Concrete is a mixture of Portland cement, aggregates, sand, water, and in some cases which respect to the purpose, admixtures. It is known to the world of construction as the most widely used material for any build structure and often looked upon as “man made rock”. Furthermore, it is the most versatile construction material and adaptable to a wide variety of usage in building any desired structures for residential, commercial and industrial, and other sections. The way I see it, the usage often two times larger than other materials for any civil projects especially in bigger scale.

In General
Concrete can be placed or molded into virtually any imaginable shape and re-produce any surface texture. With proper materials, combination, and techniques, concrete can withstand many acids, silage, milk, manure, fertilizers, water, fire, and abrasion. It can be finished to produce surfaces ranging from glass-smooth to coarsely textured, and it can be colored with pigments or painted.

The Components

The Concrete Mixer Machine

Portland Cement
The cement and water form a paste that hardens and bonds the aggregates together through hydration phase. It is a substance that hardens with time and holds or entraps objects or particles in a definite relationship to each other. Mostly and widely used product would be Portland cement.

Aggregates
Aggregates occupy largely of 60 to 80 percent of the volume of concrete. Sand, gravel and crushed stone are the primary aggregates used in the concrete mixer. All aggregates must be essentially free of silt and/or organic matter.

Water
Good water is essential for quality of concrete and it should be good enough for drinking purposes; free of trash, organic matter and excessive chemicals and/or minerals. The strength and other properties of concrete are highly dependent on the amount of water and the water-cement ratio used in the mixing of concrete.

Admixture
Admixtures are ingredients other than Portland cement, aggregates, and water. It would be added to the concrete mixture immediately before or during mixing, depending on its requirements.

The Concrete States
1) Plastic State
When the concrete is first mixed it is like ‘bread dough’. It is soft and can be worked or molded into different required shapes. In this state concrete is called plastic. Concrete is plastic during placing and compaction. The most important properties of plastic concrete are workability and cohesiveness.

2) Setting State
In the second state, concrete then begins to stiffen. The stiffening of concrete, when it is no longer soft, is called setting. Setting takes place after compaction and during finishing. Concrete that is sloppy or wet may be easy to place but will be more difficult to finish. A worker leaves footprints in setting concrete.

3) Hardening State
Finally, after concrete has set it begins to gain strength and harden. The properties of hardened concrete are strength and durability.

The Properties
Concrete has strength, durability, versatility, and economy. It has substantial strength in compression, but is weak in tension. Most structural uses, such as beams, columns, footings, slabs, staircase, and manure tank lids, involve reinforced concrete, which depends on concrete’s strength in compression and steel’s strength in tension. The compressive strengths of concrete generally range from 2,000 to 5,000 pounds per square inch (psi), but concrete can be made to withstand over 10,000 psi for special jobs.

Note: 1 psi = 6.894757293168361 kPa

The four main properties of concrete are:

The Manual Mixing Method of Concrete

Workability
Workability means how easy it is to: place, handle, compact, and finish a concrete mix. If not constructed properly, will not be as strong or durable when finally hardened. A ‘slump test’ can be used to measure the workability of concrete.

Workability is affected by:

• Amount of cement Paste: The cement paste is the soft or liquid part of the concrete mix. The more paste mixed with the coarse and fine aggregates, the more workable a mix.
• Grading of Aggregate: Well-graded, smooth, rounded aggregates improve the workability of a concrete mix.

Cohesiveness
Cohesiveness is how well concrete holds together when in plastic state.

Cohesiveness is affected by:

• Grading of Aggregate: Graded Aggregate means that there is a range of size of aggregates, from large rocks to small sands.Well-graded aggregates give a more cohesive mix, too much coarse aggregate gives a boney mix.
• Water Content: A mix that has too much water will not be cohesive and may separate and bleed. The single most important indicator of strength is the ratio of the water used compared to the amount of cement (water/cement ratio). Basically, the lower this ratio is, the higher the final concrete strength will be.

