Week 3 Lecture- Aggregate- Part I PDF

Civil Engineering Materials CIVL1012 – Week 3 Aggregate Properties- Part I Dr. Raheleh Alizadeh Angelo DelZotto School of Construction Management  Learning objectives In this session you will be able to: Understand the aggregates sources, shapes and...

Civil Engineering Materials CIVL1012 – Week 3 Aggregate Properties- Part I Dr. Raheleh Alizadeh Angelo DelZotto School of Construction Management  Learning objectives In this session you will be able to: Understand the aggregates sources, shapes and properties Distinct the nominal and maximum size of aggregates Describe and define the different types of gradation Calculate the maximum density gradation Calculate the fineness modulus Calculate specific gravity and bulk unit weight and voids in aggregate 2  What is Aggregate? Aggregates : Granular materials such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast-furnace slag. Natural: Manufactured & recycled materials: Natural sand, river rock and gravel Pulverized concrete & asphalt pits Steel mill slag Quarries (crushed) Expanded shale Styrofoam Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 3 4  Aggregate Classes Based on Density Light Weight Normal Weight Heavy Weight Bulk density of Bulk density of Bulk density of greater approximately approximately 1200- than 1750kg/m3 1000kg/m3 1750kg/m3 Magnetite and Expanded Shale, Gravel, Crushed Stone Hematite Expanded Perlite and Sand Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 5  Aggregate Geological Classification All natural aggregates result from the break down of large rock masses. All above classes are used successfully in civil engineering applications. Igneous Sedimentary Metamorphic By volcanic actions Coalesce from deposits of Form from igneous or disintegrated existing sedimentary rocks that are Hardening or crystallizing rocks/ inorganic remains of drawn back into earth’s molten materials, magma marine animals. crust and exposed to heat and pressure, reforming Cools at earth surface: Wind, water, glaciers or the grain structure extrusive igneous rocks, direct chemicals finer grains, air voids precipitation transport and Generally, have a (basalt, tuff, etc.) deposit layers of materials crystalline structure that become sedimentary Cools within the crust of rocks resulting in a the earth: intrusive stratified structure igneous rocks, larger grain size, fewer flaws (granite) Natural cementing binds Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 6  Aggregate Uses Under Stability foundations Drainage and pavements Rip-rap for Soil protection from erosion caused by concentrated runoff. erosion Stabilize unstable slopes that control are due to seepage Portland Cement Concrete 60-75% of volume 80-85% of weight As fillers Hot Mix Asphalt 80%-90% of volume 90-96% of weight Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 7 Aggregate Mining Quarry - Drilling cores/trial blast/shots - Evaluate how the rocks breaks/grading/particle shape/ soundness/ amount of fines Aggregate from river deposit - Aggregate tumble while transported in water - Qualify for larger particles/ amount of fines 8  Particle Shape & Surface Texture Angular Angularity Rounded Shape Flaky Flakiness Elongated Flaky & Elongated ▪ Angular/ Rough: High friction, good for strength & stability of asphalt ▪ Rounded/ Smooth: Low friction, good for workability of concrete ▪ Flaky & Elongated: Harmful specially for asphalt because of easy breakage and difficulty compacting in thin layers. 9  Particle Shape & Surface Texture Angular Flaky Rounded Elongated Flaky & Elongated Rounded Angular Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 10  Aggregate Sizes Coarse aggregate material retained on a sieve with 4.75 mm openings Fine aggregate material passing a sieve with 4.75 mm openings #4 sieve = four openings/linear inch Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 1  Gradation Gradation: Particle size distribution of aggregate. Evaluated by passing the aggregates through a series of sieves High density gradation (Well Graded) One-size gradation (Uniform) Good mix of all particle sizes All same size and nearly vertical grading curve Aggregates use most of the volume and High permeability, poor stability less cement or asphalt is needed Used in chip seals of pavements Gap-graded Open-Graded Missing small aggregates, holes between Missing some sizes and nearly horizontal larger aggregate section of grading curve Lower part of grading curve is skewed toward large sizes High permeability; low stability Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 12  Types of Gradation George Brown Civil Engineering Lab Notes Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc., 13  Maximum Density Gradation Maximum Density Gradation is a function of the size distribution of the aggregates Pi=(di/D)n x100 Where: Pi= percent passing a sieve of size d di= the sieve size in the question D= maximum aggregate size being used n=the value of the exponent is 0.45 (By federal highway administration) Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 14  