IMPROVING MECHANICAL PROPERTIES OF CONCRETE USING CARBON FIBERS COMPOSITES

The study aimed at improving the mechanical properties of reinforced concrete using carbonated fiber, containing different percentages of fiber. using high range water reducing agent (SP) with 8% silica fume (SF) and 8% high reactivity Metakaolin (HRM), as a partial replacement by weight of cement, on the behavior of light weight concrete (LWA) concrete is also studied. This investigation was carried out using several tests. These tests were workability fresh and hardened density, compressive strength, splitting tensile strength and modulus of rupture. Tests were performed for specimens at ages of (7,28,60,90 and 180) days.
On the basis of results of this investigation the following conclusions may be deducted:

It is possible to produce a light weight aggregate carbon fiber concrete with a dry density ranged between (1820) to (1950)Kg/m  the addition of (SF) or (HRM) does not affect the density significantly.
The required dosage of superplasticizer (SP) for carbon fiber LWAC increases with increasing the percentage volume fraction of fiber. The useful dosage range is (to 4-8%)
The addition of carbon fiber to (HRM and SF) light weight concrete increases slightly the compressive strength. Also the compressive strength increases with increasing  volume fraction of carbon fiber by about (1.15 % , 0.49% and 2.20%) for mixes containing carbon (3%, 3.75% and 4.5%) respectively, after (28) day.
The tensile strength of (LWAC) mixes increases by about (173, 242 and 296%) for mixes containing carbon fiber with volume fraction (3%, 3.75% and 4.5%) respectively, after (28) day.
An improvement in modulus of rupture is observed when the mineral admixtures (HRM) or (SF) and (SP) are used with (LWAC) mixes containing carbon fiber. Maximum increase is found to be(321.7%)when using (LWAC)mixe with (Sp) containing (4.5%) of carbon fiber by volume, after (28) day.