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FLY ASH (Bahan Baku Cmpuran Semen / Abu Batubara ) dan keutungannya

FLY ASH

(Bahan Baku Cmpuran Semen / Abu Batubara )
SNI 03-6863-2002

SOLUSI TEPAT BERKUALITAS DAN IRIT
FLY ASH sebagai solusi tepat berkualitas dan irit di saat bahan baku bangunan semakin mahal. FLY ASH adalah pilihan tepat karena memiliki kandungan mineral Si102 (silica oksida) yang paling besar dibandingkan dengan produk campuran yang beredar di pasaran saat ini. FLY ASH memiliki sifat pozzolan...ic yang dapat membantu meningkatkan kekuatan dan keawetan (durability)
FLY ASH atau abu terbang adalah bahan tambahan adukan (mortar) beton semen untuk mendapatkan kualitas yang lebih tinggi.

Pengunaan Fly Ash sebagai bahan bangunan
1. Baik untuk campuran agregat beton ( ready mix )
2. Bahan campuran pembuatan genteng, beton, paving block, batako dan sebagainya.
3. Untuk campuran mortar ( adukan luluh ) pasangan batu, pondasi, batu merah atau batako.
4. Untuk campuran mortar pasangan keramik dan bangunan.
5. Untuk campuran mortar plesteran, perataan lantai dan acian 
CARA MENCAMPUR / MENGUNAKAN FLY ASH
(dengan berat 40 kg / sak )

Hasil pengunaan 
1. Mengurang biaya material semen sehingga pembiayaan lebih hemat dan ekonomis
2. Mudah dalam pengerjaan, cepat kering, dan mengeras
3. Permukaan beton lebih rata dan halus serta kekuatan (kualitas) beton meningkat
4. Tahan lama dan tidak mudah rusak oleh pengaruh cuaca
5. Tahan terhadap rembasan air (kedap air)
6. Melekat dengan baik pada pasangan batu pondasi, bata merah atau batako
7. Tidak timbul retak-retak halus pada permukaan beton dan plesteran
Pengunaan Fly Ash ini tidak bisa dikerjakan secara sembarangan, sebab jika penambahan  Fly Ash  terlalu banyak maka mutu dari beton tersebut justru akan turun. Maka dari itu dibutuhkan takaran yang pas untuk penambahan  Fly Ash  kedalam racikan beton yang di sesuaikan dengan kondisi bangunan yang diinginkan.

KEUNTUNGAN MENGGUNAKAN FLY ASH DALAM CAMPURAN PEMBANGUNAN 

Kuat & Efisien
Lebih Kuat. Dengan menggunakan Fly Ash, dinding bangunan akan menjadi lebih kuat dan 
kokoh dibandingkan dinding yang menggunakan campuran konvensional yang hanya menggunakan semen saja.
Lebih Efisien. Karena harga Lestari Pulverized  Fly Ash  seberat 40kg hanya Rp. 30.000,- 
( Harga untuk Area YOGYAKARTA )
Kalkulasinya sebagai berikut :
Campuran Biasa (untuk pasang Bata / Plesteran) menggunakan perbandingan 1 : 5
5 Pasir + 1 Semen ==> biaya Semen Rp. 49.000,- 
10 Pasir + 2 Semen ==> biaya Semen Rp. 98.000,-
Bandingkan dengan menggunakan Fly Ash,
10 Pasir + 1 Semen + 1 Fly Ash
10 Pasir + Rp. 49.000,- + Rp. 30.000,- = Rp. 79.000,-
Ada penghematan Rp. 19.000,- 
( 20% dari biaya Semen ) dikalikan jumlah kebutuhan.
Efisien kan ? Apalagi yang dipertimbangkan ?

Kalau Bisa Lebih Hemat ya Lebih Untung !!
dalam bentuk Cair kami juga siap melayani


ANDA MEMBUTUHKAN CALL 
an. Latief : 0274 9336982/081804071032

JUAL TANAH DAN BANGUNAN SHM

TANAH DAN BANGUNAN SANGAT SANGAT BAGUS

LUAS : 400 M2
LEBAR : 13 METER
HARGA : 1.35 M

KENAPA SANGAT BAGUS???

-DITEPI JALAN YOGYA-WONOSARI
-DEPAN PASAR
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MAU BIKIN APA? KAPLING? RUKO? MINIMARKET ? BISNIS APAPUN JUGA OKE?
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LOKASI:JALAN WONOSARI Km 12YOGYAKARTA,.
TIDAK USAH KUWATIR,lihat lokasi kita antar GRATIIISS(FREE OF FEE)

SERIUS? CEPAT
0274 9366982

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Di Jual Tanah

Butuh Uang tanah di jual lokasi sangat trategis dengan bersebelahan dengan kompus STIE YKPN, Sangat cocock untuk usaha kos-kosan karena dekat dengan kompus ada UPN, STIE YKPN, Universitas Proklamasi dan kompus lainnya lokasi ada di Seturan, Caturtunggal.

