparable volumetric properties as the control sample, while mixes with higher RCA substitutions achieved higher air voids, and lower voids in the mineral aggregate (VMA), voids filled with asphalt (VFA) and binder film index (BFI). The results of this study suggested a feasible use of RCA for partial aggregate replacement in hot mix asphalt (HMA).

Evaluation of the potential of sasobit polymer as an additive in bitumen and asphaltic concrete

This paper evaluated the effects of sasobit polymer (Sasobit®) on the characteristics of asphaltic concrete with a view to investigating its suitability as an additive in asphaltic concrete. Sasobit®, bitumen and aggregates were procured from a Construction Company site office, along Shagamu-Ibadan expressway. Sasobit® modified bitumen was prepared by adding Sasobit® to bitumen with increasing weight of Sasobit® at 1.0, 1.5, 2.0, 2.5 and 3 % by the weight of the bitumen. Penetration and softening point tests were carried out on the samples and the mix-ratio for the bitumen – polymer mixture was determined. Asphaltic concrete samples with and without Sasobit® were prepared. The samples were subjected to Marshall Stability test. The stability, flow, specific density, voids filled with bitumen (VFB), air voids (VA) and voids in the mineral aggregate (VMA) weredetermined. The values of stability, flow, specific density, voids filled with bitumen, air voids and voids filled in the mineral aggregates for sample without Sasobit® were 13.63 kN 2.91 mm, 2.51, 64.64 %, 4.29 % and 18.19 %, respectively, while for those with Sasobit® at mix – ratio of 1.7 % bitumen – polymer mixture, the values were 14.67 kN, 2.41 mm, 2.55, 73.30 %, 3.96 % and 16.39 % respectively. The result showed that, Sasobit® as additive in asphaltic concrete improved its properties.
 Keywords: Sasobit®, Asphaltic Concrete, Stability, Flow, Voids filled with bitumen, Air voids, Voids in mineral aggregate

Evaluation of Different VMA Estimation Methods for Asphalt Mixtures Containing RAP

AbstractDuring asphalt mixture production, the bulk specific gravity (Gsb) of the mixture aggregate is not routinely measured to determine voids in the mineral aggregate (VMA), because this require...

Effect of Latex to Minimize the Use of Asphalt in Asphalt Concrete Wearing Course

One aspect that needs to be considered in the application of asphalt pavement is the fact that asphalt is a non-renewable resource which requires constant maintenance throughout its lifetime. Thus, developing a mix with asphalt contents reduced to the minimum is a challenge in and of itself. Latex, in this case, would seem to be potentially viable additives. The aim of this research is to investigate the effects of using latex as an additive to minimize the use of asphalt in asphalt concrete wearing courses (ACWC). Four varying amounts of latex were mixed with asphalt at 0%, 2%, 4%, and 6% of the total weight of an asphalt binder. A wet process was then employed to blend the mixtures together. Afterward, the latex-asphalt mixtures were added to an aggregate to form various mixtures ranging from 5% to 7% of the aggregate and the incremental weight of 0.5% of the latex-asphalt ACWC. For each latex-asphalt-aggregate mixes, the optimum binder content was determined based on stability, flow, Marshall quotient, voids in the mineral aggregate (VMA), voids in the mixture (VIM) and voids filled by the binder (VFB). The results of this experiment indicated that the addition of latex reduces the need for asphalt contents.

Effect of Carbon-Fiber Properties on Volumetrics and Ohmic Heating of Electrically Conductive Asphalt Concrete

This experimental study examines the influence of different sources and lengths of carbon fiber (CF) on the volumetric properties, volume resistivity, and heat-generation efficiency of electrically conductive asphalt concrete (ECAC). This type of concrete has applications to pavement anti-icing and deicing in critical areas such as airfields where having surfaces free of ice and snow is of paramount importance. This study revealed that increasing CF length decreased the ECAC air void, voids in the mineral aggregate, and increased voids filled with asphalt. The source of CF influenced the electrical conductivity and heat-generation capability of ECAC and decreasing the CF length resulted in volume resistivity reduction and enhancement of heat-generation efficiency. The analyses results obtained from volume resistivity and heat-generation characterizations performed on ECAC cylindrical specimens were used for fabricating ECAC slabs. It was demonstrated that ECAC slab can melt a dense layer of ice under harsh winter conditions simulated in the laboratory environment.

