Overview_Subgrade_Aggregat_2013.pdf

8/14/2019 Overview_Subgrade_Aggregat_2013.pdf

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Ir. Sony Sulaksono Wibowo, M.T., Ph.D

DR. Ir. Eri Susanto Hariyadi, M.T.

Semester Genap 2012/2013

PROGRAM STUDI TEKNIK SIPIL

FAKULTAS TEKNIK SIPIL DAN LINGKUNGAN

INSTITUT TEKNOLOGI BANDUNG


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Bahan danDesain Perkerasan Jalan

Copyright 2009 - ESH

Dosen :

DR. Eri Susanto Hariyadi


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Course Syllabus

1. Road Pavement Overview2. Subgrade

3. Aggregates

4. Bitumen

5. Bituminuous Mixtures

6. Pavement Design : Concept and Parameters

7. Pavement Design

a. Bina Marga : Metoda Analisa Komponenb. AASHTO 93

8. Overlay Design

9. Design of Rigid Pavement (Overview)


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References

American Association of State Highway andTransportation Officials (1993) AASHTO Guide forDesign of Pavement Structures, Washington DC, ISBN1-56051-055-2

Departemen Pekerjaan Umum (1987) PetunjukPerencanaan Tebal Perkerasan Lentur Jalan Rayadengan Metode Analisa Komponen, SNI No. 1732-1989-F

Manual Bahan Perkerasan Jalan Bina Marga Dep PU Highway Material by Kerb and Walker

The Asphalt Handbook, MS-04 Asphalt Institute


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Road Pavement Overview



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Road Pavement History

Roman Roads (300s BC) Telford Pavement (1780s)

Macadam Pavement (1800s)

The Rise of Bitumen

The Rise of Portland Cement


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Roman Roads Roman roads (see Figure 1.1) were constructed Via Appia, dates back to 312

B.C. (Amergence Interactive, 2001). At its height, the Roman road networkconsisted of over 100,000 km (62,000 miles) of roads, which is about equal tothe length of the U.S. interstate system.

A typical Roman road structure (see Figure 1.2), as seen in the UnitedKingdom, consisted of four basic layers (Collins and Hart, 1936): Summa Crusta (surfacing). Smooth, polygonal blocks embedded in the underlying

layer.

Nucleus. A kind of base layer composed of gravel and sand with lime cement.

Rudus. The third layer was composed of rubble masonry and smaller stones alsoset in lime mortar.

Statumen. Two or three courses of flat stones set in lime mortar.


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Telford Pavement Thomas Telford build roads on relatively flat grades (no more than a 1

in 30 slope) in order to reduce the number of horses needed to haulcargo. Telford's pavement section was about 350 to 450 mm (14 to 18inches) in depth and generally specified three layers. The bottom layerwas comprised of large stones 100 mm (4 inches) wide and 75 to 180mm (3 to 7 inches) in depth (Collins and Hart, 1936). It is this specificlayer which makes the Telford design unique (Baker, 1903). On top ofthis were placed two layers of stones of 65 mm (2.5 inches) maximumsize (about 150 to 250 mm (6 to 9 inches) total thickness) followed by awearing course of gravel about 40 mm (1.6 inches) thickIt was

estimated that this system would support a load corresponding to about88 N/mm (500 lb per in. of width).


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Macadam Pavement Macadam pavements introduced the use of angular aggregates. John MacAdam (born

1756 and sometimes spelled "Macadam") observed that most of the paved U.K. roadsin early the 1800s were composed of rounded gravel (Smiles, 1904). He knew thatangular aggregate over a well-compacted subgrade would perform substantiallybetter. He used a sloped subgrade surface to improve drainage (unlike Telford who

used a flat subgrade surface) on which he placed angular aggregate (hand-brokenwith a maximum size of 75 mm (3 inches)) in two layers for a total depth of about200 mm (8 inches) (Gillette, 1906). On top of this, the wearing course was placed(about 50 mm thick with a maximum aggregate size of 25 mm) (Collins and Hart,1936). Macadam's reason for the 25 mm (1 inch) maximum aggregate size was toprovide a "smooth" ride for wagon wheels. Thus, the total depth of a typicalMacAdam pavement was about 250 mm (10 inches) (refer to Figure 1.5). The term

"macadam" is also used to indicate "broken stone" pavement (Baker, 1903). By 1850,about 2,200 km (1,367 miles) of macadam type pavements were in use in the urbanareas of the UK.