Siapa cepat dia dapat

Harga hanya 1.7jt/m2 luas 1.396m2

Minat hub. An . latief   telp. 083869862519, 081215524315

Simulasi Penghematan Biaya dengan Menggunakan Fly Ash

Fly Ash dikenal dengan sebutan Pozzolan buatan, yang berasal dari proses akhir pembakaran Batubara, berupa butiran sangat halus mengandung Silika, Alumina dan kandungan Kapur yang sedikit sehingga mempunyai daya lekat yang tinggi.

Pozzolan Alam berasal dari abu vulkanik telah dipakai sebagai campuran beton sejak jaman Romawi yang bangunannya masih kokoh sampai saat ini antara lain adalah Pantheon.

Fly Ash sudah digunakan di Amerika Serikat sejak th 1938 untuk membuat jalan beton untuk Highway, dan sejak th 1990 an juga telah digunakan pada beton siap pakai (Readymix Concrete).

Butiran Fly Ash yang sangat halus dan berbentuk spherical bearing ketika dicampur dengan air dan agregat lain akan menjadi seperti pasta yang lumer dan licin dan melapisi besi beton dengan rapat dan lekat sehingga mengurangi adanya pori-pori penyebab masuknya zat asam yang mengkorosi besi, berfungsi sebagai filler pengisi celah. Fly Ash sangat tepat digunakan pada daerah rawa

Kuat & Efisien

Lebih Kuat. Dengan menggunakan Fly Ash, dinding bangunan akan menjadi lebih kuat dan kokoh dibandingkan dinding yang menggunakan campuran konvensional yang hanya menggunakan semen saja.
Lebih Efisien. Karena harga Lestari Pulverized Fly Ash seberat 40kg hanya Rp.30.000,- ( Harga untuk Area YOGYAKARTA )
Kalkulasinya sebagai berikut :
Campuran Biasa (untuk pasang Bata / Plesteran) menggunakan perbandingan 1 : 5
   5 Pasir + 1 Semen ==> biaya Semen Rp. 49.000,- 
10 Pasir + 2 Semen ==> biaya Semen Rp. 98.000,-
Bandingkan dengan menggunakan Fly Ash,
10 Pasir +   1 Semen +  1 Fly Ash
10 Pasir + Rp. 49.000,- + Rp. 30.000,- = Rp. 79.000,-
Ada penghematan Rp. 19.000,- 
( 20% dari biaya Semen ) dikalikan jumlah kebutuhan.

Efisien kan ? Apalagi yang dipertimbangkan ?

Kalau Bisa Lebih Hemat ya Lebih Untung !!

Pemanfaatan & Kegunaannya “Fly Ash”

Fly-ash atau abu terbang yang merupakan sisa-sisa pembakaran batu bara, yang dialirkan dari ruang pembakaran melalui ketel berupa semburan asap, yang telah digunakan sebagai bahan campuran pada beton. Fly-ash atau abu terbang di kenal di Inggris sebagai serbuk abu pembakaran. Abu terbang sendiri tidak memiliki kemampuan mengikat seperti halnya semen. Tetapi dengan kehadiran air dan ukuran partikelnya yang halus, oksida silika yang dikandung oleh abu terbang akan bereaksi secara kimia dengan kalsium hidroksida yang terbentuk dari proses hidrasi semen dan menghasilkan zat yang memiliki kemampuan mengikat. 
            Menurut ACI Committee 226 dijelaskan bahwa, fly-ash mempunyai butiran yang cukup halus, yaitu lolos ayakan N0. 325 (45 mili mikron) 5-27%, dengan spesific gravity antara 2,15-2,8 dan berwarna abu-abu kehitaman. Sifat proses pozzolanic dari fly-ash mirip dengan bahan pozzolan lainnya. Menurut ASTM C.618 (ASTM, 1995:304) abu terbang (fly-ash) didefinisikan sebagai butiran halus residu pembakaran batubara atau bubuk batubara. Fly-ash dapat dibedakan menjadi dua, yaitu abu terbang yang normal yang dihasilkan dari pembakaran batubara antrasit atau batubara bitomius dan abu terbang kelas C yang dihasilkan dari batubara jenis lignite atau subbitumes. Abu terbang kelas C kemungkinan mengandung zat kimia SiO2 sampai dengan dengan 70%.
Tingkat pemanfaatan abu terbang dalam produksi semen saat ini masih tergolong amat rendah. Cina memanfaatkan sekitar 15 persen, India kurang dari lima persen, untuk memanfaatkan abu terbang dalam pembuatan beton. Abu terbang ini sendiri, kalau tidak dimanfaatkan juga bisa menjadi ancaman bagi lingkungan. Karenanya dapat dikatakan, pemanfaatan abu terbang akan mendatangkan efek ganda pada tindak penyelamatan lingkungan, yaitu penggunaan abu terbang akan memangkas dampak negatif kalau bahan sisa ini dibuang begitu saja dan sekaligus mengurangi penggunaan semen Portland dalam pembuatan beton.

