This document discusses key terms and concepts related to volumetric properties of hot mix asphalt (HMA). It defines terms like bulk specific gravity, maximum specific gravity, air voids, effective specific gravity of aggregate, voids in mineral aggregate and voids filled with asphalt. It also describes testing procedures to determine values like bulk specific gravity and maximum specific gravity. Formulas are provided to calculate volumetric properties from test values including air voids, voids in mineral aggregate and voids filled with asphalt.
8-HMA Volumetrics ( Highway Engineering Dr. Sherif El-Badawy )Hossam Shafiq I
This document discusses hot mix asphalt (HMA) volumetric properties and terms. It provides definitions and calculations for key volumetric properties such as air voids (Va), voids in mineral aggregate (VMA), voids filled with asphalt (VFA), bulk specific gravity (Gmb), theoretical maximum specific gravity (Gmm), and effective specific gravity of aggregate (Gse). An example calculation is worked through step-by-step to demonstrate how to determine these volumetric properties from mix design data. Key terms involved in HMA volumetric properties and their calculations are also summarized.
Design mix method of bitumenous materials by Marshall stability methodAmardeep Singh
4.25
4.5
4.75
5
5.25
5.5
Bitumen %
1) The Marshall stability test is used to determine the optimum asphalt content for a given mix design by evaluating stability, flow, density, voids, and voids filled with asphalt at different asphalt contents.
2) Specimens are compacted in molds and tested at 60°C after being submerged in a water bath for 30-40 minutes.
3) Graphs of stability, density, and voids vs. asphalt content are used to identify the optimum asphalt content, which
The Marshall stability and flow test provides the performance prediction measure for the Marshall mix design method. The stability portion of the test measures the maximum load supported by the test specimen at a loading rate of 50.8 mm/minute. Load is applied to the specimen till failure, and the maximum load is designated as stability. During the loading, an attached dial gauge measures the specimen's plastic flow (deformation) due to the loading. The flow value is recorded in 0.25 mm (0.01 inch) increments at the same time when the maximum load is recorded.
The document discusses the Marshall method for designing asphalt concrete mixes. It describes creating trial mixes with varying asphalt contents and testing them for properties like stability, flow, density and voids. The optimum asphalt content is selected based on maximum stability, density and a specified air voids level. Test results and mix proportions are evaluated against specifications to adjust the mix design if needed.
- There are four main methods to measure the load carrying capacity of piles: static methods, dynamic formulas, in-situ penetration tests, and pile load tests.
- The ultimate load capacity (Qu) of an individual pile or pile group equals the sum of the point resistance (Qp) at the pile tip and the shaft resistance (Qs) developed along the pile shaft through friction between the soil and pile.
- Meyerhof's method is commonly used to calculate Qp in sand based on the effective vertical pressure at the pile tip multiplied by the bearing capacity factor Nq.
Sieve Analysis of Fine & Coarse Aggregate | Jameel AcademyJameel Academy
This report summarizes the results of a sieve analysis test performed on samples of fine and coarse aggregates. Sieve analysis was used to determine the particle size distribution of each aggregate by separating particles via sieves with decreasing size openings. For the fine aggregate, the average size was found to be 0.6mm. For the coarse aggregate, the maximum size was found to be 13.2mm. While the calculations and procedures appeared to be performed correctly, the results did not fully meet specification limits, indicating the aggregates may not be suitable for the intended construction purpose without further processing or testing.
This document outlines a lecture on pavement design. It discusses the purpose and types of pavements, including flexible and rigid pavements. It also covers pavement condition evaluation methods. The document presents the AASHTO empirical design method and introduces the new mechanistic-empirical method. It provides an example design problem calculating traffic loads over 40 years and designing both a flexible and rigid pavement to meet those loads using WSDOT and AASHTO methods. Key terms in pavement design and references are also outlined.
1) The document describes the process for Marshall stability test and mix design for bituminous concrete. Key steps include selecting aggregates based on strength and gradation, determining aggregate proportions, preparing specimens, and testing stability and flow.
2) Aggregate proportions are determined using an analytical method solving equations for the required gradation. Specimens are compacted and tested for stability (maximum load) and flow (deformation) at varying bitumen contents to determine the optimum mix.
3) Stability and flow values are measured using a Marshall test machine and calculations are done to determine density, voids, and other properties of the mix. The process is repeated to get the optimum bitumen content for the mix design.
8-HMA Volumetrics ( Highway Engineering Dr. Sherif El-Badawy )Hossam Shafiq I
This document discusses hot mix asphalt (HMA) volumetric properties and terms. It provides definitions and calculations for key volumetric properties such as air voids (Va), voids in mineral aggregate (VMA), voids filled with asphalt (VFA), bulk specific gravity (Gmb), theoretical maximum specific gravity (Gmm), and effective specific gravity of aggregate (Gse). An example calculation is worked through step-by-step to demonstrate how to determine these volumetric properties from mix design data. Key terms involved in HMA volumetric properties and their calculations are also summarized.
Design mix method of bitumenous materials by Marshall stability methodAmardeep Singh
4.25
4.5
4.75
5
5.25
5.5
Bitumen %
1) The Marshall stability test is used to determine the optimum asphalt content for a given mix design by evaluating stability, flow, density, voids, and voids filled with asphalt at different asphalt contents.
2) Specimens are compacted in molds and tested at 60°C after being submerged in a water bath for 30-40 minutes.
3) Graphs of stability, density, and voids vs. asphalt content are used to identify the optimum asphalt content, which
The Marshall stability and flow test provides the performance prediction measure for the Marshall mix design method. The stability portion of the test measures the maximum load supported by the test specimen at a loading rate of 50.8 mm/minute. Load is applied to the specimen till failure, and the maximum load is designated as stability. During the loading, an attached dial gauge measures the specimen's plastic flow (deformation) due to the loading. The flow value is recorded in 0.25 mm (0.01 inch) increments at the same time when the maximum load is recorded.
The document discusses the Marshall method for designing asphalt concrete mixes. It describes creating trial mixes with varying asphalt contents and testing them for properties like stability, flow, density and voids. The optimum asphalt content is selected based on maximum stability, density and a specified air voids level. Test results and mix proportions are evaluated against specifications to adjust the mix design if needed.
- There are four main methods to measure the load carrying capacity of piles: static methods, dynamic formulas, in-situ penetration tests, and pile load tests.
- The ultimate load capacity (Qu) of an individual pile or pile group equals the sum of the point resistance (Qp) at the pile tip and the shaft resistance (Qs) developed along the pile shaft through friction between the soil and pile.
- Meyerhof's method is commonly used to calculate Qp in sand based on the effective vertical pressure at the pile tip multiplied by the bearing capacity factor Nq.
Sieve Analysis of Fine & Coarse Aggregate | Jameel AcademyJameel Academy
This report summarizes the results of a sieve analysis test performed on samples of fine and coarse aggregates. Sieve analysis was used to determine the particle size distribution of each aggregate by separating particles via sieves with decreasing size openings. For the fine aggregate, the average size was found to be 0.6mm. For the coarse aggregate, the maximum size was found to be 13.2mm. While the calculations and procedures appeared to be performed correctly, the results did not fully meet specification limits, indicating the aggregates may not be suitable for the intended construction purpose without further processing or testing.
