Aggregate Base Course Research Articles

Utilization of Tunnel Waste Slag for Cement-Stabilized Base Layers in Highway Engineering.

The rapid expansion of highway infrastructure in the mountainous regions of China has led to a significant increase in tunnel construction, generating substantial amounts of tunnel waste slag. Concurrently, the development of transportation infrastructure has created a critical shortage of natural aggregates, necessitating the exploration of alternative sustainable sources. This study aimed to conduct a comprehensive evaluation of the physical and mechanical properties of tunnel waste slag and explore its potential for utilization in cement-stabilized base courses for highway engineering applications. The uniaxial compressive strength of the parent rock (tunnel waste slag) ranged from 81 MPa to 89 MPa in the desiccated state, indicating its suitability for use as a construction material. This study also determined the maximum dry density (2.432 g/cm3) and optimal moisture content (5.4%) of cement-stabilized mixtures incorporating recycled aggregates derived from tunnel waste slag. The splitting tensile strength of these mixtures at 28 days varied from 0.48 MPa to 0.73 MPa, demonstrating robust mechanical performance. Moreover, the unconfined compressive strength of these mixtures escalated from 7.0 MPa at 7 days to 11.0 MPa at 90 days, signifying a substantial enhancement in strength over time. These results validate the viability of utilizing tunnel waste slag in highway engineering and furnish valuable insights for designers, concrete manufacturers, and construction firms engaged in the development of cement-stabilized aggregate base courses.

Analysis of road construction waste generation in developing economies: A focus on surfacing and sub-base construction projects in Sri Lanka

The motivation for this study was to develop simplified tools to estimate material wastage during road construction projects. In developing countries, there is a lack of information about material wastage factors (MWFs) in road construction projects. The purpose of this study is to reveal the MWFs of materials used in road construction. To investigate MWFs, statistics were collected from a sample of 58 road contracts concluded in the southern province of Sri Lanka, comprising 245 road construction projects. Of the selected sample, 80% of the road projects utilized wearing course (asphalt concrete), aggregate base course (ABC), cationic slow setting emulsion 1 (CSS1) and sand. The mean MWFs were calculated only for ABC, wearing course and CSS1 as 8.69%, 5.21% and 6.8%, respectively, because the authors could only achieve acceptable precision levels for these three types of materials. The coefficient of variation (CV) for all these three types of materials ranged from 25% to 3%. Based on collected data, this study proposes equations to predict waste generation for CSS1 and wearing course. Implementing the derived equations to predict waste generation can aid in efficient planning and help construction companies to move towards more sustainable practices.

PETROGRAPHIC INVESTIGATION OF LIMESTONE OF THE LAKI FORMATION USED IN CONSTRUCTION SECTOR FROM JAMSHORO AND THATTA DISTRICTS, SINDH, PAKISTAN

Limestone belonging to the Laki Formation is well exposed at Nooriabad, Jhampir, and Makli Hills. Representative samples of the Laki Formation limestone were collected from different locations such as Jamshoro, Bolhari, Makli Hills, and Nooriabad. The four crush plants i.e. Afridi Crush Plant and New Hazara Crush Plant (Makli, Thatta District), Shah Rahim Crush Plant and Bhatti Crush Plant (Nooriabad, Jamshoro District) were selected for sampling. The Petrographic investigation as per ASTM- C295-03 (1) was performed using standard thin sections. The megascopic and microscopic study results reflect no hindrance in using the studied limestone. For cement concrete, this limestone can be used for the low-strength concrete and aggregate base course and sub-base. Variation in lithology, stratification and non-homogeneity was observed, however, the aggregate from the New Hazara crush plant is found fractured in nature and therefore, its use as concrete material is not suggested. The studied limestone of all crushed plants does not show any potential for Alkali Silica Reaction (ASR) and Alkali Carbonate Reaction (ACR). Based on the present study, it is concluded that the studied limestone of the Laki Formation from the above-mentioned locations is suitable for construction purposes and industrial use. For cement concrete, this limestone can be used for the low strength concrete and pavement (sub-base & base coarse) as well as aggregate base course. In the stockpile of crushed aggregate on crusher plants, the chalky limestone was found to be less stable and less durable.

Modeling geogrid-stabilized aggregate base courses considering local stiffness enhancement

Lateral restraint is the primary stabilization mechanism associated with the interlocking of aggregate particles in the geogrid apertures. This paper presents findings from a laboratory study which quantifies the local stiffness enhancement of aggregates through micromechanical interlocking provided by two different types of geogrids. These findings are applied to model the resilient response characteristics of geogrid-stabilized base course composite systems. Using three pairs of bender elements as shear wave transducers, horizontal stiffness profiles were determined above mid-heights of aggregate specimens. For two types of geogrids with square- and triangular-shaped apertures, the shear modulus profiles decreased moving away from the geogrid location. Based on a relationship for aggregates, resilient modulus was estimated from the shear modulus. Considering the variations in resilient moduli with distance from the geogrid location, the local stiffness enhancements provided by the two geogrid types were assigned to modulus profiles of a geogrid-stabilized aggregate base course in flexible pavement mechanistic analysis and modeling. The modeling results demonstrate the effect of geogrid base stabilization on the computed pavement resilient responses for both geogrid types. The sublayering approach which properly considers modeling of the geogrid influence zone could be effectively used in mechanistic analysis of a geogrid-stabilized pavement system.

The effect of an emulator inductive power transfer pad on the temperature of an asphalt pavement

This paper utilises experimental and numerical methods of determining the temperature distribution in an asphalt slab containing an energized embedded emulator Inductive Power Transfer (IPT) pad. In the series of experiments, five different ambient temperatures from 15 to 50 °C, four IPT pad power loss values from 5 to 30 W, and three pavement layer configurations were considered. A thermal camera was used to measure the surface temperature distribution of the asphalt slab, while a Fiber Bragg Grating (FBG) sensor and six thermistors were used for point temperature measurements. A numerical simulation, using a combination of experimentally determined, and literature-sourced thermal properties was developed for the experimental set-up, which was validated against the measured temperatures. Results show good agreement between the experimental and the simulation models with a maximum point-wise differential of 12.9%. It was found that increasing the ambient temperature from 15 to 50 °C, at a constant pad power loss of 30 W, increased the simulated asphalt surface temperature (25 mm offset from the pad) from approximately 32 to 65 °C. Moreover, varying the IPT pad power loss from 5 to 30 W, at an ambient temperature of 50 °C, increased the simulated asphalt surface temperature at the same location from approximately 53 to 65 °C. However, changing the asphalt thickness from 43 mm to 86 mm, or adding a compacted aggregate base course layer below the IPT-asphalt slab, only marginally decreased the temperature values. An increase in the thermal conductivity of the asphalt from 1 to 3 Wm−1°K−1, results in the temperatures reducing by a maximum of approximately 21% at the bottom of the pad. However, changing the specific heat has a very small effect on the heating and cooling rates. A numerical study of an in-service New Zealand asphalt pavement, containing an emulator IPT pad and utilising a three-day period of recorded New Zealand summer climatic data is presented. The method can be used to identify IPT-pavement hotspots and aid in the design of thermally robust IPT-pavement systems.

Base Course Stabilization Performance Using Fly Ash-Based Geopolymers and Their Effect on Water Quality Standards

The road is the main gateway to human life and links essential access points. Some structure pavement failures happened due to the base layer's instability. Fly ash has been used in several parts of pavement structures to increase stability. One significant concern with using fly ash in base course stabilization is its proportion and potential impact on water quality standards. This research aimed to evaluate base course stabilization performance using fly ash-based geopolymers, as well as assess their impact on water quality standards. Materials in this study consisted of aggregate, fly ash, water, and alkaline reagent solutions. The variation of mix considered with a variety of alkaline reagents, namely without alkaline reagents, 3 mol, 6 mol, 9 mol, and 12 mol of NaOH. The ratio between NaOH and Na2SiO3 is 1:2. The use of fly ash in the class A aggregate base course layer has not been able to meet specifications. However, by providing 9 mol of alkaline reagent, the strength of the mixture increases so that the CBR value meets the specifications due to geopolymer bonding. When the alkaline reagent solution becomes more concentrated, the optimum water content decreases, and the bond between aggregates strengthens. The effect of alkaline reagents on water quality standards increases the acidity (pH) value, while other parameters such as BOD, COD, and TSS still meet the standards. This research point to another practical approach that is effective in the field to increase the stability of the base course layer and is environmentally friendly.

Estimation of the compaction parameters of aggregate base course using artificial neural networks

The process of estimating the compaction parameters namely the maximum dry density (MDD) and optimum moisture content (OMC) through laboratory tests is time-consuming, labor-intensive, and costly. These issues can be avoided by developing prediction models that are able to accurately predict the compaction parameters from index properties that are easier to estimate in the laboratory. As a result, this study focuses on employing artificial neural networks (ANNs) for the prediction of the compaction parameters of aggregate base course samples from the grain size distribution and Atterberg limits. Additionally, different ANNs with different structures were tested in order to set the optimum hyperparameters that minimize the errors in the predictions. Specifically, this study investigates the impact of the number of hidden layers, number of neurons per hidden layer, and activation functions on the performance of the ANNs. Furthermore, the weight decay method, which is the most common regularization technique, was used during the training of the ANNs in order to avoid overfitting and control the changes in the connection weights. The results indicate that the optimum hyperparameter settings changes depending on the optimized output. Additionally, the ReLU activation function is the most stable function that produces the best predictions. Moreover, the results show that ANN approach represents a major innovative tool for accurately predicting the compaction parameters with R2 values of 0.826 and 0.911 for predicting the MDD and OMC.

Resilient Modulus Behavior and Prediction Models of Unbound Permeable Aggregate Base Materials Derived from Tunneling Rock Wastes.

Tunneling rock wastes (TRWs), which are often open- or gap-graded in nature, have been increasingly recycled and reused for sustainable construction of unbound permeable aggregate base (UPAB) courses with high porosity and desired drainability. However, there is still a lack of sufficient understanding of long-term mechanical stability of such TRW materials subjected to repeated applications of moving wheel loads. This paper aimed to characterize and predict resilient modulus (Mr) behavior of the TRW materials used in unbound permeable aggregate base applications. To achieve this goal, five different UPAB gradations were designed based on the gravel-to-sand ratio (G/S) concept. In order to study their Mr behavior, the laboratory repeated load triaxial tests were conducted under different combinations of confining pressure and deviator stress as controlled by the levels of the shear stress ratio (SSR). The prediction accuracy of fourteen classical Mr prediction models was comparatively analyzed, from which the improved Mr prediction model incorporating gradation and stress variables was proposed for TRW-derived UPAB materials and further validated by external database accordingly. The results show that under the same G/S value and confining pressure level, the higher the SSR is, the greater the final Mr values are, and the more significant the effect of G/S on Mr is. Under the same SSR level, the increase of confining pressure alleviates the effect of G/S on Mr. There appears to exist an optimal G/S value of around 1.6–1.8 that yields the best Mr behavior of the TRW-derived UPAB materials studied. The improved Mr prediction model was verified extensively to be universally applicable. It can potentially contribute to balancing long-term mechanical stability and drainability of TRW-derived UPAB materials through gradation optimization. The findings could provide a theoretical basis and technical reference for cost-effective and sustainable applications of UPAB materials derived from TRWs.

Key performance indicators of aggregate base course waste management during the construction phase of a road project from the contractor’s perspective

ABSTRACT Aggregate base course is one of the most significant and bulky material used in road construction projects. Literature on the Key Performance Indicators (KPIs) that can be used to control the of aggregate base course waste generation during the construction phase of a road project, especially from the contractor’s perspective, is scarce. Thus, the aim of this study was to identify the KPIs for managing the aggregate base course waste in road projects from the perspective of a contractor. A quantitative research approach comprising three Delphi rounds was used to collect the empirical data, which were analysed using statistical data analysis tools. The study revealed that the use of the wrong construction method is the most significant waste generation factor, while proper supervision is the most significant strategy to overcome the generation of aggregate base course waste. The experience and qualifications of technical staff related to the handling of aggregate base course waste is the most significant KPI for controlling the aggregate base course waste generation in road constructions. The study contributes to knowledge and the industry by minimising aggregate base course waste while reducing cost and time overruns and enhancing the performance and sustainability of road construction projects.

