Highway Soft Surface Probable Cause

About this Project

An inspection of a construction site on Interstate-45 (I-45) north of Houston around Conroe had a 3-shift crew working round the clock. A problem emerged where concrete placed prior to nightfall had the sand particles on surface of newly placed concrete removed and blown to the sides of the barrier wall. The surface of the pavement was soft and scaled as shown in Figure 1-D.

Note – This featured project report is an abbreviated version of the actual report prepared for the client.

Samples

Samples were taken in an affected area and another from a well performing day-placed concrete. The durably placed concrete retained its surface features, as shown in Figure 1-A; that of the affected area, powders off easily with a little effort. See Figure 1-B.

Tests Performed

(1) Scanning electron microscopy and
(2) X-ray diffraction was performed on both samples – from the affected area and from the well-performing surface.

EXECUTIVE SUMMARY

Principal Phases noted in the Two Mortar Surfaces and their Relative Percentage Proportions.

Winds blowing in the night stripped off moisture from the surface adversely affecting the hydration of the alites and belite, in the cement, to hold the particles bonded to the surface.