Describe the different particle shape and surface texture of aggregate Assignment

Describe the different particle shape and surface texture of aggregate and discuss its importance - Assignment Example Natural aggregates are extracted from large rocks found on the surface and underground, manufactured aggregate is a product of the manufacturing industries, and recycled aggregates come from by-products of industries (Best 1978). The particle shape of aggregates has two properties: Roundness and its Spherical shape. Roundness is the relative sharpness or angularity of the particle corners and edges. Sphericalness can be termed as the measure of whether the particle is compact in shape. In other words, if it is close to being a cube or a sphere as opposed to being elongated or flat (disk-like). The higher the sphericalness of the particle the closer it is to being a sphere or a cube and the lower its surface area will be. The smaller the surface area of the particle, the lesser the amounts of water needed for mixing and the lower the amount of sand need to achieve desired workability. The aggregate shape can affect the properties of concrete in both the hardened and plastic states. The shapes vary from rounded to angular. The form of the aggregates can be assessed by observation and the classification in accordance with the table below. Surface texture is a term used to describe the roughness and level of irregularity of the particle surface. Generally, terms such as granular, rough, smooth, glassy, or crystalline are used to describe the surface texture of an aggregate rather than using any scientific or quantitative method (Kandhal et al., 1998). The surface texture of aggregates affects the properties of concrete in both hardened and the plastic state. Smooth particles will need less water for mixing and, therefore, cement material at a fixed water-cement ratio. Consequently, it produces concrete that has the desired workability, but at the same time, it will have less area to bond with the cement paste than rougher particle (American Concrete Institute 2005). The surface texture and shape of particles of