Paper Contents
Abstract
Concrete has taken hold of the world of infrastructure incredibly quickly. It has become the most commonly used man-made material in construction industry. Cracks are formed in concrete as concrete is weak in tension. These cracks allow moisture and different types of chemicals into concrete and decrease its durability and strength. Nowadays repair, rehabilitation, and maintenance of structures is expensive and time-consuming. So to overcome this problem autonomous self-healing mechanism is introduced in concrete which helps to repair cracks and also improves the strength of the concrete. To prepare self-healing concrete there are two methods- The first is biological method. In this method, Bacillus Subtilis bacteria and Calcium lactate was added to the concrete mix. The production of calcium carbonate in bacterial concrete is limited to the calcium content in cement. Hence calcium lactate is externally added to be an additional source of calcium in the concrete. When cracks appear the bacteria will produce limestone and fills the cracks. This bio concrete possesses quality to repair itself and thus increasing the sustainability of concrete. The second method of self-healing concrete is a chemical method. The chemical like Sodium silicate is used to prepare self-healing concrete. In the present study for bacterial concrete Bacillus Subtilis bacterium solution of 2108cfuml concentration with 2%, 3% and 4% water replacement was mixed to concrete. For the preparation of concrete by chemical method polyethylene glycol and sodium silicate chemicals were added to the water in concrete with varying percentages i.e. 2%, 3% and 4%. The sodium silicate added will react with calcium hydroxide and forms sodium silica hydrate (N-S-H) which is a gel that has the capacity to heal the cracks.The compressive strength test, split tensile strength test and flexural rigidity test were conducted on the specimens of nominal concrete, bacteria concrete and chemical concrete to understand the mechanical properties and rate of self-healing in concrete. Experimental results reveal bacterial concrete and chemical concrete after 28 days of curing attained better mechanical properties when compared to nominal concrete. To determine the self-healing ability artificial cracks were created on the specimens. These cracked specimens were kept in water for curing and bacterial concrete specimens were healed after 28 days of curing and it took 32 days in the case of concrete used with chemicals. After healing of cracked specimens they are tested and it was found that 4% proportion of bacteria concrete attained maximum strength.
Copyright
Copyright © 2023 Dhanush.C.S. This is an open access article distributed under the Creative Commons Attribution License.
