Hi, Thank you for taking the time to answer the following questions which I am h

Question

Hi, Thank you for taking the time to answer the following questions which I am having trouble with. May the answers please be detailed and informative for revision and study!

Question 1 Name the four primary components of the concrete mixture and explain what the purpose of each is and what properties each adds to the final mixture. Question 2 Compare and contrast steel-reinforced concrete and pre-stressed concrete. What the benefits and drawbacks of each, and what are the primary applications of each in construction and civil engineering? Question:3 Name the six factors that can affect concrete shrinkage and state something that can be done to address each of these in isolation. If you want to create a concrete mixture that will experience zero creep, what would you have to do, and what would be the primary tradeoff for this decision? Question 4 Compare the modulus of elasticity of concrete to two other materials commonly used in civil engineering projects. Identify the differences between concrete and these two materials in terms of yield strength, ultimate strength, and fracture point. Question 5 Explain what creep recovery is

Explanation / Answer

Concrete is made of cement , sand , coarse aggregate and water , chemical admixture

Admixtures for Concrete Admixtures include all materials other than cement, water and aggregates that are added to concrete. Admixtures can be broadly classi! ed as follows: 1. Air-entraining admixtures 2. Retarding admixtures 3. Water-reducing admixtures 4. Accelerating admixtures (Used only in special circumstances) 5. Pozzolans 6. Workability agents 7. Miscellaneous, such as permeability-reducing agents, gas forming agents, and grouting agents 8. Water reducing and retarding admixtures 9. Water reducing

Water is the life of concrete and until cement comes in contact with it, the mortar many not achieve any binding property. However, excess water would dilute the binding property and affect its strength. This is referred to as water-cement ratio by engineers. A lower water-to-cement ratio gives better strength. An ideal water-cement ratio for houses and other normal work with M20 concrete should never exceed 0.50 (i.e. 25 litres of water for one bag of cement). Restricted water quantity is also difficult to handle. Admixtures, available as plasticisers, can be used only with advice taken from the technical team of the cement manufacturer or the admixture manufacturer.

A cement is a binder, a substance used in construction that sets, hardens and adheres to other materials, binding them together. Cement is seldom used solely, but is used to bind sand and gravel (aggregate) together. Cement is used with fine aggregate to produce mortar for masonry, or with sand and gravel aggregates to produce concrete.

Aggregates are generally thought of as inert filler within a concrete mix. But a closer look reveals the major role and influence aggregate plays in the properties of both fresh and hardened concrete. Changes in gradation, maximum size, unit weight, and moisture content can all alter the character and performance of your concrete mix.

Economy is another reason for thoughtful aggregate selection. You can often save money by selecting the maximum allowable aggregate size. Using larger coarse aggregate typically lowers the cost of a concrete mix by reducing cement requirements, the most costly ingredient. Less cement (within reasonable limits for durability) will mean less water if the water-cement (w/c) ratio is kept constant. A lower water content will reduce the potential for shrinkage and for cracking associated with restrained volume change.

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