Sebagian besar abu terbang yang digunakan dalam beton adalah abu kalsium rendah (kelas ”F” ASTM) yang dihasilkan dari pembakaran anthracite atau batu bara bituminous. Abu terbang  ini memiliki sedikit atau tida ada sifat semen tetapi dalam bentuk yang halus dan kehadiran kelambaban, akan bereaksi secara kimiawi dengan kalsium hidrosida pada suhu biasa untuk membentuk bahan yang memiliki sifat-sifat penyemenan. Abu terbang kalsium tinggi (kelas ASTM) dihasilkan dari pembakaran lignit atau bagian batu bara bituminous, yang memiliki sifat-sifat penyemenan di samping sifat-sifat pozolan.
Hasil pengujian yang dilakukan oleh Poon dan kawan-kawan, memperlihatakan dua pengaruh abu terbang di dalam beton, yaitu sebagai agregat halus dan sebagai pozzolan. Selain itu abu terbang di dalam beton menyumbang kekuatan yang lebih baik dibanding pada pasta abu terbang dalam komposisi yang sama. Ini diperkirakan lekatan antara permukaan pasta dan agregat di dalam beton. More dan kawan-kawan, Mendapatkan workabilitas meningkat ketika sebagian semen diganti oleh abu terbang.
Beton yang mengandung 10 persen abu terbang memperlihatkan kekuatan awal lebih tinggi yang diikuti perkembangan yang signifikan kekuatan selanjutnya. Kekuatan meningkat 20 persen dibanding beton tanpa abu terbang. Penambahan abu terbang menghasilakan peningkatan kekuatan tarik langsung dan modulus elastis. Kontribusi abu terbang terhadap kekuatan di dapati sangat tergantung kepada faktor air-semen, jenis semen dan kualitas abu terbang itu sendiri.
Dalam suatu kajian, abu terbang termasuk ke dalam kategori kelas F dengan kandungan CaO2 rendah sebesar 1,37 persen lebih kecil daripada 10 persen yang menjadi persyaratan minimum kelas C. Namun demikian kandungan SiO2 sukup tinggi yaitu 57,30 persen. Abu terbang ini, selain memenuhi kriteria sebagai bahan yang memiliki sifat pozzolan, abu terbang juga memiliki sifat-sifat fisik yang baik, yaitu jari-jari pori rata-rata  0,16 mili mikron, ukuran median 14,83 mili-mikron, dan luas permukaan spesifik 78,8 m2/gram. Sifat-sifat tersebut dihasilkan dengan menggunakan uji Porosimeter.
Hasil-hasil pengujian menunjukkan bahwa abu terbang memiliki porositas rendah dan pertikelnya halus. Bentuk partikel abu terbang adalah bulat dengan permukaan halus, dimana hal ini sangat baik untuk workabilitas, karena akan mengurangi permintaan air atau superplastiscizer.

Sumber :
Ir. Rony Ardiansyah, MT. IP-U
Dosen Teknik sipil UIR

FLY ASH (Bahan Baku Cmpuran Semen / Abu Batubara )

FLY ASH

(Bahan Baku Cmpuran Semen / Abu Batubara )
SNI 03-6863-2002

SOLUSI TEPAT BERKUALITAS DAN IRIT
FLY ASH sebagai solusi tepat berkualitas dan irit di saat bahan baku bangunan semakin mahal. FLY ASH adalah pilihan tepat karena memiliki kandungan mineral Si102 (silica oksida) yang paling besar dibandingkan dengan produk campuran yang beredar di pasaran saat ini. FLY ASH memiliki sifat pozzolan...ic yang dapat membantu meningkatkan kekuatan dan keawetan (durability)
FLY ASH atau abu terbang adalah bahan tambahan adukan (mortar) beton semen untuk mendapatkan kualitas yang lebih tinggi.

Pengunaan Fly Ash sebagai bahan bangunan
1. Baik untuk campuran agregat beton ( ready mix )
2. Bahan campuran pembuatan genteng, beton, paving block, batako dan sebagainya.
3. Untuk campuran mortar ( adukan luluh ) pasangan batu, pondasi, batu merah atau batako.
4. Untuk campuran mortar pasangan keramik dan bangunan.
5. Untuk campuran mortar plesteran, perataan lantai dan acian
CARA MENCAMPUR / MENGUNAKAN FLY ASH
(dengan berat 40 kg / sak )

Formula untuk pemasangan Bata / Batako
1 sak semen
1 sak Fly Ash
24 Pasir ( ukuran setara sak )
Dengan asumsi 1 : 1 : 24 disesuaikan dengan kondisi
bangunan yang diinginkan

Formula untuk campuran Kulitan/Lepan
1 sak semen
1 sak Fly Ash
24 Pasir ( ukuran setara sak )
Dengan asumsi 1 : 1 : 24 disesuaikan dengan kondisi
bangunan yang diinginkan

