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Wood cement board
1. PRODUCTION AND PROPERTIES OF WOOD-CEMENT BOARDS
FROM MACARANGA GIGANTEA
ABSTRACT
Wood-cement board (WCB) is a panel product that has the advantages of inorganic and
organic materials. However, the main problems affecting the manufacture and use of WCB are
the inhibitory effects of wood on the setting of cement and the high specific gravity of the final
product. This paper examines the potential and the use of additives that was use to facilitate
the production of a WCB from Macaranga gigantea. Wood cement boards (WCB) were
manufactured with wood/cement (w/w) ratio of 1:2.5, target density is 1300kg m-3
and Al2 (SO4)3
and Na2 SiO3 content as chemical additives is 1.5% and 3.0% . The WCB were tested for static
bending (MOR and MOE) properties in parallel (//) and perpendicular (┴) directions; internal
bond (IB), thickness swelling (TS) and water absorption (WA).
1. INTRODUCTION
Wood-cement boards (WCB) are already used thoroughly in Europe, United States, Russia
and S.E. Asia, mainly for roofs, floors and walls. They possess countless advantages compared
to panels produced with organic resins which are high durability, good dimensional stability,
acoustic and thermal insulation properties and low production cost. In recent years, several
research groups have been evaluating the suitability of different lignocellulosic materials for the
manufacture of WCB including cypress (Okino et al. 2005), rubberwood (Okino et al. 2004),
eucalyptus (Okino et al. 2004; Evans et al. 2000; Del Menezzi and Souza, 2000; Latorraca,
2000), pines (Cabagon et al. 2002; Teixeira and Pereira, 1987), acacia (Eusebio et al. 2002;
Teixeira and Guimarães, 1989), agricultural residues (Almeida et al. 2002) and fiber (Del
Menezzi etal. 2001). In spite of these studies there is no industrial plant in Brazil yet.
There are obstacles to the utilization of these materials for WCB. The main problems are the
inhibitory effect caused by wood on the cure of cement and the high density of the final product.
Wood component, mainly extractives and polysaccharides, affects reactions between wood and
cement resulting in boards of low quality. Jorge et al. (2004) argued that the nature of the
extractives also has influence on this inhibitory effect.
To solve inhibition problems, it is common to add inorganic chemicals, known as
accelerators, to accelerate the cure of cement or use pretreatments such as aqueous extraction
to remove inhibitory substances from wood. Cement chemicals accelerators usually improve the
properties of WCB (Jorge et al. 2004).
2. The objective of this project was to assess whether it is possible to manufacture a WCB
with suitable mechanical properties. Three factors were varied during the manufacture of boards
to produce composites with desired properties: low wood cement ratio to reduce board density
and distribution to improve board strength/stiffness and off sett the effect of low board density.
2. MATERIAL AND METHOD
2.1 Wood Material
Species of wood that use in producing the WCB is Macaranga gigantea’s top part from forest
learning of UiTM Pahang were felt cause of lightning. The age of the tree is undefined. The first
logs were cut on the spot it felt which was cut into three section; top, middle and bottom
transported to the workshop by backhoe.
2.2 Particle Preparation and Board Production
Actually, manufacture of wood cement board (WCB) in early stage is a bit similar as
particleboard manufacture. The different will be take a look during mixing stage. Wood cement
board mix wood, cement that is Portland and chemical additives that is aluminum sulphate
[Al2(SO4)3]. Before proceed to the process of mixing WCB at Figure 1.6 the important thing that
to be know is the flow chart of wood cement board production.
Flow chart of wood cement board production
Wood chipper flaking wood particle mixing
Hardening chamber compressing Mat forming
Curing cement bounded particle board testing
3. Figure 1.6
Next step is to take the mixer for mat forming process. This process is to get the mixture to a
mould. Same with particleboard, this process is to reduce the thickness of the mould. The mould
then send to hardening chamber for hardening the board. It is stay inside hardening chamber
about 24 hours. Figure 1.7 shows the process during WCB in hardening chamber.
4. Figure 1.7
After the board is taken out of hardening chamber, it will be dried for about three month for the
board to completely hardening. Lastly, the board will be test to know it strength properties.
Figure 1.8 shows the testing of WCB.
Figure 1.8
5. Figure 1.9 shows that WCB is prepared for testing
Figure 1.9
WOOD CEMENT BOARD
Cement calculation
Target density = 1300kg m-3
Ƿ =
Volume of mould =[450mm × 450mm× 10mm3
]
M = Ƿ
= 1300×2.025×10-3
M = 2.6325kg/2632.5g
Total weight of dry cement board
Example : to calculate cement board of ratio
Let χ = oven dry wood
= 1χ + 2.5 (cement)χ + (0.015 × 2.5)χ + (0.03 × 2.5)χ
= m(2632.5g)
χ + 2.5χ + 0.0375χ + 0.075χ = 2632.5
3.6125χ = 2632.5
6. Oven dry wood→ χ = 728.72g
Cement is = 2.5χ
= 2.5× 728.72
= 1821.8g
Chemical additives
Al2 (SO4)3 = 1.5% × 2.5χ
= 27.327g
Na2 SiO3 = 3.0%× 2.5χ
= 54.654g
*note : all chemical additives concentration was prepared@10% let MC of wood = 16%
Material Dry weight/g H2O weight/g Air dry
weight/g
Additional/g Total
Wood 728.72 +@16%
=116.595
845.315 + 42.266 887.581
Cement 1821.8 + 0 1821.8 + 91.09 1912.89
Al2 (SO4)3 10%
27.327
90%
+245.943
100%
273.27
+ 13.674 286.934
Na2 SiO3 10%
54.654
90%
+491.886
100%
546.54
+ 27.327 573.867
Total 2632.501 854.424
Based on MC = 45% ← assume that the MC of wood cement board
Raw cement board = 1184.626 – 854.424
=330.202g←actual quantity of water that will be added in the system
Total weight
H2O in system
2632.501 ×
Total quantity of
water in wood
cement
7. Wood cement ratio
1:2.0
1:2.25
1:2.5
1:2.75
1:3.0
Type of cement is Portland cement
Standard use to test =MS 544 (200)
MOR MOE WA TS IB
≥9.0mp ≥3000mpa ≤30% ≤2% ≥0.5 in pa
Cutting plan for testing
BENDING
←B1,B2,B3,B4,B5
Length= 175mm
Width = 100mm
B1
B3
B2
B4
B5
TS1 IB
TS2
TS3
IB
3
IB
IB
B
8. ←TS1,TS2,TS3
Length= 100mm
Width = 100mm
Length =50mm
Width =50mm
Mould of wood cement board
Length= 450mm
Height= 450mm
Thickness= 10mm
1 board, m = 2632.5g
Wood + cement + H2O + additives = 2632.5g
*note : additive must be below than 5%,if it is above 5% instability molecule would happen and
5% taxable exaggerating of wood,cement,H2O and additives to prevent error during mixing.
Result
Wood cement board : Size particle that use to produce wood cement board is 2.0, 1.0 and 0.5
Bending test
Particle size 2.0
Width
(mm)
Thickness
(mm)
Length
(mm)
Weight
(g)
Density
(kg/m3
)
Maximum
load
MOR
(MPa)
MOE
(MPa)
TS
IB
MOR & MOE = 175mm × 100mm
Density & TS/Wa = 100mm × 100mm
IB = 40mm × 40mm
P=1300
Aluminium sulphite[ Al2 (SO4)]
- For harden the mixture
Sodium silicate[ Na2 SiO3]
- For improve bonding