Search

The placement of $80 million of concrete by combinations of four of 52 agencies for the widen-ing of the New Jersey turnpike presented formid-able control problems. This paper discusses the control of durability, the turnpike's major concrete problem, by the use of strength, slump, and air con-tent parameters. These parameters are combined to measure the effect of slump and air entrapment on strength and uniformity of concrete as well as to rank the performance of various agencies in measuring these parameters. The coefficient of variation is used both to rank the agencies and to measure the uniformity of the concrete. Inter-relationships of parameters for determining the validity of both the test reports and the statistical analysis are also examined. Conclusions are reached concerning these parameter interrelation-ships, expectable coefficients of variations, and strength gain. [ABSTRACT FROM AUTHOR]

The durability of fiber glass protected with epoxy-phenol coatings in portland cement mortar was investigated. Aging and stress corrosion tests to 2 years, indicate normal fiber glass must be protected completely with a pinhole free coating to withstand alkali attack over lonq periods, as well as a coating which will migrate into the mortar to afford good bond strength. [ABSTRACT FROM AUTHOR]

The world has suddenly become aware of the great resources of the oceans and their potential for providing many of man's most pressing needs: energy, food, transport, minerals, and waste-disposal. However, the seas present an extremely hostile environment, requiring cooperative efforts by many engineering disciplines in order to achieve the necessary structures. These structures must be strong, safe, durable, ductile, available, and economical. Reinforced and prestressed concrete meets these criteria extremely well for many of the proposed structures, both fixed and floating. These include offshore oil storage, drilling, and production platforms: breakwaters, ocean pipelines and outfall~: offshore nuclear power plants: ocean bridges and tunnels: offshore airports and terminals: Arctic Ocean structures: barges, ships and floating stable platforms; offshore expositions and even cities: seafloor chambers and habitats. With approximately a half billion dollars in contract awards within the past year for deep sea structures in the North Sea and elsewhere, the need is emphasized for more research and development in a number of specific technical areas relating to structures, loads, foundations, and construction. Especial attention is called to the problem of very soft seafloor soils, earthquakes and tsunamis, the structural behavior of towers under cyclic loading, and construction practicability. There is a need for recommended practices for design and construction such as those developed or in progress by FIP, Det Norske Veritas, and the newly-formed ACI Committee 357, Offshore Concrete Structures. Although it is unusual to associate a material with a need, in this case, reinforced and prestressed concrete becomes more than a material; it takes on the role of a "concept" by which the oceans' vast resources may be safely and properly exploited for the benefit of man. [ABSTRACT FROM AUTHOR]

The present state of development of the mechanics for fiber reinforcing of port. land cement concrete by metallic, glass, plastic, and natural fibers is reviewed along with techniques for mixing and mix proportioning, placing, finishing, and actual and potential applications. [ABSTRACT FROM AUTHOR]

This recommended practice covers the construction of concrete pavements and concrete bases without attempting to include inflexible specifications for procedures, materials, or equipment. References are made to specifications, but only as a guide to enable a selection of requirements suitable for a particular location or class of work. The document is slanted to some degree toward use by agencies other than state highway departments or turnpike authorities with presumably large and experienced engineering staffs, and with knowledge of past performance of pavements in the area. Siections are devoted to specifying, sampling, and testing materials, and to the possible influence of materials on skid resistance, economy, and durability. Maximum aggregate size is mentioned as sometimes relating to pavement durability. Subgrades and subbases are treated only as to final preparation for paving. Recommendations for forms are included as well as recommendations for projects using slipforms. Arrangement of joints is described, and references are given for guidance in using reinforcement. Sections on normal and high-early-strength concrete proportioning rely heavily on reference to the report of ACI Committee 211, but point out the special problems connected with pavement concretes and the use of admixtures in pavement concrete. Sections on mixing, placing, finishing, and curing concrete refer to other ACI reports where pertinent, but make recommendations for the special handling necessary in the case of pavements. Concrete bases are treated where procedures vary from those used for pavements, and recommendations and references are given for cold and hot weather concreting. [ABSTRACT FROM AUTHOR]

Nonmetallic waterstops having suitable properties for use in joints in hydraulic structures of concrete have been made successfully from natural rubber, synthetic rubber, and polyvinyl chloride. To per-form satisfactorily, a waterstop must have sufficient strength and extensibility to avoid being ruptured by joint movement, and it must maintain strength and extensibility over the temperature range and in spite of any chemical attack from the environ-ment. It must also have suitable dimensions and con-figuration and be installed so as to avoid water flow around the embedded ends. Field and laboratory studies have led to the es-tablishment of various minimum property require-ments. Suitable waterstop materials should have a tensile strength of at least 1400 psi (plastic) or 2000 psi (rubber), the ability to elongate 280 percent (plastic) or 360 percent (rubber), and be able to maintain certain levels of other relevant properties after various chemical and thermal exposure. [ABSTRACT FROM AUTHOR]

This report presents recommendations for structural design, materials, and con-struction of concrete tanks, reservoirs, and other structures commonly used in water and waste treatment works where dense, impermeable concrete with high resistance to chemical attack is required. Special emphasis is placed on a structural design which minimizes the possibility of cracking and accommodates vibrating equipment and other special loads. Proportioning of concrete, placement, curing and protection against chemicals are also described. Design and spacing of expansion and con-traction Joints receive special attention. [ABSTRACT FROM AUTHOR]

These specifications are a reference standard which the engineer or architect may make applicable to any building project by citing them in the project specifi-cations. He supplements them as needed by designating or specifying individual project requirements The document covers materials and proportioning of concrete; reinforcing and prestressing steels; production, placing, and curing of concrete; and formwork design and construction. Methods of treatment of joints and embedded items, repair of surface defects, and finishing of formed surfaces are specified. Separate chapters are devoted to slab construction and finishing, architectural concrete, massive concrete, and materials and methods for constructing post-tensioned concrete. Provisions governing testing, evaluation, and acceptance of concrete as well as for acceptance of the structure are included [ABSTRACT FROM AUTHOR]

Reports on a study of the feasibility and techniques of impregnating and in-place polymerizing of liquid monomers in preformed concrete, and the use of monomers in a fresh concrete mix, followed by polymerization. Two methods of initiating polymerization--gamma radiation and thermal-catalytic--are being studied. Studies include development of impregnation techniques and determination of the effects of various polymer loadings on resultant properties. The radiation technique produces greater improvements in properties than does the thermal-catalytic method. Dramatic improvements in concrete properties resulting from the impregnation-irradiation with methyl methacrylate are discussed. For example, compressive ana tensile strength and modulus of rupture are increased by 256 to 290 percent; water permeability decreased to negligible values; water absorption decreased as much as 95 percent; and resistance to abrasion, cavitation, freezing and thawing, distilled water, soluble sulfates, and acid showed significant improvements. [ABSTRACT FROM AUTHOR]