Long-Term Performance of Flexible Pavements Constructed on Recycled Base Layers

There has been an increased interest in using reclaimed asphalt pavement (RAP) aggregates as a base course in Wisconsin for the offered economic and environmental benefits. Laboratory studies showed that RAP can have resilient modulus values higher than typical natural aggregates, and can also have higher durability, especially in freeze–thaw cycles. However, it is also recognized that RAP exhibits temperature sensitivity and larger permanent deformations than natural aggregates. How these characteristics manifest themselves in the northern U.S. climates can only be assessed by long-term observation of field performance. Wisconsin Department of Transportation (WisDOT) has been using RAP as a base course for over 30 years. The qualitative assessment of WisDOT roads constructed with RAP showed they are performing adequately. However, this impression has not yet been verified quantitatively. This paper presents a quantitative assessment and comparisons for field performance of pavement test sections constructed with RAP and natural crushed aggregate (CA) base course layers in Wisconsin. The performance was evaluated using pavement distress surveys of roadways containing RAP and CA, falling weight deflectometer (FWD), dynamic cone penetrometer (DCP) tests, and analysis of WisDOT’s available data. Based on the field evaluation, the performance of the hot mix asphalt (HMA) pavements with RAP was found adequate and comparable to those with CA base course layers. A recommendation was given that WisDOT shall continue the practice of using RAP in base course layers of HMA pavements, given proper quality checks for materials, and proper quality control/quality assurance measures being applied during construction.

Airport Pavement Stiffness Monitoring and Assessment of Mechanical Stabilization using Bender Element Field Sensor

The bender element (BE) field sensor is a newly developed embedded pavement instrumentation that measures shear wave velocity to estimate constructed layer moduli of unbound aggregate bases and subbases. This paper presents findings related to monitoring stiffness characteristics of airport pavement base courses instrumented with BE field sensors and tested under full-scale accelerated pavement testing during Construction Cycle 9 (CC9) of the National Airport Pavement Test Facility (NAPTF) by the U.S. Federal Aviation Administration (FAA). The CC9 aggregate base courses were constructed following FAA’s P-209 specification for a geosynthetic experiment using a biaxial geogrid installed at the bottom of the 8-in. (203-mm) thick base in the north test section, while the control pavement in the south test section was built without a geogrid. Two BE field sensors were installed in the north and south test sections approximately 1 in. (25 mm) above the base–subbase interface. Multiple stages of aircraft gear loads, including static dual-gear, dynamic slow-roll (moving wheel), and dynamic proof-roll, were applied to the test sections. BE field sensor data collected throughout multiple loading stages were used to investigate the stiffness characteristics of the pavement base. These preliminary tests conducted at the NAPTF CC9 experiment revealed the effects of static and dynamic aircraft gear loads on the stiffness of the aggregate base layer and how confinement influenced the moduli of the geogrid-stabilized base. Further, previously observed anti-shakedown effects caused by vehicle load wander could be quantified through changing base course modulus and deformation behavior from the BE field sensor data analysis.

Performance of cement stabilized recycled aggregate base course added with metakaolin

In order to better use the old cement concrete pavement materials in the cement stabilized base of the reconstruction or new road. In this paper, metakaolin was used to replace recycled fine aggregate with different proportions to prepare cement stabilized recycled aggregate base mixture, and the physical and mechanical properties and dry shrinkage properties of cement stabilized recycled aggregate base mixture were studied. The results of the study show that adding a proper amount of metakaolin can reduce the optimal water content of the mixture, increases the maximum dry density and 7d unconfined compressive strength of the mixture, and also reduces the total water loss and dry shrinkage of the mixture. The research results can provide new ideas for the recycling of road waste materials.

A New Low-Activity Nuclear Density Gauge for Soil Density Measurements

Abstract For decades, nuclear density gauges have been used to measure the density and moisture content of soil during compaction testing in road and embankment construction. Worldwide regulatory agencies consider nuclear density gauges as controlled devices because of their inclusion of radioisotope sources. Regulatory requirements, such as the need for licensing, special storage, special transportation procedures, gauge operator training, and personal dosimetry, have become burdens for gauge users. Recently, a new nuclear density gauge for measuring soil wet density was declared exempt from licensing and other nuclear regulatory requirements in the United States. The new gauge uses an extremely low-activity radioisotope source. It further incorporates a separate probe operating on electromagnetic principles for soil moisture measurement or any other moisture measurement method the user desires. This paper presents the design features and measurement properties of this low-activity nuclear density gauge and its associated moisture probe. The measurement properties were determined from laboratory and field studies that were conducted in North Carolina, United States. These studies showed that the sensitivity and precision of wet density measurements made by the low-activity nuclear density gauge were similar to those made by a conventional nuclear density gauge. The wet density measurements made by the low-activity gauge and conventional gauge showed a strong correlation and agreement. For the two field sites studied, a silty sand subbase and a cement-treated aggregate base course, the dry density agreement between the low-activity nuclear density gauge/moisture probe and the conventional nuclear density gauge was within 3 lb/ft3 (48 kg/m3).

