CE 405 Construction Materials & Testing Preliminary Notes PDF

CE 405: CONSTRUACTION MATERIALS AND TESTING 1.2.1 LOADING CONDITIONS PRELIM NOTES  The two basic types of loads are static and dynamic. Eac...

CE 405: CONSTRUACTION MATERIALS AND TESTING 1.2.1 LOADING CONDITIONS PRELIM NOTES  The two basic types of loads are static and dynamic. Each type affects the material differently, and LESSON 1: ENGINEERING BEHAVIOR OF MATERIALS frequently the interactions between the load types are important. Civil engineers encounter both when INTRODUCTION designing a structure. A basic function of civil and construction engineering is to  Static loading implies a sustained loading of the provide and maintain the infrastructure needs of society. The structure over a period of time. Once applied, the static infrastructure includes buildings, water treatment and load may remain in place or be removed slowly distribution systems, waste water removal and processing,  Loads that generate a shock or vibration in the dams, and highway and airport bridges and pavements. structure are dynamic loads. Dynamic loads can be classified as periodic, random, or transient. Although some civil and construction engineers are involved in the planning process, most are concerned with the design, construction, and maintenance of facilities. The common denominator among these responsibilities is the need to understand the behavior and performance of materials. MATERIAL ENGINEERING CONCEPT  Materials engineers are responsible for the selection, specification, and quality control of materials to be used in a job. These materials must meet certain classes of criteria or materials properties (Ashby and Jones, 2011).  In addition to this traditional list of criteria, civil engineers must be concerned with environmental quality. In 1997, the ASCE Code of Ethics was modified to include “sustainable development” as an ethics issue.  Civil and construction engineers must be familiar with materials used in the construction of a wide range of structures. Materials most frequently used include 1.2.1 STRESS-STRAIN RELATIONSHIP steel, aggregate, concrete, masonry, asphalt, and Materials deform in response to loads or forces. In 1678, Robert wood. Materials used to a lesser extent include Hooke published the first findings that documented a linear aluminum, glass, plastics, and fiber-reinforced relationship between the amount of force applied to a member composites. and its deformation. The amount of deformation is proportional to the properties of the material and its dimensions. I.I ECONOMIC FACTORS The economics of the material selection process are affected by The effect of the dimensions can be normalized. Dividing the much more than just the cost of the material. Factors that should force by the cross-sectional area of the specimen normalizes the be considered in the selection of the material include: effect of the loaded area. The force per unit area is defined as  AVAILABILITY AND COST OF RAW MATERIALS the stress in the specimen (i.e., s = force/area). Dividing the deformation by the original length is defined as strain ? of the specimen (i.e., e = change in length/original length) 1.2.3 ELASTIC BEHAVIOR If a material exhibits true elastic behavior, it must have an instantaneous response (deformation) to load, and the material must return to its original shape when the load is removed. Many materials, including most metals, exhibit elastic behavior, atleast at low stress levels. Elastic deformation does not change the  MANUFACTURING COST arrangement of atoms within the material, but rather it stretches  TRANSPORTATION COST the bonds between atoms. When the load is removed, the  PLACING atomic bonds return to their original position  MAINTENANCE Young observed that different elastic materials have different proportional constants between stress and strain. For a 1.2 MECHANICAL PROPERTIES homogeneous, isotropic, and linear elastic material, the The mechanical behavior of materials is the response of the proportional constant between normal stress and normal strain material to external loads. All materials deform in response to of an axially loaded member is the modulus of elasticity or loads; however, the specific response of a material depends on Young’s modulus, E, and is equal to its properties, the magnitude and type of load, and the geometry In the axial tension test, as the material is elongated, there is a of the element. reduction of the cross section in the lateral direction. In the axial compression test, the opposite is true. The ratio of the lateral Whether the material “fails” under the load conditions depends strain, ?l, to the axial strain, ?a, is Poisson’s ratio on the failure criterion. Catastrophic failure of a structural member, resulting in the collapse of the structure, is an obvious material failure  LESSON 1.1 GENERAL PHYSICAL PROPERTIES OF MATERIALS 1.1 DENSITY (DRY) Is the dry mass per unit volume of a substance under absolute 1.2.4 ELASTROPLASTIC BEHAVIOR compact condition. For some materials, as the stress applied on the specimen is increased, the strain will proportionally increase up to a point; after this point, the strain will increase with little additional stress. In this case, the material exhibits linear elastic behavior followed by plastic response. 