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JENIS PERKERASAN JALAN

PerkerasanPerkerasan BetonBeton

PerkerasanPerkerasan AspalAspal


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Jenis Konstruksi Perkerasan :

STRUKTUR PERKERASAN

Perkerasan LenturPerkerasan Kaku

1.Perkerasan Lentur (flexible pavement)2.Perkerasan Kaku (rigid pavement)


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Tipe Perkerasan UmumnyaPerkerasan aspal Perkerasan beton

KeperluanKeperluan

Bahan Pengikat Aspal Bahan Pengikat Semen

Beton - Semen

Aspal Beton Semen

LPA

LPB

Tanah dasar

Tanah dasar

Beton mutu rendah

atau LPB


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Perkerasan Lentur flexible pavement)Umumnya terdiri atas:

Lapisan Tanah Dasar (subgrade) Lapis Pondasi Bawah (subbase) Lapis Pondasi Atas (base) Lapis Permukaan (surface).


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Tipikal Susunan Perkerasan AspalWearing course (lapisan aus)

perlu aspal, batu kasar s/d halus

Binder course (lapisan antara)

perlu aspal, batu kasar s/d halus

lapis resap ikat/ (lapis ikat) perlu aspal

LPA, perlu batu kasar s/d halus

LPB, perlu batu kasar s/d halus

Tanah dasar


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PERKERASAN BETON SEMEN

STRUKTUR TERDIRI DARI PELAT BETON SEMEN TERLETAKDIATAS LAPIS PONDASI ATAU TANAH DASAR

PELAT BETON SANGAT KAKU, MENYEBARKAN BEBAN PADABIDANG YANG LUAS SEHINGGA TEGANGAN PADA LAPISAN

DIBAWAHNYA RENDAH DAYA DUKUNG PEKERASAN BETON TERUTAMA DIDAPAT

DARI PELAT BETON BUKAN DARI LAPISAN PONDASI


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LAPIS PONDASI

Lapis Pondasi Agregat :

Lapis Pondasi Atas

Lapis Pondasi Bawah

Lapis Pondasi Jalan Tanpa Penutup :

Lapis Pondasi Agregat Kelas CLapis Makadam Ikatan Air (Waterbound Macadam)

Lapis Pondasi Berbasis Semen :

Lapis Pondasi Semen Tanah

Lapis Beton Semen Pondasi Bawah (CTSB)

Lapis Pondasi Agregat dengan Cement Treated Base (CTB)


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Jenis-jenis Campuran Beraspal yang Biasanya Digunakan:

Buras Surface Dressing

Lapen

Campuran Dingin

Campuran Panas Latasir

Lataston

Laston

Semua jenis campuran tersebut harus memenuhi sifat spt ygdisyaratkan dalam spesifikasi


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1.Perkerasan beton semenbersambung tanpa tulangan,

2.Perkerkerasan beton semen

bersambung dengan tulangan

3.Perkerasan beton semen menerus

dengan tulangan

4.Perkerasan beton semen pratekan.

Perkerasan Beton Semen


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1. Perkerasan Beton Semen Bersambung Tanpa Tulangan


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2. Perkerasan Beton Semen Bersambung dengan tulangan


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3. Perkerasan Beton Semen Menerus dengan Tulangan


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FUNGSI LAPIS PONDASI pd PERKERASANBETON

MENGENDALIKAN KEMBANG SUSUT

TANAH DASAR MENCEGAH INTRUSI DAN PUMPING PADA

TANAH DASAR

MEMBERIKAN DUKUNGAN YANG MANTAPDAN SERAGAM PADA PELAT

SEBAGAI LANTAI KERJA


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JALAN BETON DI JALAN KABUPATEN