Deep Neural Network Models for the Prediction of the Aggregate Base Course Compaction Parameters

Laboratory tests for the estimation of the compaction parameters, namely the maximum dry density (MDD) and optimum moisture content (OMC) are time-consuming and costly. Thus, this paper employs the artificial neural network technique for the prediction of the OMC and MDD for the aggregate base course from relatively easier index properties tests. The grain size distribution, plastic limit, and liquid limits are used as the inputs for the development of the ANNs. In this study, multiple ANNs (240 ANNs) are tested to choose the optimum ANN that produces the best predictions. This paper focuses on studying the impact of three different activation functions: number of hidden layers, number of neurons per hidden layer on the predictions, and heatmaps are generated to compare the performance of every ANN with different settings. Results show that the optimum ANN hyperparameters change depending on the predicted parameter. Additionally, the hyperbolic tangent activation is the most efficient activation function as it outperforms the other two activation functions. Additionally, the simplest ANN architectures results in the best predictions, as the performance of the ANNs deteriorates with the increase in the number of hidden layers or the number of neurons per hidden layers.

A framework for aggregate base course waste control in road construction projects

The management of Aggregate Base Course (ABC) wastage in road construction (RC) is an under researched area. Thus, the aim of this study was to develop a framework for ABC waste control in RC projects. The study used a mixed approach consisting of 15 expert interviews and a questionnaire survey conducted among 137 experts engaged in RC projects. The collected empirical data were analyzed using manual content analysis and the weighted mean rank, respectively. The findings of the study revealed that the most significant cause of ABC wastage in RC projects is laying ABC without construction shoulders. The most significant consequence of ABC wastage in RC projects is cost overruns. The most significant measure that can be adopted to control ABC wastage in RC projects is improved transportation of the materials. A framework also was developed in the study to help control ABC wastage in RC projects.

Stress-strain response analysis of demolition wastes as aggregate base course of pavements

The sustainable construction approach by utilizing recycled aggregates has increasingly been the focus of highway construction industries and local road authorities in recent years. The efficient usage of recycled aggregates for sustainable construction is owed to more than a decade of extensive experimental research aiming to remove uncertainties in the properties and performance of recycled aggregates in transport infrastructures. Nevertheless, a lack of knowledge exists about the stress-strain response of the pavement structures constructed using recycled aggregates. The main goal of this study was to propose a response analysis approach to incorporate the repeated load triaxial (RLT) test results as a Level 1 MEPDG input parameter in a well-established pavement analysis software named FlexPAVETM. In this approach, the aggregate base course was divided into ten sublayers of equal thickness. Three different constitutive resilient modulus (Mr) models were utilized to determine the Mr of each sublayer corresponding to the stress levels achieved at that sublayer. Modeling the pavements in FlexPAVETM by assigning the corresponding Mr to the sublayers resulted in a more accurate stress-strain response compared to the conventional linear elastic analysis approach. This approach provides a more realistic and, accordingly, more accurate analysis of the behavior of unbound aggregates in pavements. The secondary goal of this study was to investigate the stress-strain response of pavements with aggregate base courses made of three types of recycled construction and demolition wastes, being recycled concrete aggregate (RCA), crushed brick (CB), and waste excavation rock (WR). The resilient properties of the demolition wastes were determined through repeated load triaxial (RLT) testing. A typical pavement profile consisting of asphalt surface course, aggregate base course, and an A6 type of natural soil as subgrade was modeled using FlexPAVETM. The response analysis was undertaken following the proposed sub layered approach. Under the loading conditions adopted in this research, with bulk stresses <185 kPa, CB and RCA exhibited a superior Mr response compared to the conventional virgin materials, while WR showed an inferior behavior.

Studies on the Volumetric Stability and Mechanical Properties of Cement-Fly-Ash-Stabilized Steel Slag.

