Abstract
         Interest in using sliplining for large diameter (>90 inches) pipe rehabilitation is on the increase. Hence 
large volumes of grout materials with good working properties and mechanical properties is needed. Since 
large amount of grout is needed, the material composition must be optimized to reduce cost and heat of 
hydration. Hence, the use of fly ash was investigated in this study. Up to 50% of fly ash was used as 
replacement for cement. A series of mechanical and chemical tests are being performed on grouts with unit 
weights varying from 43 to 55 pcf.

1. Introduction   
	Sliplining is one of the promising trenchless rehabilitation method used for 
pipelines. Many sewer pipes with various diameters are being rehabilitated using this 
method. To meet the requirements of placement and in situ performance, cellular grout 
should be lightweight with good flow properties and controllable setting time. For large 
diameter pipes (>90 in), this is more critical since large amount of grouts is needed. This 
study will focus on developing and characterization cellular grouts for sliplining large 
diameter pipeline.

2. Testing program
	Grout mix prepared in the field (Houston area) with unit weights varying from 
43 pcf to 55 pcf, with or without fly ash, were collected and used in this test program. 
Several 3x6 in. cylindrical specimens, 2x2 in. cubic specimens and 2x2x12 in. beam 
specimens were prepared for mechanical and chemical tests. The flow cone test and 
penetration test were performed. Mechanical tests include the compression tests using 
cylinder and cubic specimens. Bending test were done on beam specimens. The chemical 
immersion test is focused on the acid resistance of the grout. Cylindrical specimens are 
immersed in two different concentrations of sulfuric acid, sodium sulfate solutions and 
D.I. water. The pH of the solution, the calcium ion, the weight of the specimens and the 
ultrasonic pulse velocity are monitored during the chemical tests.

3. Results
	Compression test on 70 cylindrical specimens have been completed. The 
variation strength and elastic modulus of different types of grouts with curing time are 
shown in Figure 1 through Figure 4. The compressive strength of 43 pcf grout with or 
without fly ash didn't differ much  in the first 15 days, but the 28-day strength of grout 
without fly ash was 20% higher than that with fly ash. The 28-day strength of 55 pcf 
without fly ash was 50% higher than that with fly ash. The elastic modulus had similar 
trend like the strength. The 28-day modulus of grout without fly ash was 40% and 120% 
higher than that with fly ash for 43 and 55 pcf grouts respectively. The on-going chemical 
test has shown that visible discoloration happened to the specimens in the sulfuric acid 
with a pH  of 1 in just one week after the immersion.

4. Conclusion
	Based on the experimental results the following conclusion are advanced:
1. Fly ash reduce the 28-day compression strength of grout.
2. Fly ash affected the strength of 54 pcf more than that of 43 pcf.
3. Fly ash affected the elastic modulus more than the compressive strength.
4. Fly ash affected the setting time of 54 pcf more than the 43 pcf grout.

5. Reference
1. C.  Vipulanandan, "Testing and Developing Guidelines for Sliplining Grouts".
2. City of Houston specification (Section 02331),  "Sliplining Grout".
[3] ASTM C403, "Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance"
[4] ASTM C495, "Test Method for Compressive Strength of Lightweight Insulating Concrete"