The Romans reportedly foremost used lightweight concrete during the 18th centuries. “ The application on the ‘The Pantheon ‘ where it uses pumice sum in the building of dramatis personae unmoved concrete, ” harmonizing to Hjh Kamsiah Mohd Ismail, Mohamad Shazli Fathi and Norpadzlihatun bte Manaf ( 2003 ) , all with the Universiti Teknologi Malaysia Institutional Repository, confirms the Romans usage of lightweight concrete.
In the diary article, “ Study of lightweight concrete behaviour, ” Ismail, Fathi and Manaf recount that during the late 19th century, American and English builders used cinder, a signifier of lightweight concrete in their building undertakings like the British Museum every bit good as in low cost lodging. D’Annunzio ( 2003 ) , reports “ the usage of lightweight concrete as a roof decking and insularity system has expanded in the past five old ages. Increased use can be attributed to the recent industry-wide insularity deficits and delamination lacks ” ( p. 1 ) .
The addition can besides be attributed to the economic and environmental advantages that lightweight insulating concrete ( LWIC ) provides in roof assemblies. Lightweight insulating concrete ( LWIC ) provides The reported recent industry-wide insularity deficits and delamination lacks. The addition can besides be attributed to the economic and environmental advantages that in roof assemblies. lightweight concrete as a roof decking and insularity system has expanded in the past five old ages. Increased use can be attributed to The lightweight concrete was besides used in uilding during the First World War.
The United States used chiefly for ship building and concrete blocks. The foamed blast furnace-slag and pumice sum for block doing were introduced in England and Sweden around 1930s. Presents with the promotion of engineering, lightweight concrete expands its utilizations. For illustration, in the signifier of perlite with its outstanding insulating features. It is widely used as loose-fill insularity in masonry building where it enhances fire evaluations, reduces noise transmittal, does non decompose and termite resistant.
It is besides used for vass, roof decks and other applications. Figure 5 shows some illustrations of lightweight concrete used in different signifiers. Lightweight insulating concrete ( LWIC ) provides The reported recent industry-wide insularity deficits and delamination lacks. The addition can besides be attributed to the economic and environmental advantages that in roof assemblies. lightweight concrete as a roof decking and insularity system has expanded in the past five old ages.
Increased use can be attributed to ` Lightweight concrete can accomplish similar strengths as standard concrete, and it produces a more efficient strength-to-weight ratio in structural elements ” D’Annunzio ( 2007, p. 2 ) . John A. D’Annunzio ( 2003 ) , president of IRT Inc. , asserts in the article, “ New Lightweight Concrete Technology, ” “ as with all site installed stuffs, the quality of the finished merchandise is based on the skill degree of the applier. Structural lightweight concrete, made with accretion of lightweitght concrete sum, has been used in the United States for about 50 old ages.
The article, “ Concrete in pattern, what, why and how? , ” ( 2003 ) explains “ structural lightweight concrete has an in-place denseness ( unit weight ) on the order of 90 to 115lb/ft3 ( 1440 to 1840 kg/m3 ) compared to normal weight concrete with a denseness in the scope of 140 pound to 150lb/ft3 ( 2240 to 2400kg/m3 ) ” ( p. 1 ) . Lightweight sums, such as clay, shale or slate stuffs, are typically used to do structural lightweight concrete. These lightweight sums are fired in a rotary kiln to do this type concrete to hold a porous construction.
Air-cooled blast furnace scoria may besides be used to make lightweight concrete sums. “ There are other categories of non-structural lightweight concretes with lower denseness made with other aggregative stuffs and higher air nothingnesss in the cement paste matrix, such as in cellular concrete ”. This type of concrete is typically used for insularity belongingss merely. Lightweight concrete may be produced by shooting air in to the composing, by go forthing out the finer sizes of the sum or by replacing the sum with hollow or porous sum.
Hjh Kamsiah Mohd Ismail, Mohamad Shazli Fathi and Norpadzlihatun bte Manaf ( 2003 ) , all with the Universiti Teknologi Malaysia Institutional Repository, intent in the diary article, “ Study of lightweight concrete behaviour, ” “ peculiarly, lightweight concrete can be categorized into three groups: No-fines concrete may be defined as lightweigh concrete that is created by uniting cement and all right sum. This type of concrete has equally spaced holes throughout it.
Strucural lightweight concrete is chiefly used to minimise the dead burden of a construction that is made out of concrete. This allows the interior decorator to diminish the size of columns and termss, or other burden bearing indispensable characteristics. “ Structural lightweight concrete mixtures can be designed to accomplish similar strengths as normal weight concrete. The same is true for other mechanical and lastingness public presentation demands ”. Strucutral lightweight concrete besides produces a better strength to burden ratio for structural stuffs.
