Determining the amount of asphalt needed for a paving project requires a careful assessment of the area to be covered, the desired thickness of the asphalt layer, and the density of the asphalt mix. This assessment typically involves measuring the length and width of the area, converting these measurements to a consistent unit (e.g., feet), and then multiplying them to obtain the surface area in square feet. This area is then multiplied by the specified thickness (also converted to feet) to find the volume of asphalt needed in cubic feet. Finally, the volume is multiplied by the density of the asphalt mix (usually expressed in pounds per cubic foot) to arrive at the total weight of asphalt required. This weight is then converted to tons by dividing by 2000 (the number of pounds in a ton). For instance, covering an area of 100 feet by 50 feet with a 4-inch (0.333-foot) layer of asphalt having a density of 140 pounds per cubic foot necessitates calculating the volume (100 ft x 50 ft x 0.333 ft = 1665 cubic feet), then multiplying the volume by the density (1665 cubic feet x 140 pounds/cubic foot = 233,100 pounds), and lastly converting the weight to tons (233,100 pounds / 2000 pounds/ton = 116.55 tons).
Accurate estimation of asphalt quantities prevents material waste, minimizes project costs, and ensures the structural integrity of the paved surface. Underestimating can lead to delays and additional expenses associated with procuring more material mid-project, while overestimating results in unused asphalt that may be difficult or costly to dispose of. Historically, these estimations relied on manual measurements and calculations, which were prone to human error. Modern methods often incorporate digital surveying equipment, computer-aided design (CAD) software, and specialized estimation programs to enhance precision and efficiency. A proper material estimate is crucial for effective budget planning, resource allocation, and successful project completion.
The following sections will delve into specific methodologies and factors affecting the precision of asphalt volume estimation. The analysis will cover the impact of compaction rates, different asphalt mix designs, and practical considerations for on-site adjustments during paving operations. Best practices for data collection and computational techniques for determining the asphalt amounts needed in road construction projects will also be explored.
1. Area Measurements
The accurate determination of area is the foundational step in calculating asphalt tonnage for any paving project. Erroneous area measurements propagate through subsequent calculations, resulting in inaccurate material orders, potential project delays, and cost overruns.
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Importance of Precise Surveying
Precise surveying techniques, including the use of total stations, GPS, and laser scanners, are critical for accurate area determination. These methods provide data that minimizes errors inherent in traditional manual measurement techniques. For example, in large highway projects, even small percentage errors in area measurements can translate into significant discrepancies in asphalt tonnage requirements. Utilizing advanced surveying equipment allows for the generation of detailed topographic maps and accurate digital terrain models, which form the basis for volumetric calculations.
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Impact of Irregular Shapes
Paving projects often involve irregularly shaped areas, such as parking lots with curved edges or roadways with variable widths. Calculating the area of these shapes requires the application of geometric principles or the use of specialized software. Approximating irregular shapes with simpler geometric figures introduces inaccuracies. Software solutions that utilize CAD drawings and complex algorithms can accurately determine the area of even the most convoluted shapes, leading to a more precise asphalt tonnage estimate.
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Accounting for Surface Variations
Area measurements must account for surface variations and undulations. A simple two-dimensional measurement of a surface does not reflect the actual area if the surface is not perfectly flat. For instance, a sloped roadway will have a larger surface area than its horizontal projection. Digital terrain models derived from surveying data allow for the calculation of the true surface area, which is essential for accurate volume and, consequently, tonnage estimation. Ignoring these variations can lead to underestimation of asphalt requirements, resulting in insufficient material on-site.
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The Role of Units and Conversions
Consistency in units of measurement is paramount. Area measurements are commonly taken in feet or meters, and it is crucial to maintain uniformity throughout the calculation process. Improper unit conversions, such as using inches instead of feet, can lead to significant errors in the final tonnage estimate. Standardized conversion tables and software tools with built-in unit conversion capabilities can help prevent these mistakes.
The precision and methodology employed in area measurements directly influence the reliability of the entire asphalt tonnage estimation process. By employing advanced surveying techniques, accurately representing irregular shapes, accounting for surface variations, and maintaining consistency in units, the risk of material shortages, project delays, and increased costs can be substantially mitigated. The initial investment in accurate area measurement is therefore a crucial component of successful paving project execution.
2. Asphalt Thickness
Asphalt thickness is a critical variable directly influencing the calculation for asphalt tonnage. It represents the depth of the asphalt layer to be applied and functions as a fundamental component in determining the overall volume of material required for a paving project. An increase in asphalt thickness directly corresponds to a proportional increase in the volume needed, subsequently affecting the total tonnage. For instance, doubling the specified asphalt thickness will effectively double the required tonnage, assuming other factors remain constant. Incorrectly estimating or specifying an inadequate thickness leads to structural deficiencies and premature pavement failure, necessitating costly repairs. Conversely, overestimating thickness results in unnecessary material expenditure.
The determination of the appropriate asphalt thickness is not arbitrary; it is dictated by engineering analyses considering anticipated traffic loads, subgrade soil conditions, and environmental factors. Thicker asphalt layers are typically required in areas subjected to heavy vehicular traffic or characterized by poor subgrade support. For example, a highway designed for heavy trucks will require a substantially thicker asphalt pavement structure compared to a residential street. Furthermore, climate conditions, such as freeze-thaw cycles, influence the selection of asphalt thickness to mitigate potential damage from expansion and contraction. Design specifications typically incorporate safety factors to account for uncertainties and ensure long-term pavement performance.
In summary, asphalt thickness is inextricably linked to asphalt tonnage requirements. Its accurate specification, based on thorough engineering evaluation and consideration of project-specific conditions, is paramount for cost-effective and structurally sound pavement construction. Errors in thickness estimations directly impact material quantities, project budgets, and the long-term durability of the paved surface. Therefore, meticulous attention to detail in determining asphalt thickness is essential for successful project outcomes.
3. Material Density
Material density plays a pivotal role in the relationship to the estimation of asphalt needs for paving projects. It bridges the gap between volume calculations and weight determination, serving as the essential conversion factor for procuring the appropriate amount of material. Without accurate density information, even precise volume calculations are rendered insufficient for ordering the correct tonnage of asphalt.
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Definition and Measurement
Density is defined as mass per unit volume, typically expressed in pounds per cubic foot (lbs/ft) or kilograms per cubic meter (kg/m). Measurement involves determining the mass of a known volume of asphalt mix. Methods include laboratory tests on compacted samples and field tests on in-place pavement. Density is not a fixed value; it varies based on the specific mix design and constituent materials.
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Impact of Mix Design
Asphalt mix designs incorporate varying proportions of aggregates, asphalt binder, and additives. Each component has a distinct density, and the overall mix density is a weighted average of these constituents. Higher aggregate content, particularly dense-graded aggregates, generally increases the mix density. The type and amount of asphalt binder also affect density; polymer-modified binders, for instance, may influence the final density compared to standard asphalt cements. Changes to the mix design directly impact the density and, consequently, the required asphalt tonnage.
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Influence of Air Voids
Air voids, or the empty spaces within the compacted asphalt mix, significantly influence the material’s density. Higher air void content reduces the overall density. Proper compaction during paving operations is critical to minimize air voids and achieve the designed density. Inadequate compaction leads to lower density values, requiring a greater volume of asphalt to achieve the desired pavement performance. Conversely, excessive compaction can crush aggregates, altering the mix properties and potentially affecting the long-term durability of the pavement.
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Practical Implications for Estimating Asphalt Tonnage
Inaccurate density values introduce errors in the estimation of the material needed for a paving project. Overestimating density leads to an underestimation of the total weight, resulting in insufficient asphalt delivery and potential project delays. Underestimating density results in over-ordering, increasing project costs and potential waste disposal issues. Precise density determination, coupled with accurate volume measurements, is critical for efficient resource management and budget control in asphalt paving projects.
The multifaceted nature of material density underscores its importance in paving material estimations. The composition of the mix, compaction processes, and the presence of air voids significantly impact the material’s density. Therefore, accurate assessment of these aspects is indispensable for precisely calculating asphalt needs.
