Corrosion resistance studies on the concrete made with basalt fibres and basalt fibre reinforced rebars

In the present work, assessment of corrosion resistance for M30 grade concrete made with basalt fibres in terms of Resistivity, Potentials and Chloride ion diffusion is made to understand the corrosion resistance studies of concrete specimen made with basalt fibre and BFRP bars. The time of total charge passing till full crack failure for different effective covers considered is more for M30 grade concrete beams made with basalt fibres and BFRP rebars. The time of total charge passing at failure in M30 grade concrete beams made with basalt fibres and BFRP rebars is more because beam specimens did not develop any fissures or micro cracks. Measured electrical resistivity values of M30 grade concrete beams made with basalt fibres have shown high electrical resistance indicating their superior corrosion inhibition ability. M30 grade concrete beams made with basalt fibres and BFRP rebars used for the study exhibited very less probability (less than 5% probability) for corrosion at 28 days.


Introduction
Corrosion is major issue in reinforced concrete structure made with steel rebars. So there are various mechanisms using which the corrosion in reinforced concrete structures can be prevented. Basalt fibre are obtained from basalt rock so no corrosion can occur in basalt fibres. Basalt fibre reinforced polymer bars are made from the basalt fibres and glued into the form of bars using polymer as glue. So, in this current study, concrete specimens are prepared with basalt fibres and basalt bar embedded at the centre and various corrosion presence studies are carried out.

Methodology
For this study, basalt fibre length of 36mm and dosage of 0.4% fibre volume of the concrete is considered as optimum based on previous studies and is used for further studies. M30 grade concrete samples are made with basalt fibres and basalt fibre reinforced polymer (BFRP) bars. The mix proportion is mentioned below. * Corresponding author: giriprasadgoud7@gmail.com After 28 days of typical curing, four beams were cast and evaluated. All four corners of each beam are reinforced with 10 mm diameter HYSD bar with varied effective covers ranging from 10 mm to 40 mm. Beams measuring 150 x 150 x 500 mm are cast and cured in fresh water for 28 days. The findings of a modified constant voltage methodology appropriate for accelerated cracking investigations in beams with 10 mm diameter HYSD bar reinforcement at varied effective covers ranging from 10 mm to 40 mm at all four corners of each beam are presented in this study. The specimens to be analysed are stored in a glass tub that measures 750 mm X 300 mm X 300 mm and is filled with real sea water. All of the extended reinforcements have been cleaned, sleeved, and are ready for the power supply units to be connected. The power supply is linked in parallel to all four bars, and anodic current is impressed at a constant voltage of 20 V. The potentials for all the bars are recorded every 12 hours with reference to a freely corroding zinc electrode before and after an hour, and immediately before the test is closed for the day. The crack's length is measured and the work is terminated when it reaches 500 mm.

Electrical resistivity studies
The electrical resistivity technique is a nondestructive testing (NDT) method that determines the capacity of a medium to conduct electric current based on the presence of electrolyte, water, and salts in the concrete's pore solution.

Half-cell potentiometer Test
Measuring half-cell potentials in M30 grade concrete with basalt fibres and BFRP rebars to predict the likely rate of corrosion. ASTM C 876 suggests a criteria for evaluating the probability of corrosion based on potentials (SCE, mV).
According to it, if the potentials is more than -120, the probability of corrosion is as low as 5%, if the potentials is between -120 and -270, the probability of corrosion is nearly 50%, and if the potentials is less than -270, the probability of corrosion is as high as 95%. Half-cell potentials of M30 grade concrete produced with basalt fibres and BFRP rebars are shown in the tables.