Strength and Durability

The well made concrete is a naturally strong and durable material whereby it is dense, reasonably watertight, able to resist the changes of temperature, as well as wear and tear from weathering process. Plus, it is very important to protect the steel in reinforced concrete. The strength of concrete in the hardened state is usually measured by the compressive strength using the ‘compression test’.

Strength and durability are affected by:

Concrete Cubes in Curing

• Density: Denser concrete is more watertight (or less permeable).
• Compaction is removing the air from concrete. Proper compaction results in concrete with an increased density which is stronger and more durable.
• Curing is keeping concrete damp for a period, to allow it to reach maximum strength. Longer curing will give more durable concrete. It is critical to concrete’s long-term durability that it be kept as moist as possible for the first seven days after placement.

The Testing
In normal construction practice, concrete normally tested for 7 days and 28 days for determination of strength. There are two kinds of test category:

• Destructive Test: Compression test (Cube Crushing), Flexural Beam test, Tensile Strength test, Core test, etc.
• Non-destructive Test: Rebound Hammer test, Ultra Sonic Pulse test, Covermeter, etc.

The Different Types
There are many kinds of concrete produced depending on the usage:

The Concrete Batching Plant

• Cement Concrete
• Plain Mass Concrete
• Lean Concrete
• Structural Concrete
• Reinforced Concrete
• Prestressed Concrete
• Cast in Place / Cast In-Situ Concrete
• Precast Concrete
• Vacuum Concrete
• Pumped Concrete
• Spun Concrete
• Ready Mixed Concrete
• Water Resistant Concrete
• High Density Concrete
• Fibre Reinforced Concrete

The Typical Classes

• Normal Concretes: C8/10, C12/15, C16/20, C20/25, C25/30, C28/35, C30/37, C32/40, C40/50, C50/60, C55/67, C60/75, C70/85, C90/105, C100/115
• Lightweight Concretes: LC8/9, LC12/13, LC16/18, LC20/22, LC25/28, LC30/33, LC35/38, LC40/44, LC50/55, LC55/60, LC60/66, C70/77, LC80/88

Note: Take example, C20/25 means that the concrete compressive strength is 20 MPa with the usage of 25mm diameter aggregates.

In conclusion, these are the facts on concrete and may it be useful knowledge to you as well as for me. If there is any additional info you want to add-in, you are most welcome via comment…

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Soil is described as a natural body which consist series of layers (the soil horizons) of mineral particles of changeable thicknesses, which are different from the parent materials in their morphological, physical, chemical, and mineralogical characteristics. It is located at the top layer of the Earth’s crust.

Made Of
Soil is made up of organic substance, minerals and living organisms. Organic substance is decaying material such as rotting plants and dead animals. Minerals are crushed rocks or bedrock, formed through geological processes that has a characteristic chemical composition. Living organisms include insects, moles, worms and beetles, which churn through the earth as well as essential bacteria that help to break down organic matter. In addition, the soil nutrients are boron (B), calcium (Ca), carbon (C), chlorine (Cl), copper (Cu), hydrogen (H), iron (Fe), magnesium (Mg), manganese (Mn), molypdenum (Mo), nitrogen (N), oxygen (O), phosphorus (P), potassium (K), sulphur (S), and zinc (Zn).

The Soil Living Organisms

Formation
The formation of soil happens over a very long period of time and it took 1,000 years and beyond. Soil is formed from the weathering process of rocks and minerals. The surface rocks break down into smaller pieces through a process of weathering and is then mixed with moss and organic matter. Over these times it would create a thin layer of soil. Plants help the development of the soil by attracting animals, and when the animals die, their bodies would decompose. Decaying matter makes the soil thick and rich. This cycle continues until the soil is fully formed and may supports many species of plants.

Importance
Soil is more than just the brown dirt under our feet. It is a home for many living organisms and it provides nutrients and stability for plants to grow and produce food. Without soil, the plants which produced food necessary for people and animals to survive could not exist.

