Experimental Study of Compressive Strength and Flexural Strength of Standard Concrete by using Metakaolin as Mineral Admixture

Abstract

This experimental study investigates the influence of metakaolin as a mineral admixture on the compressive strength and flexural strength of standard concrete (M-25). Metakaolin, a highly reactive pozzolanic material, was introduced as a partial replacement for cement by weight. Metakaolin is a valuable addition to many concrete mixes. It can improve the strength, durability, and resistance of concrete, making it a more versatile and sustainable material. Here are some of the key properties of metakaolin: • High pozzolanic activity: Metakaolin is a highly reactive pozzolan, which means that it reacts with calcium hydroxide to form a gel that binds the concrete particles together. This gel helps to improve the strength, durability, and resistance of concrete. • Fine particle size: The particle size of metakaolin is smaller than the particle size of cement, which means that it can fill the voids in the concrete matrix and improve the density of the concrete. • High surface area: The high surface area of metakaolin also contributes to its pozzolanic activity. The larger surface area provides more sites for the reaction between metakaolin and calcium hydroxide to take place. • Low water content: Metakaolin has a low water content, which means that it does not contribute to the water-to-cement ratio of the concrete. This helps to improve the strength and durability of the concrete. • Chemical resistance: Metakaolin is resistant to a variety of chemicals, including acids, alkalis, and salts. This makes it a good choice for use in concrete that will be exposed to harsh environments. • Heat resistance: Metakaolin is also resistant to high temperatures. This makes it a good choice for use in refractory materials and other high-temperature applications. The research aimed to assess the impact of metakaolin on the mechanical properties of concrete, with a focus on its ability to enhance compressive The research aimed to assess the impact of metakaolin on the mechanical properties of concrete, with a focus on its ability to enhance compressive strength and flexural strength. The study involved the preparation of M-25 grade of concrete mixes with PPC 33 grade cement, locally available sand and aggregate with varying metakaolin proportions, ranging 10%, 20% and 30% by weight of cement. Specimens were cast and cured under controlled laboratory conditions. Compressive strength tests were conducted on cubical specimens, and test after 7 and 28 days and flexural strength tests were conducted on beam specimens, and test after 28 days respectively. Results revealed that the inclusion of 10% and 20% of metakaolin led to improves the 28 days compressive strength and flexural strength by 3.33% and 5.34% as compared to normal concrete respectively. The increase in strength is attributed to the pozzolanic reaction between metakaolin and calcium hydroxide, resulting in improved microstructure and reduced pore size within the concrete matrix.