THE DISSERTATION

9 Gypsum Appendix

9.1 Gypsum protocol

The objective of this section is to provide the investigator with a method of procuring, processing, and interpreting the thermal signature recorded by gypsum wallboard exposed to fire environments.

Determine subject area prior to identifying sample location (that is, make a photo overview).
Evaluate subject area recognizing distinguishing variations in gypsum wallboard surface conditions:

2.1 Plume/Thermal signatures
2.1.1 Variation of these patterns - that is, levels of calcination
Select sampling locations

3.1 Greatest degree of observable calcination
3.2 A systematic sampling survey of adjoining regions to those specifically targeted
3.3 Areas related to potentially conflicting patterns of calcination
3.4 Control specimens protected from thermally induced change as a function of the fire
Mark the selected specimen location and map

4.1 Marking for pre-removal photos
4.2 Mapping for specimen location identification accuracy
Cut 6 cm x 6 cm using a sheet rock knife or similar tool. Place specimen into poly bag for protection.
Fracture the specimen by hand, preferably halving the piece - resulting in two 3 cm x 6 cm pieces.
Photograph fracture surface.
Identify coloration and/or apparent density changes in the cross-section of the specimen. Measure the depths of these distinguishable layers from the back of the affected surface.
Prepare power diffraction specimens by extracting material from each distinguishable layer.

9.1 Example: the top/exposed surface to 2 mm below the surface
9.2 The middle region (8-10 mm) from the unexposed surface
9.3 The back side of the specimen
Perform XRD on the prepared specimens. Suggested methodology: 2-q range: 10° -60° with steps of 0.1°.
Identify the top 6 peaks based on percent intensity (percent intensity is also known as height). Capture the d-spacing and percent intensity for use in the analysis.
Compare test data to that established by experimental testing and external standards.

9.2 List of gypsum samples and test conditions

Table 14 List of gypsum samples and test conditions

Sample ID	Depth of sample	Heat Flux (kW/m²)	Duration (seconds)
1GYP2_5X	16 mm	25	1500
1GYP5_5X	16 mm	25	4500
1GYP6_5X	16 mm	50	1500
1GYP7_5X	16 mm	50	1500
1GYP8_5x_2	16 mm	63	1500
1GYP9_5x_2	16 mm	63	1500
1GYP1_5X	16 mm	75	1500
1GYP3_5X	16 mm	75	1500
1GYP4_5X	16 mm	75	1500
1GYP10_5x	16 mm	83	1500
1GYP11_5x	16 mm	83	1500
1GYP12_5x	16 mm	83	1500
1GYP8_5X	16 mm	90	1500
1GYP9_5X	16 mm	90	1500
1GYP2_1	25 mm	25	1500
1GYP5_1	25 mm	25	4500
1GYP6_1	25 mm	50	1500
1GYP7_1	25 mm	50	1500
1GYP10_1	25 mm	63	1500
1GYP11_1	25 mm	63	1500
1GYP1_1	25 mm	75	1500
1GYP14_1	25 mm	75	1500
1GYP3_1	25 mm	75	1500
1GYP4_1	25 mm	75	1500
1GYP12_1	25 mm	83	1500
1GYP13_1	25 mm	83	1500
1GYP8_1	25 mm	90	1500
1GYP9_1	25 mm	90	1500

9.3 Data, measurements, and analysis

This section contains the raw data, the analysis, and the results which were shown in the main body of the dissertation in the figures. It is intended as a supplement to the final results shown in the body of the thesis.

9.3.1 Graphs of gypsum’s response to heat

It is useful to see exactly how all the data was taken. One of the central tenets of this dissertation is that the gypsum burns more steadily than wood. The next figures, Figure 169 through Figure 176, show the results of both 16 mm and 25 mm gypsum when heated in the cone calorimeter. It is useful to note the low variability between the samples at both low and high heat fluxes, both near and far away from the surface.

