Arch 123 (Week 7) - Finals

CONCRETE AND CEMENTITIOUS MATERIALS

CEMENT

CEMENT

- This fine powder creates other materials like mortar, concrete, stucco, and grout and it acts as a binding agent in these building products. It’s often made from limestone, but other possible ingredients include clay, silica sand, and shells.

- individuals crush and combine them with materials like iron ore then heat them to high temperatures. the resulting product, called clinker, is ground

- general sense is adhesive and cohesive materials that are capable of

bonding together particles of solid matter into a compact durable mass.

MORTAR

- binds bricks, stones, and other building materials. It’s made of cement, sand, and lime. When builders add water to the mix, the cement activates and then cures as it dries. . Either substance can act as a glue for other building materials from tiles to stone.

GROUT

- is a similar product to Mortar, but it has more water in it to flow between cracks and gaps.

ADOBE

- Sun-dried mud creates adobe bricks. Sand, dirt, and other particles in the soil all go into these bricks, which individuals may also add sticks or straw to along with water. After drying, the brick shrinks and grows with the weather. Since it isn’t fired in a kiln to cure and is instead dried by the air, it isn’t suited for wet climates.

HYDRAULIC

- is a product used to stop water and leaks in concrete and masonry structures. It is a type of cement, similar to mortar, that sets extremely fast and hardens after it has been mixed with water.

- a classification of cement is made with limestone, gypsum, and clay, which is burned at high temperatures.

- example: Portland cement

NONHYDRAULIC

- The first form of cement invented is less convenient and less practical in most applications. This type of cement includes lime, gypsum plasters, and oxychloride, which means that it does not begin to harden when exposed to water.

- It needs dry conditions to strengthen at all. This type of cement includes lime, gypsum plasters, and oxychloride, which means that it does not begin to harden when exposed to water.

RAPID HARDENING PORTLAND CEMENT

- attains the same strength in one day which an ordinary cement may attain in 3 days.

ALUMINUOS CEMENT

- calcium aluminate cement, aluminous cement, (Brit.) high alumina cement. The product was obtained by pulverizing clinker, consisting essentially of hydraulic calcium aluminates resulting from fusing or sintering a suitably proportioned mixture of aluminous and calcareous materials.

HIGH ALUMINA CEMENT

- This is not a type of Portland cement and is manufactured by fusing 40 percent bauxite, 40 percent lime, 15 per iron oxide with a little of ferric oxide and silica, magnesia, etc. (Table 5.5) at a very high temperature. The alumina content should not be less than 32%. It is resistant to the action of fire, seawater, acidic water, and sulfates and is used as refractory concrete, in industries and is used widely for precasting. It should not be used in places where the temperature exceeds 18 degrees Celsius.

SUPERSULPHATE PORTLAND CEMENT

- higher water resistant than that of common Portland cement because of the absence of free calcium oxide hydrate. This cement should not be used in constructions exposed to frequent freezing-and-thawing or moistening and-drying conditions.

SULPHATE RESISTING PORTLAND CEMENT

- This cement can be used as an alternative to ordering Portland cement or Portland pozzolana cement or Portland slag cement under normal conditions. Its use however is restricted where the prevailing temperature is below 40°C.

PORTLAND CEMENT

- most common type of hydraulic cement used in building and construction. Its application includes everything from building construction, home foundations, bridges, sidewalks, and other infrastructure.

PORTLAND SLAG CEMENT

- To limit the heat of hydration of low heat Portland cement (LHC), the tricalcium aluminate component in cement is minimized and a high percentage of dicalcium silicate and tetra calcium alumino ferrite is added.

- most suitable for large mass concrete works such as dams, large raft foundations, etc.

PORTLAND PUZZOLANA CEMENT

- These have a lower rate of development of strength but ultimate strength is comparable with ordinary Portland cement. It has low heat evolution and is used in the places of mass concrete such as dams and places of high temperature.

QUICK SETTING PORTLAND CEMENT

- The quantity of gypsum is reduced and a small percentage of aluminum sulfate is added. It is ground much finer than ordinary Portland cement. It is used when concrete is to be laid underwater or in running water.

WHITE AND COLORED PORTLAND CEMENT

- It is manufactured from pure white chalk and clay free from iron oxide. The greyish color of cement is due to iron oxide.

- is made by adding 5 to 10 percent coloring pigments before grinding. Air entraining cement is used for the same purposes as that of OPC.

CALCIUM CHLORIDE CEMENT

- It is also known as extra rapid hardening cement and is made by adding 2 percent of calcium chloride. Since it is deliquescent, it is stored under dry conditions and should be consumed within a month of its dispatch from the factory. It is very suitable for cold weather.

WATER REPELLENT CEMENT

- or hydrophobic cement. A small amount of hydrophobic surfactants such as stearic acid, boric acid, or oleic acid is mixed with the ordinary Portland cement during the grinding of clinker. It is resistant to penetration of water usually most suitable for basements and for making watertight concrete.

