Voids In Mineral Aggregate Research Articles

New Model for Predicting Rutting Performance of Superpave Asphalt Mixes

This study presents a new model for predicting rutting performance and stripping characteristics of Superpave asphalt concrete (AC) mixes from laboratory Hamburg Wheel Tracking Device (HWTD) test data. A total of 33 AC mixes were used and tested for HWTD to determine the rutting and stripping susceptibility of the mixes. The combined Franken–power approach was used to fit the rut data. The pertinent regression coefficients were then correlated to the mix’s physical and volumetric properties, that is, binder grade, reclaimed asphalt pavement content, effective asphalt content, voids in mineral aggregate, and aggregate gradation. A logistic regression analysis was employed in the model to capture the stripping characteristic of the mixes. The developed model was validated with a new set of HWTD test data. The model was observed to be capable of predicting the rutting and stripping characteristics of the AC mixes, which agreed reasonably well with laboratory test results. Therefore, the proposed model could be used for mix screening purposes at the mix design stage to avoid the significant consequences of failure in the field, and as a tool to determine rutting performance when laboratory testing is not feasible.

Prediction of the hot asphalt mix properties using deep neural networks

BackgroundMarshall design process is the most common method used for estimating the Optimum asphalt content (OAC) and this process is called the asphalt mix design. However, this method is time-consuming, labor-intensive, and its results are subjected to variations.ResultsThis paper employs artificial neural network (ANN) for the estimation of Marshall test parameters (OAC, Stability, Flow, Air voids, Voids in mineral aggregate) using the aggregate gradation as the input of the prediction process. Multiple ANNs are tested in order to optimize the NN hyperparameters and produce accurate predictions. Different activation functions, number of hidden layers, and number of neurons per hidden layer are tested and heatmaps are generated to compare the performance of every ANN. Results show that the optimum ANN hyperparameters change depending on the predicted parameter. Finally, the deep NN can predict the OAC, stability, flow, density, air voids, and voids in mineral aggregate with R values of 0.91, 0.8, 0.53, 0.65, 0.77, and 0.66.ConclusionThe linear activation function is the most efficient activation function and generates more accurate results than the logistic and the hyperbolic tangent functions. Additionally, it is shown that the deep neural network approach represents a major innovative tool for the prediction of the asphalt mix properties as results of this approach outperforms results of the shallow ANN that consists of a single hidden layer which is the only approach used in the literature. Thus, the use of the deep ANN can be useful during the phase of the design of the asphalt mix process because of its ability to predict variables with high accuracy. For example, the ANN with 3 hidden layers and 16 neurons per layer with the linear activation function can predict the OAC with high accuracy (R = 0.91), which can be helpful in the design process as the ANN can be employed for the prediction of the OAC of the asphalt mix.

Volumetric Mix Design Adjustments for Improving Asphalt Mixture Durability

State highway agencies (SHAs) are looking for guidance on how they can make changes to their Superpave volumetric mix design procedures to obtain higher design binder contents to improve the cracking resistance and durability of asphalt mixtures. To assist SHAs, this paper was prepared to: (a) synthesize most common adjustments made by SHAs to their Superpave volumetric mix design procedures to obtain higher design binder contents; and (b) verify the effectiveness of these adjustments through laboratory experiments. Based on a survey of SHAs, the three most common adjustments to the Superpave mix design system to obtain higher design binder contents include: lowered design gyrations (Ndesign), increased minimum requirements for voids in mineral aggregate (VMA), and lowered design air voids (including air voids regression). These adjustments were verified in a laboratory testing program which included a virgin fine-graded mixture and a 20% reclaimed asphalt pavement (RAP) coarse-graded mixture. The results suggest that lowering Ndesign may help increase the design binder content initially but mix designers can select design gradations to reduce VMA and binder content back to levels achieved with the higher Ndesign levels. The other common adjustments (i.e., increased minimum VMA and lowered design air voids) can yield higher design binder contents. However, these approaches may be ineffective if Gsb is not accurately measured during mix design or if VMA is not controlled during mix production.