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JALAN BETON DI JALAN UTAMA IBU KOTA KABUPATEN


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Subgrade Layer


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Tanah Dasar

Tanah dasar harus dibentuk dan dipadatkan,mempunyai peranan yang penting bagi konstruksi

perkerasan jalan, karena struktur perkerasan

atau bahu jalan diletakkan diatas tanah dasar

Kekuatan tanah dasar adalah faktor utama dalam

menentukan ketebalan dari perkerasan


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Tanah DasarPersyaratan Tidak termasuk tanah yang berplastisitas tinggi, (

A-7-6 menurut AASHTO M145 atau CH menurut

"Unified atau Casagrande Soil ClassificationSystem)

Tanah dengan nilai aktif lebih besar dari 1,25, atauderajat pengembangan yang diklasifikasikan oleh

AASHTO T 258 sebagai "very high" atau "extra high",tidak boleh digunakan sebagai bahan timbunan


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Subgrade Performance

Subgrade Performance related to Pavement Designdepend on :

Load bearing capacity.

The subgrade must be able to support loads transmitted from

the pavement structure. This load bearing capacity is oftenaffected by degree of compaction, moisture content, and soil

type. A subgrade that can support a high amount of loading

without excessive deformation is considered good.

Load Bearing capacity is characterized by :

CBR Flexible Pavement

K-value Rigid pavement


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California Bearing Ratio (CBR)

The California Bearing Ratio (CBR) test is a simple strength test that compares the

bearing capacity of a material with that of a well-graded crushed stone. Introducing by California Division of Highway 1928, and be populated by O.J. Porter

The basic CBR test involves applying load to a small penetration piston at a rate of 1.3mm (0.05") per minute and recording the total load at penetrations ranging from 0.64mm (0.025 in.) up to 7.62 mm (0.300 in.)

where:

x=material resistance or the unit load on the piston (pressure) for 2.54 mm (0.1") or 5.08 mm (0.2") of penetration

y=standard unit load (pressure) for well graded crushed stone

=for 2.54 mm (0.1") penetration = 6.9 MPa (1000 psi)

=for 5.08 mm (0.2") penetration = 10.3 MPa (1500 psi)


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CBR Calculation


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CBR Values (Typical)


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CBR Classification

Design CBR Soaked Design CBR

Unsoaked Design CBR

Field CBR, placing piston and penetrated bytruck load

Undisturbed Soaked CBR, to obtained field CBR at

saturated soil and maximum swelling


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Field CBR using DCP

Correlation Between DCP & CBR :

log CBR(%)=2.81-1.32 log DD=penetration (mm/blow)

Source :

Harrison, JA : Correlation Between CBR and DCP Strength Measurement ofSoils, Proc Institution of Civil Eng. Part 2, 83 (1987), 833-844


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Modulus of Subgrade Reaction (k)

The modulus of subgrade reaction (k) is used as a primary input for

rigid pavement design. It estimates the support of the layers below arigid pavement surface course (the PCC slab). The k-value can bedetermined by field tests or by correlation with other tests. There isno direct laboratory procedure for determining k-value.

The modulus of subgrade reaction came about because work done by

Westergaard during the 1920s developed the k-value as a springconstant to model the support beneath the slab (see Figure below)


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Plate Load Test

The plate load test presses a steel bearing plate into the surfaceto be measured with a hydraulic jack.

The resulting surface deflection is read from dial micrometers

near the plate edge and the modulus of subgrade reaction is

determined by the following equation:

where:k=spring constant = modulus of subgrade reactionP=applied pressure (load divided by the area of the 762 mm (30 inch) diameter plate)

=measured deflection of the 762 mm (30 inch) diameter plate


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Correlation of k to Soil Properties

Soil Density CBR MR E k

A-1-a, well 125 - 140 60 - 80 22 - 35 30 - 43 300 - 450

A-1-a, poor 120 - 130 35 - 60 22 - 31 30 - 38 300 - 400

. . .

A-2-4,5 gravelly 130 - 145 40 - 80 22 - 40 30 - 47 300 - 500

A-2-4, 5 sandy 120 - 135 20 - 40 22 - 31 30 - 38 300 - 400

. . .

A-4, silt 90 - 105 4 - 8 < 11 6 - 18 25 - 165

A-4, mix 100 - 125 5 - 15 < 15 7 - 23 40 - 220

. . .


