Construction terms
The term concrete of a suitable quality refers to concrete that will perform satisfactorily in its intended use. To do so, it must possess
I. Strength to carry superimposed loads
II. Sufficient watertightness to prevent water penetration
III. Durability to resist wear and weather
IV. Workability to ensure proper handling, placing,finishing, and curing
I II III IV
It is a finely pulverized material consisting principally of compounds of lime, silica, alumina, and iron. It is manufactured from selected materials in closely controlled processes
Portland Cement
It should be clean and free from oil, alkali, and acid. In general, those fit to drink is suitable for use in concrete.
Mixing Water
These constitute 60% to 75% of the volume of concrete. Therefore, both the cost and quality of a concrete are affected by these kinds used in it. It should be obtained from reliable dealers whose materials are of a quality known to make suitable concrete.
Aggregates
It consists of sand or another suitable fine material.
Fine aggregate
It consists of gravel, crushed stone, or another suitable material larger than 4 in. (6.4 mm) in diameter.
Coarse Aggregate
These are materials other than portland cement, aggregates, and water that are added to concrete either immediately before or during its mixing to alter the properties of the concrete in a variety of ways.
Admixture
Because concrete is unable to maintain a particular shape before it sets, it OKLING must be placed in a form or mold. In building construction, this form or mold is called
Formworks
It may be used as a rough measure of the consistency of concrete
Slump Test
These are made to determine whether a concrete has the specified compressive strength. In these tests, concrete specimens are tested at 7 days and at 28 days after they are taken to determine the concrete's rate of strength gain.
Compression Test
It is pneumatically placed concrete, used primarily for swimming pools and other in-ground and above ground free-form structures and for repairing damaged concrete. Its major advantage is that it does not require formwork even when placed on vertical surfaces
Shotcrete
Concrete should be compacted by a method appropriate to the material and its location to:
I. Eliminate stone pockets and large air bubbles
II. Consolidate each layer with that previously placed
III. Completely embed reinforcing and fixtures
IV. Bring just enough fine material to the faces and top surfaces to produce the desired finish
I II III IV
The finishing of standard-weight concrete slabs proceeds through several steps in a defined order. These steps are
screeding, leveling, edging, jointing, floating, troweling, and broom finishing
Generally, the dry materials used in making quality concrete are heavier than water. Thus, shortly after placement, they have a tendency to settle to the bottom and displace the mixing water to the surface, which is called
Bleeding
The surface of newly placed concrete is struck off by moving a straightedge back and forth with a sawlike motion across the top of the forms.
Screeding
It is the bringing of a concrete surface to true grade with enough mortar to produce the desired finish.
Leveling
When all bleed water and water sheen have left the surface and the concrete has started to stiffen, other finishing operations such as _____ may be started. It rounds off the formed edge of a slab to prevent chipping or damage.
Edging
Except when joints will be later sawed, immediately following or during edging, pre- molded inserts are placed in concrete slabs to control cracking in the concrete as a result of shrinkage
Jointing
In general, this procedure may be done when the water sheen has disappeared and the concrete will support the weight of the finisher.
Floating
It is done on slabs that are to be left exposed or to receive thin finishes, such as resilient flooring, carpet, tile, or paint.
Troweling
Steel-troweled concrete surfaces are very smooth and become slippery when wet. They can be slightly roughened to produce a nonslip surface by them
brushing or brooming
It is the breaking away of the hardened concrete surface of a slab to a depth of about 1.6 to 4.8 mm. It usually occurs at an early age of the slab.
Scaling
It is the occurrence of numerous fine hair cracks in the surface of a newly hardened slab due to surface shrinkage. These cracks form an overall pattern similar in appearance to that of a crushed eggshell.
Crazing
It is the appearance of a powdery material on the surface of a newly hardened concrete slab.
Dusting
Concrete should be protected so that moisture is not lost during the early stages of hardening, and it should be kept at a temperature that will promote hydration and protect against injury from subsequent construction activities.