USING NANOCLAY HYDROPHILIC BENTONITE AS A FILLER TO ENHANCE THE MECHANICAL PROPERTIES OF ASPHALT

Higher traffic loads on the wheels, increased traffic volumes, and exposure to changing weather conditions result in increasing the road stresses and strains, putting the paving layers in danger of degradation such as fatigue, stripping, cracking, and rutting. A tremendous number of studies and trials have been conducted to modify asphalt to have a longer service life, less maintenance, be cheaper, and be more environmentally friendly. Recently, nanotechnology has proven very beneficial in all industries, including asphalt. It can be used to enhance the asphalt's mechanical properties. Using nano clay in asphalt is expected to improve the mechanical properties and the service life of the asphalt. So the main objective of this study is to investigate the performance of nano clay hydrophilic bentonite in improving the physical characteristics of asphalt concrete. This study uses nano clay with various replacement ratios as fillers to the ordinary used limestone filler in asphalt concrete. The used replacement percentages were (0%, 20%, 40%, 60%, 80%, and 100). The experimental tests that were conducted in this study include Marshall Stability (MS), Marshall Flow (MF), voids in mineral aggregate (VMA), theoretical maximum specific gravity (Gmm) and air voids (AV).The results showed a noticeable enhansment in the behavior of the asphalt mix with increasing the replacement percentage by nanoclay. Also, it was found that the 60% replacement rate by nanoclay has the highest Marshall stability with an increase of 93%, also the lowest flow with a decrease of 25% compared to the control asphalt mix.

Developing a prediction model for low-temperature fracture energy of asphalt mixtures using machine learning approach

ABSTRACTThis paper presents an augmented full quadratic model (AFQM), artificial neural network (ANN) and an innovative machine learning technique called self-validated ensemble modelling (SVEM) approaches to predict low-temperature fracture energy of asphalt mixtures. An experimental database including 852 fracture energy values obtained from low temperature disk-shaped compact tension (DCT) testing was utilised to develop the prediction models. The fracture energy was predicted in terms of several variables that are available during the mix design process. The collected data were categorised into three groups based on the availability of the data at different points during the mix design process. A sensitivity analysis was conducted to assess the impact of the design variables on fracture energy. Based on the model development results, both ANN and SVEM methods showed higher prediction accuracy than AFQM. Prediction models based on the ANN were time-consuming and computationally expensive due to the optimum model architecture. The SVEM technique was found to be a reliable prediction method with high prediction reliability even with a limited amount of data. Based on the sensitivity analysis, design traffic level, PG low temperature (PGLT) binder grade, amount of aggregate passing 9.5 mm sieve, and the voids in mineral aggregate (VMA) are the most effective factors impacting low-temperature asphalt mixture fracture energy. A web-based prediction model platform was developed using prediction models based on the SVEM technique which can be utilised as a predesign tool to evaluate low-temperature fracture energy of asphalt mixtures when laboratory testing is not feasible.

Environment-friendly recycled asphalt pavement design for road maintenance applications.

Potholes are one of the most common road distresses in Kuwait especially after winter season in 2018. Pavement deterioration rate significantly increases as the pavement exposes to moisture. Paving road requires using high-quality materials. This paper aims to investigate the feasibility of using recycled asphalt pavement in hot mix asphalt (HMA) design. Questionnaires and a series of laboratory tests were conducted to analyze the effects of pores on the society and test the recycled and the regular mixtures performance to choose the best option regarding it. Marshal test portrayed that the recycled mixture has a high stability and flow. According to the tensile strength ratio test requirements which set a minimum ratio of 75%, it is recommended to reduce the proportion of recycled aggregate. The Hamburg wheel tracker (HWTD) test proved that the recycled asphalt mixture has a low rutting depth for wet and dry samples compared to the general one. On the other hand, the wet recycled mixture requires a reduction by of 20% to satisfy the specifications. The physical properties for both mixtures were compared, and the voids filled with asphalt (VFA) and voids in mineral aggregate (VMA) of the recycled mixture are lower than those in the regular mixture. The recycled mixture reveals a higher efficiency in saving costs and improving mixtures used for potholes maintenance activities. All the results proved that the mixtures consisting of recycled asphalt are most preferred since they are affordable and perform reasonably well compared to mixtures made of regular asphalt. As a future work, smaller percentages of recycled aggregate should be tested to check the robustness and sustainability of the designed recycled asphalt mixture using different tests such as Hamburg wheel tracker test (wet samples) and indirect tensile strength test. Furthermore, more experiments can be run to test other mix parameters and properties such as durability.