This document outlines a lecture on pavement design. It discusses the purpose and types of pavements, including flexible and rigid pavements. It also covers pavement condition evaluation methods. The document presents the AASHTO empirical design method and introduces the new mechanistic-empirical method. It provides an example design problem calculating traffic loads over 40 years and designing both a flexible and rigid pavement to meet those loads using WSDOT and AASHTO methods. Key terms in pavement design and references are also outlined.
1) The document describes the process for Marshall stability test and mix design for bituminous concrete. Key steps include selecting aggregates based on strength and gradation, determining aggregate proportions, preparing specimens, and testing stability and flow.
2) Aggregate proportions are determined using an analytical method solving equations for the required gradation. Specimens are compacted and tested for stability (maximum load) and flow (deformation) at varying bitumen contents to determine the optimum mix.
3) Stability and flow values are measured using a Marshall test machine and calculations are done to determine density, voids, and other properties of the mix. The process is repeated to get the optimum bitumen content for the mix design.
Introduction to superpave & Performance Grading(P.G)hisham123852
This document provides an overview of the Superpave system for designing asphalt pavements. It describes Superpave as including a new mixture design and analysis system based on pavement performance. The key aspects covered include: Superpave performance grading for asphalt binders based on climatic conditions; tests used for mixture design and performance prediction; simulation of field conditions through laboratory aging and testing at relevant temperatures; and specification of binder grades based on high and low pavement temperatures.
The document summarizes the results of a Marshall test conducted to determine the optimum asphalt content for an asphalt mix. The test involved two stages: specimen preparation and specimen testing. In specimen preparation, aggregates were graded, dried, and mixed with asphalt. Specimens were molded and prepared for testing. In specimen testing, specimens were tested for properties like stability, flow, density, air voids and voids filled with asphalt at different asphalt contents. Charts were created to analyze the test results. The optimum asphalt content was determined to be 4.8% based on the asphalt content corresponding to maximum stability and density and median air voids.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Analytical Method for Asphalt Concrete Mix DesignPENKI RAMU
This document presents an analytical method for asphalt concrete mix design using granite powder as filler. It discusses selecting aggregates, developing aggregate gradation models, determining proportions using Excel Solver, estimating gradation areas with Trapezoidal rule, and evaluating mixtures using Marshall stability tests. Test results show granite powder produces comparable properties to stone dust filler and influences aging by increasing stiffness. The method allows quick, accurate mix design optimization.
05-Superpave Binder Specification ( Highway and Airport Engineering Dr. Sheri...Hossam Shafiq I
The document summarizes the Superpave asphalt binder specifications system. It describes that the system uses performance grade specifications based on climate, with grades ranging from PG 46 to PG 82. It outlines the key tests performed on original, rolled thin film oven-aged, and pressure-aged vessel aged asphalt binder samples to specify requirements to prevent different distresses like permanent deformation, fatigue cracking, and low temperature cracking. Requirements include metrics like dynamic shear rheometer stiffness values, bending beam rheometer stiffness and m-values, and rotational viscosity.
Okay, here are the steps to solve this:
1) Given:
Specific gravity (Gs) = 2.65
Void ratio (e) = 0.5
2) Critical hydraulic gradient (icr) is given by the equation:
icr = Gs - 1/(1+e)
3) Substitute the values:
icr = 2.65 - 1/(1+0.5)
= 2.65 - 1/1.5
= 2.65 - 0.667
= 1.983
So the critical hydraulic gradient for this sand deposit is 1.983.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
1. The document discusses different types of settlement in shallow foundations, including immediate/elastic settlement, primary consolidation settlement, and secondary consolidation settlement.
2. It provides methods for calculating each type of settlement, making use of theories of elasticity, consolidation test data, and parameters like compression index.
3. Settlement predictions are generally satisfactory but better for inorganic clays; the time rate of consolidation settlement is often poorly estimated.
Principles and design concepts of reinforced soil wallsPrakash Ravindran
Reinforced soil walls are cost-effective retaining structures that can tolerate large settlements. They consist of layers of soil reinforced with tensile inclusions like geogrids or geotextiles. The reinforcement improves the soil strength allowing near-vertical faces to be constructed. Key advantages include flexibility, rapid construction, and ability to absorb movements. The document discusses design principles like external stability checks against sliding and bearing capacity failure. Internal stability checks reinforcement rupture and pullout capacity. Settlements, seismic design, and typical failures are also covered.
This document discusses lateral earth pressure and provides details on Rankine's theory and graphical methods for determining active and passive earth pressures. It explains that lateral earth pressure is exerted by soil on retaining structures and depends on whether the structure is stationary or moving towards/away from the soil mass. Rankine's theory assumes dry, homogeneous soil and a vertical wall. Rebhann and Culmann's graphical methods can be used to locate the failure plane and determine the magnitude and direction of lateral earth pressures based on the soil's friction angle and the structure's orientation.
This ppt is about the cold mix asphalt. Some of its advantages and disadvantages over hot mix asphalt. Also some discussion about the test conducted on the cold mix asphalt and the result of it. And also discuss about the conclusion of above.
Pavement materials in Road Constructionsrinivas2036
Different pavement materials used in the road construction. Importance of soil, aggregate pavement materials. Tests on Soil for pavement construction. Tests on aggregate for pavement construction.
Requirements of soil and aggregates in pavement.
Asphalt mixtures are made up of aggregates, binder and air voids. In order to make a economic and satisfactory performing asphalt mixture the quantity of these individual constituent is required. Mixture design is a tool to determine these optimum quantities.
This document contains the results of a soil mechanics laboratory experiment on consolidation and permeability tests. It includes an introduction to consolidation and the principles behind the consolidation test. The document outlines the experimental procedures, summarizes the results in tables and calculations, and draws conclusions. Specifically, it was found that the soil sample had low permeability based on the small coefficient of permeability value calculated. The total settlement of the sample under loading was also small, likely due to proper compaction removing air from the soil.
The document describes the Marshall method of determining the optimum binder content for a bituminous mix design. Aggregates and binder are heated and mixed to different binder contents. Specimens are compacted with blows from a hammer and tested for properties like flow value, stability, and density. Graphs are made plotting these properties against the varying binder contents. The optimum binder content is determined as the percentage where the graphs show highest stability and density and lowest flow value.
Marsh cone test is reliable and simple method to study the rheological properties of cements and mortars.
Flow time of cement/mortar through marsh cone is indicator of viscosity, which depends upon cement super plasticizer compatibility.
This document provides information on the conventional asphalt mix design process. It discusses the key steps, which include selecting aggregates based on specified properties, determining the aggregate gradation, proportioning aggregates to meet the gradation, selecting a suitable bitumen, preparing specimens, conducting density-void analysis and measuring stability and flow to determine the optimum bitumen content. Specimens are compacted using a Marshall compactor and tested for properties like stability, flow and density at different bitumen contents to establish the job mix formula.