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Degree of Saturation Affectsk of Fine-Grained Soils

0

50

100

150

200

250

50 60 70 80 90 100

Degree of saturation (percent)

S

ubgrade

k

value

(psi/in)

A-6A-7-6

A-7-5

A-5

A-4

A-6

A-7-6

A-7-5A-5A-4


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Aggregates



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Definitions

"Aggregate" is a collective term for the mineral materials such

as sand, gravel and crushed stone that are used with a bindingmedium (such as water, bitumen, portland cement, lime, etc.)to form compound materials (such as asphalt concrete andportland cement concrete).

By volume, aggregate generally accounts for 92 to 96 percentof HMA and about 70 to 80 percent of portland cementconcrete.

Aggregates can either be natural or manufactured.

Natural aggregates are generally extracted from larger rock

formations through an open excavation (quarry). Extracted rockis typically reduced to usable sizes by mechanical crushing.

Manufactured aggregate is often by product or othermanufacturing industries.


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Aggregate Sources

Aggregates can come from either natural or manufactured sources. Natural

aggregates come from rock, of which there are three broad geologicalclassifications : Igneous rock.

These rocks are primarily crystalline and are formed by the cooling of molten rock materialbeneath the earths crust (magma).

Sedimentary rocks. These rocks are formed from deposited insoluble material (e.g., the remains of existing rock

deposited on the bottom of an ocean or lake). This material is transformed to rock by heat

and pressure. Sedimentary rocks are layered in appearance and are further classified basedon their predominant mineral as calcareous (limestone, chalk, etc.), siliceous (chert,sandstone, etc.) or argillaceous (shale, etc.).

Metamorphic rock. These are igneous or sedimentary rocks that have been subjected to heat and/or pressure

great enough to change their mineral structure so as to be different from the original rock.

Manufactured rock typically consists of industrial by products such as slag(byproduct of the metallurgical processing typically produced fromprocessing steel, tin and copper) or specialty rock that is produced to have aparticular physical characteristic not found in natural rock (such as the lowdensity of lightweight aggregate).


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Life Cycle of Aggregates


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Klasifikasi Batuan Berdasarkan Asal


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Ringkasan Sifat Teknik Batuan


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Klasifikasi Aggregat Berdasarkan ProsesPengolahan Agregat Alam:

agregat yang langsung diperoleh dari lapangan

Agregat Pecah:Batuan pecah ini dibedakan atas pecah tangan dan pecahdengan mesin pemecah batu

Agregat Daur Ulang:batuan yang diperoleh dari hasil daur ulang baik hasilpembongkaran lapisan perkerasan ataupun pembongkaranbeton

Agregat Buatan (Artifisial):agregat yang dipergunakan merupakan hasil samping/limbahdari produksi pabrik


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Aggregates Production

Aggregates are produced in a quarry or mine (see Figure) whose basic function is to convert in situ rockinto aggregate with specified characteristics. Usually the rock is blasted or dug from the quarry walls

then reduced in size using a series of screens and crushers. Some quarries are also capable of washingthe finished aggregate


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Gradation and Size

Gradation is the particle size distributionof an aggregate.

This is one of the most influentialaggregate characteristics in determininghow it will perform as a pavementmaterial.

The gradation of a particular aggregate is

most often determined by a sieve analysis(see Figure). In a sieve analysis, a sampleof dry aggregate of known weight isseparated through a series of sieves withprogressively smaller openings.

Once separated, the weight of particlesretained on each sieve is measured andcompared to the total sample weight.Particle size distribution is then expressedas a percent retained by weight on eachsieve size. Results are usually expressed intabular or graphical format.


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Sieve Analysis

AASHTO


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Maximum Aggregate Size

Maximum aggregate size can affect HMA, instability of HMA may result from

excessively small maximum sizes; and poor workability and/or segregationmay result from excessively large maximum sizes (Roberts et al., 1996). ASTMC 125 defines the maximum aggregate size in one of two ways: Maximum size.

The smallest sieve through which 100 percent of the aggregate sample particles pass.

Nominal maximum size. The largest sieve that retains some of the aggregate particles but generally not more than 10

percent by weight.

