Choosing the right plant Fibre to strengthen concrete means looking at more than just how strong it is. Other important things to consider are how easy it is to find the Fibre nearby, how it is prepared, how it deals with water, how well it can fix cracks, its price, and how good it is for the environment. While Fibres like jute, coconut husk, sisal, bamboo, hemp, and sugarcane waste have been studied a lot, there has not been a scientific reason to choose pine needle Fibres from Solan District, Himachal Pradesh, over these. This study compares seven natural Fibres using 16 different factors, uses a weighted scoring system, and includes a cost-benefit check, local supply from the Solan-Sirmour pine area, how it matches with global development goals, a statement about new ideas, and tests on M25 grade concrete at five different amounts (from 0% to 1.00% by volume). Pine needles got the highest score of 91 out of 97, which is 47% higher than bamboo (62 out of 97). This is mostly because pine needles have a water-repelling, waxy surface, hollow spaces inside, are almost free as forest waste, and help reduce fire risk. At the best amount of 0.50%, tests showed a 14.6% increase in strength when squeezed, a 21.1% increase in strength when pulled apart, a 24.4% increase in bending strength, 62.1% better crack-fixing ability (2.4 times better than normal), 33% less water soaking in, and 47% less moisture getting through. These results show that pine needle Fibres from Solan District are the best choice for making strong, crack-fixing, and water-resistant M25 concrete in Himalayan India.
Panwar et al. (Sun,) studied this question.