Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...

age difference between the liners is quite small (23 years versus 26 years). The Columbus 8-in. liner at
only 5 years old has a significantly lower porosity and higher bulk density than all of the other liners
which are over 20 years old. Such a change in density and porosity could be due to aging of the resin in
the presence of various environmental conditions, but may also result from installation differences.
As shown in Table 6-3, for bulk density/specific gravity values, a variation of 1 to 8% was found between
the TTC measured values and the values that were measured during the mercury penetration porosity
testing. The values obtained during the mercury penetration testing resulted from the intrusion of
mercury vapor under very high vapor pressures. The differences in values obtained by different testing
methods, though relatively small; do point out the difficulty in measuring performance trends over time
that may also result in only small differences in the parameters used to track the deterioration. These
issues will be discussed further in Section 6.5.4.
Sample or
Theoretical
Field
Samples
Theoretical
Porosities
Table 6-3. Comparison of Density Data
Identification/Measurements/Values Theoretical Calculations
Location
Denver
8-in.
Denver
US 48-in.
Denver
DS 48-in.
Columbus
8-in.
Columbus
36-in.
Bulk
Density
M-metrics*
* Internal Micrometrics standard procedure
** As per ASTM D792
Bulk
Density
TTC**
97
Deviation Porosity
With
Talc
Filler
With
ATH
Filler
With
No
Filler
(g/mL) (g/mL) (%) (%) (g/mL) (g/mL) (g/mL)
1.073 1.160 8.1 15.915 1.144 1.112 1.006
1.165 1.098 5.7 11.262 1.207 1.173 1.060
1.162 1.078 7.2 10.171 1.222 1.187 1.073
1.174 1.114 5.1 8.163 1.249 1.214 1.096
1.088 1.073 1.4 17.752 1.119 1.088 0.985
0.000 1.360 1.321 1.191
5.000 1.292 1.255 1.133
10.000 1.224 1.190 1.075
15.000 1.157 1.124 1.017
20.000 1.089 1.059 0.959
It is also worthwhile to compare the measured densities with theoretical calculations of bulk density when
the densities of the component materials are combined in typical proportions. These calculations are also
shown in Table 6-3 using information on proportions and component densities provided by Insituform.
The calculations assume that the felt fibers occupy 14% of the final resin volume. The remaining volume
is occupied by resin, any filler that is used, and air (the result of porosity in the liner). The amount of
filler within the resin is assumed to be 12% by volume. The component densities used in the calculations
are neat resin density 1.16 g/mL, fibers 1.38 g/mL, talc filler 2.80 g/mL, and ATH filler 2.42 g/mL. Both
the Micrometrics and the TTC bulk densities fall within the ranges calculated depending on the type and
extent of any filler used in the actual liners. Close attention to the bulk density of the final CIPP liner
could provide a worthwhile quality control parameter – but only if the constituent materials and
proportions are accurately known.