Deterioration and Rehabilitation of Berth Faces in Tidal Zones at the Port of Saint John

The Department of Justice (DOJ) Headquarters, 951 Constitution Ave. N.W., Washington, DC, has been undergoing major rehabilitation and renovation. Work started in 2001 and continued into 2002. Gilbane Building Co. is the prime contractor on the site, but there are many subcontractors involved in restoring the DOJ building. Coastal Gunite Construction Co.,

Tieton Dam Spillway Rehabilitation

Johnson Western Gunite Company rose to the challenge of rehabilitating the Tieton Dam Spillway in Yakima, WA. The spillway, built originally in 1924, was showing significant deter-ioration due to freezing and thawing, weathering, and erosion due to high-velocity water flow. The owner, the United States Department of the Interior Bureau of Reclamation, designed a repair consisting of a 12-in.-thick (300 mm) reinforced, cast-in-place concrete overlay on the floor and left wall if one was looking downstream. The budget in the original contract was not sufficient to overlay the right wall.

Determination of Early-Age Compressive Strength of Shotcrete

Tere has long been a need for a reliable, simple-to-use means of determining the early-age rate of strength gain in shotcrete.During approximately the first 24 hours after shotcrete has been placed, its compressive strength is typically too low to measure using standard core-extraction and testing procedures. Monitoring the rate of early-strength development in shotcrete is important in tunneling, mining, and other applications such as the underpinning of structures. Recent studies by the authors have demonstrated that there is a simple, direct method for determining the early-age compressive strength development of shotcrete. It involves the shooting of a set of beams in a standard steel mold and testing the beams after stripping, using an adaptation of ASTM C 116, œStandard Test Method for Compressive Strength of Concrete using Portions of Beams Broken in Flexure. This œTechnical Tip describes a procedure for deter-mining the compressive strength of shotcrete beams and presents results of tests conducted with plain and accelerated shotcretes produced by both the wet- and dry-mix shotcrete processes.

Shotcrete Meets the Challenge of Huge Water Project in Ecuador

Shotcrete Meets the Challenge of Huge Water Project in Ecuador replacing traditional œform-and-pour reinforced concrete construction methods with high-production shotcrete, the massive Trasvases Manabi Water Project in Ecuador was finished months ahead of schedule. Contractor Norberto Odebrecht, in conjunction with Shotcrete Technologies, Inc., of Idaho Springs, Colorado; and Commercial Shotcrete, Inc., of Higley, Arizona, placed over 6000 m3 (7800 yd3) of shotcrete in less than half the time it would have taken by the specified œform-and-pour method. They put the project an entire rainy season (approximately four months) ahead of schedule.

Design Guidelines for the Use of FIber-Reinforced Shotcrete in Ground Support

Developments in Shotcrete in Hobart, Tasmania, Australia in April 2001. One of the outstanding papers presented at the Conference was a paper by Grant, Ratcliffe and Papworth on œDesign Guidelines for the use of SFRS in Ground Support. Frank Papworth was asked to submit an updated paper on the subject for publication in the ASA Shotcrete Magazine and so here it is. It is more technical than most of the papers published in the ASA Shotcrete Magazine, but was selected because it was considered that it would be of considerable value to designers of fiber-reinforced shotcrete linings for ground support in civil and mining applications.
Abstract: There are presently no design guide-lines based on toughness for the use of fiber-reinforced shotcrete (FRS) in ground support for underground mine development. Typically, in the Australian mining environment, the approach to the use of FRS has been one of borrowing experiences from other mines and a œtrial-and-error method of design, installation, and assessment. There is a need for a ground support design guide that can be simply applied by œfront-line personnel.
This paper provides an overview of the performance characteristics of FRS and how the various shotcrete guides specify its use. Practical experiences with the use of FRS in Australia and Canada in various applications and ground conditions are combined with existing empirically based ground support-design methods to develop a ground support guideline that incorporates the concept of toughness. An assessment of structural synthetic fibers shows that their low modulus makes their performance characteristics different from those of steel fibers, and that they are not likely to be economical in linings where crack widths are limited, but that they are preferable where large deflections are permissible.
Fiber-reinforced shotcrete (FRS) has been used successfully for ground support for more than

Shotcrete Solution to Tricky Underpinning Problem

A downtown Vancouver excavation and shoring project involving underpinning of two adjacent structures took on a strange twist when it was discovered that the three-level, early 1920s building to the north of the excava-tion had a precariously attached brick wall founded on a rubble footing, which was required to be underpinned to construct the new building to the south. The struc-tural engineer, acting for the owner of the

Shotcrete Retrofil of a Mechanically Stabilized Earth Wall

The Municipality of Maple Ridge in British Columbia, Canada, commissioned a spe-cialty contractor to build a 9 m (29.5 ft)diameter culvert, incorporated in a mechanically stabilized earth (MSE) wall, to provide a street crossing for a stream. The culvert had been partly sunk into the stream bed to adapt to the site conditions. The MSE walls were a maxi-mum 8 m (26.3 ft) high above the ground and 70 m (230 ft) long. Figure 1 shows part of the North Face of the MSE wall.
The fill used in the construction of the MSE wall contained a fraction of fine dredged river sand. After construction, fine particles of the sand dried out and started to migrate through the galvanized metal screen that comprised part of the MSE wall. This resulted in voids at the surface of the MSE walls. The voids were a concern as they constituted a potential cause for future settlement of the sidewalks and asphalt pavement constructed between the MSE walls. The specialty contractor decided to remedy this situation by arresting the migrating fill before it came to its natural equilibrium, by refilling the surface voids and applying a shotcrete lining.
The design engineer recommended filling the voids with shotcrete and stabilizing the surface of the MSE walls with a permanent shotcrete lin-ing. The specifications called for the following procedures: