Q.: A reinforced concrete slab consisting of very narrow tee beams was poured in place with hardly any quality control at a very low slump and no vibration.

This resulted in a porous finish and even cavities within the web.

Should this be a matter of structural concern? How can these problems be corrected?

A.: We believe this should be a matter of structural concern. Whenever concrete is placed without quality control, without vibration, and with void formers that conceal the surface of the concrete, there is reason for concern about its structural integrity.Since you do not give us any indication of the loads to be carried by the slab, we cannot give you a detailed recommendation. However, if this is a residence, it may be that live loads are relatively light and that the residual strength of the slab is adequate. We suggest that you consider a load test, during which you measure deflection of the slab to verify its performance. This approach may be the least expensive one in a relatively small structure and it should tell you much about the structural capacity that you have already in place.