Although lightweight concrete is more expensive than traditional concrete, the cost is offset because of the decreased volume of lightweight concrete, leting interior decorators to utilize less, which turns out to be less cost. Advantages of Lightweight Concrete Two of the distincitive characteristics of lightweight concrete are its low denseness and thermic conduction. Ismail, Fathi and Manaf ( 2003 ) , explain “ advantages are that there is a decrease of dead burden, faster edifice rates in building and lower draw and handling costs.
Lightweight concrete maintains its big nothingnesss and non organizing laitance beds or cement movies when placed on the wall ” ( p. 1 ) . A great illustration of the lastingness of lightweight concrete is ‘The Pantheon ‘ in Rome, which was built over 18 centuries ago. Sructural lightweight concrete is in high demand for usage in building because of its lower denseness which consequences in interior decorators ‘ ability to hold a smaller foundation due to the usage of smaller burden bearing elements or cross subdivisions.
Harun Tanyildizi and Ahmet Coskun ( 2008 ) , both with the Department of building instruction, Firat University Elazig, Turkey, explain in the diary article, “ The consequence of high temperature on compressive strength and splitting tensile strength of structural lightweight concrete incorporating fly ash, ” “ lightweight sums are loosely classified in to two types-natural ( pumice, diatomaceous earth, volcanic clinkers, etc. ) and unreal ( perlite, expanded shale, clay, slate, sintered PFA, etc. ) . Lightweight concrete can easy be produced by using natural lightweight sum i. e. pumice or perlite sum ” ( A 2 ) .
The chief advantages to utilizing structural lightweight concrete are increased strength, more flexible and less coefficient of thermic enlargement. Disadvantages of Lightweight Concrete Lightweight concrete applications do hold certain disadvantages and liabilities, typically holding to make with the cabability of the contractor istalling it. John A. D’Annunzio ( 2003 ) , president of IRT Inc. , asserts in the article, “ New Lightweight Concrete Technology, ” “ as with all site installed stuffs, the quality of the finished merchandise is based on the skill degree of the applier.
Lightweight concrete has extra restraints because the success of the system is based on the proper mix ratio ” ( p. 2 ) . One of the major jobs with lightweight concrete is if the lightweight concrete is non assorted decently, it may hold empty infinites that can take to lacking strength. The compressive strength of lightweight concrete come from a froth additive, when it is assorted right, this linear casts around the cement which serves as an aggregtae. ` If the froth additive is non decently assorted, there is a chance of froth prostration, which weakens the merchandise ‘s compressive strength ” ( D’Annunzio, 2003, p. 2 ) .
One of the factors that leads to lightweight concrete weakness is the blending procedure is typically done at a jobsite, which may take to human mistakes. Concrecel USA has developed pumping equipment that percisley weighs the ingredients and accurately blend the froth and cement, to elimante the job of human mistake. Table 1 depicts the advantages and disadvantages of lightweight concrete.
Difficult to put and complete because of the porousness and angular shape of the sum. In some mixes the cement howitzer may divide the sum and float towards the surface. Significant decrease of overall weight in salvaging structural frames, picking or hemorrhoids High Performance Fiber Reinforced Lightweight Concrete Typical lightweight concrete is weaker than traditional weight concrete. It is critical to better the strength of lightweight concrete in order to advance it for usage for structural applications.
Bengi Arisoy, Department of Civil Engineering, Faculty of Engineering, Ege University, Bornova, Turkey and Hwai-Chung Wu ( 2008 ) , Advanced Infrastructure Materials Laboratory, Department of Civil and Environmental Engineering, Wayne State University, Milwakee, explain in the diary article, “ Material features of high public presentation lightweight concrete reinforced with PVA, ” “ with a much higher ductileness high public presentation fibre reinforced lightweight concrete ( HPFRLWC ) becomes superior to regular concrete because of riddance of sudden ruinous failure of otherwise brickle concrete.
Ductility consequences from imposed cleft opposition due to bridging fibres ” ( Theoretical background subdivision, 1 ) . The research workers found that fibre reinforced lightweight concrete, when made with lightweigh sums and air entraining agent, shows strain hardening by the add-on of 1. 5 % fibre volume fraction. By adding about 10-20 % all right cement replacement such as fly ash and silicon oxide smoke, it improves both ductileness and flexural strength.