Maximum Size : 0.5 inch

Nominal maximum size : 3/8 inch

Fuller Curves


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Gradation has a profound effect on material performance. But what is the best gradation? This

is a complicated question, the answer to which will vary depending upon the material, its desiredcharacteristics, loading, environmental, material, structural and mix property inputs.

Therefore, although it may not be the "best" aggregate gradation, a maximum density gradation

does provide a common reference. A widely used equation to describe a maximum density

gradation was developed by Fuller and Thompson in 1907. Their basic equation is:

where:

P=% finer than the sieve

d=aggregate size being consideredD=maximum aggregate size to be used

n=parameter which adjusts curve for fineness or coarseness (for maximum particle density n 0.5 according toFuller and Thompson)

In the early 1960s, the FHWA introduced the standard gradation graph used in the HMA industry today. This graphuses n = 0.45 and is convenient for determining the maximum density line and adjusting gradation


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Aggregate Types

Coarse Aggregate, grain size more thansieve No.8 (2.36 mm)

Fine Aggregate, grain size less than sieve

No.8 Filler, fine aggregate which passes in sieve

No.30 (0.6 mm)

Based on Asphalt Institute (MS-2) and Depkimpraswil


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Ketentuan Agregat KasarPengujian Standar Nilai

Kekekalan bentuk agregat terhadaplarutan natrium dan magnesium sulfat

SNI 03-3407-1994 Maks.12 %

Abrasi dengan mesin Los Angeles SNI 03-2417-1991 Maks. 40 %

Kelekatan agregat terhadap aspal SNI 03-2439-1991 Min. 95 %

Angularitas (kedalaman daripermukaan < 10 cm)

DoTsPennsylvaniaTest Method,PTM No.621

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Angularitas (kedalaman daripermukaan 10 cm) 80/75

Partikel Pipih dan Lonjong* ASTM D-4791 Maks. 10 %

Material lolos Saringan No.200 SNI 03-4142-1996 Maks. 1 %


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Ketentuan Agregat HalusPengujian Standar Nilai

Nilai Setara Pasir SNI 03-4428-1997 Min. 50 %

Material Lolos Saringan No. 200 SNI 03-4428-1997 Maks. 8%

Angularitas (kedalaman dari

permukaan < 10 cm)

ASTM C-1252

Min 45

Angularitas (kedalaman dari

permukaan 10 cm) Min 40

Persyaratan lain agregat :

Penyerapan air maksimum 3 %.

Berat jenis (bulk specific gravity) agregat kasar dan halus

minimum 2,5 & perbedaannya < 0,2.


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Spesifikasi bahan pengisi iller) Terdiri dari debu batu kapur (limestone dust), semen

portland, abu terbang, abu tanur semen, abu batuatau bahan non plastis lainnya

Mengandung bahan yang lolos ayakan No.200 (75

micron) tidak kurang dari 75 % terhadap beratnya

Proporsi maksimum yang diijinkan adalah 1,0 % dari

berat total campuran aspal


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Type of Aggregate Gradation

Well/Dense Graded, agregat yang ukuran butirnya terdistribusi

merata dalam satu rentang ukuran butir. Coarse graded, dominan agregat kasar

Fine graded, dominan agregat halus

Poor Graded, agregat yang ukuran butirnya tidak terdistribusimerata dalam satu rentang ukuran butir.

Uniformly graded, contains most of the particles in a very narrowsize range

Gap graded, contains only a small percentage of aggregateparticles in the mid-size range

Open graded, contains only a small percentage of aggregateparticles in the small range


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Gradasi Agregat

0

20

40

60

80

100

0,01 0,1 1 10 100

Ukuran Saringan (mm)

PersenLolos(%)

Gradasi Rapat Gradasi Senjang Gradasi Seragam


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BAHAN AGREGAT UNTUK LAPISPONDASI


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PENYIMPANGAN PADA LAPIS PONDASI

Penyimpangan kepadatan lapangan lapisanpondasi

Penyimpangan Nilai indeks Plastis daribahan lapis pondasi

Perubahan prosentase bahan lapis pondasiyang lolos saringan no.200

Terjadinya segregasi pada bahan lapis

pondasi


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SPESIFIKASI AGREGAT LAPIS PONDASI

DIFINISI :

Ukuran butir maksimum ?