By caring for our soil properly, we can make sure the longevity existence of both animals and people. The use of crop rotation, limiting harsh chemicals and composting will help to keep up a healthy balance of nutrients, living organisms and minerals in the soil. It is important to remember that the fresh foods on which we feast have an affect upon our health.

pH

Soil pH Chart

The pH level of the soil directly affects the soil life and the availability of essential nutrients for plant growth. Whether you’re planting for commercial or recreational reasons, knowing the pH of your soil can help you choose the right mix of plants and allow the right treatment for your soil.

Soil life refers to the living organisms that live in soil and break organic materials down into simpler forms. Soil bacteria, a microscopic soil occupant responsible for the decomposition of organic material into simpler nutrient forms that become food for plants, thrives at about 6.3 to 6.8 pH. While soil life plays an important part in fertilizing soil, the pH of your soil determines the form nutrients will take, as well as their availability for plant absorption.

Types
Cohesive soils
Cohesive soils have the smallest particles. Clay has a particle size range of 0.00004″ to 0.002″. Silt ranges from 0.0002″ to 0.003″. Clay is used in embankment fills and retaining pond beds.

Characteristics: Cohesive soils are dense and tightly bound together by molecular attraction. They are plastic when wet and can be molded, but become very hard when dry. Proper water content, evenly distributed, is critical for proper compaction. Cohesive soils usually need a force such as impact or pressure. Silt has a noticeably lower cohesion than clay. However, silt is still heavily reliant on water content.

Granular or Cohesionless soils
Granular soils range in particle size from 0.003″ to 0.08″ (sand) and 0.08″ to 1.0″ (fine to medium gravel). Granular soils are known for their water-draining properties.

Characteristics: Sand and gravel obtain maximum density in either a fully dry or saturated state. Testing curves are relatively flat so density can be obtained regardless of water content

Colours
A soil profile is the side view of soil, from the uppermost layer to the bottom layer. There are six layers that exist in a soil profile. They are as follows:

• The top-most layer of the soil is composed mainly of fresh soil and decaying organic matter; the color ranges from brown to black.
• The second layer of the soil consists of highly decomposing organic matter; the color ranges from brown to gray.
• The third layer of soil is composed of sand and silt. It has lost most of its nutrients; the color of this layer is light brown.
• The fourth layer consists of clay and large rocks and bedrock; the color ranges from rust to tan.
• The fifth layer of soil is bedrock; the color is gray.
• The sixth layer of soil is comprised of rock; the color is gray.

Textures
Soil texture is an important soil characteristic that drives crop production and field management. The textural class of a soil is determined by the percentage of sand, silt, and clay. Soils can be classified as one of four major textural classes: (1) sands; (2) silts; (3) loams; and (4) clays. In this fact sheet, we will discuss the importance of the soil texture, different methods to determine soil texture, and the impact of texture on management decisions.

Importance of Soil Texture
Soil texture determines the rate at which water drains through a saturated soil; water moves more freely through sandy soils than it does through clayey soils. Once field capacity is reached, soil texture also influences how much water is available to the plant; clay soils have a greater water holding capacity than sandy soils. A clay soil is referred to as a fine-textured soil whereas a sandy soil is a coarse textured soil.

Soil Textural Classes
The combined portions of sand, silt, and clay in a soil determine its textural classification. Sand particles range in size from 0.05–2.0 mm, silt ranges from 0.002–0.05 mm, and the clay fraction is made up of particles less than 0.002 mm in diameter. Gravel or rocks greater than 2 mm in diameter are not considered when determining texture. Once the sand, silt, and clay percentages of a soil are known, the textural class can be read from the textural triangle. For example, a soil with 40% sand, 40% silt and 20% clay would be classified as a loam.

The Soil Textural Triangle

The Soil Textural Triangle is used to determine soil textural class from the percentages of sand, silt, and clay in the soil. Clay percentages are read from left to right across the triangle (dashed lines). Silt is read from the upper right to lower left (light, dotted lines). Sand from lower right towards the upper left portion of the triangle (bold, solid lines). The boundaries of the soil texture classes are highlighted in blue. The intersection of the three sizes on the triangle give the texture class. For instance, if you have a soil with 20% clay, 60% silt, and 20% sand it falls in the “silt loam” class.

