Slab on Grade Concrete

Slab on Grade Concrete – Floor space – 8,500ft2 for a warehouse, South Texas

b. Problem
Scaling and wavy surface.

c. Visual Observation & Petrographic Analysis

(i) Observation

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1

Vertically sawn and polished surface of core. Show insufficient aggregate

(ii) Petrographic Analysis

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a

4 1

b

a & b show porous paste and a high w/c concrete. b shows a bleed channel (arrowed) with fines of cement & sand particles.

d. Conclusion
Cause of problem is due to insufficient aggregate and high water content used in the
Formulation of concrete.

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c

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d

Figure (c) shows concrete sample with sufficient aggregate – as compared to quantity of aggregate in (a) above.
Figure d shows an evenly set, dense cement paste as opposed to the micro porous paste in the sample of interest above – (b)