Aggregates: Construction Materials and Testing

Construction Materials and Testing University of Mindanao AGGREGATES Introduction of Aggregates Origin Properties and Testing of Aggregates Particle Size and Grading Types of Grading and Relationship with density PRESENTED BY : JUSTINE LOUIS VALDERAMA INTRODUCT...

Construction Materials and Testing University of Mindanao AGGREGATES Introduction of Aggregates Origin Properties and Testing of Aggregates Particle Size and Grading Types of Grading and Relationship with density PRESENTED BY : JUSTINE LOUIS VALDERAMA INTRODUCTION Aggregates are inert granules such as crushed stone, gravels, and minerals that are mixed with cement and sand to form concrete. Aggregates are key constituent of cement concrete and asphalt concrete (AC) or Hot mix asphalt, that are used in the structures such as building and roads.  Approximately 60 to 80 percent of the concrete mix is made up of aggregate. a.) base or subbase of c.) Permeable material b.) Ballast for railroads a road pavement for drainage system Coarse Aggregate Fine Aggregate SOURCES OF AGGREGATES Natural Aggregate Synthetic Aggregate Recycled Aggregate Natural Aggregate Synthetic Aggregate Recycled Aggregate Gravel pits Manufactured aggregates Crushed concretes River deposits Crushed clay bricks lightweight or Rock quarries heavyweioght ORIGIN, GEOLOGY AND CLASSIFICATION OF PARENT ROCK Aggregates are commonly obtained by crushing naturally occurring rock in a quarry such as shown in the picture. These are referred to as crushed rock aggregates and they are the most common source of aggregate used in civil engineering construction. PARENT ROCKS Igneous Rocks Sedimentary Rocks Metamophic Rocks PARENT ROCKS Igneous Rocks Produced by cooling and crystallization of hot molten magma formed by volcanic action. Consist of molten silicates Classified on the basis of crystal grain size ; grain size more than 2mm is referred as coarse, grain size less than 0.2 mm as fine, and the size in between as intermediate. PARENT ROCKS Igneous Rocks Sedimentary Rocks Metamophic Rocks PARENT ROCKS Sedimentary Rocks Derived from the accumulation of weathered rock products and fossils deposited in water and air on the earth’s surface and the subsequent hardening and/or cementation into rock form. PARENT ROCKS Igneous Rocks Sedimentary Rocks Metamophic Rocks PARENT ROCKS Metamophic Rocks Results from metamorphism, which refers to the process whereby existing rocks get altered to new forms due to high temperature and/or pressure. Aggregates from all three classes of rocks are used in civil engineering construction for different applications. Aggregates from all three classes of rocks are used in civil engineering construction for different applications. PROPERTIES AND TESTING OF AGGREGATES NOTE THAT SEVERAL STANDARDS TEST HAVE BEEN DEVELOPED BY ORGANIZATION SUCH AS ASTM (AMERICAN SOCIETY FOR TESTING AND MATERIALS) PARTICLE SIZE AND GRADING TYPICAL SIEVES AND VIBRATING EQUIPMENT USED FOR SIEVE ANALYSIS (a) U.S No. 4 (meaning that the opening size is 4.75mm) sieve; (b) No. 50 (opening size 300 micrometer) sieve ; (c) Sieve stack under vibration in a sieve shaker (a) (b) (c) U.S STANDARD SIEVE NO. AND CORRESPONDING OPENING SIZE OF SIEVE FOR FINE AGGREGATE (c) U.S STANDARD SIEVE NO. AND CORRESPONDING OPENING SIZE OF SIEVE FOR COARSE AGGREGATE (c) Grading and its relationship with density Gradation is an important characteristic of aggregate that influences how it performs in a civil engineering application. When compacted agregate is used as a road base material, how are base of all pack into and the strength, stiffness, and permeability of the compacted aggregate road base are highly influenced by its gradation. In general, the denser the aggregate material, the higher the strength and stiffness is, and the lower the permeability (due to the reduced void space for transmitting water). Grading and its relationship with density In 1907, Fuller and Thompson developed an equation for the maximum density gradation of the aggregate: TYPES OF GRADING Well-Graded Aggregate Contains a good mix of different-sized particles (fine to coarse). Provides better packing, reducing voids and improving strength. Requires less cement or binder in concrete or asphalt. Poorly Graded Aggregate (Uniform Graded) Consists mostly of particles of the same size. Leads to higher void content, requiring more cement or binder. Results in weaker and less durable concrete. Gap-Graded Aggregate Lacks certain intermediate sizes, creating a discontinuous grading. Can enhance specific properties, such as reducing shrinkage. Often used in special concrete mixes like exposed aggregate finishes. TYPES OF GRADING Open-Graded Aggregate Contains mostly larger particles with minimal fine materials. Results in a high void ratio, leading to increased permeability. Used for drainage applications like permeable pavements. Dense-Graded Aggregate Contains a full range of particle sizes to minimize voids. Enhances compaction, strength, and durability. Commonly used in road bases and structural concrete.  