The stability of steel-slag road materials remains a critical issue in their utilization as an aggregate base course. In this pursuit, the present study was envisaged to investigate the effects of fly ash on the mechanical properties and expansion behavior of cement-fly-ash-stabilized steel slag. Strength tests and expansion tests of the cement-fly-ash-stabilized steel slag with varying additions of fly ash were carried out. The results indicate that the cement-fly-ash-stabilized steel slag exhibited good mechanical properties. The expansion rate and the number of bulges of the stabilized material reduced with an increase in the addition. When the addition of fly ash was 30–60%, the stabilized material was not damaged due to expansion. Furthermore, the results of X-CT, XRD and SEM-EDS show that fly ash reacted with the expansive component of the steel slag. In addition, the macro structure of the stabilized material was found to be changed by an increase in the concentration of the fly ash, in order to improve the volumetric stability. Our study shows that the cement-fly-ash-stabilized steel slag exhibits good mechanical properties and volumetric stability with reasonable additions of fly ash.

Management of Aggregate Base Course Wastage in Road Construction Projects

The construction industry in a country contributes significantly to the national economy. Developing countries in Asia produce a huge amount of construction waste. Road Construction (RC) projects, which are quite risky, often end up with cost and time overruns. Construction materials account for a major portion of the cost overruns. Thus, the management of material wastage in construction projects is important. Aggregate Base Course (ABC) wastage affects the cost of RC significantly. Thus, this study was on the waste management of ABC in RC projects executed in Sri Lanka. The study adopted a qualitative research approach and the required empirical data were collected by interviewing 13 experts. The interview findings were analysed manually using content analysis. The interviews were conducted based on the findings of a literature review. The interviews findings disclosed that improper material storage in sites, material wastage during transportation, improper material utilization, and professional inefficiency as the major factors that contribute to material wastage in road projects. Material reconciliation and proper documentation were identified as the two most common strategies that can be adopted to manage the material wastage in RC projects.

Insights and Findings Following 11 Years of Test Road Exploitation

Road pavement is one of the most important components of road structure. Long-term monitoring changes in the state of road pavement under real conditions of load and climate allows to determine surface degradation mechanisms, select sustainable road building materials and their mixes, rationally employ asphalt paving technologies, and improve quality control. For a number of years, road pavement structures have been studied that should best meet the Lithuanian climate conditions and withstand the increasing impact of vehicle load. Thus, for that purpose, specially designed, constructed and tested roads or road sections for different pavement structures are most appropriate. One of those was constructed in 2007. The experimental road (hereinafter, the Test Road) consisted of 27 different pavement structures (PSs) produced of various materials. The study aims to evaluate the effect of different materials on variations in the bearing capacity of the pavement structure (PS), the sustainability of the structure, and the formation of ruts in 2007–2018. In this way, difference in bearing capacity, rutting depth between sections, and loaded and unloaded lanes was estimated. Further, the statistical analysis of these factors was conducted. Investigations have shown that the minimum bearing capacity of 754 MPa established after 11 years did not affect the formation of rut depth that was less than 1.0 cm. The PSs covered with the used asphalt granules, a larger asphalt base course on gravel, the sand mix base course, and granite aggregate mixed with sand base course were accepted as one of the PSs with the highest bearing capacity with PSs exceeding 929 MPa. The bearing capacity of the PS containing a 20 cm aggregate base course is on average higher by 30 MPa than PS holding a 15 cm aggregate base course.

EFFECT OF BASECOURSE AGGREGATE PROPERTIES ON STRENGTH OF FOAMED BITUMEN STABILIZED MATERIALS

Foamed Bitumen Stabilization (FBS) is a treatment for strengthening pavements and improving road performance, either on newly constructed or existing roads. The FBS within pavements is typically used in the basecourse layer, where the basecourse material is mixed with cement, bitumen, and water through a milling operation on site. The performance of the Foamed Bitumen Stabilized basecourse can be highly affected by various parameters such as the cement content, bitumen content, the quality of the operation as well as the basecourse aggregate characteristics. In this research, a collection of existing historical FBS mix design data from New Zealand roads are analyzed. The Indirect Tensile Strength (ITS) of the FBS material made of aggregate sourced from two different regions are compared. The results show that the aggregate percentage of fine particles and the plasticity index contributes to the final strength of FBS material. The obtained results are valuable towards optimizing the FBS mix design based on the basecourse aggregate properties.