Showing papers in "Materials protection in 1968"

Corrosion of metals in tropical environments. Copper and wrought copper alloys

Abstract: Cu and Cu alloys show weight losses in tropical water from 1.4 to 2 times that in temperate waters; tropical marine atmosphere also cause higher weight losses. Corrosion of commercially pure Cu for 16 years in tropical sea water was approximately proportional to Ct 1/2 C isa constant and t is time of exposure). Corrosion-time functions for the other high Cu and alpha-phase Cu-Zn alloys were generally curvilinear for the first 4-8 years exposures. Extrapolation of the curves shows the lack of reliability of the short-term secant rates. In the various tropical environments, 5% Al bronze had the best over-all corrosion resistance. alpha-Phase Cu-Zn corroded slightly faster than Cu in fresh water and somewhat less than Cu in other environments. The 60-40 alpha + beta brasses, with the exception of Mn bronze in fresh water, corroded considerable more than Cu in underwater exposures. Heavy dezincification occurred in the alpha + beta brasses in sea water. Moderate dezincification was evident in the duplex brasses in fresh water and marine atmosphere exposures. Small additions of As, Sn, and Mn were ineffective in inhibiting marine dezincification of high brasses. Tensile data generally show weight losses for the high Cu Alloy, and heavy dezincification in the duplex brasses with penetrations 2.2 to 5.5 times that shown by weight logs for the sea-water exposures. Corrosion of phosphor bronze and naval brass was galvanically accelerated 42 and 24% when coupled with 1/7 area strips of type 316 stainless steel. Efficient cathodic protection of bronze and brass was provided by C Steel anodes for periods of 8-12 years. Cu and its alloys showed varying fouling resistance in the bioactive tropical waters. Marine fouling collected directly on Cu panels when the corrosion rate of the Cu was too low to provide an effective Cu ion concentration. Galvanically protected Cu metals, including dezincified surfaces, were moderately to heavily covered at the 2 year inspection. Plates of Cu and high-Cu alloys showed decreasing fouling resistance with exposure time and all were heavily covered at 16 years. Corrosion of all Cu metals was very low in the tropical atmosphere, and they are considered excellent for this environment. All bronze and the Cu Zn alloys cored linearly with time after 1 or 2 years exposure in the atmosphere.

How chlorides affect concrete used with reinforcing steel

Abstract: THE CORROSION BEHAVIOR OF STEEL IN CONCRETE HAS BEEN ATTRIBUTED TO CONCRETE ABSORPTION AND TO SALT IN THE CONCRETE. THIS STUDY REPORTS THE RESULTS OF MEASURING RESISTIVITY AND ABSORPTION OF CONCRETE WHEN THE CHLORIDE ION AND CEMENT CONTENT OF CONCRETE ARE VARIED. THE RESULTS INDICATE THAT RESISTIVITY OF CONCRETE IS RELATED TO THE AMBIENT MOISTURE LEVEL IN THE CONCRETE AS WELL AS TO THE AMOUNT OF WATER AND CEMENT USED IN CONCRETE MANUFACTURE. SIGNIFICANT ADDITIONS OF CHLORIDE ION TO THE MIX ONLY AFFECTED RESISTIVITY BY VIRTUE OF INCREASING CONCRETE ABSORPTION. HOWEVER, WHEN CHLORIDE CONTAINING CONCRETE WAS OVEN DRIED AND RESOAKED, ITS RESISTIVITY DECREASED WITH INCREASING SALT CONTENT. THE INSTRUMENTS FOR MEASURING RESISTIVITY IN THE FIELD AND THE LABORATORY ARE SHOWN AND DESCRIBED. AN EMPIRICAL FORMULA IS GIVEN WHICH RELATES ABSORPTION TO CONCRETE MIX VARIABLES. /AUTHOR/

Corrosion of reinforcing steel bars in concrete

Abstract: THE USE OF DEICING SALTS TO REMOVE ICE AND SNOW FROM HIGHWAYS, STREETS AND BRIDGE DECKS HAS CAUSED SERIOUS CORROSION OF REINFORCING STEEL IN CONCRETE. THE STRUCTURE OF REINFORCED CONCRETE IS SIMULATED IN CELL DESIGNS AND THE EFFECT OF CORROSION IS SHOWN. THE AUTHORS DISCUSS THE EFFECTS OF MILL SCALE AND DIFFERENTIAL AERATION, SEVERAL INHIBITORS TESTED, AND VARIOUS POSSIBLE METALLIC AND NONMETALLIC COATINGS FOR STEEL. /AUTHOR/

Comparison of the soil corrosion resistance of ductile iron pipe and gray cast iron pipe

Abstract: DUCTILE IRON PIPE, ONE OF THE MAJOR MATERIALS OF CONSTRUCTION IN UNDERGROUND PIPELINES, AND GRAY CAST IRON PIPE ARE COMPARED IN A DISCUSSION OF THEIR SOIL CORROSION RESISTANCE, CHARACTERISTICS AND PERFORMANCE. RESULTS OF VARIOUS SOIL CORROSION PROGRAMS ARE ALSO OUTLINED. FACTORS AFFECTING THE SERVICE PERFORMANCE COMPARISON OF DUCTILE IRON, CAST IRON AND STEEL PIPING ARE DISCUSSED AS WELL AS PROTECTIVE MEASURES FOR DUCTILE PIPING IN CORROSIVE SOILS. /AUTHOR/

Corrosion prevention for the concrete and metal reinforcing in the construction industry

Abstract: IMPROVED PRACTICES AND TECHNIQUES OF FORMULATING CONCRETE HAVE INCREASED ITS ABILITY TO RESIST DETERIORATION AND CORROSION. IN MANY ENVIRONMENTS, HOWEVER, CONCRETE MAY BE SUSCEPTIBLE TO CHEMICAL ATTACK. THIS ARTICLE BRIEFLY DISCUSSES THE MAKE-UP OF CONCRETE, INCLUDING AIR-ENTRAINED CONCRETE, AND PRESENTS DOCUMENTED INFORMATION ON THE CORROSION OF REINFORCING METALS. METHODS OF PROTECTING AND REINFORCING CONCRETE ALSO ARE PRESENTED. THE INFORMATION IS INTENDED TO BE ONLY AN INTRODUCTION AND SHOULD NOT BE USED AS A GUIDE FOR PROTECTING CONCRETE STRUCTURES. THIS ARTICLE IS A CONTINUATION OF A SERIES ON THE PROTECTION OF MATERIALS IN THE CONSTRUCTION INDUSTRY. /AUTHOR/ REFERENCES: MATERIALS PROTECTION, JANUARY, 1968, VOL. 7, PAGES 19-23.