WHAT MAKES GOOD AGGREGATE MATERIALS FOR CONCRETE AND WHY ARE THEY IMPORTANT?
In every construction project involving the use of concrete, the incorporation of aggregates as filler material is indispensable. Aggregate materials, such as sand, crushed stone, and gravel, play a crucial role in the creation of concrete, as water and cement alone cannot produce concrete in a cost-effective manner.
Given the paramount significance of aggregates, it is imperative to possess the knowledge and ability to select suitable aggregates that meet the specific requirements of the construction project. Understanding the fundamental reasons behind the importance of aggregates will also foster a greater appreciation for their value in construction endeavors. This article elucidates the characteristics of good aggregates and highlights their significance.
Characteristics of Good Aggregates:
Non-Chert and Non-Friable Aggregates: Aggregates should not comprise chert, as it exhibits minimal resistance to weathering and may result in popouts. Additionally, friable aggregates, which are prone to splitting, should be avoided.
Varied Fraction Sizes: Good aggregates must encompass a range of particle sizes to facilitate adequate compaction, thereby minimizing voids within the concrete and enhancing its density.
Absence of Flaky Particles: Aggregates should not contain particles that have been elongated by more than 35% of their original size.
Limited Moisture Retention: Good aggregates should retain moisture below 10% of their weight after submersion in water for 24 hours.
Non-Porous, Hard, Chemically Inert, and Strong: Desirable aggregates possess non-porous qualities, are hard and chemically inert, and exhibit substantial strength.
Appropriate Coarse Aggregate Size: Coarse aggregates should fall within the size range of 1/8 inch to 2 inches (3 mm to 50 mm). Aggregates larger than 3 inches (76 mm) are generally deemed unsuitable.
Preferably Cubical and Angular Shape: While coarse aggregates with a fairly cubical and angular shape are desirable, broken stone or gravel aggregates with a non-glassy and rough texture are even more preferable.
Freedom from Organic Materials and Dirt Coating: Good aggregates must be free from organic matter or dirt coating, as such impurities can compromise the durability of the resulting concrete.
To maximize the efficient utilization of good aggregates, it is recommended to combine different sizes. Furthermore, achieving higher concrete density can be accomplished by employing a combination of coarse and fine aggregates in ratios of 70:30 or 60:40.
Importance of Good Aggregates in Concrete:
Aggregates play a pivotal role in augmenting the durability of concrete mixes while simultaneously reducing production costs. Typically, aggregates constitute 60% to 75% of the total volume of concrete due to their ability to solidify the mixture. As aggregates significantly contribute to the composition of concrete, they enhance its density, water resistance, dimensional stability, and alter its heat retention characteristics.
These exceptional attributes of aggregates have rendered them indispensable in various construction materials, including mortar, concrete, and asphalt. Consequently, the utilization of aggregates has become unavoidable in the construction of roads, railway tracks, buildings, sidewalks, airport runways, drainage systems, erosion control structures, water filtration mechanisms, and parking lots. Construction companies also employ aggregates as fillers in embankment and site preparation projects.
If you are about to begin a construction project and looking to purchase aggregates in large or small amounts, please feel free to give us a call for let us advice of the most suitable product for your specific requirements.