Class 7 Consolidation Test ( Geotechnical Engineering )Hossam Shafiq I
This document provides an overview of a geotechnical engineering laboratory class on conducting a consolidation test on cohesive soil. The consolidation test is used to determine key soil properties like preconsolidation stress, compression index, recompression index, and coefficient of consolidation. The procedure involves placing a saturated soil sample in a consolidometer, applying incremental loads, and measuring the change in height over time to generate consolidation curves. Students will perform the test, calculate soil properties from the results, and include 10 plots and calculations in a laboratory report.
The document discusses effective stress in soils. It defines total stress, pore water pressure, and effective stress. Total stress is the load carried by the soil grains and water. Pore water pressure depends on depth and water flow conditions. Effective stress is the difference between total stress and pore water pressure, and represents the stress carried by the soil skeleton. Effective stress applies to saturated soils and influences properties like compressibility and consolidation. It is an imaginary parameter that cannot be directly measured but is important in soil mechanics analyses.
The document provides 8 examples of calculating total stress, effective stress, and pore water pressure at different depths for various soil profiles. The examples solve for the stresses and pressures at specific points or depths by considering the layer thicknesses, soil unit weights, depth of water table, and degree of saturation. The effective stress is calculated by subtracting the pore water pressure from the total stress at each point.
This document discusses aggregate specific gravities, which are important for volumetric mix design. It defines specific gravity as the ratio of the mass of an object to the mass of an equal volume of water. There are different specific gravities measured depending on the aggregate's dry, saturated surface dry, or apparent state. Tests are described for determining the specific gravities of coarse and fine aggregates according to ASTM standards, which involve measuring the mass of the aggregate both dry and submerged in water. The specific gravities are used to calculate properties like bulk density and water absorption capacity.
Presentation by Bob Humer of the Asphalt Institute on "Recommendations for Mix Design Using RAP/RAS" for the CalAPA Spring Asphalt Pavement Conference & Equipment Expo, April 20-21, 2016, in Ontario, CA.
Introduction to superpave & Performance Grading(P.G)hisham123852
This document provides an overview of the Superpave system for designing asphalt pavements. It describes Superpave as including a new mixture design and analysis system based on pavement performance. The key aspects covered include: Superpave performance grading for asphalt binders based on climatic conditions; tests used for mixture design and performance prediction; simulation of field conditions through laboratory aging and testing at relevant temperatures; and specification of binder grades based on high and low pavement temperatures.
The document summarizes the results of a Marshall test conducted to determine the optimum asphalt content for an asphalt mix. The test involved two stages: specimen preparation and specimen testing. In specimen preparation, aggregates were graded, dried, and mixed with asphalt. Specimens were molded and prepared for testing. In specimen testing, specimens were tested for properties like stability, flow, density, air voids and voids filled with asphalt at different asphalt contents. Charts were created to analyze the test results. The optimum asphalt content was determined to be 4.8% based on the asphalt content corresponding to maximum stability and density and median air voids.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
Analytical Method for Asphalt Concrete Mix DesignPENKI RAMU
This document presents an analytical method for asphalt concrete mix design using granite powder as filler. It discusses selecting aggregates, developing aggregate gradation models, determining proportions using Excel Solver, estimating gradation areas with Trapezoidal rule, and evaluating mixtures using Marshall stability tests. Test results show granite powder produces comparable properties to stone dust filler and influences aging by increasing stiffness. The method allows quick, accurate mix design optimization.
05-Superpave Binder Specification ( Highway and Airport Engineering Dr. Sheri...Hossam Shafiq I
The document summarizes the Superpave asphalt binder specifications system. It describes that the system uses performance grade specifications based on climate, with grades ranging from PG 46 to PG 82. It outlines the key tests performed on original, rolled thin film oven-aged, and pressure-aged vessel aged asphalt binder samples to specify requirements to prevent different distresses like permanent deformation, fatigue cracking, and low temperature cracking. Requirements include metrics like dynamic shear rheometer stiffness values, bending beam rheometer stiffness and m-values, and rotational viscosity.
Okay, here are the steps to solve this:
1) Given:
Specific gravity (Gs) = 2.65
Void ratio (e) = 0.5
2) Critical hydraulic gradient (icr) is given by the equation:
icr = Gs - 1/(1+e)
3) Substitute the values:
icr = 2.65 - 1/(1+0.5)
= 2.65 - 1/1.5
= 2.65 - 0.667
= 1.983
So the critical hydraulic gradient for this sand deposit is 1.983.
Class notes of Geotechnical Engineering course I used to teach at UET Lahore. Feel free to download the slide show.
Anyone looking to modify these files and use them for their own teaching purposes can contact me directly to get hold of editable version.
1. The document discusses different types of settlement in shallow foundations, including immediate/elastic settlement, primary consolidation settlement, and secondary consolidation settlement.
2. It provides methods for calculating each type of settlement, making use of theories of elasticity, consolidation test data, and parameters like compression index.
3. Settlement predictions are generally satisfactory but better for inorganic clays; the time rate of consolidation settlement is often poorly estimated.
Principles and design concepts of reinforced soil wallsPrakash Ravindran
Reinforced soil walls are cost-effective retaining structures that can tolerate large settlements. They consist of layers of soil reinforced with tensile inclusions like geogrids or geotextiles. The reinforcement improves the soil strength allowing near-vertical faces to be constructed. Key advantages include flexibility, rapid construction, and ability to absorb movements. The document discusses design principles like external stability checks against sliding and bearing capacity failure. Internal stability checks reinforcement rupture and pullout capacity. Settlements, seismic design, and typical failures are also covered.
This document discusses lateral earth pressure and provides details on Rankine's theory and graphical methods for determining active and passive earth pressures. It explains that lateral earth pressure is exerted by soil on retaining structures and depends on whether the structure is stationary or moving towards/away from the soil mass. Rankine's theory assumes dry, homogeneous soil and a vertical wall. Rebhann and Culmann's graphical methods can be used to locate the failure plane and determine the magnitude and direction of lateral earth pressures based on the soil's friction angle and the structure's orientation.
This ppt is about the cold mix asphalt. Some of its advantages and disadvantages over hot mix asphalt. Also some discussion about the test conducted on the cold mix asphalt and the result of it. And also discuss about the conclusion of above.
Pavement materials in Road Constructionsrinivas2036
Different pavement materials used in the road construction. Importance of soil, aggregate pavement materials. Tests on Soil for pavement construction. Tests on aggregate for pavement construction.
Requirements of soil and aggregates in pavement.
Asphalt mixtures are made up of aggregates, binder and air voids. In order to make a economic and satisfactory performing asphalt mixture the quantity of these individual constituent is required. Mixture design is a tool to determine these optimum quantities.
This document contains the results of a soil mechanics laboratory experiment on consolidation and permeability tests. It includes an introduction to consolidation and the principles behind the consolidation test. The document outlines the experimental procedures, summarizes the results in tables and calculations, and draws conclusions. Specifically, it was found that the soil sample had low permeability based on the small coefficient of permeability value calculated. The total settlement of the sample under loading was also small, likely due to proper compaction removing air from the soil.
