REVIEW OF THE EFFECTS OF GEOLOGICAL AGGREGATE PROPERTIES ON THE WORKABILITY OF HIGH-STRENGTH CONCRETE

REVIEW OF THE EFFECTS OF GEOLOGICAL AGGREGATE PROPERTIES ON THE WORKABILITY OF HIGH-STRENGTH CONCRETE

Y Gopi1, I Aravind2

1PG Schoolar, Dept. of Civil Engineering, ST.Mary’s Group of Institutions, Affiliated to JNTUK, Guntur, A.P, India-522212.

2Assistant Professor, HOD of Civil Engineering, ST.Mary’s Group of Institutions, Affiliated to JNTUK, Guntur, A.P, India-522212.

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Abstract - Aggregate makes roughly 60–80% of the volume of concrete and is an essential component. They make concrete more substantial, lessen its shrinkage, and also have an economic impact. Plus, it has always been thought of as an inert filler material and is very cheap compared to other components. Consequently, the necessary emphasis on understanding the potential impact of aggregates on concrete characteristics was lacking. As a result, learning more about aggregate is crucial for making concrete with the right properties. The proportions of the concrete mix, the qualities of freshly mixed concrete, and the strength, dimensional stability, and longevity of the concrete are all greatly affected by the aggregates' characteristics. As a result, this research aims to investigate how aggregate geology affects concrete's performance. In this research, five different kinds of coarse aggregates were examined for their geological properties and how they impact the performance of concrete. These aggregates are Grey Granite (GG), Anorthosite (AS), Charnockite (CK), Limestone (LS), and Gneiss (GS). Researchers looked examined the aggregates' mineralogical composition, mineral proportions, texture, structural features, and other geological traits. M30, M50, and M80 grades of concrete were subsequently developed by combining different kinds of aggregates in concrete mixtures. It took 28 days for the concrete examples to cure after casting. We measured the compressive, split tensile, flexural, modulus of elasticity, impact, fracture, and rupture energies of the curing specimens, as well as the structural behaviour of the concrete and the coarse aggregate RPCA. Concrete mixes containing GG, AS, CK, or GS aggregates with a rough surface had worse workability compared to mixes using LS aggregates with a smooth surface, according to the findings. Aggregate texture determines surface roughness. The compressive strength of high strength concrete (HSC) concrete mixes (M80 grade) formed of various aggregates varied greatly (72 to 89 MPa), suggesting that the aggregates' geological properties significantly affected the compressive strength of HSC, but had no effect on normal strength concrete (NSC). After the AS, CK, LS, and GS mixes, the GG mix showed the greatest compressive strength. As concrete's compressive strength has increased, it has been easier to mix concrete of varying grades using the same particles. The compressive strength of concrete mixes of the same grade but with various aggregates showed large differences, suggesting that the aggregates' geological properties were the most important factor. Tensile and flexural strengths, modulus of elasticity, impact and fracture energies, RPCA, and structural performance of concrete all followed a similar pattern. Because of their roughness, GG, AS, CK, and GS aggregates showed a relatively rough surface, which improved mechanical contact with the matrix and increased concrete strength. But the flat surface of limestone aggregate makes it unable to provide concrete a greater mechanical connection. The increased compressive strength of AS, GG, and CK aggregates was caused by the minerals present, the percentage of minerals, the texture, and the structure. In order to increase the concrete's strength, these particles provide a greater physical connection with the matrix. Concrete was not as strong because to the lower compressive strength of the limestone and gneiss. The changes in the texture, mineralogy, mineral proportion, Significant differences in concrete characteristics were caused by the hardness of minerals and the structure of particles. Because their properties meet the requirements outlined in BIS -383, the aforementioned coarse aggregates may be used to make NSC. The findings clearly show that in order to make M80 grade concrete, the only acceptable coarse aggregates are grey granite, anorthosite, and charnockite; limestone and gneiss are not acceptable. Therefore, while choosing aggregates to make High Strength Concrete, it is crucial to think about the aggregates' geological properties.

Key Words:  Aggregates, Structural Behaviour, Compressive Test, Split Tensile Test, Flexural Test, Modulus of Elasticity Test, Impact Test, Fracture Test, Rupture Energies.