Using nanoclay hydrophilic bentonite as a filler to enhance the mechanical properties of asphalt

Higher traffic loads on the wheels, increased traffic volumes, and exposure to changing weather conditions result in increasing the road stresses and strains, putting the paving layers in danger of degradation such as fatigue, stripping, cracking, and rutting. A tremendous number of studies and trials have been conducted to modify asphalt to have a longer service life, less maintenance, be cheaper, and be more environmentally friendly. Recently, nanotechnology has proven very beneficial in all industries, including asphalt. It can be used to enhance the asphalt's mechanical properties. Using nano clay in asphalt is expected to improve the mechanical properties and the service life of the asphalt. So the main objective of this study is to investigate the performance of nano clay hydrophilic bentonite in improving the physical characteristics of asphalt concrete. This study uses nano clay with various replacement ratios as fillers to the ordinary used limestone filler in asphalt concrete. The used replacement percentages were (0%, 20%, 40%, 60%, 80%, and 100). The experimental tests that were conducted in this study include Marshall Stability (MS), Marshall Flow (MF), voids in mineral aggregate (VMA), theoretical maximum specific gravity (Gmm) and air voids (AV). The results showed a noticeable enhansment in the behavior of the asphalt mix with increasing the replacement percentage by nanoclay. Also, it was found that the 60% replacement rate by nano clay has the highest Marshall stability with an increase of 93%, also the lowest flow with a decrease of 25% compared to the control asphalt mix.

The Effect of Cow Dung Ash as A Filler on The Mechanical Characteristics of Hot Mix Asphalt

Highway pavements are being exposed to increasing traffic loads and severe environmental conditions, resulting in reduced service life. A lot of studies have been conducted to modify asphalt by using different materials, especially to replace the ordinary filler. Because the behaviour of the hot asphalt mix is influenced by the fillers. The use of unusual materials as fillers in asphalt mixes can help to improve the mix’s characteristics. As a result, this study uses cow dung ash materials with various replacement ratios as fillers to investigate the mechanical properties of asphalt. In the asphalt mix, a replacement percentage of limestone (0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100%) was utilized. After that, various tests were performed such as Marshall stability, Marshall flow, voids in mineral aggregate, theoretical maximum specific gravity, air voids. The results revealed a significant improvement in the asphalt mix’s behaviour, as well as an increase in the replacement percentage. According to the findings, the 50% replacement rate has the highest Marshall stability which is equal to 11.11 with a 33.5% rise and the lowest flow of 3 with a 17.83% decrease when compared to the reference mix. As a result, cow dung ash can be used as a filler to modify the mechanical properties of the asphalt mix.

Effect of Soft Clay on the Volumetric and Mechanical Properties of Hot Mix Asphalt

Abstract. To define the behaviour of asphalt mixture including various penetration grade bitumen has been a major subject of paving engineering. This search investigated the volumetric and mechanical properties of a hot-mix asphalt (HMA) mixture with the Superpave mix design. The mixture was added with powdered soft clay at five different percentages based on the bitumen weight (0%, 2%, 4%, 6%, and 8%). Performance tests were then conducted to determine the resilient modulus and volumetric properties of the mixture. Results show that bulk specific gravity increased after adding soft clay to the asphalt mixture. The amount of air and mineral aggregate voids also decreased with increasing SC contents. Furthermore, the addition of 4% SC improved mixture stiffness, as determined through indirect resilient modulus test under aging conditions. Therefore, soft clay can be added to asphalt mixtures to improve their volumetric and mechanical properties, such as strength and durability.

Data Mining Statewide Department of Transportation Volumetrically Designed Asphalt Mixture Records

In recent years, the asphalt paving industry has been strained by numerous factors including increased asphalt binder costs, funding that has not kept up with material costs, increased societal pressure to recycle, and deteriorating pavement networks. Mix design should account for the market in which it is used, which is very different now than when today’s volumetric mix design practices were developed (many of the aforementioned factors were less present). Given this reality, a statewide database of all 1,452 approved mix designs in Mississippi from 2005 to 2018 was compiled and analyzed, and the objective of this paper is to present findings, trends, and unintended consequences of exclusive reliance on volumetrics. With volumetrics-only mix design, asphalt content is primarily controlled by voids in mineral aggregate (VMA), which is influenced by aggregate bulk specific gravity (Gsb). Minor Gsb deviations (i.e., within AASHTO d2 s limits), can significantly affect VMA, so much so that 99% of Mississippi’s mixes could be failing VMA while reported VMA passes. This allows mix manipulation and economization, with 0.8% asphalt content reductions possible while still meeting volumetric requirements. Recycled materials can exacerbate this issue, and common approaches to increase asphalt content (decreasing design gyration level or using finer gradations) are ineffective with fixed VMA requirements. Overall, the mix design database analysis agrees with numerous smaller studies but does so with an entire state’s actual practice. This presents a compelling case that volumetrics-only mix design has limitations, and supports ongoing efforts to reintegrate mechanical tests.

Application of Multi-Criteria Decision-Making in Achieving the Right Mix Asphalt Mixtures

Marshall Test is one of the tests used for asphalt mixture. This test has six parameters, including stability, unit weight, flow, void in mineral aggregate, voids in total mix, and voids filled with asphalt. Further, the additional cost of various additives to the asphalt mixture for building one kilometer of the road is a negative parameter. However, using additives improves the technical characteristics of the asphalt mixture. Therefore, making a proper choice among the alternatives would be a hard task. This paper tries to provide an appropriate method for mixing the design of asphalt mixtures to select the best alternative by considering all technical criteria. For this purpose, the concordance analysis method, which is one of the compensation models of the Multi-Criteria Decision-Making (MCDM), was used. The results showed that the concordance analysis method using a pairwise comparison strategy combines the different criteria to prioritize alternatives and to propose the best alternative. Therefore, this method can be used as a superior method for mixing the design of asphalt mix compared to conventional methods.

THE EFFECT OF SEA WATER IMMERSION ON BUTON ASPHALT (AS-BUTON) MIXTURE

One of the causes of flexible pavement damage is being submerged in water with a high acidity, such as seawater. To overcome this condition, a study on the use of buton asphalt (as-buton) was conducted. The advantages of as-buton are that it has higher adhesion and is more resistant to temperature changes. As-buton modification by mixing Lawele as-buton Southeast Sulawesi with oil asphalt pen 60/70. This study focuses on determining the effect of the addition of as-buton to the modified asphalt mixture and the effect of seawater immersion on as-buton mixture based on the Marshall characteristic test. The percentage by weight of as-buton used is 5%, 7.5%, and 10%. The immersion was carried out in freshwater and seawater immersion for up to 24 hours at a temperature of 30°C. The result of this study show that the addition of as-buton increase the value of stability, void in mixture, Marshall quotient (MQ), and void in mineral aggregate, but reduce the flow, void filled with asphalt, and density. The increase of stability and MQ value in seawater-immersion due to the addition of as-buton was higher than that in freshwater. The stability value of the 10% modified as-buton mixture in freshwater-immersion increased by 169.338 kg (14.61%) and in seawater-immersion increased by 1261.669 kg (55.65%). The flow value in freshwater-immersion decreased by 1.9 mm (25.33%) while in seawater-immersion decreased by 1 mm (14.08%). For further research, variations in the addition of as-buton will be carried out to produces a modified asphalt mixture.

A triangular representation of the volumetric properties of asphalt mixtures

The volumetric properties of asphalt mixtures are important parameters for evaluating the performance of asphalt. Volumetric properties (grading requirements, air void content, minimum and maximum voids filled with bitumen and voids in mineral aggregate) are usually presented first in specifications. The visualisation of volumetric properties is therefore important for the understanding of the composition of an asphalt mix. A triangular representation of requirements for the volumetric properties of asphalt mixtures is therefore a valuable method to illustrate the volumetric requirements. Such representation gives a better insight into the requirements and helps on decisions when authorities decide about these requirements.

