Evaluation of blowholes in the surface of concrete slabs or paving stones

Figure: MPVA Neuwied

Fig. 1 a+b: Blowholes and their visual conspicuity

Figure: MPVA Neuwied

Figure 2: Visibility of shrinkage cavities in grazing light

Figure: MPVA Neuwied

Fig. 3: Detailed image of a blowhole filled with material

Figure: MPVA Neuwied

Fig. 4: Brownish discoloration on some concrete slabs

Figure: MPVA Neuwied

Fig. 5: Concrete paving stones submitted for laboratory testing

Figure: MPVA Neuwied

Fig. 6 a+b: Holes in the surface of the paving stones

Figure: MPVA Neuwied

Fig. 7: Frayed edges and burrs on the paving stones

Figure: MPVA Neuwied

In the context of legal disputes, the expert author was commissioned to answer questions concerning, among other things, the defectiveness and cause of shrinkage spots and rust discoloration in concrete slab or paving stone surfaces.

1 Initial question

1.1 Issue case 1 (concrete slabs)

The plaintiff had ordered approx. 133 m2 of concrete slabs at a net price of 20.50 euros via the construction trade. Shortly after the concrete slabs were laid by a landscaping contractor, the plaintiff complained about the appearance of cavities and holes as well as rust stains in the surface of the concrete slabs.

In the course of the legal dispute, the expert was commissioned to answer questions regarding the defectiveness and cause of the blowholes and the rust stains, among other things. In addition, the client complained that a muddy...