Figure 169 Temperature versus time profiles: 16 mm gypsum, 25 kW/m²heat flux

Figure 170 Temperature versus time profiles: 25 mm gypsum, 25 kW/m²heat flux

Figure 171 Temperature versus time profiles: 16 mm gypsum, 50 kW/m²heat flux

Figure 172 Temperature versus time profiles: 25 mm gypsum, 50 kW/m²heat flux

Figure 173 Temperature versus time profiles: 16 mm gypsum, 75 kW/m²heat flux

Figure 174 Temperature versus time profiles: 25 mm gypsum, 75 kW/m²heat flux

Figure 175 Temperature versus time profiles: 16 mm gypsum, 90 kW/m²heat flux

Figure 176 Temperature versus time profiles: 25 mm gypsum, 90 kW/m²heat flux

9.3.2 Analysis: rate of isotherm progression

In this section, we detail the calculations which were performed to draw our conclusions about the rate of isotherm progression. The manner of analysis is detailed below.

There were three isotherms which were followed. They were the 80° C isotherm (corresponding to dihydrate), the 200 ° C isotherm (corresponding to b-hemihydrate), and the 500° C isotherm (corresponding to anhydrous). For each thermocouple, the time between insertion into the calorimeter and the time when the thermocouple hit the isotherm was measured. The distance between the exposed surface and the thermocouple was already known. Because we used the 4 mm and the 12 mm thermocouples for these measurements, there were three different zones generated. ⁴⁷

With a known distance, and a measured time, the rate of isotherm progression could be calculated. The detailed calculations are shown in Table 15 and closely parallel those of the wood samples shown in Table 7 and Table 8.

Table 15 Time required for isotherm to progress through Zone 0 and Zone 1 in gypsum

(TC=thermocouple)

COL. LABEL	B	C	D	E	F	G	H	I
			Time until hemihydrate forms⁴⁸ (sec)		Time until Insoluble b -CaSO₄forms⁴⁹ (sec)		Time until anhydrous forms⁵⁰ (sec)
Gypsum Thickness	Heat Flux (kW/m²)	Sample ID	4 mm TC	12 mm TC	4 mm TC	12 mm TC	4 mm TC	12 mm TC
16 mm	25	1gyp2_5x	22	114	159	975
16 mm	25	1gyp5_5x	27	130	220	1139		3206
16 mm	50	1gyp6_5x	18	96	108	879	1177	1313
16 mm	50	1gyp7_5x	14	94	96	867	805	1276
16 mm	63	1gyp8_5x_2	13	65	74	566	536	1113
16 mm	63	1gyp9_5x_2	11	52	84	734	592	1119
16 mm	75	1gyp1_5x	9	45	60	496	415	1089
16 mm	75	1gyp3_5x	10	44	50	499	377	1086
16 mm	75	1gyp4_5x	9	49	53	547	330	1070
16 mm	83	1gyp10_5x
16 mm	83	1gyp11_5x	4	56	33	611	126	982
16 mm	83	1gyp12_5x	16	54	191		834
16 mm	90	1gyp8_5x	10	70	79	659	344	913
16 mm	90	1gyp9_5x	7	70	55	590	184	884
25 mm	25	1gyp2_1	30	146	226	1394
25 mm	25	1gyp5_1	17	153	184	1443
25 mm	50	1gyp6_1	15	136	122	1327	1550
25 mm	50	1gyp7_1	10	110	82	1335	1052
25 mm	63	1gyp10_1	15				994
25 mm	63	1gyp11_1
25 mm	75	1gyp1_1	8	67	70	536	500
25 mm	75	1gyp14_1	15	130	122	1199	794
25 mm	75	1gyp3_1	7	60	50	471	383
25 mm	75	1gyp4_1	7	84	24	590	185
25 mm	83	1gyp12_1	8	123	70	980	439
25 mm	83	1gyp13_1	13	152	118	1336	637
25 mm	90	1gyp8_1	17	99	116	938	568
25 mm	90	1gyp9_1	11	85	110	818	510

Table 16 Calculation of rate of isotherm progression through gypsum Zone 0

This table uses the raw data set forth in Table 15 and calculates the rate of isotherm progression. The column labels refer to Table 15.