The Use of Steel Slag as Substitution of Coarse Aggregate on Indirect Tensile Strength and Marshall Properties of AC-WC

High traffic levels on road can causing road damage, especially cases of permanent deformation and fatigue cracking. One solution is to utilize waste of material, such as steel slag as coarse aggregate and polymer modified asphalt as binding material. This paper explores experimental laboratory investigation on the use of steel slag on Marshall characteristics and indirect tensile strength of AC-WC mixture by using Starbit E-60 and Pen 60/70. Laboratory works begin with physical testing of material, then, finding the optimum bitumen content (OBC) for each type of the mixtures. Finally, Marshall Standard and indirect tensile strength (ITS) at OBC were conducted. Results shows that the use of steel slag for AC-WC mixture are proven to improve resistance to permanent deformation as well as fatigue cracking. Substitution of steel slag for coarse aggregates were able to increase Marshall stability, Marshall Quotient and indirect tensile strength (ITS) of the mixtures, however, it slightly decreases the volumetric performance of mixture, such as voids in total mixes become higher and voids filled with asphalt as well as voids in mineral aggregates tend to decrease.

Effects of fillers on stability properties of stone matrix asphalt mix

Failures in asphalts occurs because of the development of vehicles with high intensity of loads tends to increase in usage of automobiles which results in use of rut resistant Bituminous mixes in the surface course. Rutting and Fatigue cracking are the results of the damage caused due to primary parameters. Cracking can be prevented by maintaining Probable temperature during the preparation of bituminous mix to the laying of mixes. To prevent rutting, the Stone lattice black-top also known as Stone Matrix Asphalt (SMA) can be utilized as a fraction of the bituminous layer. In this study SMA is preferred to check its implementation in all viewpoint such as stability (kg), volume of voids in mineral aggregates (VMA,) deformation (mm), with the usage of different types of Non Conventional fillers which enhances the properties of the mix. Fillers plays a vital role in improving the stability and durability, where as reduction leads to increase voids in the mix. Distinctive fillers like glass powder, magnetite, cement kiln powder and fly ash have been used in the mixes. Twelve sets of test sample were set up by utilizing typical sorts of filler having varied sum in the mixture. Samples prepared at diverse asphalt contents(4.5%,5.5%,6.5%) respectively varying fillers. The Marshall properties obtained for the conventional filler flyash has been set up to exhibit higher stability contrasted with magnetite, glass powder, cement kiln Powder, but have satisfied the minimum requirements. Magnetite filler indicates least deformation at 5.5 % bitumen content and the rate of air voids from the results they are observed to be diminished with the expansion of bitumen substance.

Effect of Incorporating Super Bond Additives on Volumetric and Mechanical Characteristics of Cold Mix Asphalt Concrete using Asbuton

Asbuton is the natural asphalt of Buton Island, Southeast Sulawesi. Asbuton has substantial reserves with deposits estimated at between 150 to 300 million tons. Asphalt mixture using Asbuton can be done with a cold mix. This mixture requires a rejuvenating agent that serves to soften and rejuvenate the asphalt properties contained in Asbuton. The rejuvenation process that is less than optimal results in the low quality of the asphalt mixture. Therefore, it is necessary to conduct a study to improve the performance of cold mixtures using Asbuton. In this study, super bond additives were used. This study aims to determine the extent to which the performance of asphalt-concrete mixtures using Asbuton with the addition of super bond additives in the rejuvenating agent is increased. The addition of additives was varied with levels of 0.0%, 0.2%, 0.3%, and 0.4%, so that the impact could be known. The best asphalt concrete mix characteristics were obtained at the addition of 0.4% additives. Where, for volumetric characteristics the values ​​obtained are: Void in the Mix (VIM) 5.08%, Void in Mineral Aggregate (VMA) 19.6% and Void Filled with Bitumen (VFB) 74.0%. While the mechanical characteristics are: Stability 609 kg, Flow 2.7 mm and Marshall Quotient 223 kg/mm. Only the Marshall Quotient value does not meet the minimum requirements, because it is < 250 kg/mm.