Construction Materials and Testing University of Mindanao CHARACTERISTICS OF AGGREGATES SHAPE AND SURFACE TEXTURE STRENGTH AND STIFFNESS HARDNESS, TOUGHNESS, AND ABRASION RESISTANCE SOUNDNESS AND DURABILITY PRESENTED BY : AIRENE B. ESCOBILLO SHAPE AND SURFACE TEXTURE Individual aggregate particle shape and surface texture are important characteristics that contribute to how the aggregate particles will pack into a dense form. GUESS THE SHAPE! SHAPE FLAT ELONGATED FLAT AND ELONGATED ANGULAR SUB-ROUNDED ROUNDED SURFACE TEXTURE OF COARSE AGGREGATE When aggregate is used as an unbound material in application such as road pavement or foundation construction, it is usually compacted to achieve higher density in order to improve its strength and stiffness. In addition to the shape of individual particles, surface texture is also an important characteristic that determines how the aggregate particles will move around during compaction to pack into a dense form. SURFACE TEXTURE OF FINE AGGREGATE Surface texture and angularity of fine aggregates are also important as they significantly influence the characteristics or mix design of materials. STRENGTH AND STIFFNESS The strength and stiffness of aggregate is dependent on its composition, texture, and structure (Neville, 2011). 1. STRENGTH OF AGGREGATES CRUSHING STRENGTH IMPACT STRENGTH TENSILE STRENGTH 2. STIFFNESS OF AGGREGATES ELASTIC MODULUS DEFORMATION RESISTANCE RESILIENCE TO LOAD REPETITION HARDNESS, TOUGHNESS, AND ABRASION RESISTANCE These characteristics ensure that structures can withstand mechanical stresses, environmental factors, and long-term wear.  HARDNESS - ensures that aggregates resist surface wear and scratching. TOUGHNESS - helps aggregates absorb shocks and impacts without breaking. ABRASION RESISTANCE - prevents excessive surface wear, improving safety and durability. SOUNDNESS AND DURABILITY The ability of aggregate to withstand weathering is generally referred as soundness, which is a measure of its durability under environmental and chemical changes. Properties and testing of aggregates John Lloyd Cubero CHEMICAL STABILITY OF AGGREGATE IN PCC     Construction Materials and Testing University of Mindanao AGGREGATES PRESENTED BY ROSEMARIE SUMBILON  USES OF AGGREGATES LIGHTWEIGHT AND HEAVYWEIGHT AGGREGATES AGGREGATES FROM INDUSTRIAL BY PRODUCTS AND WASTE HANDLING, TRANSPORTATION and STORAGE OF AGGREGATES Uses of Aggregates widely used for constructing the base, subbase, and/or the surfacing/wearing course of road pavements in different forms such as: Unbound Stabilized, using portland cement as stabilizer for the aggregate Cementitously stabilized aggregates in which blends of cement, fly ash, slag, and lime are used as the stabilizer  Stabilized with bituminous materials as road base/subbase Stabilized with other materials (resins, fibers, geosynthetics, etc.) as road base/subbase Recycled aggregate Lightweight and Heavyweight Aggregates  Lightweight Aggregates are aggregates with a dry density below 1 2 0 0 kg/cu.m is a coarse aggregate used to make lightweight concrete for structural as well as non- structural applications. These aggregates are known for absorbing little water and maintaining their low density.  Heavyweight Aggregates contains aggregates that are natural or synthetic which typically weigh more than 2 ,0 8 0 kg/m3 and can range up to 4 ,4 8 5 kg/m3. Aggregates from Industrial By-Products and Waste Air-cooled blast furnace slag (ACBFS) aggregate: Blast furnace slag is a by-product obtained during the production of steel from pig iron in a blast furnace. ACBFS is produced through relatively slow solidification of molten blast furnace slag under atmospheric conditions. Compared to a naturally derived aggregate, ACBFS has: -higher porosity and absorption -low specific gravity -high Los Angeles abrasion loss, and -high sulphate and sulphur content Recycled aggregate: Utilizing the recycled aggregates and clean fill materials obtained from such demolition and renewal from constructing roads, buildings, and other structures are beneficial by reducing the amount of materials from demolition to be disposed in places like landfills. Two main sources of recycled aggregates: - aggregate from Reclaimed Asphalt Pavement (RAP) -building demolition waste Reclaimed Asphalt Pavement (RAP) -mainly used for making Hot Mix Asphalt (HMA) by blending it with virgin aggregate. The asphalt cement coating on the RAP material has the beneficial effect of reducing the asphalt cement binder required for the HMA. Aggregate from building demolition waste -Building demolition waste is generally crushed and screened similar to RAP before reuse. The resulting aggregate, also referred to as a crushed concrete, could be used in PCC or in the construction of road base/subbase as either cement-stabilized or unbound material. This recycled aggregate could also be blended with virgin aggregate to satisfy the specification requirement such as gradation and density for a particular application.  Handling, transportation and storage of aggregates  Aggregate used Civil engineering construction generally consists of particles of different sizes and shapes. Aggregate particles tend to segregate such that bigger size particles move to the bottom and the smaller ones get near the surface, when they roll down the slope of a stockpile or when tipped off a transporting truck. Tips for Managing and Storing Aggregate Materials: 1.Keep materials dry 2. Use the right container 3. Monitor inventory levels 4. Use the right equipment 5. Follow proper handling and safety procedures References: Kultermann, E. and Spence, William. (2 0 1 7 ). Construction Materials, Methods, and Techniques: Building a sustainable future. 4 th Edition. Australia: Cencage Learning Sivakugan, N., et al. (2 0 1 8 ) Civil Engineering materials (International Ed.). Australia: Cengage Learning Thank you for listening!