International Concrete Abstracts Portal

Sulfur concrete has the potential to solve some serious industry corrosion problems. This article describes the rehabilitation of a large basement area situated beneath a copper electro-winning operation. About 29,000 ft2 (2694 m2) of deteriorated portland cement concrete floor was overlayed with 3 1/2 in. (89 mm) of unreinforced sulfur concrete. A general background of sulfur concrete, its characteristics, and a description of techniques, materials, and equipment used during construction are given. The conclusions point to the need for improvements in equipment and tech-niques to reduce costs and the need for development of standards and recommended guidelines.

Arcosanti is a small community being built in the Arizona desert by students from all over the world who pay tuition for 5-week workshops to learn basic con-struction skills by hands-on experience. Arcosanti has evolved as a learning process and an educational in-stitution teaching basic concrete construction fun-damentals and trade skills. This article describes the construction practices at Arcosanti and the workshop program.

Describes the construction of the Strontia Springs Dam, a 290 ft (88 m) high double-curved concrete,arch dam located 22 miles (35 km) southwest of Denver on the South Platte River.*

Contract research is a contractual arrangement be In many cases, contract research can be a cost-effective investment for engineers and contractors wishing to explore new design and construction concepts. The model for discussion of contract research is the Portland Cement Association’s Construction Technology Laboratories in Skokie, Illinois. Discussed are the history of PCA’s contract research program and the program facilities and staffing, and the important characteristics of contract research along with some specific examples.

A nine-story, 139-unit building for the elderly in Chicago’s Chinatown was built of totally precast concrete elements. Featuring shop-fabricated precast concrete ornamental panels coated in bright red and green aliphatic urethane colors, the building clearly reflects the Chinese culture of its tenants and the surrounding community.

Vacuum dewatering in effect produces a zero-slump concrete from fresh concrete with a high water-cement ratio. The process involves three basic steps: (1) filter pads are placed over the fresh concrete; (2) a suction mat is placed over the filter pad, with a hose connecting the suction mat to a vacuum pump; (3) the vacuum pump is operated for several minutes, depending upon the thickness of the concrete slab. Vacuum dewatering lowers the water con-tent of a freshly placed concrete slab by 15-25 percent, increases the density, strength, and frost resistance of the slab, and decreases the slab’s absorption, abrasion, and shrinkage. This article discusses the mechanics of the process, the steps in the procedure, and conclusions as to vacuum dewatering’s cost effectiveness as a construction technique for certain applications.

Sulfur concrete uses sulfur as the binding agent for aggregate and therefore replaces the cement and water components of a regular portland cement con-crete mix. Sulfur concrete may prove to be a cost-effective substitute for portland cement concrete in certain applications which take advantage of its unique characteristics: (1) high strength and fatigue resistance; (2) excellent corrosion resistance against almost all acids and salts; (3) extremely rapid set and strength gain; (4) remeltable and reusable without changing its chemical properties; (5) relatively safe to use. However, sulfur concrete’s commercial success will depend upon solving two key problems: (1) developing the necessary sulfur supply and transport infrastructure to enable the price of sulfur delivered to be competitive with the price of cement delivered; (2) developing material and performance specifications to speed acceptance by government and industry. This article develops the above conclusions within the framework of three broad subject areas: the history of sulfur concrete’s development; the physical and chemical characteristics of sulfur concrete; and the practical application of sulfur concrete. [Author]

The Houston Ship Channel Bridge connects part of a future 12 mile (19 km) radius beltway that will circle the Houston central business district. The three main spans of the 10,450-ft (3185-m) bridge are 375 ft, 750 ft, and 375 ft (114 m, 229 m, 114 m). The main spans are constructed with cast-in-place concrete segments using the free-balanced cantilever method. This article discusses the analysis of alternate designs, design, value engineering, construction management, on-site testing, and construction of the foundations, piers, and superstructure. [Author]

The 75-story Texas Commerce Tower in Houston is the tallest composite concrete-steel building in the world, employing a unique ruptured tube structural frame concept. The building has a typical four-corner shape but with one corner chopped at a 45 deg angle to create a fifth side. The construction of the foundation mat involved one of the largest concrete placements ever made for a commercial project. The top 72 floors were built in only 11 months using custom-built jump form systems and pumped cast-in. place concrete.

An aeroelectric system cools air in a large concrete chimney-like structure which produces a down draft that drives turbines and turns generators to produce electricity. While giving a general introduction to the entire system and its development, this article focuses on the design and construction of the concrete chimney, which presents the greatest single challenge towards the realization of aeroelectric solar power.