Types of Bitumen  Penetration Grade Bitumens Refinery bitumens are produced with a range of viscosities and are known as penetration grade bitumens. The term derives from the test that is used to characterise them according to hardness. The range of penetration grades for road bitumens is from 15 to 450, although the most commonly used […]

Constituents of Bituminous Materials Bituminous materials consist of a graded aggregate bound together with bitumen. In addition, the mixture contains a small proportion of air. Thus bituminous materials are three-phase materials and their properties depend upon the properties of the individual phases as well as the mixture proportions. The two solid phases are quite different

Durability of Steel in Concrete Nearly all structural concrete contains steel, either in the form of reinforcement to compensate primarily for the low tensile and shear strength of the concrete, or as prestressing tendons that induce stresses in the concrete to oppose those due to the subsequent loading.  Sound concrete provides an excellent protective medium

Degradation of Concrete The degradation agencies that affect concrete can be divided into two broad groups: those whose action is initially chemical, before subsequently leading to loss of physical integrity; these include sulphates, seawater, acids and alkali– silica reactions those which directly lead to physical effects, such as freeze–thaw and fire. We will now consider

Durability can be defined as the ability of a material to remain serviceable for at least the required lifetime of the structure of which it forms a part. Standards and specifications increasingly include requirements for a design life, which can typically be 50 or 100 years, but for many structures this is not well defined,

There are a wide variety of methods and techniques available for the non-destructive testing of structural concrete, which can be broadly divided into those that assess the concrete itself, and those which are concerned with locating and determining the condition of the steel embedded in it. We are going to describe three well-established tests for

Mix design is the process of selecting the proportions of cement, water, fine and coarse aggregates and, if they are to be used, additions and admixtures to produce an economical concrete mix with the required fresh and hardened properties. It is often, perhaps justifiably, referred to as ‘mix proportioning’ rather than ‘mix design’. The cement

Cracking and Fracture in Concrete  Development  of Microcracking  The non-linear stress–strain behaviour of concrete in compression is largely due to the increasing contribution of microcracking to the strain with increasing load. Four stages of cracking behaviour have been identified (Glucklich, 1965): Stage 1, up to about 30% maximum stress. The pre-existing transition-zone cracks remain stable,

Strength Influencing Factors of Cement Concrete In this article we will consider the strength of concrete with Portland cement as the sole binder. The effect of additions will be discussed as well. Transition/Interface Zone  Before looking at the relationships between the strength of concrete and the many factors that influence it, we need to introduce

Strength is probably the most important single property of concrete, since the first consideration in structural design is that the structural elements must be capable of carrying the imposed loads. The maximum value of stress in a loading test is usually taken as the strength, even though under compressive loading the test piece is still