WATERPROOF CEMENT

- It is manufactured by adding stearates of Ca and Al and gypsum treated with tannic acid, etc. at the time of grinding. It is resistant to the penetration of water. Water retaining structures like tanks, reservoirs, retaining walls, swimming pools, bridge piers, etc.

AGGREGATES

- are the materials used as filler with binding material in the production of mortar and concrete. They are derived from igneous, sedimentary, and metamorphic rocks or manufactured from blast furnace slag, etc.

- form the body of the concrete, reduce the shrinkage, and affect the economy. They occupy 70-80 percent of the volume and have considerable influence on the properties of the concrete.

- properties that are selected for these are strength, particle shape, specific gravity, bulk density, voids, porosity, moisture content, and bulk.

- are classified as normal-weight, heavy-weight and light-weight aggregate

depending on weight and specific gravity

NATURAL AGGREGATES

- obtained by crushing from quarries of igneous, sedimentary, or metamorphic rocks.

- require sieving and washing before they can be used in concrete.

ARTIFICIAL AGGREGATES

- Broken bricks, blast furnace slag, and synthetic aggregates

- Broken bricks known as brickbats are suitable for mass concreting, for example, in foundation bases.

- produced by thermally processed materials such as expanded clay and shale used for making lightweight concrete.

COARSE AGGREGATE

- Aggregate retained on 4.75 mm sieve is identified as coarse. They are obtained by natural disintegration or by artificial crushing of rocks. The maximum size of aggregate can be 80 mm. The size is governed by the thickness of the section, spacing of reinforcement, clear cover, mixing, handling, and placing methods.

ALL-IN-AGGREGATE

- Naturally available aggregates of different fractions of fine and coarse sizes - The deficiency of any particular fraction can be corrected for use in the mix but they are not recommended for quality concrete.

GRADED AGGREGATE

- Aggregate most of which passes through a particular size of the sieve

FINE AGGREGATE

- Aggregate passing through 4.75 mm sieve

- They may be natural sand—deposited by rivers, crushed stone sand—obtained by crushing stones, and crushed gravel sand. The smallest size of is 0.06 mm.

ROUNDED AGGREGATE

- These are generally obtained from a river or seashore and produce minimum voids (about 32 percent) in the concrete. They have a minimum ratio of surface area to the volume, and the cement paste required is minimum. Poor interlocking bond makes it unsuitable for high-strength concrete and pavements.

IRREGULAR AGGREGATES

- They have voids about 36 percent and require more cement paste as compared to rounded aggregate. Because of irregularity in shape, they develop a good bond and are suitable for making ordinary concrete.

ANGULAR AGGREGATES

- They have sharp, angular, and rough particles having maximum voids (about 40 percent).

- provides a very good bond than the earlier two, is most suitable for high strength concrete and pavements; the requirement of cement paste is relatively more.

FLAKY AGGREGATES

- These are sometimes wrongly called elongated aggregate. However, both of these influence the concrete properties adversely. The least lateral dimension of this should be less than 0.6 times the mean dimension.

NATURAL CEMENT

- formed by calcining a naturally occurring mixture of calcareous and argillaceous substances at a temperature below that at which sintering takes place. A hydraulic cement made from naturally occurring limestone containing up to 25 percent argillaceous material.

LIMES

- calcium oxide (CaO), occurring naturally in limestone, marble, chalk, coral, and

shell

PURE LIMESTONE

- called calcite and that containing magnesite is called dolomitic limestone. The mineral containing calcium carbonate and magnesium carbonate in equimolecular quantities is called dolomite.

STONE LIME

- is almost pure lime obtained by calcination of limestone and is used for making lime-sand mortar for superstructures; lime-surkhi mortar for substructures and: lime terracing and flooring.

- has hydraulic properties.

KANKAR LIME

- is an impure lime obtained by calcination of kankars dug out from underground sources. These occur in the form of nodules and compact blocks. It is suitable for making Limesand mortar substructures. It is commonly used for making hydraulic lime.

SHELL LIME

- is very pure lime obtained by calcination of shells of sea animals and corals. It is used for lime punning, whitewash and color wash, soil stabilization, and glass production.

MAGNESIAN LIME

- is manufactured from dolomite and contains magnesia more

than 5%. It is used for making mortar and plaster.

LOW TEMPERATURE GYPSUM DERIVATIVES

- common name, however, is plaster of Paris. It is a fine powder, usually white.

OXYCHLORIDE CEMENT

- Lightly calcined magnesium oxide mixed with a solution of magnesium chloride forms a cement known as magnesium oxychloride cement or Sorel cement.

MASONRY CEMENT

- mortar cement, are intended to be mixed with sand and used for setting unit masonries, such as brick, tile, and stone.