Gypsum Thickness	Heat Flux (kW/m²)	Sample ID	Rate of hemi-hydrate isotherm⁵¹ moving through Zone 0⁵² (mm/s)⁵³	Rate of Insoluble b CaSO4 isotherm⁵⁴ moving through Zone 0 (mm/s)	Rate of anhydrous isotherm⁵⁵ moving through Zone 0 (mm/s)
			=4 mm / Column D	=4 mm / Col F	=4 mm / Col H
16 mm	25	1gyp2_5x	0.181818	0.025157
16 mm	25	1gyp5_5x	0.148148	0.018182
16 mm	50	1gyp6_5x	0.222222	0.037037	0.003398
16 mm	50	1gyp7_5x	0.285714	0.041667	0.004969
16 mm	63	1gyp8_5x_2	0.307692	0.054054	0.007463
16 mm	63	1gyp9_5x_2	0.363636	0.047619	0.006757
16 mm	75	1gyp1_5x	0.444444	0.066667	0.009639
16 mm	75	1gyp3_5x	0.400000	0.080000	0.010610
16 mm	75	1gyp4_5x	0.444444	0.075472	0.012121
16 mm	83	1gyp10_5x
16 mm	83	1gyp11_5x	1.000000	0.121212	0.031746
16 mm	83	1gyp12_5x	0.250000	0.020942	0.004796
16 mm	90	1gyp8_5x	0.400000	0.050633	0.011628
16 mm	90	1gyp9_5x	0.571429	0.072727	0.021739
25 mm	25	1gyp2_1	0.133333	0.017699
25 mm	25	1gyp5_1	0.235294	0.021739
25 mm	50	1gyp6_1	0.266667	0.032787	0.002581
25 mm	50	1gyp7_1	0.400000	0.048780	0.003802
25 mm	63	1gyp10_1	0.266667		0.004024
25 mm	63	1gyp11_1
25 mm	75	1gyp1_1	0.500000	0.057143	0.008000
25 mm	75	1gyp14_1	0.266667	0.032787	0.005038
25 mm	75	1gyp3_1	0.571429	0.080000	0.010444
25 mm	75	1gyp4_1	0.571429	0.166667	0.021622
25 mm	83	1gyp12_1	0.500000	0.057143	0.009112
25 mm	83	1gyp13_1	0.307692	0.033898	0.006279
25 mm	90	1gyp8_1	0.235294	0.034483	0.007042
25 mm	90	1gyp9_1	0.363636	0.036364	0.007843

Table 17 Calculation of rate of isotherm progression through gypsum Zone 1

This table is a parallel of Table 16 for Zone 1. It uses the raw data set forth in Table 15 and calculates the rate of isotherm progression. The column labels refer to Table 15.

Gypsum Thickness	Heat Flux (kW/m²)	Sample ID	Rate of hemi-hydrate isotherm moving through Zone 1⁵⁶ (mm/s)	Rate of Insoluble b CaSO4 isotherm moving through Zone 1 (mm/s)	Rate of anhydrous isotherm moving through Zone 1 (mm/s)
			=8 mm /(Col E - Col. D)	=8 mm /(Col G - Col. F)	=8 mm /(Col I - Col. H)
16 mm	25	1gyp2_5x	0.086957	0.009804
16 mm	25	1gyp5_5x	0.077670	0.008705
16 mm	50	1gyp6_5x	0.102564	0.010376	0.058824
16 mm	50	1gyp7_5x	0.100000	0.010376	0.016985
16 mm	63	1gyp8_5x_2	0.153846	0.016260	0.013865
16 mm	63	1gyp9_5x_2	0.195122	0.012308	0.015180
16 mm	75	1gyp1_5x	0.222222	0.018349	0.011869
16 mm	75	1gyp3_5x	0.235294	0.017817	0.011283
16 mm	75	1gyp4_5x	0.200000	0.016194	0.010811
16 mm	83	1gyp10_5x
16 mm	83	1gyp11_5x	0.153846	0.013841	0.009346
16 mm	83	1gyp12_5x	0.210526
16 mm	90	1gyp8_5x	0.133333	0.013793	0.014060
16 mm	90	1gyp9_5x	0.126984	0.014953	0.011429
25 mm	25	1gyp2_1	0.068966	0.006849
25 mm	25	1gyp5_1	0.058824	0.006354
25 mm	50	1gyp6_1	0.066116	0.006639
25 mm	50	1gyp7_1	0.080000	0.006385
25 mm	63	1gyp10_1
25 mm	63	1gyp11_1
25 mm	75	1gyp1_1	0.135593	0.017167
25 mm	75	1gyp14_1	0.069565	0.007428
25 mm	75	1gyp3_1	0.150943	0.019002
25 mm	75	1gyp4_1	0.103896	0.014134
25 mm	83	1gyp12_1	0.069565	0.008791
25 mm	83	1gyp13_1	0.057554	0.006568
25 mm	90	1gyp8_1	0.097561	0.009732
25 mm	90	1gyp9_1	0.108108	0.011299

9.3.3 Determination of exposure time and heat flux

In this section, we present tables showing the isotherm progression calculated using the rates observed in Table 16 and Table 17. They are presented for three isotherms (the 80° isotherm, the 200° isotherm, and the 500° isotherm) for two depths of gypsum (16 mm and 25 mm depths) in Table 18 through Table 23 below.

