Report On Concrete Deterioration Statistical Analysis

Introduction

Concrete is an artificial stone material composed of cement, sand, water and gravel. During solidification compacted mixture of binder (cement) with aggregate formed concrete. As the filler can be used gravel, sand and gravel. Concrete deterioration (corrosion) is a process of destruction of its structure, embrittlement, under the influence of the environment. Corrosion of concrete can be of three types.

Forms of Concrete deterioration:

1. Dissolve the components of cement stone.
This is the most common form of corrosion of concrete deterioration. Concrete products are operated mainly outdoors, wherein they are exposed to rainfall or other liquids. An integral part of the concrete is calcium hydroxide is formed (Ca(OH)2 ) - slaked lime. It is the most readily soluble components, so it dissolves over time and gradually imposed in violation of the concrete structure.
2. Corrosion of concrete in the interaction of cement paste with the water contained in the acids.

With the reaction on acids, concrete deterioration flows with increasing volume or with lime leaching of soluble compounds.

Increased volume reaction occurs as following:
Ca(OH)2 + CO2 = CaCO3 + H2O
CaCO3  is not soluble in water. It gradually deposited in the pores of the cement paste, which is due to the increase in volume of the concrete, and later his cracking and destruction. After contact with concrete aqueous acids formed readily soluble calcium bicarbonate, which is aggressive to concrete, and in the presence of water dissolved in it and gradually washed out of the structure of concrete blocks
3. Corrosion of concrete due to the formation and crystallization of sparingly soluble substances in the pores.
In addition to the above concrete corrosion damage in the presence of microorganisms may flow biocorrosion. Fungi, bacteria and some algae can penetrate into the pores of concrete blocks and develop there. In the beginning laid the products of their metabolism and gradually destroy the structure of concrete blocks. There are several types of damage of concrete corrosion usually occurs simultaneously.

Corrosion of concrete (reinforced concrete structures) in extreme conditions:

Extreme conditions can be called a concrete impact on the stone at very low temperatures and various substances with increased aggressiveness. Widespread case of corrosion of concrete in extreme conditions is the destruction of the material under the influence of sulphate (chemical corrosion of concrete). First of all, interact with sulphates aluminate components of concrete blocks and calcium hydroxide. It is very undesirable an interaction of aluminate minerals and sulfates. The result is a few modifications of hydrosulphatealuminates, the most dangerous of which is the ettringite. This salt as they grow (increase crystals) forms within the concrete is very high voltages, which are significantly higher than the strength characteristics of the cement paste. As a result, under the influence of solutions, which include sulfates, corrode concrete proceeds very rapidly.
When reacting with sulphates of calcium hydroxide is formed CaSO4•2H2O. Over time, the substance accumulates in the pore space of concrete, gradually destroying it. Resistance to sulfate-containing environments is highly dependent on the mineralogical composition of the concrete. If the content of the cement-based minerals tricalcium silicate and aluminum is limited, it is in this environment is more stable. If the design uses a poured concrete iron armature, i.e. reinforced concrete, the occurrence of another type of destruction - the reinforcement corrosion in concrete. Under the influence of water environment or in the presence of hydrogen sulfide in the air, chlorine, sulfur gas valves in the middle of the concrete and rusting iron corrosion products are formed. By volume, they exceed the initial volume of the valve that leads to the emergence and growth of the internal stress, and in the future - cracking of concrete.
Through the pores in the cement stone to the fixture penetrates the air and moisture. Approach to the surface of the metal is not uniformly performed due to which different areas of the surface are observed at different potentials - electrochemical corrosion occurs. The flow rate of electrochemical corrosion of reinforcement depends on the moisture permeability, porosity of concrete blocks and the presence of cracks in it. The presence of solutes in water increases with increasing corrosion of reinforcement in the electrolyte concentration. When concrete is prolonging storage in air for surface forms a very thin (5 - 10 microns) a protective film which is insoluble in water and does not react with the sulfates. Process of formation of the protective film under the influence of atmospheric carbon dioxide is called carbonation. Carbonation protects concrete against corrosion, but contributes to corrosion of reinforcement in concrete. Impossible reinforced concrete, which includes calcium chloride (more than 2% by weight of cement). Calcium chloride accelerates the corrosion of reinforcement both in air and in water.
In this paper I will demonstrate an understanding of the techniques included in the engineering statistics. I will use concrete defect database to analyze using statistical techniques the rates of deterioration of structural members from 1 to 9.

Body

I’m given with 5 data sets of concrete deterioration - #1, 3, 5, 7 and 9. There are following variables used in the samples:
Defect – the type of concrete deterioration. Each type of defect is corresponding to the number of data set
Age – the age of concrete
We have to generate 5 data subsets for the defects of 1, 3, 5, 7 and 9, however, we would like to take whole samples (the conditions say I have to take a minimum of 70 observations, but nothing restricts me to take the whole sample, there is no maximum constraint).
The variable we observed is Age variable. We recode Age variable for each data set as Age1, Age3, Age5, Age7 and Age9. Thus, there are five variables which will be observed according to the outline of assignment specification.

Following steps mentioned in assignment specification.

Create a histogram of 5 sets of the data