L.H. Anneza

Calcium Lactate addition in Bioconcrete: Effect on Compressive strength and Water penetration

This paper presents compressive strength and water penetration of bioconcrete with addition of calcium lactate. Bioconcrete has higher engineering concrete properties and durability compared to normal concrete but the natural production of calcium carbonate is limited to the calcium content in cement. Therefore, additional calcium is added as an additional calcium source to study the influence towards compressive strength and water penetration. The bacteria used in this research are Enterococcus faecalis and Bacillus sp . Calcium lactate was added into concrete mix in concentrations of 0.001mol/l, 0.005mol/l and 0.01mol/l of liquid used. The concentration of bacteria added into the mix is by partial replacement of water used in casting, which are 3% for Enterococcus faecalis and 5% for Bacillus sp . Both compressive strength and water penetration test used cubes of 150mm × 150mm × 150mm. The cubes were tested after 28 days. The result of compressive strength for control is 36 MPa while partial replacement of bacteria yields 38.2 MPa for 3% Enterococcus faecalis and 37.0 MPa for 5% Bacillus sp . Calcium lactate with 0.005 mol/L has the best performance with 42.8 MPa for Enterococcus faecalis and 39.6 MPa for Bacillus sp . Whereas for water penetration, the best concentration of calcium lactate which yielded the lowest water penetration is 0.01 mol/l for both Enterococcus faecalis and Bacillus sp which are 8.7 cm and 8 cm respectively. The addition of calcium lactate into bioconcrete is quite promising for improvement of concrete properties and durability.

Compressive Strength and Water Penetration of Concrete with Enterococcus faecalis and Calcium Lactate

This paper presents the compressive strength and water penetration of Bioconcrete with calcium lactate. The bacteria used in this concrete is Enterococcus faecalis, which was isolated and enriched to suit the concrete environment. Bioconcrete is a sustainable and environmentally friendly method to improve concrete properties, but the natural production of calcite by the bacteria is limited. Therefore, the objective of this research is to add in calcium lactate as additional food source for the bacteria and determine the effect on the compressive strength and water penetration of concrete. The Bioconcrete is fabricated in the standard size of 150mm × 150mm × 150mm cubes. The calcium lactate added into the mix is in concentrations of 0.001 mol/l, 0.005mol/l and 0.01 mol/l measured according to the amount of water used in fabrication. Both compressive strength and water penetration is tested after the 28th day by using Universal Testing Machine (UTM) and Water Permeability testing machine respectively. It is found that by adding calcium lactate into Bioconcrete, the compressive strength improves by a maximum of 16.4% which is 41.9 Mpa using the concentrations of 0.005 mol/l of calcium lactate. Compared to control which was 36 Mpa and concrete with only Enterococcus faecalis of 38.2 Mpa. The water penetration has a similar trend of decreasing the water penetration of concrete with Enterococcus faecalis and calcium lactate. A maximum decrease of water penetration is from calcium lactate of concentration 0.01 mol/l of 26.2% which is 8.7 cm compared to control of 11.8 cm and concrete with only Enterococcus faecalis of 9.2 cm. Adding calcium lactate as an additional food source for bacteria in concrete has positive results and further study with the same concept is encouraging

Isolation and Identification of Concrete Environment Bacteria

This paper presents the isolation and molecular method for bacteria identification through PCR and DNA sequencing. Identification of the bacteria species is required in order to fully utilize the bacterium capability for precipitation of calcium carbonate in concrete. This process is to enable the addition of suitable catalyst according to the bacterium enzymatic pathway that is known through the bacteria species used. The objective of this study is to isolate, enriched and identify the bacteria species. The bacteria in this study was isolated from fresh urine and acid mine drainage water, Kota Tinggi, Johor. Enrichment of the isolated bacteria was conducted to ensure the bacteria survivability in concrete. The identification of bacteria species was done through polymerase chain reaction (PCR) and rRDNA sequencing. The isolation and enrichment of the bacteria was done successfully. Whereas, the results for bacteria identification showed that the isolated bacteria strains are Bacillus sp and Enterococus faecalis.