Rumus Fuller

P = 100 (d/D) ^ n

Dimana :

P = % agregat lolos masing-masing saringan.

D = ukuran maksimum agregat

d = ukuran saringan yang bersangkutan


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Agregat Untuk Lapis Pondasi dan Lapis PondasiBawah Lapis Pondasi terdiri dari Agregat Kelas A sedangkan Lapis

Pondasi Bawah terdiri dari Agregat Kelas B. Agregat kasar (tertahan pada ayakan 2,38 mm) harus terdiri

dari partikel yang keras dan awet.

Agregat kasar Kelas A yang berasal dari kerikil harus 100 %mempunyai paling sedikit satu bidang pecah.

Agregat halus (lolos ayakan 2,38 mm) harus terdiri daripartikel pasir atau batu pecah halus

Agregat untuk lapis pondasi harus bebas dari bahan organikdan gumpalan lempung atau bahan-bahan lain yang tidakdikehendaki.


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PROSEN PECAHPembanding, TRL-1993 RN-31 mensyaratkanprosen pecah minimum 40 % untuk mencapai

CBR minimum 80 %, sedangkan AASHTO-1990mensyaratkan prosen pecah 50 % 75 %, tanpamenyebut batasan CBR yang ingin dicapai

ABRASIPembanding ASTM -1993 mensyaratkan abrasi

maksimum 50 % dan AASHTO 1990 mensyaratkanabrasi maksimum 40 % untuk kelas A, 45 % untukkelas B dan 50 % untuk kelas C.



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(INDEKS PLASTISITAS)

40

50

60

70

80

90

100

110

4 6 8 10 12 14 16 18

Indek Plas tis itas ( %)

CB

R(

%

)

Pros en Pecah

50%

0%

100%



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(INDEKS PLASTISITAS)

AGREGAT LP KELAS A

Indeks plastisitas LPA maks adalah 6 %. Sebagai pembanding ASTM-1993, AASHTO-1990 dan RN-31 mencantumkan batasan maksimum nilai

indeks plastisitas 6 % untuk lapis pondasi atas

AGREGAT LP KELAS BIndeks plastisitas LPB maks adalah 10 %. Sebagai pembanding RN-31mencantumkan batasan maksimum nilai indeks plastisitas 12 % untuk lapis

pondasi bawah, CBR 35 %

BAHU JALANSesuai spesifikasi untuk jalan tanpa bahan penutup (kelas C), atau agregatLP kelas B dengan nilai Indeks plastisitas 4-10 %


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BAHAN AGREGAT UNTUK CAMPURANBERASPAL


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Sifat-sifat Agregata) Ukuran butir

b) Gradasic) Kebersihan

d) Kekerasan

e) Bentuk partikelf) Tekstur permukaan

g) Penyerapan

h) Kelekatan terhadap aspal


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Kebersihan Agregatsecara visual.

Pengujian laboratorium

Analisa saringan basah, yaitu dengan menimbang agregat sebelumdan sesudah dicuci lalu membandingkannya. Sehingga akan

memberikan persentase agregat yang lebih halus dari 0,075 mm

(No. 200).

Pengujian setara pasir (Sand Equivalent Test) adalah satu metoda

lainnya yang biasanya digunakan untuk mengetahui proporsi

relatif dari material lempung yang terdapat dalam agregat yang

lolos saringan No. 4,75 mm (No. 4).


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Alat Uji

Setara

Pasir


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Kekerasan

Uji kekuatan agregat di laboratorium

dilakukan dengan: uji abrasi dengan mesin Los Angeles (Los

Angeles Abration Test)

uji beban kejut (Impact Test)

uji ketahanan terhadap pecah (Crushing

Test) .


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Mesin Los Angeles


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Abrasion Resistance : Los Angeles

A common test used to characterize abrasion resistance is the Los Angeles (L.A.) abrasiontest. For the L.A. abrasion test, the portion of an aggregate sample retained on the 1.70

mm (No. 12) sieve is placed in a large rotating drum that contains a shelf plate attachedto the outer wall (the Los Angeles machine see Figure).

