In our day to day contact with concrete- its manufacture, transportation, handling, placing, and curing- we rarely interest ourselves in it on a close up basis. We see a wide expanse of floor but we fail to get down on our knees and examine the pore structure of the surface. Or, we neglect looking at a cross sectional view of a slab at the edges. Often such an examination would be highly enlightening. It might well help in evaluating specific problems and it could give us a better understanding of how concrete works and why it acts as it does. Despite air entrainment, the sight of concrete that is spalling and generally deteriorating at the surface due to alternate freezing and thawing is still with us. This type of deterioration can be caused by such factors as lack of air entrainment, improper amount or type of entrained air, high water/cement ratios, high water content, improper finishing procedures, excessive bleeding, or lack of curing. Examination revealed that in the cause of the deterioration was too high a water content in the mix and a resulting poor water/cement ratio. Low strengths, a weak surface and other major complaints were leveled against the concrete in a paving job. The problem was as a result of insufficient control, the air content had soared to 30 percent. The SWISS cheese-like appearance made if apparent why concretes with abnormally high air contents exhibit low strengths and poor resistance to weathering- the very reason for incorporating air. One of the concrete applications most frequently faulted is floors. This building element can be especially troublesome when it is in an industrial building or warehouse where it must withstand heavy traffic. One of the approaches employed for such floors is the use of special aggregates. A close up reveals why the natural aggregates used in one factory floor resulted in dusting and deterioration of the surface. When sawed sections were taken and examined they revealed that the aggregates at the surface were cracking and shattering as a result of the abrasion and impact common to industrial floors. Since most natural aggregates are hard materials, they are also brittle. The result is that they are unable to withstand the abuse, the abrasion and impact to which such floor surfaces are exposed.