Mortar samples surrounding buried pipe.

a. Name & Location of the Project
Mortar samples surrounding buried pipe. – Water District in California.
b. Problem
Varying quality of two mortar samples surrounding buried pipe,
(i) “Sample in between pipe”- mortar – gray in color and strong
(ii) “Pipe joint”- mortar – whitish gray and soft

c. Evaluation by Petrographic analysis & SEM

7

A, Mortar sample from in-between pipe. Dense cement paste surrounding all aggregates

8 1

A, Mortar sample from in-between pipe. Dense cement paste surrounding all aggregates

Evaluation by SEM

9

Mortar sample from in-between pipe.

10

Mortar sample from pipe joint.

d. Conclusion
Cement used in mortar appear to have elevated amount of tricalcium aluminate, C3A. In-between pipe where there was no leaked wastewater from the pipe the integrity of the mortar was maintained , whereas at the joint with sulfates in the leaked water copious amounts of ettringite was formed in voids weakening the mortar sample.