Properties of Young Guapuruvu (<i>Schizolobium parahyba</i>) Wood from a Forest Recovery Area

Athanázio-Heliodoro, Julia Carolina; Pacheco, Luana; Gaiad, Natália; Lara-Palma, Hernando Alphonso; Ballarin, Adriano Wagner

doi:10.1590/2179-8087.036616

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Original Article, Wood Science and Technology • Floresta Ambient. 25 (3) • 2018 • https://doi.org/10.1590/2179-8087.036616 copy

Properties of Young Guapuruvu (Schizolobium parahyba) Wood from a Forest Recovery Area

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Guapuruvu is one of the fastest growing Atlantic Forest species. It is also considered one of most important species in forest recovery areas, starting to compete with other individuals during the second stage of succession, as well as showing a capacity to be harvested and processed at this stage, after fulfilling its function as a pioneer. There are no conclusive studies about the technological potential of the wood from the young guapuruvu trees characteristic of this context. The present study evaluated the physical-mechanical properties and quality of guapuruvu wood from young trees (15 years old) from forest recovery areas in accordance with NBR 7190. The presence of tension wood did not influence the homogeneity of the wood, which is classified as strength class C20 – hardwood, with characteristic strength of 21.47 MPa in compression parallel to the grain, characteristic tension strength of 23.12 MPa parallel to grain and modulus of elasticity (MOE) of 5,925 MPa. Basic and apparent densities were 290 kg/m³ and 336 kg/m³ respectively. However, its low density did not lead to low mechanical strength. The high ratio between the values of its mechanical properties and apparent density, added to its high homogeneity – despite the presence of tension wood – demonstrated the good quality of its wood.

Keywords:
mechanical properties; Schizolobium parahyba; wood quality

	ρ_b ¹ 1 Basic density;	ρ₁₂ ² 2 Density at 12% EMC;	βr ³ 3 Radial shrinkage;	βt ⁴ 4 Tangential shrinkage;	βl ⁵ 5 Longitudinal shrinkage;	βv ⁶ 6 Volumetric shrinkage;	Anis. ⁷ 7 Anisotropy index;
	(kg/m³)		(%)
Minimum	256	291	1.81	4.85	0.07	7.61	1.88
Maximum	321	388	4.67	12.27	0.86	20.22	3.67
Arith. Mean ⁸ 8 Arithmetic mean;	290	336	2.69	7.24	0.34	11.19	2.74
S. Dev. ⁹ 9 Standard deviation;	28.85	34.74	0.60	1.28	0.15	2.19	0.39
C. Var. ¹⁰ 10 Coefficient of variation.	9.96	10.34	22.20	17.64	44.50	19.55	14.24

	E_c0 ¹ 1 Modulus of elasticity in compression parallel to grain;	f_c0 ² 2 Compression strength parallel to grain;	E_t0 ³ 3 Modulus of elasticity in tension parallel to grain;	f_t0 ⁴ 4 Tension strength parallel to grain;	E_M ⁵ 5 Modulus of elasticity in static bending;	f_M ⁶ 6 Modulus of rupture in bending;	f_V ⁷ 7 Shear strength parallel to grain;	E_c90 ⁸ 8 Modulus of elasticity in compression perpendicular to grain;	f_c90 ⁹ 9 Compression strength perpendicular to grain;	f_t90 ¹⁰ 10 Tension strength perpendicular to grain;	f_H ¹¹ 11 Janka hardness;
	(MPa)
Minimum	4,532	17.27	4,184	18.59	3,598	27.94	3.68	257	2.12	1.98	12.50
Maximum	6,902	26.83	7,574	50.45	7,999	55.04	7.62	901	3.34	4.65	29.40
Arith. Mean	5,728	22.81	6,172	36.50	5,925	40.47	5.35	497	2.46	3.55	18.89
S. Dev. ¹² 12 Standard deviation;	718	2.12	981	8.35	1,022	6.26	0.67	172	0.33	0.65	3.65
C. Var. ¹³ 13 Coefficient of variation.	12.54	8.61	15.89	22.88	17.25	15.46	12.50	34.55	13.36	18.16	19.33

Species	Physical properties		Mechanical properties							Ref ¹⁰ 10 References:
	ρ₁₂ ¹ 1 Density at 12% EMC;	ρ_b ² 2 Basic density;	f_c0 ³ 3 Compression strength parallel to grain;	E_c0 ⁴ 4 Modulus of elasticity in compression parallel to grain;	f_t90 ⁵ 5 Tension strength perpendicular to grain;	f_v0 ⁶ 6 Shear strength;	f_M ⁷ 7 Modulus of rupture in bending;	E_M ⁸ 8 Modulus of elasticity in static bending;	f_H ⁹ 9 Janka stiffness;
	(kg/m³)		(MPa)
*S. parahyba*	336	290	22.81	5,728	3.55	5.35	40.47	5,925	18.89	^a a Present study;
*S. parahyba*	314	N.A.	20.95	5,640	3.10	5.01	45.10	4,970	16.13	^b b Mainieri & Chimelo (1989) ,
*S. amazonicum*	370	300	27.00	7,320	1.55	8.00	50.00	8,900	N.A.	^c c Almeida et al. (2013a , b );
*H. brasiliensis*	681	550	41.90	9,920	3.22	7.72	N.A.	N.A.	N.A.	^d d Eufrade et al. (2015)

Physical properties		Mechanical properties						Ref ³ 3 References:
Physical properties		Parallel to grain				Perpendicular to grain
ρ_ap12%	ρ_bas	f_c0,k	f_t0,k	f_v0,k	f_M,k	f_c90,k	f_t90,k
(kg/m³) ¹ 1 Mean values;		(MPa) ² 2 Characteristic values;				(MPa) ² 2 Characteristic values;
336	290	21.47	23.12	5.07	34.64	2.36	3.02	^a a Present study;
650	500	20.00	26.00	4.00	26.00	5.00	N.A.	^b b Reference values presented by NBR 7190 for structural class C20 – hardwood ( ABNT, 1997 ).

$\frac{f_{c 0, k} \times 100}{ρ_{a p}}$	$\frac{f_{v 0, k} \times 100}{ρ_{a p}}$	$\frac{f_{c 90, k}}{f_{c 0, k}}$	$\frac{f_{t 0, k}}{f_{c 0, k}}$	$\frac{f_{v 0, k}}{f_{c 0, k}}$	Ref ¹ 1 References:
6.39	1.51	0.11	1.07	0.23	^a a Present study;
4.00	0.80	0.25	1.30	0.12	^b b Reference values presented by NBR 7190 for structural class C20 – hardwood ( ABNT, 1997 ).

Wood	Mechanical Properties			Physical properties
	E_M ¹ 1 Modulus of elasticity in static bending;	f_M ² 2 Modulus of rupture in bending;	f_H ³ 3 Janka hardness;	β_t ⁴ 4 Tangential shrinkage;	β_r ⁵ 5 Radial shrinkage;	β_v ⁶ 6 Volumetric shrinkage;	Anisot. ⁷ 7 Anisotropy index.
	(MPa)			(%)
Opposite	5,909	40.38	19.35	7.41	2.73	11.42	2.76
Tension	5,938	40.55	18.49	7.09	2.65	10.98	2.72

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[1] *Julia Carolina Athanázio-HeliodoroFaculdade de Ciências Agronômicas, Universidade Estadual Paulista – UNESP Rua José Barbosa de Barros, 1780, Fazenda Lageado, CEP 18610-307, Botucatu, SP, Brasil e-mail: juliaheliodoro@hotmail.com