Formula untuk campuran pembuatan Batako
1 sak semen
1 sak Fly Ash
20 Pasir ( ukuran setara sak )
Dengan asumsi 1 : 1 : 20 disesuaikan dengan
bangunan yang diinginkan

Formula untuk Campuran Cor
1 sak semen
1 sak Fly Ash
4 pasir ( ukuran setara sak )
5 coral ( ukuran setara sak )
Dengan asumsi 1 : 1 : 4 : 5 atau disesuaikan dengan
kondisi bangunan yang diinginkan

Formula untuk campuran Ondrongan / Acian
1 sak semen
3 sak Fly Ash
Dengan asumsi 1 : 30 di sesuaikan dengan kondisi
bangunan yang diinginkan

Formula untuk campuran Paving K 300 +
Pasir : 200 kg
Abu Batu : 240 kg
0,5 Coral : 40 kg
Fly Ash : 40 kg ( 1 sak )
Total bahan : 520 kg; Semen 40 kg (1 sak) = 13kg
Jadi perbandingan campuranya adalah 1 : 13
Total bahan + semen = 560 : 3.1 = 180 biji 44 = 4 M²

Formula campuran untuk Paving K 250
Pasir : 250 kg
Abu Batu : 290 kg
0,5 Coral : 60 kg
Fly Ash : 80 kg ( 2 sak )
Total bahan + : 680 kg ; semen 40 kg (1 sak) = 17kg
Total bahan + semen 720 : 3.1 = 225 biji : 44 = 5,3 M²

Formula campuran untuk Paving Segi 6 K 250
Pasir : 540 kg
0,5 Coral : 60 kg
Fly Ash : 80 kg ( 2 sak )
Total bahan + : 680 kg ; semen 40 kg (1 sak) = 17kg
Jadi perbandingan campurannya adalah 1 : 17
Total bahan + semen 720 : 3.2 = 225 biji : 30 = 7,5 M²

Formula untuk campuran Genteng Beton
Pasir : 160 kg
Fly Ash : 80 kg ( 2 sak )
Total bahan : 240 kg ; semen 40 kg (1 sak) = 6kg
Jadi perbandingan campuranya adalah 1 : 6
Total bahan 280 : 3.4 = 82 biji : 90 = 9 M²

Hasil pengunaan

1. Mengurang biaya material semen sehingga pembiayaan lebih hemat dan ekonomis
2. Mudah dalam pengerjaan, cepat kering, dan mengeras
3. Permukaan beton lebih rata dan halus serta kekuatan (kualitas) beton meningkat
4. Tahan lama dan tidak mudah rusak oleh pengaruh cuaca
5. Tahan terhadap rembasan air (kedap air)
6. Melekat dengan baik pada pasangan batu pondasi, bata merah atau batako
7. Tidak timbul retak-retak halus pada permukaan beton dan plesteran
Pengunaan Fly Ash ini tidak bisa dikerjakan secara sembarangan, sebab jika penambahan Fly Ash terlalu banyak maka mutu dari beton tersebut justru akan turun. Maka dari itu dibutuhkan takaran yang pas untuk penambahan Fly Ash kedalam racikan beton yang di sesuaikan dengan kondisi bangunan yang diinginkan.

hub. 0274 9336982, 081215524315 dan 085643366982, an latief
atau email atieffin@gmail.com

Harga 30.000,-/sak : Netto 40 kg

FLY ASH (ASH COAL) SNI 03-6863-2002

QUALITY AND APPROPRIATE SOLUTIONS IRIT

FLY ASH as the proper quality and economical solutions when building increasingly expensive raw materials. FLY ASH is the right choice because it has a mineral content Si102 (silica oxide) compared with the greatest mix of products on the market today. FLY ASH has pozzolanic properties that can help increase strength and durability (durability)

FLY ASH or fly ash slurry is additional material (mortar) of cement concrete to get higher quality.

Use of Fly Ash as a building material

Good for concrete aggregate mix (ready mix)
Mixed materials manufacture tile, concrete, paving blocks, bricks and so forth.
To mix mortar (mortar yield) pairs of stone, masonry, stone or brick red.
To a mixture of ceramic mortar and building partner.
To a mixture of plaster mortar, leveling the floor and acian

The results of the use of Fly Ash

1. Reduce the cost of cement material so that financing is more efficient and economical
2. Easy in workmanship, quick dry, and harden
3. Concrete surface is more flat and smooth and the strength (quality) of concrete increases
4. Durable and not easily damaged by the influence of weather
5. Resistant to water rembasan (waterproof)
6. Well attached to the masonry foundation, red brick or concrete block
7. Not arose fine cracks in concrete and stucco surfaces

Use of Fly Ash can not be done arbitrarily, because if the addition of Fly Ash too much then the quality of the concrete is actually going down. Therefore it takes the right dose for the addition of Fly Ash concrete blend into adjusted to the desired condition of the building

