# Effect of Primary Spruce Lamella Aging on the Bending Characteristics of Glulam Beams
## 3 Results and Discussion  
### Bending Characteristics of Glulam Beams Affected by Aging of Lamellas  
3.1.1. Influence of Lamella Aging Methods and Their Locations in Beams  
For the 1 st-4 th groups of three-layer glulam beams, consisting of spruce lamellas of type I (Section 2.1) and PUR glue (Figures 2 and 3), the bending characteristics MOR and MOE were determined (Table 1 and Figure 4). The MOR of glulam beams, in many cases, significantly depended--as determined by [PERSON]'s tests--both on the method of lamella aging and their locations in the beams (Table 1). The highest MORs were determined for glulam beams in the first (reference) group consisting only of sound spruce lamellas (81.63 MPa) and those in the second group, in which the middle lamella was initially aged at lower temperatures of 160 or 180 \({}^{\circ}\)C (81.74 or 82.65 MPa). However, the MOR in the second group of glulam beams was evidently smaller at the 99.9% or 99% significance level if the middle \begin{table}
\begin{tabular}{c c c} \hline \hline
**Glulam Beam** & **MOR (MPa)** & **MOE (MPa)** \\ \hline
**1 st group (S-S-S)** & & \\ Sound & 81.63 (2.66) & 10,432 (742) \\ \hline
**2 nd group (S-A-S)** & & \\ GD bio-attack & 72.78 (5.38) b & 10,864 (693) d \\ LD bio-attack & 74.45 (0.82) c & 9956 (1298) d \\ T-160 \({}^{\circ}\)C & 81.74 (1.63) d & 9566 (332) d \\ T-180 \({}^{\circ}\)C & 82.65 (1.93) d & 11,574 (391) d \\ T-200 \({}^{\circ}\)C & 77.53 (2.65) d & 9540 (1360) d \\ T-220 \({}^{\circ}\)C & 68.29 (4.75) a & 10,564 (1470) d \\ CuSO\({}_{4}\)5H\({}_{2}\)O & 75.29 (5.69) c & 9701 (598) d \\ ZnCl\({}_{2}\) & 70.78 (5.60) a & 9806 (674) d \\ H\({}_{3}\)BO\({}_{3}\) & 80.03 (3.05) d & 10,905 (1055) d \\ (NH\({}_{4}\))\({}_{2}\)SO\({}_{4}\) & 73.08 (7.18) b & 8856 (384) b \\ \hline
**3 rd group (A-S-A)** & & \\ GD bio-attack & 60.98 (3.21) a & 8292 (913) a \\ LD bio-attack & 67.37 (3.74) a & 9614 (426) d \\ T-160 \({}^{\circ}\)C & 80.85 (3.50) d & 9145 (1456) c \\ T-180 \({}^{\circ}\)C & 79.88 (6.54) d & 11,554 (499) d \\ T-200 \({}^{\circ}\)C & 70.38 (6.50) a & 10,443 (484) d \\ T-220 \({}^{\circ}\)C & 62.60 (4.63) a & 9518 (731) d \\ CuSO\({}_{4}\)5H\({}_{2}\)O & 71.09 (4.58) a & 10,591 (704) d \\ ZnCl\({}_{2}\) & 68.92 (1.36) a & 9151 (414) c \\ H\({}_{3}\)BO\({}_{3}\) & 71.20 (1.63) a & 8415 (517) a \\ (NH\({}_{4}\))\({}_{2}\)SO\({}_{4}\) & 70.82 (5.38) a & 9052 (269) c \\ \hline
**4 th group (A-A-A)** & & \\ GD bio-attack & 60.02 (9.86) a & 7540 (1032) a \\ LD bio-attack & 74.99 (7.18) c & 9738 (670) d \\ T-160 \({}^{\circ}\)C & 80.97 (7.51) d & 9841 (860) d \\ T-180 \({}^{\circ}\)C & 76.03 (6.19) d & 9826 (1436) d \\ T-200 \({}^{\circ}\)C & 69.29 (7.38) a & 10,155 (543) d \\ T-220 \({}^{\circ}\)C & 62.56 (2.17) a & 8508 (811) a \\ CuSO\({}_{4}\)5H\({}_{2}\)O & 69.20 (4.20) a & 9686 (396) d \\ ZnCl\({}_{2}\) & 70.32 (3.55) a & 10,542 (1689) d \\ H\({}_{3}\)BO\({}_{3}\) & 75.45 (2.54) a & 10,825 (920) d \\ (NH\({}_{4}\))\({}_{2}\)SO\({}_{4}\) & 69.87 (1.54) a & 9012 (1399) c \\ \hline \hline \end{tabular} Notes: Mean values are from 6 measurements. Standard deviations are in parentheses. [PERSON]’s tests were used to evaluate the bending characteristics of the 2 nd, 3 rd or 4 th groups of glulam beams consisting of 1, 2 or 3 aged ”A” lamellas, relative to the 1 st (reference) group of glulam beams consisting of 3 sound “S” lamellas, with indexes of significance: a—very significant decrease at 99.9% level; b—significant decrease at 99% level; c—less significant decrease at 95% level; and d—significant change (decrease or increase) at +95% level.  
\end{table} 
Table 1: The bending characteristics MOR and MOE of the three-layer glulam beams in the 1 st, 2 nd, 3 rd and 4 th groups (Figure 3) prepared from Norway spruce lamellas of type I and PUR glue (Figure 2).