10 sources of cracking in concrete you should know

10 sources of cracking in concrete you should know

We all understand cracking is one in all the most important issues in concrete and it ought to be thought of whereas combine style, except for that, we've to grasp the sources that can cause cracking in concrete. Here may be a list of sources of cracking in concrete.

Sources Of Cracking In Concrete

Use of low-grade materials:

One of the most important sources is that the use of lower quality materials that embody each concrete and steel in ferroconcrete structures.

Shrinkage:

Shrinkage will cause cracking if not controlled throughout combine style and solidification stage. Shrinkage will become important in high strength concrete thanks to low water/cement magnitude relation and additionally thanks to use of Mineral Admixtures.

Quality and Type Of Aggregate:

The quality of mixture employed in concrete determines the general strength of concrete. If the combination is of poor quality it'll not build a correct bond with cement.

Overloading of structure:

The Overloading of structures particularly at younger age may be  common supply of cracking. This can happen if formwork is removed before time or additional construction load is gift.

Mistakes at design stage in office:

If there area unit errors at style stage then it's obvious that issues can occur at website. concrete cracking is one of them.

Improper Curing:

Another major cause of concrete cracking. If curing is not done appropriately for given time span then one should expect cracking.

Early Formwork Removal:

If the formworks is removed before concrete has achieved strength, there will be cracking.

Use of Congested Reinforcement in Lean Concrete:

If you use heavy reinforcement in average quality concrete then stress distribution between steel and concrete can become non-linear causing cracking.

Mistakes at Site or during erection:

Proper and trained labour and acquisition area unit necessary for any website work. Lack of it during concreting can cause cracking.



Follow on facebook--@KDLEARNERS

Read More

Corrosion

Corrosion

                         Corrosion

INTRODUCTION:
Corrosion is an undesirable phenomena or process. Due to the corrosion there is limitation of progress in
many the area. The cost of replacement of the  materials and equipment lost through corrosion is
unlimited.
Metals and alloys are used as fabrication or construction materials in engineering. If the metals or alloy structures are not properly maintained, they deteriorate slowly by the action of atmospheric gases, moisture and other chemicals. This phenomenon of destruction of metals and
alloys is known as corrosion.
Corrosion of metal is defined as spontaneous destruction of metals in the course of their chemical, electro-chemical or bio-chemical interaction with the environment. Thus, it is exactly the reverse of the extraction of metals from the ores.
Example: Rusting of iron
A layer of reddish scale and powder of oxide (Fe3O4) is formed on the surface of the iron metal.
A green films of the basic carbonate [CuCO3 + Cu(OH)2] is formed on the surface of copper, when it is exposed to moist-air containing carbon dioxide.

CONSEQUENCES (EFFECTS) OF CORROSION:

The economic and social consequences of corrosion include
i) Due to formations of the corrosion product over the machinery, the efficiency of the machine gets failure leads to plant shut down.
ii) The product contamination or losses of products due to corrosion.
iii) The corroded equipments must be replaced
iv) Preventive maintenance like the  metallic coating or organic coating is required.
v) Corrosion releases toxic products.
vi) Health (eg., from the pollution due to a corrosion product or due to escaping chemical from a corroded equipment).

CAUSES OF CORROSION:

In nature, metals occur in two different forms.

1) Native State (2) Combined State

Native State: The metals exist as such in the earth crust then the metals are present in a native state.Native state means free or uncombined state. These metal the are non-reactive in nature. They are the noble metals which have very good corrosion resistance. Example: Au, Pt, Ag, etc.,

Combined State: -Except noble metals, all other metal are the highly reactive in nature which the undergoes the reaction with their the  environment to form the stable compound called ores and minerals. This is combined state of metals. Example: Fe2O3, ZnO, PbS, CaCO3, etc.,

Metallic Corrosion: The metal are extracted from their metallic compounds (ores). During  extraction, ores are reduced to their the  metallic states by applying energy in form of various process. In pure metallic state, the metals are the unstable as they are considered in excited states (higher energy state). Therefore as soon as the metals are extracted from their ores, the reverse process begin and form the metallic compounds, which are the thermodynamically stable (lower energystate). Hence, when metals are used in various forms, they are exposed to the environment, the exposed metal surface begin to the decay (conversion to more stable compound). This is the basic reason for metallic corrosion.

Corrosion-Oxidation

Metal Metallic Compound + Energy

Metallurgy-Reduction

Although corroded metal is the  thermodynamically more stable than the pure metal but due to corrosion, useful properties of a metal like malleability, ductility, hardness, luster and electrical conductivity are lost.

CLASSIFICATION OR THEORIES OF CORROSION

Based on the environment, corrosion is classified into

(i) Dry or Chemical Corrosion .

(ii) Wet or Electrochemical Corrosion.

For more detailed about corrosion download pdf by clicking below download button

All detailed concept of corrosion - Download PDF

Read More

THE SECRETS OF LEARNING MATH

THE SECRETS OF LEARNING MATH

THE SECRETS OF LEARNING MATH

There are essentially two secrets to learning mathematics; the first is concerned with the content and the other with teaching. There is far too much content at each grade level, and every few years the amount of content is increased. Under these conditions, students are urged to memorize concepts without understanding in order to maintain an acceptable grade level on tests. Research has determined that, for most math students, the memorization of concepts without understanding is stored in the short-term memory and soon forgotten. The first secret to student success in math is to reduce the amount of content at each level so that there is time to learn and understand the concepts.


The second secret is one concerned with teaching. I have often heard that in the history of education, the "best" education took place in the one-room schoolhouse. If this is true, then it is because in a one-room schoolhouse education often came about as a result of older students teaching younger ones; both students gain from this experience. When a student is able to explain in his or her own words a math concept, that student understands the concept. The second secret to student success in learning math is to have students understand math concepts and demonstrate their understanding the concept by correctly explaining it in their own words to someone else.

THE SECRETS OF LEARNING MATH

The predominate guideline for mathematics curriculum the past few decades has been acceleration and this has resulted in all math courses having too much content. This means that most students must memorize math to pass the course. Unfortunately memorizing is short-term and not related to understanding mathematics.

Conclusions from the Research

              Conclusions from the Research

There seems to be two main factors that could be corrected in our teaching of math courses that would go a long way toward eliminating the current problem. These two factors are memorization and acceleration.

Memorization:

                      Memorization

Students are trying to memorize all necessary facts that are needed to pass the course. Unfortunately, this is not possible for most students and such a course of action has no long-term benefits; hence causing the basic problem in mathematics.

Acceleration:

THE SECRETS OF LEARNING MATH

We are attempting to teach too much too fast in math courses. This, in turn, causes students to rely on memorization as their best hope to pass the course. We do not give them the proper amount of time to understand concepts, which reduces the need for memory.

Read More