With the price of Rp. 30 000, -
Weight: 40kg
Packing sacks

Contact:
an. Laief: 0247 9336982 / 085643366982
Email: atieffin@gmail.com

Fly Ash

Fly ashes are finely divided residue resulting from the combustion of ground or powdered coal. They are generally finer than cement and consist mainly of glassy-spherical particles as well as residues of hematite and magnetite, char, and some crystalline phases formed during cooling. Use of fly ash in concrete started in the United States in the early 1930's. The first comprehensive study was that described in 1937, by R. E. Davis at the University of California (Kobubu, 1968; Davis et al., 1937). The major breakthrough in using fly ash in concrete was the construction of Hungry Horse Dam in 1948, utilizing 120,000 metric tons of fly ash. This decision by the U.S. Bureau of Reclamation paved the way for using fly ash in concrete constructions.
In addition to economic and ecological benefits, the use of fly ash in concrete improves its workability, reduces segregation, bleeding, heat evolution and permeability, inhibits alkali-aggregate reaction, and enhances sulfate resistance. Even though the use of fly ash in concrete has increased in the last 20 years, less than 20% of the fly ash collected was used in the cement and concrete industries (Helmuth 1987).
One of the most important fields of application for fly ash is PCC pavement, where a large quantity of concrete is used and economy is an important factor in concrete pavement construction. FHWA has been encouraging the use of fly ash in concrete. When the price of fly ash concrete is equal to, or less than, the price of mixes with only portland cement, fly ash concretes are given preference if technically appropriate under FHWA guidelines (Adams 1988).

Classifications and Specifications

Two major classes of fly ash are specified in ASTM C 618 on the basis of their chemical composition resulting from the type of coal burned; these are designated Class F and Class C. Class F is fly ash normally produced from burning anthracite or bituminous coal, and Class C is normally produced from the burning of subbituminous coal and lignite (as are found in some of the western states of the United States) (Halstead 1986). Class C fly ash usually has cementitious properties in addition to pozzolanic properties due to free lime, whereas Class F is rarely cementitious when mixed with water alone. All fly ashes used in the United States before 1975 were Class F (Halstead 1986: ACI Comm. 226 1987c).
Fly ash which is produced at base loaded electric generating plants is usually very uniform. Base loaded plants are those plants which operate continuously. The only exception to uniformity is in the start-up and the shut-down of these plants. Contamination may occur from using other fuels to start the plant, and inconsistencies in carbon content occur until the plant reaches full operating efficiency. The ash produced from the start-up and shut-down must be separated from what is produced when the plant is running efficiently. In addition, when sources of coal are changed, it is necessary to separate the two types of fly ashes. Peak load plants are subjected to many start-up and shut-down cycles. Because of this, these plants may not produce much uniform fly ash.
The most-often-used specifications for fly ash are ASTM C 618 and AASHTO M 295. While some differences exist, these two specifications are essentially equivalent. Some state transportation agencies have specifications that differ from the standards (Admixtures and Ground Slag 1990). The general classification of fly ash by the type of coal burned does not adequately define the type of behavior to be expected when the materials are used in concrete.
There are also wide differences in characteristics within each class. Despite the reference in ASTM C 618 to the classes of coal from which Class F and Class C fly ashes are derived, there was no requirement that a given class of fly ash must come from a specific type of coal. For example, Class F ash can be produced from coals that are not bituminous. and bituminous coals can produce ash that is not Class F (Halstead 1986). It should be noted that current standards contain numerous physical and chemical requirements that do not serve a useful purpose. Whereas some requirements are needed for ensuring batch-to-batch uniformity, many are unnecessary (RILEM 1988).