The document describes the Marshall method of determining the optimum binder content for a bituminous mix design. Aggregates and binder are heated and mixed to different binder contents. Specimens are compacted with blows from a hammer and tested for properties like flow value, stability, and density. Graphs are made plotting these properties against the varying binder contents. The optimum binder content is determined as the percentage where the graphs show highest stability and density and lowest flow value.
Marsh cone test is reliable and simple method to study the rheological properties of cements and mortars.
Flow time of cement/mortar through marsh cone is indicator of viscosity, which depends upon cement super plasticizer compatibility.
This document provides information on the conventional asphalt mix design process. It discusses the key steps, which include selecting aggregates based on specified properties, determining the aggregate gradation, proportioning aggregates to meet the gradation, selecting a suitable bitumen, preparing specimens, conducting density-void analysis and measuring stability and flow to determine the optimum bitumen content. Specimens are compacted using a Marshall compactor and tested for properties like stability, flow and density at different bitumen contents to establish the job mix formula.
Class 7 Consolidation Test ( Geotechnical Engineering )Hossam Shafiq I
This document provides an overview of a geotechnical engineering laboratory class on conducting a consolidation test on cohesive soil. The consolidation test is used to determine key soil properties like preconsolidation stress, compression index, recompression index, and coefficient of consolidation. The procedure involves placing a saturated soil sample in a consolidometer, applying incremental loads, and measuring the change in height over time to generate consolidation curves. Students will perform the test, calculate soil properties from the results, and include 10 plots and calculations in a laboratory report.
The document discusses effective stress in soils. It defines total stress, pore water pressure, and effective stress. Total stress is the load carried by the soil grains and water. Pore water pressure depends on depth and water flow conditions. Effective stress is the difference between total stress and pore water pressure, and represents the stress carried by the soil skeleton. Effective stress applies to saturated soils and influences properties like compressibility and consolidation. It is an imaginary parameter that cannot be directly measured but is important in soil mechanics analyses.
The document provides 8 examples of calculating total stress, effective stress, and pore water pressure at different depths for various soil profiles. The examples solve for the stresses and pressures at specific points or depths by considering the layer thicknesses, soil unit weights, depth of water table, and degree of saturation. The effective stress is calculated by subtracting the pore water pressure from the total stress at each point.
This document discusses aggregate specific gravities, which are important for volumetric mix design. It defines specific gravity as the ratio of the mass of an object to the mass of an equal volume of water. There are different specific gravities measured depending on the aggregate's dry, saturated surface dry, or apparent state. Tests are described for determining the specific gravities of coarse and fine aggregates according to ASTM standards, which involve measuring the mass of the aggregate both dry and submerged in water. The specific gravities are used to calculate properties like bulk density and water absorption capacity.
Presentation by Bob Humer of the Asphalt Institute on "Recommendations for Mix Design Using RAP/RAS" for the CalAPA Spring Asphalt Pavement Conference & Equipment Expo, April 20-21, 2016, in Ontario, CA.
Group 3 conducted a soil lab with 5 members. The experiments included determining water content by oven dried method, sieve analysis, modified proctor test, and specific gravity of soil solids. To determine specific gravity, a pycnometer was filled with dry soil and water, vacuumed to remove air, and weighed. The specific gravity was calculated using a formula that divides the weight of soil by the difference in weight between the pycnometer filled with soil and water, and the pycnometer filled just with water. Specific gravity is an important property used to determine void ratio, porosity, and degree of saturation. The results can help determine the type of soil as sand, silt or clay based on the specific gravity range
This document provides information on calculating the dry weight of aggregates versus total weight of asphalt mixes, determining the amount of binder replacement from reclaimed asphalt pavement (RAP), and examples of calculating binder replacement. It establishes a maximum binder replacement of 25% for surface courses and 40% for lower courses when using RAP. Tables are included that relate the dry weight of aggregates to total mix weight and examples are shown for calculating binder replacement based on the binder content in the RAP and total mix. References for further information are also listed.
6-7 Binder ( Highway Engineering Dr. Sherif El-Badawy )Hossam Shafiq I
This document discusses different types and properties of asphalt materials used in pavement construction. It describes how asphalt binder is produced from crude oil and its main components. Different asphalt types are outlined, including asphalt cement, emulsions, and cutbacks. The properties, classification systems, and test methods for asphalt binders are summarized, including specifications based on penetration, viscosity, and the Superpave performance grading system.
This document outlines the aggregate property requirements for Superpave hot mix asphalt, including criteria for coarse aggregate angularity, flat and elongated particles, fine aggregate angularity, clay content, and aggregate gradation band limits. It provides tables specifying minimum property requirements based on expected traffic levels. Sample gradation band charts are given for various nominal maximum aggregate sizes used in Superpave mixes.
03-Properties of Asphalt Traditional ( Highway and Airport Engineering Dr. Sh...Hossam Shafiq I
This document discusses the properties and temperature susceptibility of asphalt binders. It describes how binder performance is affected by temperature and loading rate. The stiffness and viscosity of asphalt changes drastically with temperature, going from solid to fluid. The document outlines various test methods and specifications used to characterize and grade asphalt binders, including penetration grades, viscosity grades, and grades based on viscosity after aging. It compares the advantages and disadvantages of different grading systems and specifications.
06-Traffic Characterization ( Highway and Airport Engineering Dr. Sherif El-B...Hossam Shafiq I
This document discusses traffic characterization and loadings for pavement design. It covers topics like vehicle characteristics, axle configurations, traffic composition, sources of traffic data, load equivalency factors, truck factors, and how to calculate estimated 18-kip equivalent single-axle loads (ESALs) using traffic data. The goal is to account for the full spectrum of traffic loads that pavement will experience over its design life when determining appropriate pavement thickness.
Presentation by Dr. Adam Hand, University of Nevada, Reno, on the latest research and performance data on the use of RAP, RAS and other Durable Asphalt Pavement Mixes. Presentation delivered during the CalAPA Fall Asphalt Pavement Conference Oct. 26-27, 2016 in Sacramento, Calif.
01-Introduction ( Highway and Airport Engineering Dr. Sherif El-Badawy )Hossam Shafiq I
This document outlines the course objectives, content, and materials for a course on Highway and Airport Engineering and Planning. The course covers topics like Superpave binder characterization and mix design, aggregate requirements, airport planning and design, runway and taxiway design. It aims to provide the ability to classify and select binders, design hot mix asphalts, and perform airport planning and design. The course materials include textbooks on pavement materials and airport planning/design, links to additional resources, and a schedule of topics over 15 weeks.
This document discusses the fundamentals of rheology and describes various types of rheometers used to measure the rheological properties of asphalt binders. It explains that rheology is the study of flow and deformation and introduces constitutive relationships between force and deformation. It then describes different types of rheometers, including shear rheometers that apply drag or pressure-driven flows, and other rheometers that measure stiffness and strength through bending beam or direct tension tests. Specific examples of equipment are also shown, such as concentric cylinder and parallel plate shear rheometers, a bending beam rheometer, and a direct tension testing device.