Table 18 Average time for 80 C isotherm to progress to depths of 4 and 12 mm in 16 mm gypsum

Heat flux (kW/m²)	Depth from exposed surface (mm)	Average time until 80° isotherm reaches depth (seconds) ⁵⁷	Max time until 80° isotherm reaches depth (seconds)	Min time until 80° isotherm reaches depth (seconds)
25	0	0.00	0.00	0.00
25	4	24.24	27.00	22.00
25	12	121.43	130.00	114.00

50	0	0.00	0.00	0.00
50	4	15.75	18.00	14.00
50	12	94.74	98.00	92.00

63	0	0.00	0.00	0.00
63	4	11.92	13.00	11.00
63	12	57.77	65.00	52.00

75	0	0.00	0.00	0.00
75	4	9.31	10.00	9.00
75	12	45.81	50.00	43.00

83	0	0.00	0.00	0.00
83	4	6.40	16.00	4.00
83	12	50.31	68.00	42.00

90	0	0.00	0.00	0.00
90	4	8.24	10.00	7.00
90	12	69.70	73.00	67.00

Table 19 Average time for 80 C isotherm to progress to depths of 4 and 12 mm in 25 mm gypsum

Heat flux (kW/m²)	Depth from exposed surface (mm)	Average time until 80° isotherm reaches depth (seconds) ⁵⁸	Max time until 80° isotherm reaches depth (seconds)	Min time until 80° isotherm reaches depth (seconds)
25	0	0.00	0.00	0.00
25	4	21.70	30.00	17.00
25	12	146.91	166.00	133.00

50	0	0.00	0.00	0.00
50	4	12.00	15.00	10.00
50	12	121.50	136.00	110.00

63	0	0.00	0.00	0.00
63	4	N/A⁵⁹	N/A	N/A
63	12	N/A	N/A	N/A

75	0	0.00	0.00	0.00
75	4	8.38	15.00	7.00
75	12	77.94	130.00	60.00

83	0	0.00	0.00	0.00
83	4	9.90	13.00	8.00
83	12	135.77	152.00	123.00

90	0	0.00	0.00	0.00
90	4	13.36	17.00	11.00
90	12	91.15	99.00	85.00

Table 20 Average time for 200 C isotherm to progress to depths of 4 and 12 mm in 16 mm gypsum

Heat flux (kW/m²)	Depth from exposed surface (mm)	Average time until 200° isotherm reaches depth (seconds) ⁶⁰	Max time until 200° isotherm reaches depth (seconds)	Min time until 200° isotherm reaches depth (seconds)
25	0	0.00	0.00	0.00
25	4	184.59	220.00	159.00
25	12	1049.03	1139.00	975.00

50	0	0.00	0.00	0.00
50	4	101.65	108.00	96.00
50	12	872.65	879.00	867.00

63	0	0.00	0.00	0.00
63	4	78.68	84.00	74.00
63	12	638.75	734.00	566.00

75	0	0.00	0.00	0.00
75	4	54.02	60.00	50.00
75	12	512.38	554.00	486.00

83	0	0.00	0.00	0.00
83	4	56.28	191.00	33.00
83	12	634.28	769.00	611.00

90	0	0.00	0.00	0.00
90	4	64.85	79.00	55.00
90	12	621.44	659.00	590.00

Table 21 Average time for 200 C isotherm to progress to depths of 4 and 12 mm in 25 mm gypsum

Heat flux (kW/m²)	Depth from exposed surface (mm)	Average time until 200° isotherm reaches depth (seconds)⁶¹	Max time until 200° isotherm reaches depth (seconds)	Min time until 200° isotherm reaches depth (seconds)
25	0	0.00	0.00	0.00
25	4	202.85	226.00	184.00
25	12	1414.64	1485.00	1352.00