4. Compaction Rate
Compaction rate, defined as the degree to which asphalt is compressed during the paving process, directly affects asphalt tonnage estimation. A higher compaction rate reduces the volume of the asphalt layer post-compaction, effectively increasing its density. Conversely, a lower rate results in a less dense layer with a larger volume for the same mass of material. This relationship means that the initial volume calculation must be adjusted based on the anticipated compaction rate to accurately determine the required asphalt weight. For instance, if a paving project calls for a final compacted thickness of 4 inches and the estimated compaction rate is 10%, the initial asphalt layer needs to be slightly thicker than 4 inches to account for the reduction in volume during compaction. Failure to accurately account for the compaction rate results in underestimation or overestimation of the necessary asphalt tonnage, leading to potential structural deficiencies or material waste.
The effect of compaction rate on material requirements extends beyond simply adjusting the initial volume calculation. It also influences the overall performance and longevity of the paved surface. Proper compaction enhances the structural integrity of the asphalt layer, reducing permeability, increasing resistance to deformation, and improving durability. A higher compaction rate, achieved through proper paving techniques and equipment, contributes to a denser and more stable pavement structure, reducing the risk of premature failure and minimizing maintenance costs. For example, neglecting proper compaction during airport runway construction can lead to rutting and cracking under heavy aircraft loads, necessitating frequent repairs and disruptions to air traffic. Therefore, accurate tonnage estimates must be coupled with rigorous quality control measures to ensure that the design compaction rate is achieved in the field.
In summary, the compaction rate is an indispensable element in calculating asphalt tonnage, affecting both the accuracy of material estimates and the long-term performance of paved surfaces. Proper consideration of compaction rates, supported by field testing and adherence to established paving practices, is critical for ensuring project success. Underestimation of compaction leads to material shortages and potential structural weaknesses, while overestimation results in costly material waste. Therefore, careful attention to compaction rates is essential for optimizing material utilization, minimizing project costs, and maximizing pavement lifespan.
5. Waste Factor
The waste factor is a critical, often overlooked, component in determining asphalt tonnage for paving projects. It represents an allowance for material losses incurred during various stages of the construction process and directly influences the accuracy of material orders, preventing potential shortages and project delays. A systematic consideration of anticipated waste minimizes both material overage and shortage, optimizing project costs and resource utilization.
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Material Handling Losses
Asphalt materials are subject to losses during loading, transportation, and unloading processes. Spillage from trucks, adherence to truck beds, and minor losses during transfer from storage facilities to paving equipment contribute to this waste. For example, a project involving multiple long-haul deliveries may experience a higher waste percentage due to increased handling. The waste percentage attributed to material handling is directly incorporated into the total tonnage calculation to ensure sufficient material availability.
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Application Inefficiencies
Application inefficiencies, such as edge trimming, paver overlap, and material left in the paver at the end of a paving run, represent another source of waste. Irregularly shaped paving areas or complex intersections often necessitate additional trimming, increasing the application waste factor. Contractors typically estimate application waste based on project complexity and historical data. Accurate estimation of application waste directly influences the material order, preventing shortages in areas requiring extensive trimming or custom fitting.
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Weather and Environmental Factors
Adverse weather conditions, including high winds and temperature fluctuations, can exacerbate asphalt material loss. Wind can scatter loose aggregate during placement, while temperature changes may affect workability, increasing material usage and potential waste. In projects scheduled during periods of inclement weather, a higher waste factor is typically applied to compensate for these potential losses. The environmental waste factor becomes crucial when projects are unable to avoid unfavorable weather conditions.
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Mix Design Variations
Subtle variations in the asphalt mix design, arising from batching inconsistencies or aggregate gradation fluctuations, can impact the volume-to-weight relationship. Minor changes in the mix composition can lead to deviations in the planned density, influencing the actual amount of material needed to achieve the required thickness. Incorporating a waste allowance mitigates the risk of running short on material due to unforeseen variations in the mix design. Ongoing monitoring and quality control procedures help minimize the need for large waste factors related to mix inconsistencies.
