PERENCANAAN CAMPURAN BETON K-275
Data-data pemeriksaan Laboratorium tentang bahan-bahan yang dipakai, sebagai berikut :
I. Agregat Halus (Pasir)
- Modulus Kehalusan = 2,635 %
- Berat Jenis Pasir (ssd) = 2,565 gr/cm3
- Berat isi loose (ssd) = 1,600 gr/cm3
- Absorbtion = 1,85 %
- Kadar Air = 1,85 %
II. Agregat Kasar (Batu)
- Ukuran Maksimal = 1 1/2”
- Berat Jenis (ssd) = 2,632 gr/cm3
- Berat isi loose = 1,65 gr/cm3
- Absorbtion = 0,69 %
- Kadar Air = 2,10 %
- Lolos # 200 = 0,75 %
III. Portland cement
- Berat isi = 1,250 gr/cm3
- Berat Jenis = 3,15 gr/cm3
- Berat per zak = 50 kg
IV. Gradasi batu :
- 2 “ - 100 - 100
- 1 ½” - 97,9 - 95 – 100
- ¾ - 42,6 - 35 – 70
- 3/8 - 13,8 - 10 – 30
- # 4 - 1,9 - 0 - 5
V. Gradasi Pasir :
- 3/8 - 100 - 100
- # 4 - 99,1 - 95 – 100
- # 8 - 89,5 - -
- #16 - 69,5 - 45 – 80
- #30 - 45,9 - -
- #50 - 25,0 - 10 – 30
- #100 - 7,5 - 2 – 10
- #200 - 1,2 - 0 - 3
A) Kebutuhan bahan-bahan komposisi campuran untuk 1 m3 original, sebagai berikut :
a) P. Cement = 378,7 kg
b) Water cement = 178 lt
c) Fine aggregat (FA) = 692 kg
d) Coarse Aggrergat (CA) = 1110 7 kg
B) Kebutuhan bahan-bahan komposisi campuran untuk 1 m3 dalam
keadaan kering permukaan (ssd), sebagai berikut :
a) P. Cement = 378,7 kg
b) Water cement
= 178 – ((1126,3-1110,7)+(719,5-692)) = 134,9 lt
c) Fine Agrregate (FA)
= (105,9 / 101,85) x 692 kg = 719,5 kg
a) Coarse Aggregat (CA)
= (102,1 / 100,69) x 1110,7 kg = 1126,3 kg
C) Komposisi campuran untuk 1 zak (50 kg), yaitu :
a) P. Cement = 50 kg
b) Water cement = 17,8 lt
c) Fine Aggregat (FA) = 95 kg
d) Coarse Aggregate (CA) = 148,7 kg
C) Komposisi campuran untuk ½ zak cement (25 kg), yaitu :
a) P. Cement = 25 kg
b) Water cement = 8,9 kg
c) Fine Aggregate (FA) = 47,5 kg
d) Coarse Aggregae (CA) = 74,4 kg
E) Komposisi pencampuran dilapangan, yaitu :
a) Perbandingan berat (kg)
- P.cement = 50 kg
- Water cement = 17,8 lt
- Fine Aggregate (FA) = 95 kg
- Coarse Aggregate (CA) = 148,7 kg
- Volume kotak : 0,40 x 0,37 x 0,20 cm
b) Perbandingan Volume (%)
- P. Cement = 1 zak (50 kg) = 1 box
= 50 / (30 x 1,25)
- Fine Aggregate (FA) = 95 / (30 x 1,60) = 2 box
- Coarse Aggregate (CA) = 148,7 / (30 x 1,65) = 3 box
I. Laboratory Data.
A) Required strenght for = 225 + (1,64 x 60) = 323,4 kg/cm2
B) Maximum size coarse aggregate (CA) = 38,1 mm
C) Slump = 90 (mm) = 3,5 (in) ( 50 – 100 mm)
D) Water-cement ratio :
a) 323,4 = - 210 + 215 C/W = 0,403 %
b) 323,4 = 60 + 176 C/W = 0,459 %
c) Specification w/c = 0,50 %
w/c (selected) = 0,47 %
E) Fine Modulus = 2,635 g/cm3
F) Spgr of sand (ssd basis) = 2,565 g/cm3
G) Spgr CA ( ssd basis) = 2,632 g/cm3
H) Type of portland cement, spgr = 3,15 g/cm3
I) Minimum cement content = 340 – 400 kg/m3
Suggested : Water cement and fine aggregate % of total aggregate, for non Air – entrained concrette. Adjustment for water content and fine aggregate % for changed condition.
II. Computation proportion :
a) Water cement = 166 kg/m3 x (1+(3,5 – 35)x 3 % = 166 kg/m3 angular coarse aggregate be used + 12 kg/m3 = 178 kg/m3
b) Fine aggregate % of total aggrgate = 36 % + ((2,635 – 2,75) x 0,5 % + (0,47 – 0,55) x 1 % / 0,05)) = 36 % angular aggregae be used + 3 % = 39 %
c) Air contenet = 1 % (table)
d) Weight of cement = 178 kg/m3 / 0,47 = 378,7 kg/m3 ( 340 – 400) kg/m3
e) Solid volume of cement = 378,7 / 3,15 = 120,22 lt
f) Solid volume of aggregate = 1000 – (120,22 + 178 + (1% x 1000) = 691,8 kg
g) Solid volume of fine aggregate = 39 % x 691,8 = 269,8 kg
h) Required weight of sand = 269,8 x 2,565 = 692 kg
i) Solid volume of coarse agregate = 691,8 – 269,8 = 422 kg
j) Required weight of coarse aggregate = 422 x 2,632 = 1110,7 kg
The estimate batch quantities peroubles water of concrette :
a) P.Cement = 378,7 kg = 1
b) Water content = 178 lt = 0,47
c) Fine Aggrgate (FA) = 692 kg = 2 ( 1,8)
d) Coarse Aggregate (CA) = 1110,7 kg = 3 ( 2,9 )
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