Many decisions in design are based on engineering judgement, but not only on the understanding of theory or any computational tools. Even experience in extensive design in academic context can provide only limited perspective in engineering decision making. Most lessons in engineering decision making come from the cases of histories of failures of structures, which(…)
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CONCRETE CHEMICALS AND APPLICATIONS
Concrete Chemicals (Admixtures) and Applications Admixtures are materials other than cement, aggregate and water that are added to concrete either before or during its mixing to alter its properties, such as workability, curing temperature range, set time or color. Some admixtures have been in use for a very long time in concrete construction, such as(…)
CONCRETE MIX DESIGN USING CRUSHED SAND
The process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of the required, strength, durability, and workability as economically as possible, is termed the concrete mix design. The proportioning of ingredient of concrete is governed by the required performance of concrete in 2 states, namely(…)
MAINTENANCE OF CONCRETE STRUCTURES
Maintenance of Concrete Structures: Modern concrete is a very durable construction material and, if properly proportioned and placed, will give very long service under normal conditions. Many concrete structures, however, were constructed using early concrete technology, and they have already provided well over 50 years of service under harsh conditions. Such concrete must be inspected(…)
QUANTITY & RATE ANALYSIS FOR REINFORCED CONCRETE
Today we will see how to prepare rate analysis for Reinforced Concrete (RCC) work. First step to rate analysis is the estimation of labour, materials, equipments and miscellaneous items for particular quantity of reinforced concrete. The second step is to determine the component of structure for which the RCC rate analysis is required, as the(…)
FACTORS AFFECTING CONCRETE ADMIXTURES PERFORMANCE
The various factors which affect the performance of concrete admixtures are: 1. Type of super-plasticizer: The admixture will be more effective if molecular weight of the super-plasticizer is high. 2. Dosage: The quantity of admixture should be optimum. Excess of admixture may cause segregation or bleeding. It may also cause excessive retardation. The optimum does(…)
CONCRETE PERMEABILITY TEST
When concrete is permeable it can cause corrosion in reinforcement in presence of oxygen, moisture, CO2, SO3- and Cl- etc. This formation of rust due to corrosion becomes nearly 6 times the volume of steel oxide layer, due to which cracking develops in reinforced concrete and spalling of concrete starts. So, if the concrete is(…)
METHODS OF EVALUATION OF EXISTING BUILDINGS
Evaluation of Existing Buildings The available methods are evaluation by structural analysis based on known material properties, dimensions and loading, evaluation by analysis and physical load testing, and evaluation by analysis and structural modeling depending on the nature of the structure and the level of information available about the existing condition of the structure. Evaluation(…)