The waste factor, encompassing handling losses, application inefficiencies, weather impacts, and mix design variations, is an integral part of accurate tonnage estimation. By incorporating a realistic waste allowance based on project specifics and historical data, paving operations can optimize material procurement, minimize project costs, and ensure adequate material availability to meet design specifications.
6. Haul Distances
Haul distances exert a considerable influence on the actual asphalt tonnage required for a project due to material losses and temperature variations that occur during transport. Extended haul distances increase the likelihood of asphalt cooling and solidifying, especially during colder weather. This cooling can lead to clumping and sticking within the truck bed, resulting in material being left behind at the plant or along the route. Furthermore, longer distances equate to longer transport times, increasing the potential for asphalt segregation, where larger aggregate particles settle, leading to an uneven mix distribution. This segregation can necessitate additional material to compensate for the compromised homogeneity of the mix upon arrival at the paving site. For example, a highway project requiring asphalt from a plant located 100 miles away will likely experience greater material loss and temperature reduction compared to a project sourced from a plant just 10 miles away. To counteract these effects, contractors must often over-order asphalt to ensure sufficient workable material reaches the site, effectively increasing the required tonnage.
Consideration of haul distances necessitates careful logistical planning. Insulated truck beds can help to mitigate temperature loss, but they do not eliminate it entirely. The ambient temperature, traffic conditions, and the duration of the haul all contribute to the rate of cooling. Scheduling deliveries to minimize wait times at the paving site is crucial to prevent further cooling and potential hardening of the asphalt. In some cases, using multiple asphalt plants closer to different sections of the project may be a more cost-effective solution than relying on a single plant with long haul distances, even if the unit price of asphalt is slightly higher. This strategic approach can reduce the overall required tonnage by minimizing material losses and maintaining optimal workability.
In conclusion, haul distances are not merely a logistical concern but a significant factor in accurate asphalt tonnage estimation. Their impact extends beyond transportation costs, influencing material losses, temperature variations, and overall mix quality. By incorporating haul distance considerations into the initial tonnage calculations and implementing appropriate mitigation strategies, paving projects can minimize material waste, reduce expenses, and ensure the delivery of high-quality asphalt to the paving site. Failure to account for haul distances can lead to material shortages, compromised pavement quality, and ultimately, increased project costs.
7. Mix Design
The asphalt mix design directly dictates the physical properties of the material, thereby establishing a fundamental link to the required asphalt tonnage for a given project. The specific blend of aggregates, binder, and additives in the mix determines its density a critical factor in converting volume calculations to weight, and subsequently, tonnage. A mix design with a higher proportion of dense aggregates, for instance, will yield a higher density compared to one with a greater volume of lighter binder. Consequently, for the same project volume, the mix with a higher density will necessitate a greater tonnage. Therefore, the mix design acts as a primary determinant of the pounds-per-cubic-foot figure used to translate volumetric requirements into orderable material quantities. Without precise knowledge of the mix design and its resultant density, tonnage estimations become speculative and prone to significant error, potentially leading to material shortages or surpluses during construction.
Furthermore, the mix design indirectly influences asphalt tonnage requirements through its impact on compaction characteristics. Mixes designed for optimal compaction generally achieve higher densities in situ, minimizing air voids and reducing the overall volume of material required to achieve the specified pavement thickness. Conversely, poorly designed mixes may resist compaction, leading to lower densities and necessitating a greater volume of asphalt to meet the desired structural integrity. These characteristics must be considered when calculating tonnage, especially since actual field compaction may vary from laboratory testing. The selection of appropriate mix designs is driven by factors like anticipated traffic loads, environmental conditions, and desired pavement performance, but its inherent density characteristics remain a critical variable in the calculation of material amounts.
In summary, the asphalt mix design serves as a cornerstone in determining the tonnage required for paving projects. Its direct influence on density, coupled with its indirect impact on compaction, underscores the importance of accurate characterization and understanding. Improperly specified or poorly controlled mix designs introduce uncertainty into tonnage calculations, potentially undermining project budgets and pavement performance. Therefore, meticulous attention to mix design is an essential prerequisite for accurate tonnage estimation and the successful execution of any asphalt paving endeavor.
