Performance designed concretes

Penetration of chlorides from seawater with subsequent corrosion of embedded steel represents a serious problem and threat to the durability and long-term performance of many concrete structures in marine environments. Recent field investigations of relatively new concrete structures in Norwegian harbors have shown that chloride-induced corrosion may occur already after a service period of approximately 10 years [1-2]. In order to obtain a more controlled durability and longterm performance of concrete structures in marine environments, a proper durability design should be carried out [3]. As part of such design, surface hydrophobation of the most exposed parts of the structure may be one of several protective measures that should be considered. 

Recently, a new innovative design method is being developed for the design of breakwater caissons which is called the performance design method. Performance design can be considered as a design process that systematically and clearly defines performance requirements and respective performance evaluation methods. In other words, performance design allows the performance of a structure to be explicitly and concretely described. 

The concrete block walls of the cell housing the generator tube and associated components are 1.7 meters thick. The facility also includes a Kaman Nuclear dual-axis rotator assembly for simultaneous transfer and irradiation of reference and unknown sample, and a dual Na iodide (Nal) scintillation detector system designed for simultaneous counting of activated samples. Automatic transfer of samples between load station to the rotator assembly in front of the target, and back to the count station, is accomplished pneumatically by means of two 1.2cm (i.d.) polyethylene tubes which loop down at both ends of the system and pass underneath the concrete shielding thru a pipe duct. Total one-way traverse distance for the samples is approx 9 meters. In performing quantitative analysis for a particular element by neutron activation, the usual approach is to compare the count rates of an unknown sample with that of a reference standard of known compn irradiated under identical conditions... 

Asphalt concrete is properly proportioned to resist the potentially damaging effects in the road. Asphalt concrete paving mixtures should be evaluated for the following properties stability, flow, air voids, stripping resistance, resilient modulus, compacted density, and unit weight. Table 4.18 provides a list of standard laboratory tests that are presently used to evaluate the mix design or expected performance of fresh and hardened asphalt concrete. 

The mix proportions for concrete paving mixtures are determined by attaining optimum characteristics of the mix in both the plastic and hardened states. The designed mixture can be properly placed and consolidated, finished to the required texture and smoothness, and will have the desired properties necessary for pavement performance. Concrete paving mixtures should be... 

In this chapter we describe concrete steps towards building a system or component type specification, to describe how an object behaves in response to any external such as a request to perform some action. The approach here is mostly top-down Chapter 16, How to Implement a Component (p.627) describes how to design the insides of a component, and Chapter 18, How to Reverse-Engineer Types (p.671) covers how to reverse engineer a specification from an existing implementation. 

In most cases the material is performing well and has shown to be much more resistant to salt and acid attack than regular concrete. The material still suffers from brittle failure at the ultimate stress, thus requiring different design considerations. 

The magnitude of some of these effects is reduced in sulfur-bonded concretes and mortars. Sulfur concrete mixes of the kind described fail in compression in a much more brittle manner than portland cement concretes of similar strength. This brittleness could effect performance thus design methods used for structures made with portland cement concrete may be inapplicable. 

There are four major considerations in designing a sulfur-asphalt pavement—mix design, construction, performance, and economics. None of these are unique to sulfur-asphalt, but they must all be considered explicitly in order to show under which conditions the new sulfur-asphalt paving material may be expected to be superior to the widely used and accepted asphalt concrete pavement. 

Mix design, performance, and economics have been considered traditionally in pavement design in a largely empirical or intuitive way which does not allow simple comparisons to be made between candidate materials such as concrete and asphalt. A more efficient and consistent means of considering them is warranted because of the current need to use the most economical materials in a rapidly changing market situation. 

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