1.2 BULK DENSITY 1.2.5 VISCOELASTIC BEHAVIOR Refers to the mass per unit volume of the substance under This is an assumption for elastic and elastoplastic materials. conditions that powdery or granular materials are packed. It is However, no material has this property under all conditions. In the mass of a unit volume of materials in the natural state. some cases, materials exhibit both viscous and elastic responses, which are known as viscoelastic. Typical viscoelastic materials used in construction applications are asphalt and plastics. 1.3 DENSITY INDEX TIME-DEPENDENT RESPONSE - Viscoelastic materials have The ratio of bulk density and density. It indicates the degree to a delayed response to load application. For example, Figure which the volume of the material is filled with solid matter. 1.8(a) shows a sinusoidal axial load applied on a viscoelastic material, such as asphalt concrete, versus time. Figure 1.8(b) shows the resulting deformation versus time. 1.3 NON MECHANICAL PROPERTIES 1.3 UNIT WEIGHT Nonmechanical properties refer to characteristics of the Is the weight of the material per unit volume. material, other than load response, that affect selection, use, and performance. There are several types of properties that are of interest to engineers, but those of the greatest con 1.3 DENSITY AND UNIT WEIGHT  Density is the mass per unit volume of material.  Unit weight is the weight per unit volume of material. 1.4 TRUE OR ABSOLUTE SPECIFIC GRAVITY  Specific gravity is the ratio of the mass of a substance If both the permeable voids are excluded for determining the relative to the mass of an equal volume of water at a true volume of solids, the specific gravity obtained is called the specified temperature. true or absolute specific gravity. 1.3.2 THERMAL EXPANSION The coefficient of thermal expansion is very important in the design of structures. Generally, structures are composed of many materials that are bound together. If the coefficients of thermal expansion are different, the materials will strain at 1.5 APPARENT OR MASS SPECIFIC GRAVITY different rates. The material with the lesser expansion will If both the permeable and impermeable voids included to restrict the straining of other materials. This constraining effect determine the true volume of solids. will cause stresses in the materials that can lead directly to fracture. 1.6 POROSITY Is defined as the ratio of the total pore volume to the apparent volume. 1.3.3 SURFACE CHARACTERISTICS Corrosion and Degradation - Nearly all materials deteriorate over their service lives. The mechanisms contributing to the deterioration of a material differ depending on the characteristics of the material and the environment. Abrasion and Wear Resistance - Since most structures in civil engineering are static, the abrasion or wear resistance is of less importance than in other fields of engineering. For example, mechanical engineers must be concerned with the wear of parts in the design of machinery. 1.7 VOIDS  ASTM D 854 - AASHTO T100: Specific Gravity of Soils Empty space in the materials AGGREGATES  Aggregates are used primarily as an underlying material for foundations and pavements as rip-rap for erosion control, and as ingredients in portland cement and asphalt layers. Aggregate underlying materials, or base courses, can add stability to a structure, provide a drainage layer, and protect the structure from frost 1.8 HYGROSCOPICITY damage. Ability of the material to absorb water vapor from the air.  In portland cement concrete, aggregates comprise Moisture content is the percentage of the water contained in a around 75% to 85% of the weight and 60% to 75% of material to its dry mass. the volume. They act as a filler to reduce the amount of cement paste needed in the mix.  In asphalt concrete, aggregates constitute 75% to 85% of the volume and 92% to 96% of the mass. 1.9 WATER ABSORPTION QUALITY TEST FOR AGGREGATES Refers to the percentage of the absorbed water’s volume to the materials natural volume. When the material absorbs water to saturation. LESSON 1.2: CIVIL ENGINEERING MATERIALS USED IN CONSTRUCTION  All structures have to be founded on the ground, and this requires a good understanding of soil, rocks, and PORTLAND CEMENT aggregates.  Portland cement concrete is the most widely used  Concrete and steel are two of the most used materials manufactured construction material in the world. in civil engineering for construction of building and  Portland cement is an instant glue (just add water) that bridges. bonds aggregates together to make portland cement  In spite of the lower load carrying capacity compared concrete. to steel or concrete and shrinking supplies worldwide,  Production of portland cement starts with two basic raw timber is still being used as a building material. ingredients: a calcareous material and an argillaceous  Aggregates, asphalt and bitumen are used widely in material. roadwork.  