In this study three series of four test panels were molded varying the mortar content. In the three series, the dry-mix shooting process were regulated with three different conditions. In each test panel samples and cores were taken to determine shotcrete mix proportions and physical properties. The results show a good correlation between stiffness and W/C in according with the exponential model proposed by Powers, confirming the Proctor needle as a good instrument to dry-mix shotcrete workability control. The compaction and compressive strength were as high as the volume of paste incorporated in the shotcrete. This feature provides a typical dry rheological behavior to the fry-mix shotcrete, where the Abram's Law is not valid. It occurs regardless of the fine and coarse aggregates proportion, although the influence of which on rebound is very clear. It is recommended that one should not fix a maximum W/C for a given compressive strength in the dry-mix shotcrete specifications. On the contrary, the consistency measurement by the Proctor needle, appears to be a good instrument for dry-mix shotcrete workability control. The use of the aggregates gradation recommended by the Aci is a good way to achieve better shotcreting conditions with a minimum rebound.

Highlights the importance of insuring uniformity of in-place concrete for quality assurance in construction. The functional requirements of strength, serviceability, and durability can be assured by quality assurance in design, specification, choice of materials, and workmanship. Steps to insure uniformity of cement received in an irrigation project from different sources are described. Tests to establish uniformity of concrete in dam construction and shotcrete for tunnel lining are highlighted with the help of case studies.

Addresses shotcrete used primarily for rehabilitating concrete structures. Field experience has demonstrated that the use of detailed specifications and strict on-site surveillance can minimize workmanship problems that have been a concern with the shotcrete process. This paper discusses key points that make the specifications a useful tool. Types of shotcrete quality found in practice are illustrated. Preconstruction testing, ongoing quality control testing during construction, a core grading system, and tensile bond strength tests are discussed. Several brief case histories are presented where the use of the core grading system has proved successful. In the case histories, an independent laboratory conducted evaluations of in-place shotcrete, developed specifications for new work, and provided on-site surveillance during placement. The case histories include a drydock, cooling tower, parking garage, swimming pool, lighthouse, and two chimneys. The system adopted has resulted in structures that should provide durable, long-term service.

Traces the development of superplasticizers in Japan and Germany, and discusses the properties of superplasticized fresh and hardened concrete. Data are presented on the use of superplasticizers in Australia, Canada, Japan, Singapore, U.K., U.S., and Western Europe. The performance of superplasticized concrete under freezing and thawing conditions both in the laboratory and the field is discussed, and the use of superplasticizers in the development of innovative concretes is described. The ASTM and Canadian specifications dealing with superplasticizers are discussed, and the paper is concluded with a list of pertinent references.

The Pier 6-C structure in the inner harbour area of Vancouver was selected as the site for construction of the Canada Place Trade and Convention centre. The project includes a five-berth cruise ship facility and a major 514 room hotel. The original Pier B-C was constructed by Canadian Pacific Railway between 1923 and 1927, and consisted of a central berm projecting 330 m (1080 ft.) from the shore, surrounded by a reinforced concrete deck supported by approximately 6000 precast reinforced concrete piles driven into the berm. A detailed assessment of the structure showed that it was suitable, after rehabilitation of deteriorated areas, for use as the substructure for the Canada Place project. As construction progressed substantial additional damage was done to the pier because of movements caused by installation of additional pre-cast concrete piles and steel caissons to support the new structures. This paper describes the original assessment of the pier structure, evaluation of construction damage, and preparation of repair specifications. While extensive repair by shotcreting procedures was required, this paper concentrates on the epoxy injection repair aspects of the remedial work. Epoxy injection was used to achieve structural repair of reinforced concrete beams, piles, pilecaps, seawalls and deck slabs.