An orientation on changes to Caltrans asphalt pavement specifications to incorporate elements of the national "Superpave" standard. Presented by Joe Peterson, chief, Office of Roadway Materials Testing for Caltrans at the Dec. 3, 2014 CalAPA L.A. and High Desert Technical Committee meeting in Fontana.
The document discusses the history and methods of hot mix asphalt (HMA) mix designs. It describes the Marshall and Hveem mix design methods, which were developed in the 1930s-1940s to determine the optimal blend of aggregates and asphalt binders. The Marshall method uses compacted cylindrical specimens subjected to impact compaction and stability testing, while the Hveem method employs kneading compaction and a stabilometer to evaluate shear strength. Both aim to achieve sufficient stability, air voids, and workability within the mix. The Superpave gyratory compactor method was later introduced as a improved alternative.
09-Runway Configuration ( Highway and Airport Engineering Dr. Sherif El-Badawy )Hossam Shafiq I
The document discusses various runway configurations including single, parallel, staggered parallel, intersecting, and open-V runways. It also describes different types of taxiways like entrance, exit, parallel, bypass, and connecting taxiways that make up the ground movement network at an airport. Flight rules depend on weather conditions, with visual flight rules applied during good visibility and instrument flight rules in low visibility conditions.
Tetanus, also known as lockjaw, is caused by Clostridium tetani bacteria and the neurotoxin it produces. It occurs worldwide but is more common in developing countries. The toxin causes painful muscle spasms and contractions. Symptoms range from lockjaw to painful arching of the back. Treatment involves wound cleaning, muscle relaxants, tetanus immunoglobulin, antibiotics and careful nursing. Prevention relies on active immunization with tetanus toxoid vaccines throughout life.
This document discusses time-dependent behavior in rocks that occurs over a wide range of strain rates in rock mechanics and engineering applications. It introduces the topic, explaining there are 15 orders of magnitude between high strain rates like explosions and low strain rates like gradual deformation over decades. The document then covers dynamic rock properties, stress waves, time-dependent concepts like creep and relaxation, and rheological models. It discusses the relevance for rock engineering, including concerns over extrapolating short-term test data to designs that must last 1,000 years.
Lecture 06 Signalized Intersections (Traffic Engineering هندسة المرور & Dr. U...Hossam Shafiq I
This document discusses types of traffic signals and signal timing procedures. It describes pre-timed and actuated signals, and defines key terms like cycle length, phase, split, effective green time, and lost time. It provides a step-by-step procedure for developing signal timing plans, including determining critical lane volumes, yellow and red intervals, cycle length, effective green allocation to phases, and checking pedestrian requirements. An example application of the timing procedure to an intersection of major arterials is presented over multiple slides.
Lec 09 Pavement Design (Transportation Engineering) Hossam Shafiq I
This document provides an overview of pavement engineering, including definitions of flexible and rigid pavements, pavement materials like asphalt and concrete, and design considerations. Pavements are designed based on serviceability to provide a comfortable ride. Flexible pavements use layers of asphalt and granular materials over a subgrade, while rigid pavements use a concrete surface over a granular base. Aggregates are an important material and their properties like gradation and durability influence mix design. Pavements are monitored for distresses and maintenance needs.
- A gravity dam is an engineering structure that resists forces through its own weight. Forces that must be considered in dam design include the weight of the dam, water pressure, uplift, wave pressure, and earthquake forces.
- To calculate these forces, parameters like the material density, water depth, dam dimensions, and earthquake coefficients are used in specific equations. An example calculation is provided to demonstrate how to determine the expected forces on a given dam structure.
It,s all about Index properties of Rocks.
It can help those students who want to give presentation about this topic.
Also it can give you information about Pocks and very helpful in Geo mechanics.
The document discusses Superpave asphalt binder specifications. It provides sources of information on Superpave specifications and describes how the performance grade specification system works based on climate. The performance grade takes into account the average 7-day maximum pavement temperature and the 1-day minimum pavement temperature. It then outlines how the Superpave specification addresses key distresses like permanent deformation, fatigue cracking, and low temperature cracking through test requirements on properties like stiffness and viscosity.
The document discusses the Superpave performance graded specification for asphalt binders. The specification grades asphalt binders based on the climate and expected pavement temperatures. A variety of tests are used to evaluate the binder properties related to different distresses at different temperatures. The rotational viscosity test evaluates workability at construction temperatures. The dynamic shear rheometer test evaluates rutting resistance at high in-service temperatures after both short-term aging from mixing and long-term aging. The bending beam rheometer and direct tension tests evaluate stiffness and strength respectively at low in-service temperatures. Conditioning such as short-term aging with the rolling thin film oven test and long-term aging with the pressure aging vessel better simulate
The document discusses the history and evolution of asphalt binder specifications. Early specifications focused on consistency and graded binders based on penetration testing. Later, specifications incorporated viscosity grading which characterizes binders across a range of temperatures relevant to mixing and compaction. Current performance-based specifications further consider aging characteristics by testing rolled thin film oven aged residues. Viscosity grading provides more information on asphalt properties and performance compared to penetration grading. Specifications have evolved with technological advances to better ensure desirable asphalt characteristics for pavement performance.
The document discusses different types and uses of asphalt binders. It describes how asphalt binder is produced from petroleum crude oil through refining processes like solvent deasphalting and residuum oil supercritical extraction. These processes break down the crude oil into components that are blended to produce asphalt binders of desired properties. The asphalt binders are then used to manufacture hot mix asphalt for paving roads through batch and continuous mix drum plants. Other asphalt products discussed include cutback asphalts and emulsions, along with their compositions and uses.
This document discusses modified asphalt binders, which are used to improve the performance of asphalt pavements. Modifiers such as polymers and fillers are added to asphalt binders to increase rutting resistance at warm temperatures and inhibit cracking from traffic and environmental stresses. The document describes different types of modifiers and provides examples of polymeric modifiers. It also discusses traditional testing methods for modified binders and uses microscopy images to illustrate how polymers interact within asphalt binders.
This document discusses techniques for rehabilitating and maintaining asphalt overlays on concrete pavements, including crack and seat, break and seat, rubblization, and saw and seal. Crack and seat and break and seat involve fracturing concrete slabs to shorten their length and allow for interlocking of pieces. Rubblization involves fracturing concrete into pieces smaller than 9 inches to prevent reflection cracking in overlays. Saw and sealing joints is used to control the rate of deterioration of reflection cracks.
The document discusses various aspects of asphalt pavement rehabilitation and maintenance using hot mix asphalt overlays. It covers topics such as bituminous patching, surface leveling, cold milling, crack sealing, subsurface drainage, reflection cracking control methods, recycling existing pavement, pavement widening, shoulder rehabilitation, and design of overlays along projects. The key steps for an effective overlay project involve examining preoverlay repairs, subsurface drainage improvements, and methods for controlling reflection cracking from the existing pavement.
This document discusses hot mix asphalt (HMA) overlays for rehabilitating flexible and rigid pavements. It defines functional and structural overlays, and describes how they are used to address surface defects versus structural defects. The rehabilitation process and factors considered for overlay design like pre-overlay repair, materials selection, and traffic loads are also summarized. Thick and thin overlays as well as reconstruction are presented as options to correct deficiencies.
This document discusses moisture sensitivity in HMA (hot mix asphalt). It describes several reasons for moisture damage including loss of cohesion in the asphalt binder, loss of adhesion between the binder and aggregate, and degradation of the aggregate. It also discusses factors that influence moisture sensitivity related to the aggregate properties, asphalt binder properties, HMA mix properties, and weather conditions during construction. Methods for adding antistripping additives like liquid antistrips or lime are presented, as well as several tests for evaluating moisture sensitivity like the boiling water test or freeze-thaw pedestal test.
This document discusses thermal cracking in asphalt pavements. Thermal cracking occurs when temperature decreases cause the pavement to contract and develop tensile stresses that can exceed the material strength. Three factors influence thermal cracking: low pavement surface temperature, cooling rate, and pavement age. The Thermal Stress Restrained Specimen Test (TSRST) directly measures the development of thermal stresses during cooling and identifies the fracture temperature and strength. Test results show lower air voids and some aggregate types can increase fracture temperature and strength. Desirable material properties to resist thermal cracking include low-temperature asphalt binder viscosity and aggregate with high abrasion resistance and low freeze-thaw loss. Pavement structure characteristics like thickness, base
This document discusses test methods for characterizing permanent deformation in hot mix asphalt (HMA). It describes loaded wheel testers like the Asphalt Pavement Analyzer (APA), Hamburg Wheel Tracker, and Purdue Wheel Tracker that apply cyclic wheel loads to HMA samples. Terms related to permanent deformation testing like creep, repeated loading, and dynamic loading are defined. Parameters for different loaded wheel testers and typical APA test results are shown. The document also briefly mentions the gyratory shear compactor, simple shear tester, and uniaxial and triaxial testing for HMA characterization.
This document discusses fatigue cracking in asphalt pavements. It describes how fatigue cracking can start from the bottom of the pavement layer and work its way up, or can start at the top edges due to tire-pavement interactions. Common fatigue testing methods are described, including flexural beam testing where failure is defined as 50% loss of stiffness. Test results depend on whether constant stress or constant strain is used. Other testing methods like cantilevered beam and diametral are also mentioned. Advanced topics covered include notched beam testing, dissipated energy calculations, and models for predicting fatigue life from binder and mix properties.
Stiffness measurements of hot mix asphalt (HMA) mixtures are important for predicting pavement performance and stresses/strains. Various methods exist to measure stiffness through axial, diametral, flexural, or shear testing under repeated or dynamic loading. Stiffness decreases with increasing temperature and air voids, and decreasing asphalt content. Proper characterization of HMA stiffness at different conditions is essential for evaluating fatigue cracking and permanent deformation.
This document discusses typical distresses that can occur in flexible asphalt pavements and their causes. It describes various types of cracking like fatigue cracking, thermal cracking, block cracking, longitudinal cracking, reflection cracking, as well as other distresses such as rutting, corrugations, slippage, stripping, raveling, reduced skid resistance, roughness, and swelling from frost. Each distress is explained in terms of how it manifests visually and what factors can contribute to its development, such as heavy traffic loads, inadequate drainage, mix design issues, or temperature susceptibility of the asphalt binder. The document provides an overview of the main distresses that can affect flexible pavements and their underlying mechanisms.
This document discusses quality control and quality assurance control charts. It explains that control charts can be used to monitor processes and detect variation, including chance causes and assignable causes. Control charts have benefits like early detection of issues, establishing process capability, and providing a permanent record of quality. Examples are provided of how to construct X-bar and R control charts and interpret the results to determine whether a process is in statistical control.
This document discusses quality control and quality assurance procedures for obtaining representative samples of asphalt mixtures and their components. It describes how to properly sample materials at different stages, including at plants, trucks, and roadways. The key aspects covered are sampling locations and techniques, sample size requirements, handling and storage of samples, and potential issues that can arise from improper sampling procedures like segregation. Maintaining representative samples is important for ensuring accurate test results and mixture quality.
This document discusses quality control and quality assurance sampling procedures for construction projects. It addresses requirements for a sampling program, including frequency, location, and size of samples. Different types of sampling are described, such as judgment, quota, systematic, stratified, and random sampling. Random sampling is preferable to avoid bias, and it is best to use random number tables to select sample locations. Stratified random sampling involves dividing a construction site into sublots for sampling. The document provides an example of how to use random numbers to select sample locations within sublots for both roadway and hot mix asphalt plant sampling.
This document discusses basic concepts of statistics as they relate to quality control and quality assurance in construction. It explains that variability is inherent in all materials and processes, but can be controlled. Sources of variability include sampling, testing, materials, and construction methods. The goal of quality control/quality assurance is to reduce variability as much as possible by addressing these sources. Key statistical terms discussed include mean, median, range, variance, precision, accuracy, and bias. Frequency histograms are presented as a tool to visualize variability in data.
This document provides an overview of quality control and quality assurance procedures for construction projects. It discusses different types of specifications like proprietary, method, and end result specifications. It also covers topics like process control, acceptance testing, sampling procedures, warranties, and reasons for sampling materials. The overall purpose is to introduce fundamental concepts regarding specifications, testing, and quality assurance/quality control as they relate to construction quality management.
The document discusses acceptance and compliance procedures for hot mix asphalt. It explains how specification limits are set using typical industry standard deviations and allowing three standard deviations from the target value. It also introduces the concept of percent within limits (PWL) which is used to determine payment based on both the accuracy and precision of the test results. The PWL is calculated using quality indices determined from the test average, standard deviation, and specification limits. Examples are provided to demonstrate calculating quality indices and determining the PWL.
