Polypropylene fibre reinforced concrete (PFRC) is known for its increased resistance to cracking and improved ductility. However, it has its drawbacks. One significant negative is its lower modulus of elasticity compared to traditional concrete, leading to potentially less stiff structures that may not be suitable for all applications. Additionally, the fibers can decrease the workability of the concrete mix, making it harder to place and finish. This can lead to an increased reliance on admixtures to improve workability, potentially raising costs. Another issue is the uniform distribution of fibers; if not adequately mixed, it can lead to weak spots within the concrete. Furthermore, the long-term durability of PFRC in various environmental conditions, such as exposure to UV light or chemicals, remains an area of ongoing research.

The number 3287.

In 1791. Rev. William Gregor made the initial discovery of titanium in a mineral known as manachite now called ilmenite in Cornwall. Being an amateur mineralogist. Gregor recognized that the mineral contained new elements and successfully extracted calcite or oxide from it. referring to it as soil lead ore. Around the same time. in 1795. German scientist Martin Heinrich Klaproth also came across titanium independently while studying the mineral rutile. Unaware that he had stumbled upon a previously discovered element. Klaproth named it after the Titan in Greek mythology. It was later established that both Gregor and Klaproth had identified the same element. with Gregor being credited as the original discoverer. However. the element is still commonly referred to by Klaproth's chosen name. Almost a century later. in 1910. Matthew A. Hunter of Rensselaer Polytechnic Institute managed to produce pure metallic titanium 99.9% using his method of heating sodium to 700-800CC with TiCl4. Despite this breakthrough. titanium did not become commercially available until the 1950s.