Work Undertaken with Mortar and Concrete

Work at Courtaulds [22,23] in the early 1970s attempted to incorporate carbon fiber in a cement slurry, which was difficult due to the size of the cement particles. They tended to be filtered out by the fiber reinforcement, so a cement with a fine particle size (Swiftcrete, an ultra rapid hardening Portland cement with a maximum diameter of about 45 pm) was used and the fiber spread as thinly as possible, using either an air knife, or a water flume and then held in the spread position by sizing with a water based compatible size such as sodium carboxymethylcellulose [22,23]. These larger particles limit the carbon fiber content to about 5% v/v, but in practice, due to a non-uniform distribution, a value of some 12% v/v was attainable. 

Waller [24] followed this laboratory work by field trials, hopefully to use the product as decking in multi-storey car parks, but at that time, carbon fiber was considered too expensive for such an application. 

workers at Harwell produced samples of carbon fiber reinforced cement (cfrc) by the process of filament winding under tension, giving good fiber alignment and distribution [25]. 

Work undertaken by Majumdar et al [26,27] at The Building Research Station, Garston showed that the carbon fiber possessed excellent durability in a cement slurry with a modulus of rupture (maximum stress) of 33 MPa and an Izod impact strength of 4 kJm for a loading of 1.3% fiber. 

however, Sugama [28] stated that chemical bonding does exist between carbon fiber and the cement matrix, whilst Yuan et al [29] showed that oxidative surface treatment followed by treatment with KH-550 x-aminopropyl triethoxysilane ((H2N(CH2)3Si(OC2H5)3) 

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