week 2- Aggregate (handout 2022(S)).pptx.pdf

1/24/2024 CIVI321 ENGINEERING MATERIALS Chapter #2 Aggregate A.M. Soliman, PhD, P.Eng Assistant Professor Department of Building, Civil & Environmental Engineering (BCEE) 1 www.key2cusco.com www.ancient-egypt.info Civil Engineering Materials http://www.treehugger.com/ Pyramids (Giza, Egypt) http://w...

1/24/2024 CIVI321 ENGINEERING MATERIALS Chapter #2 Aggregate A.M. Soliman, PhD, P.Eng Assistant Professor Department of Building, Civil & Environmental Engineering (BCEE) 1 www.key2cusco.com www.ancient-egypt.info Civil Engineering Materials http://www.treehugger.com/ Pyramids (Giza, Egypt) http://www.ushistory.org/civ/6c.asp Dry-Stone walls (Machu Picchu, Peru) Roman Concrete 2 1 1/24/2024 3 4 2 1/24/2024 Aggregate Fine Coarse “Aggregate is a rock-like material” 5 ? WHAT are the uses of Aggregate in Civil Applications? 6 3 1/24/2024 Aggregate Annual per person: ~ 10–15 tons in Canada ~ 10 tons in the U.S. Source: Construction Aggregates: National And Regional Trends by R.D. Irvine and G.O. Vagt, Natural Resources Canada, Ottawa, Ontario - BC Aggregate Forum Drains Concrete Asphalt Subbase Rail Road 7 Road Application Concrete Aggregate +Cement Without Binder With Binder Asphalt Railway Application Aggregate +Bitumen 8 4 1/24/2024 Importance of Aggregate Aggregate represents 60% – 75% of concrete Volume. (i.e. 70% to 85% of its mass) Binder Aggregate www.concreteanswers.org 9 WHY do we use Aggregate? 10 5 1/24/2024 WHY DO WE USE AGGREGATE? Significant Economic Benefits for the final cost Vs. Vs. 11 WHY DO WE USE AGGREGATE? Cement + Water Change in Volume Shrinkage Cracks Stable Aggregate ……Volume stability 12 6 1/24/2024 Are there different types of Aggregate? 13 Concrete Aggregate: Size a. Fine Aggregate b. Coarse aggregate Sand and/or crushed stone Gravel and crushed stone Particle size < 5 mm (0.2 in.) Particle size ≥ 5 mm (0.2 in.) Content usually 35% to 45% by Typically between 9.5 and mass or volume of total aggregate 37.5 mm (3/8 and 1½ in.) Riverside Sand Rounded gravel Crushed stone 14 7 1/24/2024 Concrete Aggregate: Weight a. Normal-Weight (ASTM C 33) Produce normal-weight concrete 2200 to 2400 kg/m3 (140 to 150 lb/ft3) Most common aggregates Sand Gravel Crushed stone 15 Concrete Aggregate: Weight (ASTM C 330) lightweight concrete 250 to 1450 kg/m3 (15 to 90 lb/ft3) b. Light-Weight Diatomite Expanded polystyrene Pumice Concrete ! Structural lightweight concrete 1450 to 1850 kg/m3 (90 to 120 lb/ft3) 16 8 1/24/2024 c. Heavy-Weight Radiation Shielding (ASTM C 637, C 638) Produce high denisty concrete up to 6400 kg/m3 (400 lb/ft3) Most common aggregates Magnetite Steel punchings or shot Iron Iron Steel punchings or shot 17 Concrete Aggregate: Source a. Natural gravel and sand Gravel Sand 18 9 1/24/2024 Concrete Aggregate: Source b. Rocks and minerals Sedimentary rocks Claystone Sandstone Igneous rocks Granite Basalt Metamorphic rocks Meta-quartzite Marble (Minerals) Pyrite (Iron sulfide) Gypsum (Sulfate) 19 Concrete Aggregate: Source c. Crushed air-cooled blast-furnace slag 20 10 1/24/2024 Concrete Aggregate: Source d. Recycled or crushed waste concrete Recycled: Brick Glass 21 Concrete Aggregate Classification Size Source Weight Fine < 5 mm Natural gravel and sand Normal Coarse ≥ 5 mm Rocks and minerals Light Crushed blast-furnace slag Heavy Recycled waste concrete Aggregates can represent all these types For example: Recycled Sand is a fine aggregate (< 5 mm) and a normal weight aggregate 22 11 1/24/2024 How to Evaluate Aggregate Characteristics The majority of the tests and characteristics listed are referenced in ASTM C 33 (AASHTO M 6/M 80). 