8. Equipment Calibration
Equipment calibration directly affects the accuracy of asphalt tonnage determination. Asphalt plants utilize various metering systems to proportion aggregates, binder, and additives according to the mix design. Inaccuracies in these metering systems propagate through the entire process, resulting in deviations from the intended mix proportions. For example, if the aggregate feed belt scale is miscalibrated, it delivers an incorrect amount of aggregate per unit time. This directly alters the asphalt mix density, leading to a different volume-to-weight relationship than anticipated. Consequently, the calculated asphalt tonnage based on volume will deviate from the actual material needed, causing either a shortage or surplus at the project site. The effect is amplified over large projects, where cumulative errors can become substantial. Regular calibration of plant equipment, including scales, flow meters, and temperature sensors, is essential for maintaining mix consistency and accurate tonnage estimations.
Paving equipment, such as asphalt pavers and rollers, also requires calibration for optimal material application and compaction. Paver screeds, which control the thickness and grade of the asphalt layer, must be properly calibrated to ensure uniform material distribution. Miscalibration leads to inconsistent layer thicknesses, requiring more or less asphalt than initially estimated for certain areas. Similarly, roller calibration is crucial for achieving the desired compaction rate. Under-compacted areas require additional material to reach the specified density, while over-compacted areas may be unnecessarily dense, wasting asphalt. Properly calibrated paving equipment guarantees consistent application and compaction, minimizing variations in asphalt tonnage requirements across the project site. This aspect becomes particularly important for projects with stringent quality control specifications, where deviations from the design parameters can lead to penalties or rework.
In conclusion, equipment calibration is an indispensable element in precise asphalt tonnage calculations. Calibration errors at both the asphalt plant and paving site introduce systematic deviations in mix proportions, material distribution, and compaction rates, ultimately affecting the required asphalt weight. Consistent and rigorous calibration protocols, coupled with regular equipment maintenance, are essential for minimizing these errors and ensuring accurate material procurement, cost control, and structural integrity in asphalt paving projects. Neglecting calibration can lead to material waste, project delays, and compromised pavement performance, highlighting the practical significance of this often-overlooked aspect of asphalt construction.
Frequently Asked Questions
This section addresses common inquiries regarding the process of determining asphalt tonnage for paving projects. These answers provide clarity on key aspects and considerations for accurate material estimation.
Question 1: What are the primary variables influencing the volume calculation in asphalt tonnage estimation?
The dominant variables in the volume calculation are the surface area to be paved and the specified asphalt thickness. Accurate measurements of length and width, combined with precise thickness specifications, form the foundation for determining the total volume of asphalt required.
Question 2: Why is accurate material density so critical when determining asphalt tonnage?
Material density serves as the conversion factor between volume and weight. Precise knowledge of the asphalt mix density, typically expressed in pounds per cubic foot, allows for the translation of the calculated volume into the total weight, and consequently, the tonnage required for the project.
Question 3: How does the compaction rate impact asphalt tonnage needs?
The compaction rate reflects the reduction in volume that occurs during the paving process. A higher compaction rate necessitates a slightly greater initial volume of asphalt to achieve the desired final thickness, influencing the total asphalt tonnage ordered.
Question 4: What factors contribute to the “waste factor” and why is it essential?
The waste factor accounts for material losses during handling, application inefficiencies, and other unavoidable losses on-site. Accurate estimation of the waste factor ensures sufficient material availability, preventing project delays and cost overruns associated with insufficient asphalt supplies.
Question 5: How do extended haul distances affect asphalt tonnage estimations?
Longer haul distances increase the potential for material cooling and segregation, potentially leading to losses during transport. To compensate for these potential losses and maintain workable material, additional asphalt is typically required, increasing the overall tonnage.
Question 6: Why is equipment calibration important for accurate asphalt tonnage determination?
Properly calibrated equipment at the asphalt plant ensures the accurate proportioning of mix components, while calibrated paving equipment guarantees consistent material distribution and compaction. These factors minimize variations in the required asphalt thickness and density, ultimately ensuring the accuracy of the total tonnage estimation.