Mix Design

The substitution rate of fly ash for portland cement will vary depending upon the chemical composition of both the fly ash and the portland cement. The rate of substitution typically specified is a minimum of 1 to 1 ½ pounds of fly ash to 1 pound of cement. It should be noted that the amount of fine aggregate will have to be reduced to accommodate the additional volume of fly ash. This is due to fly ash being lighter than the cement.
The amount of substitution is also dependent on the chemical composition of the fly ash and the portland cement. Currently, States allow a maximum substitution in the range of 15 to 25 percent.
Effects of fly ash, especially Class F, on fresh and hardened concrete properties has been extensively studied by many researchers in different laboratories, including the U.S. Army Corps of Engineers, PCA, and the Tennessee Valley Authority. The two properties of fly ash that are of most concern are the carbon content and the fineness. Both of these properties will affect the air content and water demand of the concrete.
The finer the material the higher the water demand due to the increase in surface area. The finer material requires more air-entraining agent to five the mix the desired air content. The important thing to remember is uniformity. If fly ash is uniform in size, the mix design can be adjusted to give a good uniform mix.
The carbon content, which is indicated by the loss of ignition, also affects the air entraining agents and reduces the entrained air for a given amount of air-entraining agent. An additional amount of air-entraining agent will need to be added to get the desired air content. The carbon content will also affect water demand since the carbon will absorb water. Again uniformity is important since the differences from non-fly ash concrete can be adjusted in the mix design.
Fresh Concrete Workability. Use of fly ash increases the absolute volume of cementitious materials (cement plus fly ash) compared to non-fly-ash concrete; therefore, the paste volume is increased, leading to a reduction in aggregate particle interference and enhancement in concrete workability. The spherical particle shape of fly ash also participates in improving workability of fly ash concrete because of the so-called "ball bearing" effect (Admixtures and Ground Slag for Concrete 1990; ACI Comm. 226 1987c). It has been found that both classes of fly ash improve concrete workability.
Bleeding. Using fly ash in air-entrained and non-air-entrained concrete mixtures usually reduces bleeding by providing greater fines volume and lower water content for a given workability (ACI Comm. 226, 1987c; Idorn and Henrisken, 1984). Although increased fineness usually increases the water demand, the spherical particle shape of the fly ash lowers particle friction and offsets such effects. Concrete with relatively high fly ash content will require less water than non-fly-ash concrete of equal slump (Admixtures and ground slag for concrete, 1990).
Time of Setting. All Class F and most Class C fly ashes increase the time of setting of concrete (Admixtures and ground slag 1990; ACI Comm. 226, 1987c). Time of setting of fly ash concrete is influenced by the characteristics and amounts of fly ash used in concrete. For highway construction, changes in time of setting of fly ash concrete from non-fly-ash concrete using similar materials will not usually introduce a need for changes in construction techniques; the delays that occur may be considered advantageous (Halstead 1986).
Strength and Rate of Strength of Hardened Concrete. Strength of fly ash concrete is influenced by type of cement, quality of fly ash, and curing temperature compared to that of non-fly-ash concrete proportioned for equivalent 28-day compressive strength. Concrete containing typical Class F fly ash may develop lower strength at 3 or 7 days of age when tested at room temperature (Admixtures and ground slag for concrete, 1990; ACI Comm. 226 1987c). However, fly ash concretes usually have higher ultimate strengths when properly cured. The slow gain of strength is the result of the relatively slow pozzolanic reaction of fly ash. In cold weather, the strength gain in fly ash concretes can be more adversely affected than the strength gain in non-fly-ash concrete. Therefore, precautions must be taken when fly ash is used in cold weather (Admixtures and ground slag 1990).
Freeze-thaw Durability of Hardened Concrete. On the basis of a comparative experimental study of freeze-thaw durability of conventional and fly ash concrete (Soroushian 1990; Virtanen 1983; Lane and Best 1982), it has been observed that the addition of fly ash has no major effect on the freeze-thaw resistance of concrete if the strength and air content are kept constant. The addition of fly ash may have a negative effect on the freeze-thaw resistance of concrete when a major part of the cement is replaced by it. The use of fly ash in air-entrained concrete will generally require an increase in the dosage rate of the air-entraining admixture to maintain constant air. Air-entraining admixture dosage depends on carbon content, loss of ignition, fineness, and amount of organic material in the fly ash (ACI Comm. 226, 1987c).
Carbon content of fly ash, which is related to the coal burned by the producing utility of the type and condition of furnaces in the production process of fly ash, influences the behavior of admixtures in concrete. It has been found that high-carbon-content fly ash reduces the effectiveness of admixtures such as air-entraining agents (Joshi, Langan, and Ward 1987: Hines 1985).
Alkali-silica Reaction of Hardened Concrete. One of the important reasons for using fly ash in highway construction is to inhibit the expansion resulting from ASR. It has been found that 1) the alkalies released by the cement preferentially combine with the reactive silica in the fly ash rather than in the aggregate, and 2) the alkalies are tied up in nonexpansive calcium-alkali-silica gel. Thus hydroxyl ions remaining in the solution are insufficient to react with the material in the interior of the larger reactive aggregate particles and disruptive osmotic forces are not generated (Halstead 1986; Olek, Tikalsky, and Carrasquillo 1986; Farbiarz and Carrasquillo 1986).
In a paper presented at the 8th International Conference on alkali-aggregate reactivity held in Japan in 1989, Swamy and Al-Asali indicated that ASR expansion is generally not proportional to the percentage of cement replacement by fly ash. The rate of reactivity, the replacement level, the method of replacement, and the environment all have a profound influence on the protection against ASR afforded by fly ash. Several investigators (Mehta, 1980; Diamond, 1981; Hobbs, 1982) have stated that ASR expansions correlated better with water-soluble alkali-silica contents than with total alkali content. The addition of some high-calcium fly ash containing large amounts of soluble alkali sulfate might increase rather than decrease the alkali-aggregate reactivity (Mehta, 1983). The effectiveness of different fly ashes in reducing long-term expansion varied widely; for each fly ash, this may be dependent upon its alkali content or fineness (Soroushian, 1990).

