Materials Testing is conducted for many reasons. It can provide data regarding tested materials, prototypes and other product samples.
Regulation of Industrial Materials
The integrity of bridges, dams, nuclear reactors, roads, buildings and other infrastructure relies on the parts that make them up. Given the importance of this, the government enforces standards to ensure all structures and/or surfaces meet safety requirements. Materials testing plays a key role in fulfilling those requirements.
Concrete and Aggregate
Concrete and aggregate that is used in construction projects need to meet strict regulations and quality standards. Testing helps ensure compliance and quality. It also helps evaluate the performance of available materials. Concrete is made up of three primary components: water, aggregate, and cement. Aggregates refer to particulate materials that are used in construction such as sand, gravel, crushed stone, slag, and silt. The standard materials that are used in producing cement are limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore. These ingredients are heated at high temperatures to form a rock-like substance that is ground after into fine powder. Concrete is then formed when Portland cement is combined with water, sand, and rock to harden.
Testing equipment and accessories used for testing concrete and aggregates should conform to the American Society for Testing and Materials(ASTM), American Association of State Highway and Transportation Officials(AASHTO) and other applicable standards. The process of concrete testing includes but is not limited to curing, and strength measurement. The aggregates are examined for durability, grading, particle shape, particle surface, texture, abrasion, skid resistance, and voids.
Asphalt or bitumen is a sticky, black semi-solid bituminous material that comes from natural deposits. It can also be made from the synthetic distillation of petroleum. Asphalt binds mixed aggregates creating asphalt concrete that is mostly used for roofing, paving and road construction. It is estimated that there are approximately 102 million tonnes of asphalt that are being used in the world per year. A high percentage of material produced is used for asphalt concrete for roads, airport runways, car parks, and footways. The following are more applications of asphalt: waterproofing, sealing, insulating purposes, pipe coatings, carpet tile backing, damp proofing, soundproofing, pipe or cable coating, paint application, newspaper ink production, reservoir and pool linings.
Mix designs for asphalt are formulated in the lab, then carefully tested to produce hot-mix asphalt for a wide variety of paving applications. The performance of asphalt pavements must continuously improve to meet the growing demand in the transportation industry. Modern asphalt pavements must resist rutting, thermal variations, high load cycles, hydraulic pressures from water, and more. Testing asphalt for characteristics such as air void content, density, shear strength, stiffness and fatigue resistance provides assurances that this construction material is up to the task.
Producing pavement mixes with long life and low maintenance costs begins with extensive testing. Aggregates, binder types, and additives are evaluated separately before finding the correct proportions for blending. Once a suitable mix design has been established, quality control and testing can now assure the installation of the proper pavement.
Soils are classified by their chemical composition and particle size distribution. Gravel, sand, and silt are the larger soil particles. Their mineralogy is often inherited from their parent material. Soils may also include products of weathering or residues of plant and animal life. Quartz is the most common mineral in the sand or silt fraction because of its resistant to chemical weathering. The other common minerals are feldspars, micas and ferromagnesian minerals like pyroxenes, amphiboles, and olivines. Clay is the most active mineral component of soil because of its high specific surface area and its unbalanced negative charge. Many soil minerals like gypsum, carbonates, or quartz are small enough to be classified as clay based on their physical size, but chemically they do not possess the same value as clay minerals do.
Soil material is a critical component of the mining, construction, and landscape development industries. Soil acts as a foundation for most construction projects. The movement of massive volumes of soil can be involved in surface mining, road building, and dam construction. Earth sheltering is an architectural practice of using soil for external thermal mass against building walls. Many building materials are actually soil based.
Soil consistency is useful in estimating the ability of soil in supporting buildings and roads. Testing the soil determines its suitability and whether it can accommodate your construction project. Check for its strength, density, compaction, contamination, organics, and sand content so you can asses their impact on your construction project.
Materials testing helps to understand, certify and check if a particular material is suitable for a specific application. The materials must meet the standards and other stringent criteria before they are put into use. The process may include characterizing the properties and verifying the composition or elemental content of the material.
Testing is essential for anyone who is committed to providing reliable products while minimizing damage and expenses. Materials testing happens early on during product development to evaluate a planned production process. The testing process plays a significant role in failure analysis investigation, mainly to help identify defective products, substandard materials and most of all, the cause of failure.
Encyclopedia of Soil Science, Edited By WARD CHESWORTH University of Guelph Canada
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