The material is then extracted and separated into material passing the 1.70 mm (No. 12)sieve and material retained on the 1.70 mm (No. 12) sieve. The retained material (largerparticles) is then weighed and compared to the original sample weight. The difference inweight is reported as a percent of the original weight and called the "percent loss"

Toughness Resistance :


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g

Crushing & Impact Test

Toughness Resistance :


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g

Parameters

Aggregate Crushing Value (ACV) : ratio of the weight of fines

passing the 2.36mm sieves (No.8) to the total weight of thesamples as result for crushing test.

Indian Road Congress have specified ACV of coarse aggregate PCC

should not exceed 30 percent, for wearing surfaces ACV should

not exceed 45 percent

Aggregate Impact Value (AIV) : ratio of the weight of fines

passing the 2.36mm sieves (No.8) to the total weight of the

samples as result for impact test.


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Particle Shape

Flakiness Index : the percentage by weight of particles whose leastdimension (thickness) is less than three-fifths (0.6) of their meandimension. This test is not applicable to sizes smaller than 6.3 mm

Elongation Index : the percentage by weight of particles whosegreatest dimension (length) is greater than 1.8 times their meandimension. This test is not applicable to sizes smaller than 6.3 mm

Angularity Number : the amount by which the percentage voidsexceeds 33 after being compacted in a prescribed manner.


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Bentuk butir

Kubikal Lonjong Pipih

V X X


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Alat Uji Kepipihan


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TeksturTekstur agregat utk keamanan (skid resistance)

Tekstur:

Makro: Utk lalulintas lambat, Diuji dengan Sand patch

Mikro: Untuk lalulintas cepat, Diuji dengan Pendulum Test


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Daya Serap Agregat

Keporusan agregat menentukanbanyaknya zat cair yang dapat

diserap agregat.

Syarat penyerapan terhadap air 3%


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Durability and Soundness

Durability and soundness are terms typically given to an aggregatesweathering resistance characteristic.

The most common soundness test involves repeatedly submerging anaggregate sample in a saturated solution of sodium or magnesiumsulfate. This process causes salt crystals to form in the aggregatepores, which simulate ice crystal formation (see Figure 3.10 and3.11)


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Aggregate Surface Texture

Smooth

Rough

Porous,

dapat dibedakan atas agregat berpori sedikit dan berpori

banyak. Agregat berpori banyak pada umumnyamempunyai tingkat kekerasan yang rendah, sehingga

mudah pecah dan terjadi degradasi.

Affi it f A h lt


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Affinity for Asphalt

Jenis Aggregat terkait Affinity :

Hydrophilic Aggregate, mudah diresap air, sulit dilekatiaspal

Contoh : granit dan aggregat yang mengandung silika

Hydrophobic Aggregate, sulit diresap air, mudah dilekati

aspal Contoh : Diorit, andesit

Testing : SNI-03-2439-1991 ; AASHTO T182-84

Affinity for Asphalt dinyatakan dalam PERSEN , yaitu

persentase luas permukaan aggregat yang dilapisi

aspal terhadap seluruh luas permukaan

A t S ifi G it


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Aggregates Specific Gravity

AASHTO M 132 and ASTM E 12 define specific

gravity as : "the ratio of the mass of a unit volumeof a material at a stated temperature to the mass of

the same volume of gas-free distilled water at a

stated temperature.

Four types of aggregate specific gravity :

Bulk specific gravity

SSD (saturated surface dry) specific gravity

Apparent specific gravity Effective specific gravity

S ifi G it C l l ti


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Specific Gravity Calculation

Bulk volume = Vs + Vpp

Net volume = bulk volume minusvolume absorbed water

bulk

SSD

SSD

V

WG

C t h S l


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Contoh Soal

Suatu aggregat mempunyai berat dalam

kondisi kering sebesar 2017.1 gram. Jikaaggregat tersebut direndam dalam air pada

kondisi jenuh akan mempunyai berat 1276.1

gram. Aggregat ini mempunyai berat SSDsebesar 2034.2 gram. Hitunglah berat jenis

Bulk, berat jenis Apparent, dan berat jenis

SSD aggregat ini.

Overview_Subgrade_Aggregat_2013.pdf

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Transcript of Overview_Subgrade_Aggregat_2013.pdf