Curing
When concrete is kept moist, the drying of surfaces between water applications must be prevented. Alternate cycles of wetting and drying are conducive to surface crazing or cracking.
Sprinkling
It is sometimes used on flat surfaces, such as pavements, sidewalks, and floors. A small dam of earth or other water-retaining material is placed around the perimeter of a surface, and the enclosed area is kept flooded with water.
Ponding
Slab construction depends on the following factors:
I. Slab type
II. Site preparation, including preparation of the slab bed, grading, and backfilling
III. Precautions to control ground and surface moisture
IV. Thermal control when required
I II III IV
Site characteristics that may affect the design and construction of slabs on grade, building foundations, and site improvements include:
I. Underlying soil type and properties
II. Moisture conditions
III. Thermal conditions
IV. Geographic factors that may require construction precautions to control termites or unusual condition
I I III IV
It consists of removing site improvements and vegetation that will not be a part of the new work. This includes removal of trees and other vegetation, clearing and grubbing, topsoil stripping, and removing above- and below- grade site improvements.
Site clearing
It consists of removing trees, shrubs, and other vegetation, including their roots and stumps
Clearing and grubbing
Earthwork includes
I. Excavation and filling to make way for a building
II. Backfilling after the building has been built
III. Grading preparatory to installing paving, walkways, lawns, and landscaping
I II III
Related site construction components include:
I. Underpinning existing structures to protect them from damage during adjacent excavation
II. Slope protection and erosion control
III. Chemically treating the soil to protect the building against subterranean termites
I II III
It is the time-consuming and expensive process of supporting the foundations of an existing building by placing new footings, pilings, or caissons beneath the existing footings.
Underpinning
It is usually defined as the removal of whatever materials are found down to the level required by the contract documents and disposal of the materials excavated
Excavation
For slab-on-grade construction, some preparation must be made to the subgrade, depending on the type of soil and other conditions encountered at the site. The slab bed for ground-supported slabs should:
I. Provide the necessary bearing capacity for slab support
II. Control ground moisture
III. Establish the proper slab elevation
I II III
Compacting applies energy to soil to consolidate it by compressing air volds to
increase the soil's dry density. Proper compacting:
I. Minimizes setting
II. Increases load-bearing characteristics
III. Increases soll stability IV. Reduces water penetration
I II III
These are open woven mats of nylon or other synthetic fibers. They are staked down over a slope to permit water to flow without eroding the underlying soil.
Filter fabrics
It is a layer of stone or broken concrete designed to form a pathway for the flow of water and to prevent erosion of underlying soil
Riprap
It is the prevention of water from entering an excavation, when possible, and the removal of water that does find its way in. Groundwater can be prevented from entering an excavation by means of berms and drainage channels or ditches.
Dewatering
In exchanging or sharing electrons, atoms and ions interact with their neighbors, are attracted to them, and bond into matter. There are four types of bonding:
Metallic, Covalent, Secondary
Anyone who has been alone in a building on a quiet evening knows that materials are "alive." The creaks and groans are material responses to external stimuli such as heat, wind, and gravity loads. These stimuli fall into four categories, which define the four major properties exhibited by materials
Mechanical, Thermal, Electrical, and Chemical
This is an important property, because it enables calculation of the elastic strain accompanying a particular stress or loading condition, and it enables calculation of deflection.
Modulus E
The stress value on the curve marking the transition from elastic to plastic behavior is called the
yield point or yield strength
At this point, the material rapidly begins "necking down," as does a piece of chewing gum stretched to the breaking point.
Ultimate Strength
It is a measure of a material's ability to resist indentation or penetration.
Hardness
It is a measure of a material's ability to withstand cyclic (repeated) stresses. When repeatedly stressed, even at stresses below yield strength, many materials will fracture without warning.
Fatigue resistance
It is a measure of a material's ability to dissipate or deaden mechanical vibration.
Damping capacity
It marks a material's capacity to absorb impact without fracturing. It is defined as the total energy, from elastic deformation to fracture, that a material can absorb before breaking under impact.
Impact strength or toughness