The effect of the densification process on dowel tensile performance with different types of glues

Ersin Ercan; Kadir Aydin; Cansu Özder; Musa Atar

doi:10.2478/ffp-2022-0021

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The effect of the densification process on dowel tensile performance with different types of glues

Folia Forestalia Polonica

Volume 64 (2022): Issue 4 (December 2022)

By: Ersin Ercan, Kadir Aydin, Cansu Özder and Musa Atar

Open Access

|Dec 2022

Figures & Tables

Cutting pattern of heart planks from a log

Table 1

Pre-compression dimensions of draft test samples

Compression ratio	Dimensions (mm)
Compression ratio	length (longitudinal direction)	width (tangent direction)	thickness (radial direction)
50%	800	10	20
75%	800	10	40

Hydraulic press used in densification processes

Table 2

Technical properties of the hydraulic press

Press temperature	Compression ratio
Pressure capacity	100 ton – 250 Bar
Temperature range	0–250°C
Pressure piston stroke	500 mm
Table size	60 × 60 cm
Motion	auto/manual, 8–11 mm/sec.

Table 3

Densification process

Densification
Press temperature	Compression ratio	Time
140°C	50%	press heating + 15 minutes
140°C	75%	press heating + 15 minutes

Table 4

Test parameters

Poplar	800 × 10 × 8	PVAc	Control	6	Eastern spruce	800 × 10 × 8	PVAc	Control	6
			50%	6				50%	6
			75%	6				75%	6
		D-VTKA	Control	6			D-VTKA	Control	6
			50%	6				50%	6
			75%	6				75%	6
	800 × 10 × 10	PVAc	Control	6		800 × 10 × 10	PVAc	Control	6
			50%	6				50%	6
			75%	6				75%	6
		D-VTKA	Control	6			D-VTKA	Control	6
			50%	6				50%	6
			75%	6				75%	6

Table 5

Compression ratios in air dry moisture after densification processes

Wood	Densification conditions	Thickness before compression	Thickness after compression	Press thickness	Compression ratio	Std.
Poplar	140°C 50%	20 mm	10.14 mm	10 mm	47.80%	0.16
Poplar	140°C 75%	40 mm	10.57 mm	10 mm	73.57%	0.58
Eastern spruce	140°C 50%	20 mm	10.22 mm	10 mm	48.90%	0.31
Eastern spruce	140°C 75%	40 mm	10.86 mm	10 mm	72.85%	0.51

Table 6

Density values and moisture content of dowels

Densification ratio	Density values (g/cm³)		Moisture content (%)
Densification ratio	poplar	eastern spruce	poplar	eastern spruce
Control	0.390	0.401	8.218	8.925
50%	0.508	0.540	4.558	6.485
75%	0.622	0.629	4.381	5.187

Table 7

Descriptive Statics

Parameters			Tensile performance (kg/cm²)^*
densification	dowel diameter (mm)	glue type	poplar	eastern spruce
control	8	PVAc	177.302	139.665
	8	D-VTKA	176.582	206.168
	10	PVAc	171.640	134.923
	10	D-VTKA	154.833	178.178
50%	8	PVAc	227.615	183.760
	8	D-VTKA	226.072	192.995
	10	PVAc	160.153	187.593
	10	D-VTKA	110.105	115.582
75%	8	PVAc	177.780	189.280
	8	D-VTKA	203.208	222.127
	10	PVAc	159.003	303.547
	10	D-VTKA	120.853	136.205

* Arithmetic average.

Table 8

Variance analysis of tensile performance test

Source	Degree of freedom	Sum of square	Mean of square	F	α < 0.05
Wood species (A)	1	2,811.562	2,811.562	7.3974	0.0075^*
Densification (B)	2	14,244.143	7,122.071	18.7386	0.0000^*
AB	2	21,040.921	10,520.461	27.6799	0.0000^*
Diameter (C)	1	41,772.206	41,772.206	109.9050	0.0000^*
AC	1	15,980.963	15,980.963	42.0468	0.0000^*
BC	2	16,775.502	8,387.751	22.0686	0.0000^*
ABC	2	9,586.050	4,793.025	12.6107	0.0000^*
Glue (D)	1	8,853.084	8,853.084	23.2930	0.0000^*
AD	1	43.263	43.263	0.1138	0.0000^*
BD	2	28,015.219	14,007.609	36.8548	0.0000^*
ABD	2	20,149.924	10,074.962	26.5078	0.0000^*
CD	1	42,854.177	42,854.177	112.7517	0.0000^*
ACD	1	9,539.593	9,539.593	25.0992	0.0000^*
BCD	2	15,928.969	7,964.484	20.9550	0.0000^*
ABCD	2	9,423.694	4,711.847	12.3971	0.0000^*
Error	120	45,609.062	380.076
Total	143	302,628.332

* Statistically significant.