NATURAL PUZZOLANAS

- All puzzolanas are rich in silica and alumina and contain only a small quantity of alkalis. Following are some of the naturally occurring puzzolanas.

ARTIFICIAL PUZZOLANAS

- fly ashes, silica fume, surkhi, ground blast-furnace slag

FLY ASHES

- produced by coal combustion, generally in an electrical generating station. The ash that would normally be released through the chimney is captured by various means, such as electrostatic precipitators.

SILICA FUME

- or micro silica, is a condensed gas, the by-product of metallic silicon or ferrosilicon alloys produced by electric arc furnaces. (While both terms are correct, micro silica (MS) is a less confusing name.)

SURKHI

- It is one of the artificial puzzolana obtained by burning clay soils at specified predetermined temperatures.

- is extensively used in making mortar and concrete as an adulterant for the economy. But its chief function is to impart strength and hydraulic properties to mortar.

GROUND BLAST-FURNACE SLAG

- is a by-product obtained while smelting iron ore in a blast furnace. Rice husk ash - The combustion of agricultural residues volatilizes the organic matter and silica-rich ash is produced. Of all the agricultural wastes, rice husk yields the largest quantity of ash with about 93 percent silica which gives it pozzolanic properties.

MORTAR

- are composed of cementitious material, fine aggregate, sand, and water. They are used for bedding unit masonry, plasters, and stuccoes, and with the addition of coarse aggregate, for concrete.

- used for unit masonry and plasters. Properties vary greatly, being dependent on the properties of the cementitious material used, the ratio of cementitious material to sand, characteristics, and grading of the sand, and the ratio of water to solids. Properties – Workability, water retention, strength, coefficients, coefficient of thermal expansion Ex. High bond mortars

CONCRETE

- composite man-made material is the most widely used building material in the construction industry. It consists of a rationally chosen mixture of binding material such as lime or cement, well-graded fine and coarse aggregates, water, and admixtures (to produce concrete with special properties). The most useful property of concrete is its compressive strength. However, it is weak in tension.

BATCHING OF MATERIALS

- For good quality concrete, a proper and accurate quantity of all the ingredients should be used. The aggregates, cement, and water should be measured with an accuracy of ± 3 percent of batch quantity and the admixtures by 5 percent of the batch quantity. There are two prevalent methods of batching materials, volume batching and weigh batching. The factors affecting the choice of the batching method are the size of the job, required production rate, and required standards of batching performance. For most important works weigh batching is recommended.

VOLUME BATCHING

- is generally recommended for small jobs only. The amount of each solid ingredient is measured by loose volume using a standard box known as a gauge box.

WEIGH BATCHING

- used for all important works

- For smaller works manual batching is done. All the operations of weighing and batching the ingredients are done manually. The weighting may also be done by ordinary platform weighing machines. For large-size works weigh bucket equipment are used. The weigh buckets are fed from hoppers and these discharge the ingredients by gravity, straight into the mixer.

HAND MIXING

- It is used for small jobs. It is done over an impervious floor. Measured quantities of coarse aggregate and fine aggregate are spread over the floor in alternate layers. Then cement is poured over it and the ingredients are mixed dry with a shovel until color uniformity is achieved. This mix is spread out in thickness of 200 mm and water is sprinkled. The mix is kept on turning over till a uniform color is achieved.

- it is desirable to add some more cement (10%) to cater to the possible inferior concrete produced by this method.

MACHINE MIXING

- For quality works mixing is carried out by mixer. Mixers can be broadly classified as batch mixers and continuous mixers. The batch mixers produce concrete batch by batch with a time interval, whereas continuous mixers produce concrete continuously till the plant is working. Batch mixers are used for small and medium-size works. Continuous mixers are used for large-size works, e.g., dams. A typical vertical batching mixing plant for large-size work.

SITE MIXED

- for delivery by chute, pump, truck, conveyor, or rail dump cars. (Mixing procedure for normal-aggregate concretes and lightweight aggregate concretes to be pumped are usually different because the greater absorption of some lightweight aggregates must be satisfied before pumping.)

CENTRAL-PLANT MIXED

- for delivery in either open dump trucks or mixer trucks.

CENTRAL PLANT BATCHING

- (weighing and measuring), for mixing and delivery by truck (‘‘dry-batched’’ ready mix).

AIR ENTRAINMENT

- Use of entrained air is recommended for all concrete exposed to weathering or deterioration from aggressive chemicals.

ACCELERATOR

- The usual objective for use of an accelerator is to reduce curing time by developing 28-day strengths in about 7 days (ASTM C494).

RETARDERS

- Admixtures that provide controlled delay in the set of a concrete mix without reducing the rate of strength gain during subsequent curing offer inexpensive prevention of much hot weather concreting problems (ASTM C494).