2. HMA Volumetric Terms
• Bulk specific gravity (BSG) of compacted HMA
• Maximum specific gravity
• Air voids
• Effective specific gravity of aggregate
• Voids in mineral aggregate, VMA
• Voids filled with asphalt, VFA
HMA Volumetrics 2
4. Summary of Terms
• VMA = Voids in mineral aggregates
• Va = Air voids
• VFA = Voids filled with asphalt binder
• Gb = Specific gravity, asphalt binder
• Gse = Effective specific gravity of aggregate
• Gsb = Bulk specific gravity of aggregate
• Pbe = % by mass of effective asphalt binder
• Pb = % by mass of total asphalt binder
• Pba = % by mass of absorbed asphalt binder
• MT = Total mass
• Ms = Mass of solids
• Mb = Mass of asphalt binder
• Gmb = Specific gravity of compacted HMA
• Gmm = Maximum specific gravity of loose HMA
HMA Volumetrics 4
5. BSG of Compacted HMA
• Asphalt binder mixed with aggregate and
compacted into a sample
Mass agg. and AC
Gmb =
Vol. agg., AC, air voids
HMA Volumetrics 5
6. Testing
• Mixing of asphalt and aggregate
• Compaction of sample
• Mass of dry sample
• Mass under water
• Mass saturated surface dry (SSD)
HMA Volumetrics 6
7. Testing
Obtain mass of dry
compacted sample
HMA Volumetrics 7
8. Testing
Obtain mass of
specimen at SSD
HMA Volumetrics 8
9. Calculations
• Gmb = A / ( B - C )
Where:
A = mass of dry sample
B = mass of SSD sample
C = mass of sample under water
HMA Volumetrics 9
10. Summary of Terms
• VMA = Voids in mineral aggregates
• Va = Air voids
• VFA = Voids filled with asphalt binder
• Gb = Specific gravity, asphalt binder
• Gse = Effective specific gravity of aggregate
• Gsb = Bulk specific gravity of aggregate
• Pbe = % by mass of effective asphalt binder
• Pb = % by mass of total asphalt binder
• Pba = % by mass of absorbed asphalt binder
• MT = Total mass
• Ms = Mass of solids
• Mb = Mass of asphalt binder
• Gmb = Specific gravity of compacted HMA
• Gmm = Maximum specific gravity of loose HMA
HMA Volumetrics 10
11. Maximum Specific Gravity
Loose (uncompacted) mixture
Mass agg. and AC
Gmm =
Vol. agg. and AC
HMA Volumetrics 11
12. Testing
• Mixing of asphalt and aggregate
• Cool to room temperature
• Mass in air
• Mass under water
HMA Volumetrics 12
13. Testing
Loose Mix at Room Temperature
HMA Volumetrics 13
14. Testing
Residual
Manometer
Metal Bowl
with Lid
Vacuum
Pump
Shaker Table
HMA Volumetrics 14
15. Calculations
• Gmm = A / ( A - C )
Where:
A = mass of dry sample
C = mass of sample under water
HMA Volumetrics 15
16. Summary of Terms
• VMA = Voids in mineral aggregates
• Va = Air voids
• VFA = Voids filled with asphalt binder
• Gb = Specific gravity, asphalt binder
• Gse = Effective specific gravity of aggregate
• Gsb = Bulk specific gravity of aggregate
• Pbe = % by mass of effective asphalt binder
• Pb = % by mass of total asphalt binder
• Pba = % by mass of absorbed asphalt binder
• MT = Total mass
• Ms = Mass of solids
• Mb = Mass of asphalt binder
• Gmb = Specific gravity of compacted HMA
• Gmm = Maximum specific gravity of loose HMA
HMA Volumetrics 16
17. Percent Air Voids
Calculated using both specific gravities
Gmb
Air voids = ( 1 - ) 100
Gmm
Mass agg + AC
Vol. agg, AC, Air Voids Vol. agg, AC
Mass agg + AC
=
Vol. agg, AC, Air Voids
Vol. agg, AC
HMA Volumetrics 17
19. Effective Specific Gravity
Surface Voids Mass, dry
Gse =
Effective Volume
Solid Agg.
Vol. of water-perm. voids
Particle
not filled with asphalt
Absorbed asphalt
Effective volume = volume of solid aggregate particle +
volume of surface voids not filled with asphalt
HMA Volumetrics 19
20. Effective Specific Gravity
100 - Pb
Gse =
100 - Pb
Gmm Gb
Gse is an aggregate property
HMA Volumetrics 20
21. Summary of Terms
• VMA = Voids in mineral aggregates
• Va = Air voids
• VFA = Voids filled with asphalt binder
• Gb = Specific gravity, asphalt binder
• Gse = Effective specific gravity of aggregate
• Gsb = Bulk specific gravity of aggregate
• Pbe = % by mass of effective asphalt binder
• Pb = % by mass of total asphalt binder
• Pba = % by mass of absorbed asphalt binder
• MT = Total mass
• Ms = Mass of solids
• Mb = Mass of asphalt binder
• Gmb = Specific gravity of compacted HMA
• Gmm = Maximum specific gravity of loose HMA
HMA Volumetrics 21
23. Voids in Mineral Aggregate
VMA = 100 - Gmb Ps
Gsb
VMA is an indication of film thickness on
the surface of the aggregate
HMA Volumetrics 23
24. Example Calculations
• Given that Gmb = 2.455, Ps = 95%, and Gsb = 2.703
(2.455) (95)
VMA = 100 - = 13.7
2.703
HMA Volumetrics 24
25. Voids Filled with Asphalt
VFA = VMA - Va
100 x
VMA
VFA is the percent of VMA that
is filled with asphalt cement
HMA Volumetrics 25
26. Mass Relationships
Air Ma = 0
Mb = P b MT
Asphalt
MT = Mb + Ms
Aggregate Ms = Ps MT
HMA Volumetrics 26
27. Percent Binder Absorbed
Pba = Gse - Gsb
100 ( ) Gb
Gsb Gse
Pba is the percent of absorbed
asphalt by mass of aggregate
HMA Volumetrics 27
28. Summary of Terms
• VMA = Voids in mineral aggregates
• Va = Air voids
• VFA = Voids filled with asphalt binder
• Gb = Specific gravity, asphalt binder
• Gse = Effective specific gravity of aggregate
• Gsb = Bulk specific gravity of aggregate
• Pbe = % by mass of effective asphalt binder
• Pb = % by mass of total asphalt binder
• Pba = % by mass of absorbed asphalt binder
• MT = Total mass
• Ms = Mass of solids
• Mb = Mass of asphalt binder
• Gmb = Specific gravity of compacted HMA
• Gmm = Maximum specific gravity of loose HMA
HMA Volumetrics 28
29. Effective Asphalt Content
Pba
Pbe = Pb - Ps
100
The effective asphalt content is the total
asphalt content minus the percent lost to
absorption
(based on mass of total mix).