There you have it, approximately 7 things that you should know about the most precious material, the soil. This for an additional info and cheers to our Mother Earth…

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Previously we have looked at various civil engineering materials used in construction and now I’m adding another one. This engineering resource was acknowledged the one has the closest relationship with our precious Mother Earth and noted to have large resultant impact in engineering. Soils, in the Geotechnical sense, could be considered as engineering materials. In every aspect of civil engineering activities, most construction projects are supported by the Earth ground which is 30% of its total mass.

Soil as Civil Engineering Materials

Soil in Latin defined as the Earth or ground, also as the face or surface of the Earth. Furthermore soil can be defined in many different ways for different purposes, whereas in engineering could be too broad for its applications. Nevertheless, the best possible explanation would be as follows;

Any naturally occurring deposit forming the outer part of the Earth’s crust, consisting of an assemblage of discrete particles (usually mineral, sometimes with organic matter) that can be separated by gentle mechanical means, together with variable amounts of water and air.

The study of soil mechanics covers the investigation, description, classification, testing and analysis of soils in determination of their inter-reaction with structures built in or upon them, or built with them. Their physical characteristics can be determined by experiment, and the application analysis methods enable these properties to be used to predict its likely behavior under defined working conditions. But unlike the other engineering materials such as concrete and metal, relatively control were exercised during manufacture, soil are naturally occurring materials, which more often than not to be used in its natural state.

The variety of soils is very wide in reality, and no two or more sites have identical soil conditions or profiles. Therefore necessary to evaluate the physical properties and engineering behavior of the soils present at construction site such as burrow pits. Generally soils can be classified into two categories namely coarse grained soils (gravels and sands) and fine grained soils (silts and clays). In terms of color we may often encounter yellowish, brownish, grayish, whitish or dark in color, or a mixer in between these soils.

Soil as material is a vital constituent in construction industries where it serves as a platform or foundation for most structures. Massive volumes of soil usage involving works in surface mining, Earthworks, road embankment fill, dam construction, and so forth. Besides that, some of the most significant impacts on soil properties occur as a result of activities associated with construction such as by contaminating soil as a result of accidental spillage or the use of chemicals, reduction of soil quality by mixing topsoil with subsoil, wasting soil by mixing it with construction waste or contaminated materials, etc.

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• Materials Used In Construction

Whenever we want to build something, we must have resources or materials in order to make it a reality. In construction, a material that going to be used varies depending on what it is you intend on building. The information covered in this segment will show you about various materials solely used for construction purposes. Construction materials can be generally categorized into two main sources, the natural resources and synthetic (artificial products)

Concrete
Concrete, the most widely and popular used substance is an artificial construction material made by mixing cement, coarse aggregate, fine aggregate or sand, and water together in appropriate proportions. The usage of concrete considered as must-have materials, which allow us to build architectural structures, small to super-structures, road or highway pavements, deep and shallow foundations, bridges or flyovers, dams or retaining walls, parking structures, deep tunnels, military bunkers, and so forth. And most important characteristic of concrete is the ability to withstand the pressure or force of heavy loads due to its high compressive strength (supported by aggregates and reinforced steel bars). In addition, it can easily be molded into any desired shape and is a reasonably cheap material for any construction projects.

1. Portland Cement

Portland Cements

First substance for concrete, cement is a substance that hardens with time and holds or entraps objects or particles in a definite relationship to each other. For concrete production, Portland cement is commonly used (approximately 10% to 15% of volume) and manufactured by a standardized process consisting of grinding of raw materials, limestone and clay. The different types of cement namely Normal portland cement (type I), Modified portland cement (type II), High-early-strength Portland (type III), Low-heat portland cement (type IV), Sulphate-resistant portland cement (type V), Portland blast-furnace slag cement (type IS), Pozzolan cement (type IP), and Air-Entrained Cement. The differences in cement types are due to the usage, construction requirement and resource location. Besides that other used could be as cement-mortar for plastering works, sewer waterproofing and for sub-base layers for heavily trafficked roads.

