Mechanical properties of concrete with Enter-ococcus faecalis and calcium lactate

摘要

Concrete is an important material used globally, diverse as it can be applied in all construction type or modify to be apply in specialize construction fields. Adding bacteria in concrete can improve the concrete properties and increase durability due deposited calcite by bacteria. However, calcite deposition by bacteria is limited by calcium available in cement. The objective of this research is to determine the effect of adding calcium lactate as an additional calcium source and bacteria on the concrete properties. The bacteria used is locally isolated and enriched to suite concrete environment. The type of the bacteria used is identified as Enterococcus faecalis. The calcium lactate is added into concrete mix with concentrations of 0.001 mol/1, 0.005 mol/1 and 0.01 mol/1. Whereas, the bacteria is added as 3% Enterococcus Faecalis. Mechanical properties test such as compressive strength, flexural strength and tensile strength was conducted. Cubes of size 150mm × 150mm × 150mm were prepared for compressive strength test while of Dia 150mm by 300mm cylinder were prepared for tensile strength test. Flexural strength test was performed on prism of size 100mm × 100mm × 500mm. The result of compressive strength shows that adding Enterococcus faecalis with 0.005 mol/1 of calcium lactate gave the highest strength of 42.8 MPa compared to control of 36 MPa. The tensile strength and flexural strength has a similar trend as compressive strength results.Where, both results were optimum with 0.005 mol/1 concentration of calcium lactate . The result of tensile strength shows that Enterococcus faecaliswith 0.005 mol/1 obtained 3.18 MPa compared to control of 2.54 MPa. Flexural strength test result was 6.67 MPa for Enterococcus faecalis with 0.005 mol/1 compared to control of 4.78 MPa. The overall results of bacteria with added calcium lactate showed promising result and further study on self healing capability is encouraging.