23 Aggregate Characteristics and Tests 24 12 1/24/2024 Aggregate Characteristics and Tests 25 Grading of Aggregate Grading is the particle-size distribution of an aggregate as determined by a sieve analysis using wire mesh sieves with square openings. (ASTM 33) The square grid will allow the smaller to pass through 26 13 1/24/2024 ASTM Sieve Sizes Fine aggregate : 7 standard sieves with openings from 150 μm to 9.5 mm (No. 100 to 3/8 in.) 150.00 75.00 50.00 Coarse aggregate: 13 sieves with openings from 37.50 1.18 mm to 100 mm (0.046 in. to 4 in.) 19.00 9.50 4.75 2.36 1.18 600* 300* 150* pan * Size in micro-meter 27 1- Is the aggregate grading good or poor ? Based on particle size distribution curve Range of Particle Sizes Curves indicate the limits specified in ASTM C 33 28 14 1/24/2024 EXAMPLE The following are the sieve analysis results for concrete aggregate samples (#1,#2,#3) taken from a construction site. Which aggregate sample satisfies the ASTM C33 grading limits. Sieve size % pass ASTM Limits (% pass) #1 #2 #3 Lower Limit Upper Limit 4.75 96 98 100 95 100 2.36 85 90 95 80 100 1.18 80 50 90 50 85 600 30 20 55 25 60 300 6 12 25 5 30 150 0 5 8 0 10 29 2- Is this aggregate suitable to the construction project or not ? 1- Maximum size of aggregate: is the smallest sieve that all of the aggregate must pass through. Aggregate weight on the sieve = zero must pass Percentage of pass = 100 % Percentage of retained aggregate = 0% 2- Nominal maximum size : is the standard sieve opening immediately smaller than the smallest sieve through which all of the aggregate must pass (i.e. maximum size). 30 15 1/24/2024 Nominal Maximum Size Size should not exceed 1/5 the narrowest dimension between sides of forms (bw) 3/4 clear spacing between rebars and between rebars and the form 1/3 depth of slabs (hs) c = 50 mm c = 50 mm 31 EXAMPLE Determine the Nominal maximum size 19 32 16 1/24/2024 EXAMPLE The following is the sieve analysis result for a concrete aggregate sample taken from a construction site. Do you approve this aggregate to be used in casting 15 cm depth concrete slab Sieve size Soil Weight on sieve 50.0 0 37.5 0 19 301 9.50 947.5 4.75 216.5 2.36 280 1.18 290.5 600 433.5 300 340 150 439.5 pan 1.50 33 WHY PARTICLE SIZE IS IMPORTANT?! 34 17 1/24/2024 PARTICLE SIZE SURFACE AREA 35 PROPERTIES OF CONCRETE Effect of Particle size on the Surface Area 3 mm 3 mm 3 mm 3 mm 54 mm2 162mm2 The smaller the Particle size, the higher the Surface Area 36 18 1/24/2024 Dispersion of Aggregates The amount of cement paste required in concrete is greater than the volume of voids between the aggregates. Illustration of the dispersion of aggregates in cohesive concrete mixtures In order to provide workability to the concrete 37 Cement Requirement Larger coarse aggregate Lower surface area Less cement is required in mixtures having large coarse aggregate 38 19 1/24/2024 Water Requirement Larger coarse aggregate Lower surface area Less water is required in mixtures having large coarse aggregate 39 Fineness Modulus (FM) Obtained by adding the sum of the cumulative percentages by mass of a sample of aggregate retained on each of standard sieves and dividing the sum by 100. 𝐹𝑀 = ∑ 𝐶𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑣𝑒 𝑝𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑜𝑓 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 𝑟𝑒𝑡𝑎𝑖𝑛𝑒𝑑 𝑜𝑛 𝑒𝑎𝑐ℎ 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑠𝑖𝑒𝑣𝑒 100 The higher the FM the coarser the aggregate FM= 2.8 - 3.10 FM= 2.5 – 2.8 FM= 2.3 – 2.5 Coarse Medium Fine Note: Retained= Did not pass 40 20 1/24/2024 Fineness Modulus (FM) 𝐹𝑀 = ∑ 𝐶𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑣𝑒 𝑝𝑒𝑟𝑐𝑒𝑛𝑡𝑎𝑔𝑒 𝑜𝑓 𝑎𝑔𝑔𝑟𝑒𝑔𝑎𝑡𝑒 𝑟𝑒𝑡𝑎𝑖𝑛𝑒𝑑 𝑜𝑛 𝑒𝑎𝑐ℎ 𝑠𝑡𝑎𝑛𝑑𝑎𝑟𝑑 𝑠𝑖𝑒𝑣𝑒 100 Standard sieves for fine aggregate : 4.75 mm (No. 4), 2.36 mm (No. 8), 1.18 mm (No. 16), 600 µm (No. 30), 300 µm (No. 50), 150 µm (No.100). 𝐶𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑣𝑒 % 𝑜𝑓 𝑟𝑒𝑡𝑎𝑖𝑛𝑒𝑑 𝑜𝑛 𝑠𝑖𝑒𝑣𝑒 4.75 +𝐶𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑣𝑒 % 𝑜𝑓 𝑟𝑒𝑡𝑎𝑖𝑛𝑒𝑑 𝑜𝑛 𝑠𝑖𝑒𝑣𝑒 2.36 +𝐶𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑣𝑒 % 𝑜𝑓 𝑟𝑒𝑡𝑎𝑖𝑛𝑒𝑑 𝑜𝑛 𝑠𝑖𝑒𝑣𝑒 1.18 +⋯ +𝐶𝑢𝑚𝑢𝑙𝑎𝑡𝑖𝑣𝑒 % 𝑜𝑓 𝑟𝑒𝑡𝑎𝑖𝑛𝑒𝑑 𝑜𝑛 𝑠𝑖𝑒𝑣𝑒 150 μ𝑚 𝐹𝑀 = 100 41 EXAMPLE The following is the sieve analysis result for a concrete aggregate sample taken from a construction site. Is the aggregate fine, medium or coarse? (Sample weight = 1200 g ) Sieve size Soil Weight on sieve 4.75 116.5 2.36 180 1.18 190.5 600 33.5 300 340 150 338 pan 1.50 42 21 1/24/2024 EXAMPLE 𝑷𝒆𝒓𝒄𝒆𝒏𝒕𝒂𝒈𝒆 𝑾𝒆𝒊𝒈𝒉𝒕 = 𝑺𝒐𝒊𝒍 𝒘𝒆𝒊𝒈𝒉𝒕 𝒐𝒏 𝒔𝒊𝒆𝒗𝒆 𝑻𝒐𝒕𝒂𝒍 𝑺𝒂𝒎𝒑𝒍𝒆 𝒘𝒆𝒊𝒈𝒉𝒕 𝑷𝒆𝒓𝒄𝒆𝒏𝒕𝒂𝒈𝒆 𝑾𝒆𝒊𝒈𝒉𝒕# 𝟒. 𝟕𝟓 = 𝟏𝟏𝟔.𝟓 𝟏𝟐𝟎𝟎 Sieve size Soil Weight on sieve (g) Percentage Weight 4.75 116.5 9.71 2.36 180 1.18 190.5 600 33.5 300 340 150 339.5 pan 1.50 x 100 x 100= 9.71% Cumulative % weight 43 EXAMPLE 𝐹𝑀 =.... FM= 2.8 - 3.10 FM= 2.5 – 2.8 FM= 2.3 – 2.5.. = 2.9 Coarse Medium Fine ………? 44 22 1/24/2024 Combined Aggregate Grading Combined grading of fine and coarse aggregate together, as they exist in a concrete mixture. Optimum combined aggregate grading for concrete The combined gradation can be used to better control: Workability, Shrinkage, and Other properties of concrete. 45 Reduction of Voids When different sizes are combined, the void-content decreases 46 23 1/24/2024 Moisture Conditions The absorption and surface moisture of aggregates should be determined so that the total water content of the concrete can be controlled and correct batch weights. State: Total moisture: Adjusting batch water: Coarse and fine aggregate will have moisture contents at Saturated surface dry 47 Aggregate and Concrete Problems 48 24 1/24/2024 D-Cracking D-cracking Cracking of concrete pavements caused by the freeze-thaw deterioration of the aggregate within concrete D-cracking along a transverse joint caused by failure of carbonate coarse aggregate 49 Harmful Reactive Substances Aggregates are potentially harmful if they contain compounds known to react chemically with portland cement concrete and produce any of the following: (1) significant volume changes of the paste, aggregates, or both; (2) Interference with the normal hydration of cement; and (3) otherwise harmful by-products. Note: Several of the rocks listed react very slowly and may not show evidence of any harmful degree of reactivity until the concrete is over 20 years old. 50 25 1/24/2024 Popouts Iron Particles in Aggregates A popout is the breaking away of a small fragment of concrete surface due to internal pressure that leaves a shallow, typically conical depression. Iron oxide stain caused by impurities in the coarse aggregate. 