Blended Cements

The following will discuss on the Type "IP", "P" and "I(PM)" cements. The specifications for these cements are in AASHTO M-240 and ASTM C-595. Blended cements can be manufactured by either intimate blending of portland cement and pozzolan or intergrinding of the pozzolan with the cement clinker in the kiln. Type "I(PM)" (pozzolan modified cement) allows up to 15 percent replacement of cement with fly ash. The Type "IP" and Type"P" are pozzolan-modified portland cements which allow 15-40 percent replacement with pozzolans. The differences in the two types of cements is in the ultimate strength and the rate of strength gain of the concretes. Most States specify limits on the pozzolanic content on Type "IP" cement. These limits are between 15 and 25 percent.

Restraints on the Use of Fly Ash Concrete in Highway Constructions

It is well known now that both classes of fly ash improve the properties of concrete, but several factors and cautions should be considered when using fly ashes especially in highway construction, where fly ash is heavily used. In a report prepared by the Virginia Highway and Transportation Research Council (VHTRC) and summarized by Halstead (1986), several restraints relating to the use of fly ash concrete for construction of highways and other highway structures were discussed. These restraints include the following: 1) special precautions may be necessary to ensure that the proper amount of entrained air is present; 2) not all fly ashes have sufficient pozzolanic activity to provide good results in concrete; 3) suitable fly ashes are not always available near the construction site, and transportation costs may nullify any cost advantage; and 4) mix proportions might have to be modified for any chance in the fly ash composition.
Since the cement-fly ash reaction is influenced by the properties of the cement, it is important for a transportation agency not only to test and approve each fly ash source but also to investigate the properties of the specific fly ash-cement combination to be used for each project (Halstead 1986).

Recommendations

1. The standard specifications for fly ash (ASTM C-618 or AASHTO M-295) should be used. The included optional specification for uniformity as described below should also be required. This concerns the variation in the amount of air entraining agent to maintain an 18 percent air content in the mortar. A maximum variation in the amount of air entraining agent of 20 percent is specified.
2. The State highway agencies should develop certification programs similar to those in existence for portland cement. This program should include testing by the supplier with check tests on grab samples taken by the agency. The plan should also require that the supplier's laboratory participate in the Cement and Concrete Reference Laboratory (CCRL) program which includes inspection of facilities and testing of comparative samples.
   Until the certification programs are in place, it is suggested that the States test the fly ash and use sealed silos and transports. Five tests per silo should be run to insure uniformity of the fly ash. Once uniformity of a source is established, sampling could be reduced to one per 400 tons as specified in ASTM C-311. It is recommended that 10,000 tons of fly ash be tested before reducing the testing frequency.
3. The air content of each load of concrete should be monitored at least in the beginning of production. This would indirectly monitor the uniformity of the fly ash.
4. Specifications should contain strength requirements with minimum substitution ratio and maximum replacement. This would allow maximum substitution without sacrificing strength. The water cement ratio should be based on the total cementious materials, i.e., the portland cement plus the fly ash substituted.
5. Substitution ratios on a minimum of 1 to 1 on a mass basis with a maximum substitution should be specified. A substitution rate of 15 to 25 percent maximum is currently being specified for typical concrete production. These values should be established based on the actual fly ashes and portland cements that are available.
6. Mix designs should be performed by the State on each combination of materials, or by the contractor with the requirement to provide the test data to the State for verification with trial batches.
   Since the chemical composition of fly ashes and portland cements vary considerably, substantial problems could result if fixed rates and percentages of substitutions are used for all combinations of fly ashes and cements.

Exemptions

The EPA guideline on the substitution of fly ash requires the State highway agency to document the reasons for not allowing the substitution of fly ash for cement if it feels that it is technically inappropriate. The following two cases will not require documentation.

1. Fly ash should not be substituted for a portion of Type "IP", Type "I" (PM) or Type "P".
2. Substitution should not be specified for high early strength concrete. In this case, concrete that contains fly ash gains strength slower so it would not be capable of having high early strength.

References

1. Sections of this document were obtained from the Synthesis of Current and Projected Concrete Highway Technology, David Whiting, et al, SHRP-C-345, Strategic Highway Research Program, National Research Council.

2. ACI Committee 226. 1987a. Ground granulated blast furnace slag as a cementitious constituent in concrete ACI 226.AR-87. Detroit: American Concrete Institute.

3. Adams, T. H. 1988. Marketing of fly ash concrete. In MSU seminar: Fly ash applications to concrete (January), 1.10, 5.10. East Lansing: Michigan State University.

4. Admixtures and ground slag for concrete. 1990. Transportation research circular no. 365 (December). Washington: Transportation Research Board, National Research Council.

5. Davis, R. E., R. W. Carlson, J. W. Kelly, and A. G. Davis. 1937. Properties of cements and concretes containing fly ash. Proceedings, American Concrete Institute 33:577-612.
6. Diamond, S. 1981. Effects of two Danish fly ashes on alkali contents of pore solutions of cement fly ash pastes. Cement and Concrete Research 11:383-94.