2. Aggregates

Aggregates are vital ingredients in most construction projects, the prime volumes being in road pavements, road bases and of course concrete. Aggregates have amazingly huge variety of usage because of its internal compressive strength and durability. The fact is, more than 80 % of concrete-mix and 90% of asphalt pavements are aggregates. Moreover, aggregates are also being used to protect our environment, through soil erosion-control programs, water purification, and reduction of sulfur dioxide emissions generated by electric power-plants. It came from two categories; coarse aggregate and fine aggregate. We normally used limestone, granite and sandstone as construction materials. In some localities, the deposits are hard to obtain and large rocks must be crushed to form the aggregate.

Timber

Timbers

As a construction material, it is available in the form of a vast range of products, from roof truss, timber frame walls, glulam beams to I-beams for flooring and roofing, also from doors and windows to floors and staircases, as well as formworks of structures like beams and columns. There are many kinds of timber; however categorized as softwood (hemlock, western red cedar, etc.) and hardwood (black walnut, American white oak, etc.). If no proper treatment and installation, wood or timber can be easily destroyed by fungi, boring insects, decay, weathering, or fire.

Metal

Steels Bars

There is no straightforward definition for metal; however, any chemical element having ‘metallic properties’ is classed as a metal. The properties are defined as sheen, electrical conductivity, good thermal, and the potential of being permanently deformed or shaped at room temperature. Metal is used as structural framework for larger buildings such as skyscrapers, or as an external surface covering. There are many types of metals used for building such as titanium, chrome, gold, or silver. Steel is a metal alloy which major component is iron, and is the usual choice for metal structural building materials because of its strength, versatility, durability, economic value, and if refined well and/or treated lasts a long time. Among its most popular uses today are standing seam metal roofs and it also 100% recyclable for future use. Corrosion becomes metal’s prime enemy when it comes to longevity.

Bitumen

Bitumen

In general, bitumen is a black or dark brown, oily, non-crystalline viscous material, possessing adhesive and water-proofing qualities that occurred naturally from decomposed organic materials. It is also known as asphalt or tar. It consists essentially of hydro-carbons (80% carbon, 15% hydrogen, with oxygen, nitrogen, sulphur, and lesser metals). The type of bitumen to be used depends upon the type of soil to be stabilized, method of construction, and weather conditions. Normal types would be paving grade bitumen and cutback bitumen.

Bricks

Bricks

Bricks categorized with different used; load bearing wall, non-load bearing wall, insulation wall, and covering wall. A standard dimension of bricks is 215mm x 102.5mm x 65 mm and upon selection would be based on their usage. The common substance of bricks is clay and calcium silicate. Various types of bricks: common brick, engineering brick, face bricks, sand-lime brick, mortar brick, press bricks, glazed bricks, fire-brick, and cored brick. The arrangement works of bricks consider important and some of the popular arrangement is brick edge, brick head, and American, English, and Flemish arrangement.

Polymers
Polymers are substances made up of very large molecules which are formed by the chaining together of smaller molecules (as in polyethylene) or by condensation and the removal of moisture (as in nylon). By tradition, the industry has produced two main types of synthetic polymer – plastics and rubbers. Another way of classifying polymers is in terms of their form or function, varying from additives to other bulk materials (e.g. viscosity modifiers in plaster), coatings to products (e.g. paints), film and membranes to fibers (e.g. textiles) and bulk products such as moldings, containers and pipe. The construction sector is one of the world’s largest consumers of polymer composites, such as trimmings, baths, kitchenware, vanities, cladding, decoration and finishing.

Therefore, each of these materials is essential for civil engineering construction towards future undertaking. It is up to the respective workforce to ensure the effective method in utilizing resources.

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