SUPERPLASTICIZERS

- these admixtures, which are technically known as ‘‘high-range water reducers,’’ produce a high-slump concrete without an increase in mixing water. Slumps of up to 10 in. for a period of up to 90 min can be obtained.

WATERPROOFING

- The various water-repellent admixtures are intended to prevent capillarity, but the most severe leakage in concrete occurs at honeycombs, cold joints, cracks, and other noncapillary defects.

CEMENT REPLACEMENT

- The most common applications of these admixtures are for low heat, low-strength mass concrete, or concrete masonry.

SPECIAL PURPOSE ADMIXTURES

- for corrosion inhibitors, fibers for concrete mixers, for increasing tensile strength admixture, for coloring concrete, neutralize alkali reaction, gas-forming admixtures, pumping aids, permeability, and other miscellaneous admixtures.

CONSTRUCTION JOINTS

- are formed when fresh concrete is placed against hardened concrete.

EXPANSION JOINTS

- are provided in long components to relieve compressive stresses that would otherwise result from a temperature rise.

CONTRACTION JOINTS

- (control joints) are provided to permit concrete to contract during a drop in temperature and to permit drying shrinkage without resulting in uncontrolled random cracking.

ACID-RESISTANT CEMENT

- consists of an aqueous solution of sodium silicate (soluble glass), an acid-resistant aggregate, and an additive (hardening accelerant).

- is used for lining chemical apparatus and for building towers, tanks, and other installations for the chemical industry. Soluble glass is also used for preparing acid-resistant and heat-resistant coatings.

EXPANDING CEMENT

- is used for repairing concrete and reinforced concrete constructions, for water-proofing tunnels and pit shafts, in underground and underwater constructions, for water-impermeable joints.

OIL WELL CEMENT

- is used to secure oil-well pipe casing with the surrounding earth and rocks.

REINFORCED CEMENT CONCRETE

- is a composite material made up of cement concrete and reinforcement in which the concrete resists compression with reinforcement resisting the tension and shear.

PRE-STRESSED CONCRETE

- A concrete in which stresses of suitable magnitude and distribution are introduced to counteract, to the desired degree, the stresses resulting from external loads.

- is achieved by either pre-tensioning or post-tensioning. It is widely used for the construction of precast units such as beams, floors, roofing systems, bridges, folded plate roofs, marine structures, towers, and railway sleepers.

POLYMER CONCRETE

- It is widely used for the construction of precast units such as beams, floors, roofing systems, bridges, folded plate roofs, marine structures, towers, and railway sleepers. strength, resistance to oil, grease, and abrasion. They also improve the bond between the new and old concrete and are useful for prefabricated structural elements and prestressed concrete. The disadvantages are that they are very brittle and expensive.

- finds its application in the production of prefabricated elements, prestressed concrete, ferrocement products, marine works, nuclear power plants, and industrial applications. Because of its high sulfate and acid resistance properties, it is most suitable for sewage disposal works.

FIBER REINFORCED CONCRETE

- Conventional concrete is modified by random dispersal of short discrete fine fibers of asbestos, steel, sisal, glass, carbon, polypropylene, nylon, etc.

- is useful in hydraulic structures, airfield pavements, highways, bridge decks, heavy-duty floors, and tunnel linings.

FERROCEMENT

- is a composite material in which the filler material (called the matrix), cement mortar, is reinforced with fibers, usually steel mesh dispersed throughout the composite, which results in better structural performances than individual ones. The fibers impart tensile strength to the mass.

- suitable for liquid retaining structures, boat building, gas containers, caissons, canal lining, etc.

SHOTCRETE

- is the concrete conveyed through a hose and is pneumatically projected at a high velocity on a surface. It is similar to gunite (mortar) but with coarse aggregates.

- finds its applications in tunneling, repairing old concrete and thin sections. Though costly,requires shuttering and formwork only on one side resulting in the economy and making it particularly suitable for thin sections. The fact that it can be conveyed over a considerable distance in a small diameter pipe makes it suitable for sites where access is difficult. However, it cannot be used in confined spaces as the expansion of compressed air causes turbulence, which makes accurate placing difficult. Also, the variable quality of the finished product, highly skilled personals and its cost are some of the main disadvantages limiting its application.

GYPSUM

- is a cementitious material composed of at least 70% of CaSO4 2H2O by weight

(Art. 4.6). It is the main ingredient of many building products.

GYPSUM BOARD

- This product consists of a core of set gypsum surfaced with specifically manufactured paper firmly bonded to the core. It is designed to be used without the addition of plaster for walls, ceilings, or partitions and provides a surface suitable to receive either paint or paper.

- is produced so that it is ready to receive paint or paper

GYPSUM LATH

- is similar to gypsum board in that it consists of a core of set gypsum surfaced with paper.

- is specially designed or treated so that plaster will bond tightly to the paper.