Achieving precision in asphalt tonnage estimation requires careful consideration of numerous factors, from accurate measurements to density assessments and the inclusion of realistic waste allowances. Diligence in these areas leads to efficient resource management and successful paving project execution.
The following section delves into the practical aspects of managing asphalt delivery and placement to further optimize paving operations.
Calculation for Asphalt Tonnage Tips
The following tips offer guidance to improve accuracy and efficiency in asphalt tonnage determination for paving projects. Implementing these strategies can mitigate risks associated with material shortages or overages, contributing to cost-effective project management.
Tip 1: Prioritize Precise Area Measurement: Emphasize the importance of employing accurate surveying techniques, potentially leveraging GPS or laser scanning technology, to determine the precise area requiring asphalt coverage. Small inaccuracies in area measurements translate directly into significant discrepancies in the final tonnage calculation, especially for large projects. For instance, utilizing satellite imagery combined with ground truthing can provide a detailed topographic map, ensuring accurate surface area data.
Tip 2: Conduct Thorough Subgrade Evaluation: Recognize that subgrade conditions influence the required asphalt thickness. A comprehensive geotechnical investigation should be conducted to determine the bearing capacity of the subgrade soil. Weak or unstable subgrades necessitate thicker asphalt layers to provide adequate structural support, directly impacting the overall tonnage calculation. Soil testing and analysis results must be integrated into the pavement design process.
Tip 3: Obtain Accurate Material Density Data: Do not rely on generic density values. Obtain the specific density for the intended asphalt mix design from the asphalt plant. Mix designs with different aggregate gradations and binder types exhibit varying densities. Precise density data ensures accurate conversion from volume to weight, a critical step in tonnage determination. Review and confirm the material density specification prior to commencing paving operations.
Tip 4: Account for Compaction Rate Variation: Acknowledge that field compaction rates may differ from laboratory compaction tests. Incorporate a realistic compaction factor based on project-specific conditions and equipment capabilities. Overestimating compaction leads to material shortages, while underestimating results in over-ordering. Monitor compaction in real-time using density gauges to ensure that the design compaction rate is achieved.
Tip 5: Factor in Site-Specific Waste: Accurately estimate waste based on project complexity and site conditions. Complex intersections or irregularly shaped paving areas typically generate more waste than simple rectangular surfaces. Account for material losses during handling, spillage, and equipment cleanup. Historical data from similar projects can provide valuable insights into expected waste percentages.
Tip 6: Optimize Haul Logistics to Minimize Loss: Minimize haul distances whenever feasible to reduce cooling and segregation during transport. Coordinate delivery schedules to avoid prolonged wait times at the paving site. Consider using insulated truck beds, particularly during colder weather, to maintain asphalt temperature and reduce material losses due to hardening.
Tip 7: Calibrate Equipment Regularly and Verify Calibration: Implement a routine calibration schedule for all equipment involved in asphalt production and placement. This includes scales, flow meters, pavers, and rollers. Verifying calibration accuracy before each project ensures proper material proportioning, uniform distribution, and effective compaction, minimizing deviations from the calculated tonnage requirements. Keep meticulous records of all calibration activities.
Implementing these tips can significantly enhance the accuracy and reliability of asphalt tonnage calculations. Precise estimation minimizes material waste, reduces project costs, and ensures that the paved surface meets the required structural standards.
The following section summarizes the key concepts and benefits of accurate asphalt tonnage determination.
Conclusion
This discussion has underscored the multifaceted nature of precise “calculation for asphalt tonnage” in paving projects. It has illustrated that determining the correct amount of material requires a thorough understanding of various interconnected factors. These include meticulous area measurements, accurate assessment of material density, consideration of compaction rates, anticipation of material waste, and evaluation of logistical considerations such as haul distances. The analysis also highlighted the critical role of properly calibrated equipment and the impact of asphalt mix design on overall tonnage needs.
Adherence to these principles is not merely an exercise in mathematical precision but a fundamental aspect of responsible project management. Accurate asphalt amount estimations contribute directly to cost containment, efficient resource allocation, and the long-term structural integrity of paved surfaces. Therefore, investment in accurate determination of the appropriate amount of asphalt remains a crucial element for all involved in the paving industry.