51 Alkali- Aggregate Reactivity ( AAR ) Definition: is a reaction between the active mineral constituents of some aggregates and the sodium and potassium alkali hydroxides and calcium hydroxide in the concrete. Two Forms: Alkali-Silica Reaction (ASR) Alkali-Carbonate Reaction (ACR ) ASR is of more concern than ACR because the occurrence of aggregates containing reactive silica minerals is more common. While ACR aggregates have a specific composition that is not very common. 52 26 1/24/2024 Alkali-Silica Reaction (ASR) Visual Symptoms Network of cracks Closed or spalled joints Relative displacements Fragments breaking out of the surface (popouts) Relative displacements Network of cracks Popouts 53 Mechanism Alkali hydroxide Expansion + Reactive silica Moisture H2O Alkali Silica Gel + Alkali Silica gel filling microcracks Alkali silica gel filling air pores 54 27 1/24/2024 Alkali Reactive hydroxide silica Moisture H2O If one of these conditions is absent ASR cannot occur. Observe the alkali-silica reaction rim around the reactive Aggregate and the crack formation. fluorescent mode 55 Testing methods Mortar-Bar Method (ASTM 227) Chemical Method (ASTM C 289) Petrographic Examination (ASTM C 295) ASTM 227 Concrete Prism Test (ASTM C 1293 ) Rapid Mortar-Bar Test (ASTM C 1260 or AASHTO T 303) ASTM C 1293 56 28 1/24/2024 How To Control ASR ? Alkali Reactive hydroxide silica Non-reactive aggregates Limit alkali loading Moisture H2O Lithium-based admixtures Supplementary cementing materials Limestone sweetening (~30% replacement of reactive aggregate with crushed limestone 57 Effect of Supplementary Cementing Materials on ASR Influence of different amounts of fly ash, slag, and silica fume by mass of cementing material on mortar bar expansion (ASTM 1260) after 14 days when using reactive aggregate 58 29 1/24/2024 Spraying 30% LiNO3 solution Spraying 30 % LiNO3 solution with a tanker truck 59 Alkali-Carbonate Reaction (ACR) Influencing Factors 1- Clay content, or insoluble residue content, in the range of 5% to 25% 2- Calcite-to-dolomite ratio of approximately 1:1 3- Small size of the discrete dolomite crystals (rhombs) suspended in a clay matrix 60 30 1/24/2024 Alkali-Carbonate Reaction (ACR) Testing methods Petrographic Examination (ASTM C 295) Concrete Prism Test (ASTM C 1105 ) Rock cylinder method (ASTM C 586) Petrographic Examination 61 How To Control ACR ? Selective quarrying to avoid reactive aggregate Limit aggregate size to smallest practical 62 31 1/24/2024 Handling and Storing Aggregates Store in a way to Avoid contamination Avoid segregation Larger aggregates segregate more Store sizes separately to reduce segregation Stockpile of aggregate at a ready mix plant Dry aggregates segregate more 63 Recycled-Concrete Aggregate Heavily reinforced concrete is crushed with a beam crusher Stockpile of recycled-concrete aggregate 64 32 1/24/2024 Water Absorption Comparison of water absorption of three different recycled aggregate particle sizes and one size of natural and lightweight coarse aggregate. 65 33