Improvement of high public presentation FRLWC may be summarized as follows: 50-150 times ( 5000-15000 % ) addition in flexural supplanting ( ductileness ) at ultimate burden than field lightweight concrete, 50-250 % addition in ultimate flexural strength than field lightweight concrete, 30-65 % lessening in weight than normal weight concrete ( Arisoy ; A ; Wu, 2003, Conclusion subdivision, 1 ) . Proper Mixing Methods The concrete mixture design, particularly for lightweight concrete, has stressed compressive strength, and besides the lastingness of the concrete.
Chao-Lung Hwang Department of Construction Engineering, National Taiwan University of Science and Technology, Taiwan and Meng-Feng Hung ( 2005 ) , Department of Civil Engineering, National Taiwan University of Science and Technology, Taiwan assert in the diary article, “ Durability design and public presentation of self-consolidating lightweight concrete, ” “ ACI 318 construction codification stresses both the maximal w/cm ratio to foreground the use of pozzolanic stuff, and the minimal 28-day compressive strength to vouch building safety while sing lastingness of normal weight concrete ” ( A 2 ) .
If a concrete construction clefts or become porous, it is more sustable to be subjective to harsh outside elements, such as acerb rain and saltwater, that may take to its impairment and the quality of a construction. Lightweight sum has a porous characteristic, because of that its compressive strength is typically low and the capacity it has for absorpution is reasonably high. “ Hence, it needs big sum of cement paste to accomplish suited workability and designed compressive strength.
This may go against the lastingness demand of normal weight concrete as mentioned ” (4 ) . Because the porous sum reduces the denseness of the lightweight sum concrete ( LWC ) and because it fractures easy when assorted, it is critical to plan the LWC with increased strength and lastingness. In assorted field conditions, lightweigh concretes, in respects to carbonation public presentation, have typically performed adequately. T. Y. Lo, W. C. Tang and A.
Nadeem ( 2008 ) , all with the Department of Building and Construction, City University of Hong Kong, Kowloon, Hong Kong, explain in the diary article, “ Comparison of carbonation of lightweight concrete with normal weight concrete at similar strength degrees, ” “ some field probes on the carbonation public presentation of LWC in ships and Bridgess at exposure age from 15 to 43 old ages, compressive strength from 23 to 35 MPa and denseness from 1650 to 1820 kg/m3 have been reported ”.
The deepness of carbonation in these constructions varied in respects to exposure conditions, denseness and strength, and was typically less than 10 millimeter. What consequence wet content, porousness and cement to H2O ratio have on the bounds of carbonation, have been studied by research workers. For illustration, Swenson and Sereda, outstanding research workers found that the wet content in lightweight concrete, whether high or low, was non favourable to rapid carbonation.
Swamy and Jiang found that carbonation was higher for concrete with higher entire porousness at a given H2O to cement ratio. Bilodeau et Al. attributed the low carbonation in high strength LWC to low H2O to cement ratio ”. Finally, Gunduz and Ugur analysed the carbonation of pumice sum lightweight concrete and expressed the carbonation was lessened when the sum to cement ratio of lowered. Volcanic Pumice This one is manner over my caput demand to add a small from 8-next page 80 in natural research
Pumice, a natural stuff, comes from vents when gases are released and the lava solidifies. Khandaker M. A. Hossain, Associate Professor in the Department of Civil Engineering at Ryerson University, Toronto, Canada and Mohamed Lachemi ( 2007 ) , a Canada Research Chair in Sustainable Construction and a Professor in the Department of Civil Engineering at Ryerson University, both ACI members, assert in the diary publication, “ Mixture Design, Strength, Durability, and Fire Resistance of Lightweight Pumice Concrete, ” “ universe pumice production was 14. million metric tones Mt in 2004. Globally, Italy remains the dominant manufacturer of pumice, with production estimated to be 4. 6 Mt per twelvemonth ” ( A3 ) .
Pumice is chiefly used an an sum in lightweight edifice block and other edifice merchandises. Volcanic pumice ( VP ) has been utlizied as an sum in bring forthing lightweight concrete. Pumice has been used for builing over 2000 old ages, particularly in Rome and Europe where many pumice constructions are still standing to this twenty-four hours. ` Lightweight concrete made with pumice and pozzolanic cement with volcanic ash/lime ( developed in Mexico by the Totonacas ) has survived more than 2000 old ages and provides an illustration of a low strength concrete and really long-run public presentation ” ( Hossain ; A ; Lachemi, 2007, A4 ) . Using pumice and perlite as additives has been found to provide increased opposition to the freeze and melt of concrete, cement pastes and howitzer.