The raw materials used to manufacture portland  Geosynthetics are becoming increasingly popular in cement are lime, silica, alumina, and iron oxide. roadwork and slopes, and new products are coming  Since hydration starts at the surface of cement into the market every year. particles, the finer the cement particles, the larger the  Metals, polymer, and composites also have their surface area and the faster the hydration. place in civil engineering construction. QUALITY TEST FOR PORTLAND CEMENT SOIL  ASTM C 451: Standard Test Method for Early  Soils, rocks, and aggregates are natural materials of Stiffening of Hydraulic Cement (Paste Method) geologic origin, fondly known as Geomaterials.  ASTM C 359: Standard Test Method for Early  Soils are used as construction materials in roadwork Stiffening of Hydraulic-Cement (Mortar Method) and embankments and as backfills behind retaining  ASTM C 150: Standard Specification for Portland walls and in trenches where pipelines are buried. Cement  Soils are different from other engineering materials  ASTM C 109: Standard Test Method for Compressive since they cover large areas and volumes and are Strength of Hydraulic Cement Mortars (Using 2-in. or often heterogeneous; it means that it can vary within [50-mm] Cube Specimens) few meters laterally and vertically. CONCRETE QUALITY TEST FOR SOIL  Civil and construction engineers are directly Soil Classification and Compaction (SOL) Samples responsible for the quality control of portland cement  ASTM D 422 - AASHTO T88: Particle Size Analysis of concrete and the proportions of the components used Soils in it.  ASTM D 4318 - AASHTO T89: Determining the Liquid  The quality of the hydration is governed by the Limit of Soils chemical composition of the portland cement,  ASTM D 4318 - AASHTO T90: Determining the Plastic concrete, and development of microstructure, Limit and Plasticity Index of Soils admixtures, and aggregate characteristics.   The quality is strongly affected by placement,  The wood produced in one growing season constitutes consolidation, and curing as well. a single growth ring.  Each annual ring is composed of earlywood, produced QUALITY TEST FOR CONCRETE by rapid growth during the spring, and latewood from  ASTM C 143: Standard Test Method for Slump of summer growth. Hydraulic Cement Concrete  Wood is composed of cellulose, lignin, hemicellulose,  AASHTO T 126: Standard Method of Test for Making extractives, and ash-producing minerals. Cellulose and Curing Concrete Test Specimens in the Laboratory accounts for approximately 50% of the wood  ASTM C 39: Compressive Testing for Concrete substance by weight. Cylinders QUALITY TEST FOR WOOD MASONRY  ASTM D 245-06: Standard practice for establishing  A masonry structure is formed by combining masonry structural grades and related allowable properties for units, such as stone, blocks, or brick, with mortar. visually graded lumber.  Masonry is one of the oldest construction materials.  ASTM D 143-21: Standard test methods for small clear Examples of ancient masonry structures include the specimens of timber. pyramids of Egypt, the Great Wall of China, and Greek  ASTM D 198-21A: Standard test methods of static and Roman ruins. tests of lumber in structural sizes.  Concrete Masonry Units can be either solid or hollow clay bricks, glass blocks, and stone are typically solid.  Concrete masonry units are manufactured using a relatively dry (zero-slump) concrete mixture consisting of Portland cement, aggregates, water, and admixtures. QUALITY TEST FOR MASONRY  ASTM C 90: Standard Specification for Loadbearing Concrete Masonry Units  ASTM C 150: Standard Specification for Portland Cement STEEL  Steel and steel alloys are widely used in civil engineering.  Wrought iron is used on a smaller scale for pipes and general blacksmith work.  Cast iron is used for pipes, hardware, and machine parts that are not subjected to tensile or dynamic loading.  The properties of steel can be altered by applying various heat treatments. QUALITY TEST FOR STEEL  ASTM A370: Standard test methods and definitions for mechanical testing of steel products. ASPHALT  Asphalt binders were used in 3000 B.C., preceding the use of the wheel by 1000 years.  Asphalt is used mostly in pavement construction but is also used as sealing and waterproofing agents.  The characteristics of asphalt depend on the chemical composition and the distribution of the molecular weight hydrocarbons.  Asphalt concrete is also used in patching and repairing both asphalt and portland cement concrete pavements. QUALITY TEST FOR ASPHALT  ASTM D 946: Standard specification for penetration- graded asphalt binder for use in pavement construction. WOOD  Wood, because of its availability, relatively low cost, ease of use, and durability (if properly designed), continues to be an important civil engineering material.