Keranji: A Versatile Heavy Hardwood for Durable Construction
**Introduction**
Keranji, the standard Malaysian name for the timber of *Dialium* species (Leguminosae), is a highly regarded hardwood in Peninsular Malaysia, Sabah, and Sarawak. The major species include *Dialium indum*, *D. platysepalum*, *D. procerum*, and *D. kunstleri*. The sapwood of Keranji is white to yellowish-white, becoming light brown on exposure, while the heartwood is golden brown or red-brown, darkening over time.
Keranji is also known by various names across regions:
– **Brunei:** Keranji
– **Cambodia:** Kralanh, Kralanh lomie
– **Indonesia:** Kedjongong, Kerandji, Kerandji asap, Keranji, Nyamut
– **Laos:** Kheng, Mai kheem pheep
– **Myanmar:** Taung-kaye
– **Thailand:** Kayi-khao, Khleng, Yi-thongbung
– **Vietnam:** Xoay
**Density**
Keranji is classified as a Heavy Hardwood with a density ranging from 755 to 1250 kg/m³ when air-dried.
**Natural Durability**
Under typical Malaysian conditions, Keranji is considered moderately durable.
**Preservative Treatment**
Keranji timber is difficult to treat, and its heartwood is resistant to preservative treatments.
**Texture**
Keranji’s texture ranges from fine to moderately coarse and even, with a deeply interlocked and occasionally wavy grain.
**Strength Properties**
Keranji falls into Strength Group A (Engku, 1988) or SG 3 (MS 544: Part 2: 2001).
**Strength Properties of Keranji**
| Species | Test Condition | Modulus of Elasticity (MPa) | Modulus of Rupture (MPa) | Compression Parallel to Grain (MPa) | Compression Perpendicular to Grain (MPa) | Shear Strength (MPa) |
|——————|—————-|—————————–|—————————|————————————-|——————————————|———————–|
| D. platysepalum | Green | 18,800 | 109 | 54.5 | – | 10.9 |
| | Air dry | 20,100 | 134 | 72.0 | – | 16.0 |
| D. wallichii | Green | 21,000 | 129 | 68.8 | 9.24 | 10.9 |
| D. patens | Green | 19,200 | 156 | 88.7 | 19.72 | 17.0 |
**Machining Properties**
Keranji’s ease of machining varies by species. It can range from easy to very difficult to resaw and cross-cut. Planing can be easy to slightly difficult, with surfaces ranging from smooth to rough due to grain pickup.
**Machining Properties of Keranji**
| Species | Test Condition | Sawing | Planing | Boring | Turning | Re-sawing | Cross Cutting | Ease of Planing | Quality of Finish | Ease of Boring | Quality of Finish | Ease of Turning | Quality of Finish |
|—————–|—————-|——————-|——————–|——————-|——————|——————|——————|——————|——————-|——————|——————-|——————|——————-|
| D. laurinum | Green | Slightly difficult| Slightly easy | Moderately easy | Smooth | Moderately easy | Smooth | – | – | – | – | – | – |
| | Air dry | – | – | – | – | – | – | – | – | – | – | – | – |
| D. patens | Green | Difficult | Slightly difficult | Slightly difficult| Tangential: smooth, radial: rough due to grain pickup | Easy | Moderately smooth| – | – | – | – | – | – |
| | Air dry | Very difficult | Difficult | Slightly difficult| Moderately smooth| Fairly easy | Moderately smooth| Easy | Smooth | – | – | – | – |
| D. platysepalum | Green | Easy | Easy | Easy | Smooth | Easy | Smooth | – | – | – | – | – | – |
| | Air dry | Difficult | Slightly difficult | Easy | Smooth | Easy | Smooth | Easy | Smooth | – | – | – | – |
| D. wallichii | Green | Difficult | Difficult | Slightly difficult| Moderately smooth| – | – | – | – | – | – | – | – |
| | Air dry | Very difficult | Difficult | Slightly difficult| Moderately smooth| – | – | – | – | – | – | – | – |
**Nailing Property**
Keranji timber has good nailing properties.
**Air Drying**
Keranji seasons slowly with slight degrade, such as cupping, bowing, twisting, splitting, surface-checking, and susceptibility to insect and fungal attacks on the sapwood. Thirteen mm thick boards take about 2 months to air dry, while 38 mm thick boards take approximately 6 months.
**Kiln-Drying**
Kiln Schedule E is recommended for Keranji. The timber is prone to surface-checking and end-splitting. Twenty-five mm thick boards take about 10 days to kiln-dry from 50% to 10% moisture content.
**Kiln Schedule E**
| Moisture Content (%) | Temperature (Dry-bulb) | Temperature (Wet-bulb) | Relative Humidity (%) (approx.) |
|———————-|————————|————————|——————————–|
| Green | 120 °F (48.5 °C) | 115 °F (46.0 °C) | 85 |
| 60 | 120 °F (48.5 °C) | 113 °F (45.0 °C) | 80 |
| 40 | 125 °F (51.5 °C) | 116 °F (46.5 °C) | 75 |
| 30 | 130 °F (54.5 °C) | 117 °F (47.0 °C) | 65 |
| 25 | 140 °F (60.0 °C) | 120 °F (49.0 °C) | 55 |
| 20 | 155 °F (68.0 °C) | 127 °F (53.0 °C) | 45 |
| 15 | 170 °F (76.5 °C) | 136 °F (58.0 °C) | 40 |
**Shrinkage**
Shrinkage varies among species. *D. platysepalum* shows high shrinkage with radial shrinkage averaging 2.3% and tangential shrinkage averaging 3.7%. In contrast, *D. wallichii* exhibits low shrinkage, with radial shrinkage averaging 1% and tangential shrinkage averaging 1.7%.
**Movement in Service**
The movement of seasoned Keranji timber is classified under Type II.
**Uses**
Keranji is suitable for a wide range of applications:
– **Heavy construction:** posts, beams, joists, rafters, fender supports, columns (heavy duty)
– **Gymnasium equipment**
– **Railway sleepers**
– **Tool handles (impact)**
– **Vehicle bodies (framework and floorboards)**
– **Mallets, poles, telegraphic and power transmission posts and cross arms**
– **Bridges, pallets (permanent and heavy duty type)**
– **Laboratory benches**
– **Heavy-duty furniture and flooring (high traffic areas)**
– **Piling**
– **Door and window frames and sills**
– **Staircase components (balustrade, carriage, newel, riser, stringer, tread, bullnose, round end, and winder)**
– **Interior finishing, panelling, mouldings, joinery, and cabinet making**
Discover the potential of Keranji timber for your construction needs at Creatimber, where quality meets durability and expert craftsmanship.