SERAT ECENG GONDOK SEBAGAI BAHAN ALTERNATIF ADMIXTURE PADA LASTON TIPE XI SNI 03-1737-1989 DITINJAU TERHADAP NILAI-NILAI UJI MARSHALL

In Indonesia, the road construction has experienced a fairly good development. From a wide range of road constructions, flexible pavement is the most chosen one because its characteristics: easy, fast, and efficient. However, flexible pavement has many weaknesses, for example the premature damage on the road surface after some time passed by the traffic so that the road cannot reach the planned age. For that, it is done a research to add a hot asphalt mixture material that aims to improve the quality of the mixture results. The selected ingredient is natural water hyacinth. The method used is trial and error with reference of SNI 03-1737-1989. Variations used are 2%, 4%, 6%, 8% and 10% of the asphalt weight, asphalt level used is 5.72 %. Of the 5 variations of mixture used on Type XI Asphalt Concrete Layer, it is obtained the result that the water hyacinth fiber level which has the best score and meet the specifications of SNI 03-1737-1989 is on the percentage of 6% which obtained from calculation data using graphs and regression model where Marshall Stability is equal to 644,46 Kg, flow 3,39 mm, VMA (voids in the mineral aggregate) is equal to 13,83 %, VFWA (voids filled with asphalt) is equal to 65,35%, VIM (voids in the mix) is equal to 2,52 %, density of 2.31 gr/cc, and Marshall Quotient of 164.03 Kg / mm.

Effect of Mix Design Variables on Thermal Cracking Performance Parameters of Asphalt Mixtures

To address asphalt pavement thermal cracking, researchers have developed performance-based evaluation tools for asphalt mixtures. A minimum fracture energy obtained from a disc-shaped compact tension test and Black space parameters determined by the stiffness and relaxation properties of asphalt mixtures are two such methods to ensure good thermal cracking resistance. Mix specifiers and producers strive to meet the requirements set by these performance-based criteria by adjusting their mix designs. However, there is a lack of information and consensus on the effect of mix design variables (such as binder grade and mix volumetrics) on thermal cracking performance of mixtures as it relates to fracture energy and Black space location. This study strives to fill this gap by quantifying the effect of: (1) recycled asphalt content, (2) effective binder content, (3) air voids, (4) asphalt film thickness, (5) voids in mineral aggregates, and (6) PG low and high temperature grades on thermal cracking resistance. A large dataset, 90 mixtures from the Minnesota Department of Transportation and 81 mixtures from University of New Hampshire database, was used for the study. The results indicate a strong correlation between binder related properties (binder content, asphalt film thickness, PG spread) and fracture energy. The correlation coefficients obtained from this study for PG spread, effective binder content, and air void can be confidently employed to achieve targeted fracture energy thresholds. The same can be achieved for the Glower-Rowe parameter at 15ºC by employing the correlation coefficients obtained for PG low temperature, virgin asphalt content, and voids in the mineral aggregate.

Determination of voids in the mineral aggregate and aggregate skeleton characteristics of asphalt mixtures using a linear-mixture packing model

Voids in the mineral aggregate (VMA), as a main design parameter in the Superpave mixture design method, is an important factor to ensure asphalt mixture durability and rutting performance. Moreover, an asphalt mixture’s aggregate skeleton, related to VMA, is another important factor that affects critical asphalt mixture properties such as durability, workability, permeability, rutting, and cracking resistance. The main objectives of this research are to propose an analytical approach for estimating changes in VMA due to gradation variation and determining the relevant aggregate skeleton characteristics of asphalt mixtures using the linear-mixture packing model, an analytical packing model that considers the mechanisms of particle packing, filling and occupation. Application of the linear-mixture packing model to estimate the VMA of asphalt mixtures shows there is a high correlation between laboratory measured and model estimated values. Additionally, the model defines a new variable, the central particle size of asphalt mixtures that characterizes an asphalt mixture’s aggregate skeleton. Finally, the proposed analytical model shows a significant potential to be used in the early stages of asphalt mixture design to determine the effect of aggregate gradation changes on VMA and to predict mixture rutting performance.

