CIGMAT Report: Update From This Unique, Industry-Specific Ongoing Research Program

By C. Vipulanadan, PhD, P.E., professor of Civil Engineering, director of CIGMAT and the Texas Hurricane Center for THC-IT | September 2010 Vol. 65 No. 9
1) Macro-cells 2) Macro-holes in the Macro-cell walls 3) Macro-cell walls. Fig. 1: Microstructure of a polyurethane grout.

Using a 3D model, studies were also performed to investigate the development of the grouted soil bulb around a leaking lateral joint – a typical bulb is shown in Figure 4. These model studies were critical in developing a comprehensive test protocol for grouts to rehabilitate civil infrastructures.

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Fig. 4: Typical grouted soil bulb around a lateral joint.

Currently, there is no systematic method for evaluating the performance of grouts under service conditions. Hence, a testing protocol was developed to evaluate the grouts with a combination of full scale and laboratory tests for applications in the rehabilitation and new construction of wastewater facilities.

Wastewater facilities are typically wet and experience hydrostatic pressure under normal service conditions. The application of grouts to leaking joints and cracks is considered a challenge and must be evaluated. Another cause for evaluation to determine performance is the bonding between the concrete/clay brick surface and the grouting material. Chemical resistance of grouts and grout-modified materials to the sewer corrosive environment also is important.

To select the grouting material to solve the I/I problems, their performance and installation must be well understood. Restoring leaking joints and cracks in concrete structures requires considering grouted soil mass around the joints and grout behavior within leaking cracks.

The durability of a grouting material is as important as its ability to perform in its intended applications. Durability is concerned with life expectancy or endurance characteristics of the coating material. A durable grout is one that can withstand the effect of service conditions in which it is subjected; therefore, it is important to identify grouting materials for specific applications such as leak control in wastewater treatment and collection systems or other concrete structures.

Since several factors in the field can affect the performance of grouting, it is important to identify them through controlled experiments where variables are studied one at a time. In this document, a comprehensive testing program was developed to evaluate grouting for leak control applications.

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