Example 1: Maximum Density Gradation For an aggregate mix with Dmax=20 mm, find the percentage of aggregate passing sieve 9.5 mm. P=(di/D)n x100 15  Sample calculations of aggregate distribution required to achieve maximum density Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 16  Semi Logarithmic Graph Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 17  Example 2: Calculation of percent passing for each sieve size A sample of fine aggregate was tested for its gradation, and the results are given below. Calculate the percent passing for each sieve and plot the percent passing versus sieve size on a semi logarithmic gradation chart. Sieve (mm) Amount retained on each sieve (g) 4.75 0 2.36 32.5 1.18 57 0.600 61.8 0.300 63.9 0.063 157.7 0.020 95.9 0.006 53.3 pan 10.6 18  Example 2: Solution Cumulative Cumulative Percentage Sieve size (mm) Amount Amount Retained Percent Passing Retained (g) Retained (g) B=(A /total)*100 C= 100 – B A 4.75 0 + 0 0.0 100 2.36 32.5 = 32.5 6.1 93.9 1.18 57.0 89.5 16.8 83.2 0.6 61.8 151.3 28.4 71.6 0.3 63.9 215.2 40.4 59.6 0.063 157.7 372.9 70.0 30 0.02 95.9 468.8 88.0 12 0.006 53.3 522.1 98.0 2 pan 10.6 532.7 100.0 Total 532.7 19  Example 2: Semi Logarithmic gradation graph 100 90 80 70 60 % passing 50 40 30 20 10 0 0.001 0.01 0.1 1 10 Sieve size (mm) 20  Maximum Aggregate Sizes, Nominal Maximum Aggregate Size Traditional Definition Maximum aggregate size : the smallest sieve size that allows all the aggregates to pass. Nominal maximum aggregate size: the first sieve to retain some aggregate, generally less than 10%. Superpave definition Maximum aggregate size: one sieve size larger than the nominal maximum aggregate size. Nominal maximum aggregate size: one sieve larger than the first sieve to retain more than 10% of the aggregate. Note: Superpave method is developed for asphalt pavement design Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 21  Example: Maximum and Nominal Maximum Aggregate Size Cumulative Cumulative Percentage Sieve size (mm) Amount Amount Retained Retained (g) Retained (g) B=(A /total)*100 A 9.5 0 0 0.0 4.75 0 0 0.0 2.36 32.5 32.5 6.1 1.18 57.0 89.5 16.8 0.600 61.8 151.3 28.4 0.300 63.9 215.2 40.4 0.063 157.7 372.9 70.0 0.020 95.9 468.8 88.0 0.006 53.3 522.1 98.0 pan 10.6 532.7 100.0 Total 532.7 22  Fineness Modulus Fineness Modulus: measure of the gradation fineness Used for: Portland Concrete mix design Daily quality control for concrete mix design FM =  R i 100 Ri = cumulative percent retained on standard sieve sequence Sieve numbers: 0.15, 0.3, 0.6, 1.18, 2.36, 4.75, 9.5, 19. 0, 37.5, 75.0, 150.0 mm When the fineness modulus is determined for fine aggregates, sieves larger than 9.5mm are not used. The ranges of 2.3 - 3.1 for fine aggregate types in concrete. Larger FM being coarser aggregate Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 23  Example 3: Fineness Modulus Calculate the fineness modulus of the sieve analysis results from the previous example. Is the answer within the typical range for fineness modulus? Sieve size, mm Cumulative Percent Retained 4.75 0 2.36 6.1 1.18 16.8 0.60 28.4 0.30 40.4 0.15 70 0.075 88 0.006 98 Total 161.7 Fineness Modulus = 161.7/100= 1.62 The fineness modulus for fine aggregates should be in the range of 2.3-3.1 to be allowed to use it in concrete. It is not within the typical range for fine aggregate to use in concrete production. Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 24  Soundness & Durability Definition: The ability of aggregate to withstand weathering Water freezing in voids of aggregates generates stresses that can fractures & disintegrates aggregates Test method: using salt solution to simulate freezing Prepare sample, minimum mass, specified gradation Soak for 16 hrs in either sodium sulfate or magnesium sulfate solution Dry for 4 hrs Repeat cycle 5 times Measure gradation Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. 25  Aggregate Moisture States Free moisture Internal impervious voids Voids partially filled Bone dry Air dry Saturated surface dry Moist dried in oven moisture condition moisture condition moisture condition to constant mass state undefined state undefined state undefined Ws Wm WSSD=Ws + Wp Wm Moisture content Absorption Moisture content Wm − Ws WSSD − Ws Wm − Ws M= 100 A= M 100 M= 100 Ws Ws Ws Wp: weight of water in the permeable voids Absorption: moisture content when the aggregates are in the SSD condition Free moisture is the moisture content in excess of the SSD condition. % free moisture = M - A Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc.  Example 4: Aggregate Moisture Content Three samples of fine aggregate have the properties shown in table below. Determine in percentage: (a) Total moisture content and (b) Free moisture content for each sample and the average of the three samples Sample Measure A B C Wet mass (g) 521.0 522.4 523.4 Dry mass (g) 491.6 491.7 492.1 Absorption (%) 2.5 2.4 2.3 Percent free moisture = M - A Mamlouk/Zaniewski, Materials for Civil and Construction Engineers, Fourth Edition. Copyright © 2017 Pearson Education, Inc. Questions?