Improving the voided reinforced concrete beams behavior by strenthining the compression zone concrete using polyvinyl alcohol

الملخص EN

Determining dimensions of continuous RC beam depend on the critical span.

Practically, changing the dimensions of others spans is difficult.

So that, this work aimed to discuss the possibility of adding voids within the beams which its dimensions are more than required in order to reduce the cost and dead load.

The selected percent of voids to volume of tested beams was 10%.

The shape of voids was a first variable (spherical voids or conic voids).

Also, the alteration in behavior when a (5cm) concrete layer thickness of compression zone was replaced with a concrete layer modified with adding polyvinyl alcohol (PVA) was investigated, as a second variable.

After testing six samples, the result showed that the failure criteria of normal concrete voided beams is transformed from flexural behavior to shear behavior, while the failure criteria of control solid specimen was flexure behavior.

Also, the modified beams failed in flexural behavior except the beam with conic voids failed in shear behavior.

Corresponding to this transform, the ultimate load varied in the same manner.

Where, the normal concrete voided beams failed with lesser ultimate load than control solid beam of about (6.4% and 18.3%) for spherical and conic voids, respectively.

While, the ultimate load of modified concrete beams is increased of about (13.8%, 5.4% and 3.1%) for solid beam, spherical and conic voided beams respectively in comparing control specimen.