HMA Volumetrics 29
30. Summary of Terms
• VMA = Voids in mineral aggregates
• Va = Air voids
• VFA = Voids filled with asphalt binder
• Gb = Specific gravity, asphalt binder
• Gse = Effective specific gravity of aggregate
• Gsb = Bulk specific gravity of aggregate
• Pbe = % by mass of effective asphalt binder
• Pb = % by mass of total asphalt binder
• Pba = % by mass of absorbed asphalt binder
• MT = Total mass
• Ms = Mass of solids
• Mb = Mass of asphalt binder
• Gmb = Specific gravity of compacted HMA
• Gmm = Maximum specific gravity of loose HMA
HMA Volumetrics 30
31. Hot Mix Asphalt (HMA) Volumetric
Properties
Using
Phase Diagrams
HMA Volumetrics 31
33. VOL (cm3 ) Gmb = 2.329 MASS (g)
air Ma = 0
effective asphalt
Gb = 1.015
Pb = 5% by mix
absorbed asphalt
1.000 Mm = 1.0 x 2.329 x 1.0 = 2.329
aggregate
Gsb = 2.705
Gse = 2.731
M= V x G x 1.000
HMA Volumetrics 33
34. VOL (cm3 ) Gmb = 2.329 MASS (g)
air 0
effective asphalt
Gb = 1.015 Mb = 0.05 x 2.329 =0.116
Pb = 5% by mix
absorbed asphalt
1.000 2.329
aggregate
Gsb = 2.705
Gse = 2.731 Ms = 2.329 - 0.116 = 2.213
HMA Volumetrics 34
35. VOL (cm3 ) MASS (g)
air 0
effective asphalt
Gb = 1.015 0.116
absorbed asphalt
1.000 2.329
aggregate
0.818 Gsb = 2.705
0.810 2.213
Gse = 2.731
Vse = 2.213 = 0.810
M
2.731x 1.0
Vsb = 2.213 = 0.818 V=
G x 1.000
2.705x 1.0
HMA Volumetrics 35
36. VOL (cm3 ) MASS (g)
air 0
effective asphalt
0.114 Gb = 1.015 0.116
0.008 absorbed asphalt
1.000 2.329
aggregate
0.818 0.810 Gsb = 2.705
2.213
Gse = 2.731
M
Vb = 0.116 = 0.114
1.015 x 1.0 V=
G x 1.000
Vba = 0.818 - 0.810 = 0.008
HMA Volumetrics 36
Volumetric calculations are the foundation of any good mix design. By the end of this block the student will understand: * HMA volumetric terms. * Important factors which can influence key mass-volume relationships and calculations.
As with aggregates, it is the specific gravities of materials which define the relationships between mass and the volume it occupies. Air voids, VMA, and VFA are the volumetric measurements which are used in mix design calculations.
Mass determinations are usually simple: you place a material on a scale and read the mass. In HMA, it is determining key volumes which proves to be difficult. Think of the basic phase diagram outline as an empty bucket. The first thing you add to the bucket is the aggregate. The volume of aggregate has two components: volume of the solid particle and volume of the water-permeable voids. The next thing that is added to the bucket is the asphalt cement. Because the aggregate has surface voids, some of the asphalt fills a portion of these voids. The remainder of the asphalt remains on the surface of the aggregate. This is the asphalt that is available for “sticking” the aggregate together and is referred to as the “effective” asphalt. When the sample is compacted, the total volume will also contain a percentage of air voids. VMA is the sum of the air voids and the volume of effective asphalt (i.e., the asphalt film).
This slide provides a review of all of the volumetric variables used in this section.
The specific gravity of the compacted sample is defined in this slide.
This specific gravity is determined as described in this slide.
The mass of the oven dry specimen is being determined in this photograph. The next step is to place the specimen in the water bath directly below the scale (not shown) and determine its mass under water.
Calculations are simple.
This slide provides a review of all of the volumetric variables used in this section.
Maximum specific gravity is the densest configuration that the mix can assume (0% air voids). This value, along with the compacted specific gravity is used to calculate air voids in the compacted specimen.
There are three steps in determining the maximum specific gravity.
This step removes any air trapped between the asphalt binder-coated aggregate particles. The metal bowl is partially filled with water, a known mass of loose mix is added. More water is added to cover the mix and the lid is placed on top. The bowl is then clamped in the shaker unit. The vacuum is increased until the residual manometer reads 30 mm of mercury and the shaking action is started. The sample is vacuumed for 10 minutes. At the end of the this step, the vacuum is shut off and the pressure released slowly so that air is not pulled back into the mix. The lid is then removed and the bowl with the mix is placed in the bowl holder in the water bath (not shown). The mass of the sample under water is recorded after 10 minutes.
The maximum specific gravity calculations are also simple.
This slide provides a review of all of the volumetric variables used in this section.
Once both test results are obtained, the air voids in the compacted sample are calculated.
The effective aggregate specific gravity is the ratio of the mass of the aggregate divided by the volume of the solid aggregate particle and the surface voids not filled with asphalt binder. This property is calculated by testing the asphalt binder-coated aggregate.
This aggregate property is calculated using the maximum specific gravity of the mixture, the percent of asphalt (by mass) in the sample used to determine the maximum specific gravity, and the specific gravity of the asphalt. If the asphalt specific gravity is not known, an assumption of 1.000 is usually made.
This slide provides a review of all of the volumetric variables used in this section.
VMA is calculated using the bulk specific gravity of the compacted sample, the percent of stone (i.e, 100 - the percent asphalt binder), and the bulk specific gravity of the aggregate. Because it is difficult and time consuming to obtain the bulk specific gravity of the aggregate, a number of states are substituting the effective specific gravity of the aggregate. This value is simply a calculation using test results that have to be determined anyway. Altering the VMA calculation this way will result in an increase in the value. If this substitution is made, then either a correction factor is needed or the VMA requirements need to be adjusted for local aggregate properties.
This slide shows a simple calculation using the bulk specific gravity of the aggregate.
VFA is the volume of the effective asphalt binder and is expressed as the percent of the VMA which is asphalt binder.
As stated earlier, mass relationships are simple. Both the mass of asphalt binder and aggregates are expressed as a percentage of the total mass of the mixture.
Volumetric terms which use P with a subscript indicate percent by mass of a particular component. In this case, the percent of asphalt binder absorbed by the aggregate is expressed as a percent of the mass of aggregate. Both aggregate and mixture specific gravities are needed to get this value.
This slide provides a review of all of the volumetric variables used in this section.
The percent effective asphalt binder is expressed as a percent of the total mass of the mix rather than just the aggregate.
This slide provides a review of all of the volumetric variables used in this section.
A predetermined mass of the dry loose mix is placed in the metal bowl and covered with water. A vacuum lid is fitted and secured to the bowl and placed on a vibratory shaker table. The vacuum pump is started and the manometer reading used to determine the proper vacuum adjustment. Once the proper pressure is obtained, the shaker table is started. This provides gentle agitation to help in the removal of any air voids between particles. This is continued for 5 to 15 minutes. All of this effort is to ensure that the air voids are as close as possible to zero. At the end of this time, the vacuum pump and shaker are turned off and the pressure gradually released. The container is removed from the shaker, the lid removed and the bowl with the sample is suspended under water for 10 minutes. At the end of this time and the mass under water is determined (the tare of the bowl is factored out).
The loose mix is warmed and separated into loose, individually coated aggregates.
There are three basic steps in determining the maximum specific gravity.
The maximum specific gravity determines the mass and volume that would be occupied by the mix if there were no air voids present.
As with the specific gravity equations for aggregates, this equation is also the relationship between the mass of the specimen to the mass (volume) of water it displaces.
The last step is to determine the mass of saturated surface dry specimen (SSD). SSD is obtained by quickly blotting the sample so that the surface is still wet but not shiny.
Air voids are calculated from the bulk and maximum specific gravities. The ratio of these two specific gravities is actually the volume percent of solids (in decimal form).
This slide provides a simple example of how to use the laboratory data to calculate air voids.
The effective specific gravity of the aggregate is determined after the aggregate is coated with asphalt binder. The mass is the dry mass of the aggregate without asphalt binder but the volume is the volume of the dry particle plus only the surface.
This slide shows a simple example of this calculation.