Assessment of asphalt binder and mixes modified with Zycotherm and Sulphur

In the present study, bituminous concrete mixes were prepared by adding Zycotherm as modifier and Sulphur as an extender. The physical properties of bitumen blended with Zycotherm and Sulphur were evaluated. For preparing the hot mix asphalt specimens, bitumen was modified with 0.05%, 0.1% and 0.15% of Zycotherm. Sulphur was used as an extender and its percentage was fixed at 35%. Comparison was made between the optimum binder content (OBC) of mixes prepared with neat and modified bitumen prepared using the Marshall mix design. For this purpose, a total of 8 type of asphalt mixtures were made. The OBC was determined and other parameters such as Marshall stability, flow value, voids filled with bitumen (VFB), voids in mineral aggregates (VMA) and unit weights were evaluated at this binder content. Based on the above experimentation and testing, it was concluded that the aggregates and bitumen (virgin and modified) results satisfy the standard requirements and the results are within the specified limits. In terms of physical properties, bitumen containing Sulphur results in changes up to large extent compared to Zycotherm modified bitumen. Addition of Zycotherm results in minor change in the physical properties of bitumen but the incorporation of 0.1% Zycotherm with 35% Sulphur, indicates the utmost Marshall stability and Marshall quotient value at the optimum binder content of 5.43 %.

Study on Tyre Rubber Modified Bitumens Mix for Road Asphalt Mixtures

Abstract: In this study the strength & stability characteristics of bituminous mix for 80/100 grade bitumen is to studied and the effect of waste crumb rubber strength and stability characteristics in Bituminous mix and rubber bituminous mix is analyzed. Keywords: voids in mineral aggregates (VMA), voids filled with bitumen (VFB) Method, Crumb rubber, Crumb rubber bituminous mix, stability, flow, Bulk Density

Pengaruh Serbuk Abu Cangkang Kerang Sebagai Bahan Pengganti Filler Pada Campuran Aspal

Asphalt is the main ingredient in road pavement. The specification of the Asphalt Concrete Wearing Course (AC-WC) mixture refers to the Specifications of the Ministry of Public Works, Directorate General of Highways 2010 revision 1 (BM 2010). Marshall test includes: stability, flow, Marshall Quotient, Voids In Mixture (VIM), Voids in Mineral Aggregate (VMA), and Voids Filled by Asphalt (VFA). In the AC-WC mixture that uses fine aggregate, namely clam shell filler. The shells used are from the Tanjung Balai area. From the results of the study, the effect of partial replacement of oyster shell filler was 15% and 25% which showed a change in the stability value for 15% mixture of 1192 kg and 25% of 1245 kg while the Specifications of the Ministry of Public Works of the Directorate General of Highways 2010 revision 1 of 800 kg had met specification requirements.

Analysis of the Effects of Voids in Mineral Aggregate on Pavement Fatigue Performance Using AASHTOWare Pavement ME Design and FlexPAVE

Abstract Deviation of volumetric properties of asphalt mixtures, such as voids in mineral aggregates (VMA), from the agency–specified thresholds can cause minor to significant changes in pavement performance. This paper presents the results of the study on the effects of the deficiency of VMA parameters (ΔVMADesign) on the fatigue performance of asphalt pavements. Dynamic modulus and fatigue tests were performed on two types of mixtures (one with 9.5-mm nominal maximum aggregate size (NMAS) and the second one with 19-mm NMAS) at three levels of ΔVMADesign. The results were analyzed using two simulation models (i.e., FlexPAVE 1.1Alpha and AASHTOWare Pavement ME Design version 2.3.0 (Pavement ME)). The results showed that fatigue service life reduction was linearly correlated to an increase in ΔVMADesign and could reach almost 50 % for a pavement with ΔVMADesign of 3 %. Additionally, while both Pavement ME and FlexPAVE showed comparable results in terms of top-down cracking/damage predictions, the results of the analysis performed by FlexPAVE in terms of bottom-up damage prediction were more consistent with respect to the expected behavior of pavement structure in terms of damage.