7. Diamond, S. 1985. Very high strength cement-based materials: A perspective. Materials Research Society Symposia Proceedings 142:223-43.

8. Farbiarz, J., and R. L. Carrasquillo. 1986. Effectiveness of fly ash replacement in the reduction of damage due to alkali-aggregate reaction in concrete. Report no. FHWA/TX-87/15+450-1 (May). Texas State Department of Highways and Public Transportation.

9. Halstead, W. J. 1986. Use of fly ash in concrete. NCHRP 127 (October). Washington: Transportation Research Board, National Research Council.

10. Helmuth, R. 1987. Fly ash in cement and concrete. Skokie, III.: Portland Cement Association.

11. Hines, D. 1985. Fly ash use in lean concrete base. Colorado Department of Highways final report. Report no. CDOH-SMB-R-85-13 (December).

12. Hobbs, D. W. 1982. Influence of pulverized-fuel ash and granulated blast furnace slag upon expansion caused by the alkali-silica reaction. Magazine of Concrete Research 34:83-93.
Idorn, G. M., and K. R. Henrisken. 1984. State of the art for fly ash uses in concrete. Cement and Concrete Research 14 (4):463-70.

13. Joshi, R. C., B. W. Langan, and M. A. Ward. 1987. Strength and durability of concrete with high proportions of fly ash and other mineral admixtures. In Durability of building materials. Vol. 4, 253-70. Amsterdam: Elsevier Science Publishers.

14. Kohubu, M. 1969. Fly ash and fly ash cement. In Proceedings, Fifth international symposium on the chemistry of cement (1968). Part IV, 75-105. Tokyo: Cement Association of Japan.

15. Lane, R. O., and J. F. Best. 1982. Properties of fly ash in portland cement concrete. Concrete International. Design and Construction 4 (7):81-92. RILEM. 1988. Siliceous by-products for use in concrete. Final report: 73-SBC RILEM Committee. Materials and Structures 21 (121):69-80.

16. Mehta, P. K. 1980. Performance test for sulfate resistance and alkali-silica reactivity of hydraulic cements. In ASTM STP 691: Durability of building materials and components, 336-45.
Mehta, P. K. 1983. Pozzolanic and cementitious by-products as mineral admixtures for concrete: A practical review. In ACI special publication SP-79: The use of fly ash, silica fume, slag and other mineral by-products in concrete, ed. V. M. Malhotra, 1-46. Detroit: American Concrete Institute.

17. Olek, J., P. J. Tikalsky, and R. L. Carrasquillo. 1986. Production of concrete containing fly ash for pavement applications. Research report 364-2 (May). Austin: University of Texas Center for Transportation Research

18. Soroushian, P. 1990. Durability characteristics of fly ash concrete. In Recent advances in concrete technology seminar, MSU-CTS 4 (February), 6.1-6.18. East Lansing: Michigan State University.

20. Virtanen, J. 1983. Freeze-thaw resistance of concrete containing blast-furnace slag, fly ash or condensed silica fume. In ACI special publication SP-79: The use of fly ash, silica fume, slag and other mineral by-products in concrete, ed. V. M. Malhotra, 923-42. Detroit American Conrete Institute

IMPROVING OUR ENVIRONMENT

Conserving Energy, Reducing Emissions, 
 
Because fly ash use displaces cement use, it also reduces the need for cement production – a major energy user and source of “greenhouse gas” emissions.
For every ton of cement manufactured, about 6.5 million BTUs of energy are consumed. For every ton of cement manufactured, about one ton of carbon dioxide is released. Replacing that ton of cement with fly ash would save enough electricity to power the average American home for 24 days, and reduce carbon dioxide emissions equal to two months use of an automobile.
Experts estimate that cement production contributes to about 7 percent of carbon dioxide emissions from human sources. If all the fly ash generated each year were used in producing concrete, the reduction of carbon dioxide released because of decreased cement production would be equivalent to eliminating 25 percent of the world’s vehicles.
Conserving landfill space is also an important consideration. Every ton of coal combustion products that is used to improve our nation’s highways and buildings is a ton that is not deposited in a landfill, saving the same amount of space that the average American uses over 455 days.
Concrete itself is an environmentally sound building material. Roads and structures built from concrete last longer and require less maintenance than other materials. When used in freeways, concrete can result in less vehicle fuel consumption. Because concrete reflects light, less energy is needed to illuminate the roadway. Concrete is recyclable, with 45 to 80 percent of crushed concrete usable as aggregate in new construction.
Additionally, recent studies conducted by the Environmental Council of Concrete Organizations have determined certain metropolitan areas experience higher overall temperatures than surrounding less-developed areas. Using lighter colored concrete products instead of asphalt pavement can help reduce excessive temperature, further conserving energy.