Study on the correlation between aggregate skeleton characteristics and rutting performance of asphalt mixture

While the rutting performance of asphalt mixture is largely affected by the skeleton characteristics of the aggregate, the relationship between skeleton formation and rutting performance is not adequately understood. This study experimentally investigates the whole process of asphalt mixture skeleton formation by employing multilevel mixing gradation design method and digital image processing technology on three mixtures. The strength formation process of the mixture is analyzed by performing a laboratory test to establish the dynamic stability estimation model. Results indicate that a small discontinuity in gradation is helpful to enhance the density of the mixture even though skeleton formation and skeleton embedding are not necessarily correlated. With successive mixing of finer aggregate particles, the void ratio and Voids in the Mineral Aggregate (VMA) of the mixture were decreased continually but the stability and dynamic stability were increased. The number of contact points increased firstly and then decreased, and the inclination angle decreased monotonically. The number of contact points should be controlled within a reasonable range during the gradation design. However, a small initial inclination of aggregates possesses a higher dynamic stability. The estimation model proposed in this study could distinguish the influence of the asphalt type for mixtures with the same initial skeleton characteristics.

Evaluation of the Cooling and Pavement Performance of Basic Oxygen Furnace Slag Used in Asphalt Mixture

Basic oxygen furnace slag (BOF) is widely used in road construction, but there is a lack of characteristics in different asphalt mixtures. This study investigates the properties of hot-mixed asphalt (HMA), containing stone mastic asphalt (SMA), porous asphalt (PA), and dense-graded BOF as a partial substitution for natural aggregates. The purpose of this study is to evaluate various BOF slag contents in the asphalt mixtures that would affect the cooling behavior after compaction. Asphalt mixture specimens contained 0%, 20%, 40% and 60% BOF slag, respectively, as coarse aggregate. Test results showed that BOF slag has a lipophilic property, so that it can be adsorbed by asphalt cement, thereby reducing the cost of asphalt. The stability value of all the asphalt mixtures increases with the proportion of BOF slag replacement. In addition, the voids in the mineral aggregate (VMA) value variable exhibited significant differences among asphalt mixtures, and could determine the deviation of the cooling trend of asphalt mixtures. Furthermore, it was found that the cooling procedure of the BOF slag used in dense-graded asphalt mixture takes about 100 min, and that the temperature tends to be moderate; however, it took about 120 min of cooling the SMA and PA mixture with BOF slag. In addition, the distribution of voids of the dense asphalt mixture was not uniform. This would result in various locations of inconsistent thermal energy temperature on asphalt mixtures.

Aggregate Degradation Characteristics of Stone Mastic Asphalt Mixtures

Stone Mastic Asphalt (SMA) mixtures are designed to have a high coarse aggregate content and stone-on-stone contact, which results in more stress on the coarse aggregates during compaction and traffic loading. As a result, aggregates tend to break down more in SMA mixtures than in conventional dense graded mixtures. Aggregate degradation during compaction and traffic loading may cause changes in the original gradation and thus may also affect the volumetric parameters of SMA mixtures. Therefore, this study was conducted to determine the degree of aggregate degradation in SMA mixtures due to the compaction process. Aggregates of two Nominal Maximum Aggregates Sizes (NMAS), designated as SMA14 and SMA20, were compacted using 50 blows of the Marshall Hammer and 100 gyrations of the Superpave Gyratory Compactor (SGC). The verified samples were then prepared and extracted using the Centrifuge Method. The relationship between aggregate degradation and influencing factors, such as compaction effort and volumetric properties were investigated. Aggregate degradation by the Marshall Hammer was found to be significantly higher than degradation by the SGC. Voids in the mineral aggregate (VMA) of either compaction method decrease or are almost the same when aggregate degradation is not significant. SGC method can be selected to represent the field roller that results in a similar trend of aggregate degradation.