50	0	0.00	0.00	0.00
50	4	98.08	122.00	82.00
50	12	1326.61	1375.00	1287.00

63	0	0.00	0.00	0.00
63	4	N/A	N/A	N/A
63	12	N/A	N/A	N/A

75	0	0.00	0.00	0.00
75	4	47.53	122.00	24.00
75	12	601.82	1199.00	445.00

83	0	0.00	0.00	0.00
83	4	87.87	118.00	70.00
83	12	1129.58	1336.00	980.00

90	0	0.00	0.00	0.00
90	4	112.92	116.00	110.00
90	12	873.67	938.00	818.00

Table 22 Average time for 500 C isotherm to progress to depths of 4 and 12 mm in 16 mm gypsum

Heat flux (kW/m²)	Depth from exposed surface (mm)	Average time until 200° isotherm reaches depth (seconds) ⁶²	Max time until 200° isotherm reaches depth (seconds)	Min time until 200° isotherm reaches depth (seconds)
25	0	0.00	0.00	0.00
25	4	N/A	N/A	N/A
25	12	N/A	N/A	N/A

50	0	0.00	0.00	0.00
50	4	956.09	1177.00	805.00
50	12	1167.15	1648.00	941.00

63	0	0.00	0.00	0.00
63	4	562.61	592.00	536.00
63	12	1113.48	1169.00	1063.00

75	0	0.00	0.00	0.00
75	4	370.72	415.00	330.00
75	12	1077.35	1155.00	1004.00

83	0	0.00	0.00	0.00
83	4	218.93	834.00	126.00
83	12	1074.93	1690.00	982.00

90	0	0.00	0.00	0.00
90	4	239.76	344.00	184.00
90	12	867.50	1044.00	753.00

Table 23 Average time for 500 isotherm to progress to 4 and 12 mm depth in 25 mm gypsum

Heat flux (kW/m²)	Depth from exposed surface (mm)	Average time until 500° isotherm reaches depth (seconds) ⁶³	Max time until 500° isotherm reaches depth (seconds)	Min time until 500° isotherm reaches depth (seconds)
25	0	0.00	0.00	0.00
25	4	N/A	N/A	N/A
25	12	N/A	N/A	N/A

50	0	0.00	0.00	0.00
50	4	1253.34	1550.00	1052.00
50	12	N/A	N/A	N/A

63	0	0.00	0.00	0.00
63	4	994.00	994.00	994.00
63	12	N/A	N/A	N/A

75	0	0.00	0.00	0.00
75	4	354.74	794.00	185.00
75	12	N/A	N/A	N/A

83	0	0.00	0.00	0.00
83	4	519.78	637.00	439.00
83	12	N/A	N/A	N/A

90	0	0.00	0.00	0.00
90	4	537.44	568.00	510.00
90	12	N/A	N/A	N/A

9.3.4 XRD Peaks Analysis

This dissertation has shown how X-ray diffraction can be used to determine the heat flux, and hence the time, to which a gypsum sample was exposed. The X-ray diffraction has shown three distinct areas of peaks, which are outlined in Table 24 below.

This table breaks the XRD data down into the three regions, defined as follows:

H: hydrate: 2q =11-16 degrees.

HH: hemihydrate: 2q =28-33 degrees

A: anhydrous: 2q = 37-42 degrees

For each type of material, the data in the table shows the approximate height of any peaks which were in the corresponding degree ranges. Note: peak heights are very approximate, and not all peaks are registered here.

Table 24 XRD peaks analysis table, showing three crystalline forms

Type of material	Region à	Hydrate region (one range)	Hemihydrate region (two ranges)		Anhydrous region (two ranges)
	Degree rangeà	2q =11-16	2q = 28-30	2q = 30-33	2q = 37-40	2q = 40-42

H	Control	3200	2700	1300

HH	222 C	1800	2100	1800
HH	280 C	1800	2100	1800

HH, A	350 C	1900	2200	2100
HH, A	380 C		1000		600	600
HH, A	400 C		800	800

A	500 C			1200	700	700
A	600 C			1200	700	700
A	700 C			1300	900	800
A	800 C			2200	1300	1200
A	900 C			2200	1500	1200
A	1000 C			2500	1600	1600
A	1100 C			N/A	2000	1600
A	1200 C			2100	1600	1300