Table 9

Tensile performance test results according to wood species

Wood species^*	Tensile performance (kg/cm²) X – HG
Eastern spruce	182.50^a
Poplar	173.66^b
Densification ratio^**
75%	191.4^a
50%	175.5^b
Control	167.4^c
Dovel diameter^***
8 mm diameter dowel	195.11^a
10 mm diameter dowel	161.05^b
Types Glue^****
PVAc glue	185.92^a
D-VTKA glue	170.24^b

HG:

* LSD – ±6.423,

** LSD – ±7.866,

*** LSD – ±16.129,

**** LSD – ±6.423.

LSD– Least small significant difference, HG: Homogeneity Groups.

Tensile performance according to wood species, densification ratio, dowel diameter and glue type

Table 10

Tensile performance test results according to binary interactions

Wood + Densification	X-HG	Densification + Diameter	X-HG	Densification + Glue	X-HG
Es + d^75%	212.8^a	d^50% + 8^mm	207.6^a	d^75% + PVAc	212.1^a
P + d^50%	181.0^b	d^75% + 8^mm	202.8^a	d^50% + PVAc	189.8^b
P	170.1^bc	d^75% + 10^mm	179.9^b	C + Dv	178.9^bc
Es + d^50%	170^bc	C + 8^mm	174.9^b	d^75% + Dv	170.6^cd
P + d^75%	169.9^bc	C + 10^mm	159.9^c	d^50% + Dv	161.2^de
Es	164.7^c	d^50% + 10^mm	143.4^d	C + PVAc	155.9^e
LSD = ±11.09		LSD = ±11.12		LSD = ±19.21

Wood + diameter	X-HG	Wood + Glue	X-HG	Diameter + Glue	X-HG
P + 8^mm	201.2^a	Es + PVAc	189.8^a	8^mm + Dv	204.5^a
Es + 8^mm	189.0^b	P + PVAc	182.1^b	10^mm + Dv	186.1^b
Es + 10^mm	176.0^c	Es + Dv	175.2^c	8^mm + PVAc	185.7^b
P + 10^mm	146.1^d	P + Dv	165.3^d	10^mm + PVAc	136.0^c
LSD = ±15.68		LSD = ±11.12		LSD = ±9.083

[i] Es – eastern spruce; P – poplar; d^50% – 50% densification ratio; d^75% – 75% densification ratio; C – Control; PVAc – polyvinyl acetate glue; Dv – desmodur-VTKA glue; HG – homogeneity groups.

Table 11

Tensile performance (kg/cm²) test results according to quadruple (Duncan Test) interactions

Wood species + Densification ratio + + Diameter of dowel + Glue type	X-HG (kg/cm²)
P + d^50% + 8^mm + PVAc	227.6^a
P + d^50% + 8^mm + Dv	226.1^a
Es + d^75% + 8^mm + Dv	222.1^a
Es + C+8^mm + Dv	206.2^b
P + d^75% + 8^mm + Dv	203.2^bc
P + d^75% + 8^mm + PVAc	196.6^bcd
Es + d^50% + 8^mm + Dv	193.0^cde
Es + d^75% + 8^mm + PVAc	189.3^cde
Es + d^50% + 10^mm + PVAc	187.6^cde
Es + d^50% + 8^mm + PVAc	183.8^cdef
Es + d^75% + 10^mm + PVAc	177.8^def
Es + C+10^mm + Dv	178.2^defg
P + C + 8^mm + PVAc	177.3^defg
P + C + 8^mm + Dv	176.6^efg
Es + C + 10^mm + PVAc	171.6^efg
P + d^50% + 10^mm + PVAc	160.2^fgh
P + d^75% + 10^mm + PVAc	159.0^fghi
P + C + 10^mm + Dv	154.8^ghi
Es + C + 8^mm + PVAc	139.7^hij
Es + d^75% + 10^mm + Dv	136.2^hij
Es + C + 10^mm + PVAc	134.9^ij
P + d^75% + 10^mm + Dv	120.9^jk
Es + d^50% + 10^mm + Dv	115.6^jk
P + d^50% + 10^mm + Dv	110.1^k

[i] LSD value – ±15.73.

References

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DOI: https://doi.org/10.2478/ffp-2022-0021 | Journal eISSN: 2199-5907 | Journal ISSN: 0071-6677

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Language: English

Page range: 214 - 225

Submitted on: Jan 27, 2022

Accepted on: Mar 10, 2022

Published on: Dec 10, 2022

Published by: Forest Research Institute

In partnership with: Paradigm Publishing Services

Keywords:

dowel tensile performance,

glue,

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© 2022 Ersin Ercan, Kadir Aydin, Cansu Özder, Musa Atar, published by Forest Research Institute
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Volume 64 (2022): Issue 4 (December 2022)

The effect of the densification process on dowel tensile performance with different types of glues

Figures & Tables

Figure 1

Table 1

Figure 2

Table 2

Table 3

Table 4

Figure 3

Figure 4

Table 5

Table 6

Table 7

Table 8

Table 9

Figure 5

Table 10

Table 11

Figure 6

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