Working Report 2012-14 Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples Urban Åkesson April 2012 POSIVA OY FI-27160 OLKILUOTO, FINLAND Tel +358-2-8372 31 Fax +358-2-8372 3709 Working Report 2012-14 Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples Urban Åkesson Swedish Cement and Concrete Research Institute April 2012 Working Reports contain information on work in progress or pending completion. Laboratory Measurements of the Coefficient of Thermal Expansion of Olkiluoto Drill Core Samples ABSTRACT The coefficient of thermal expansion and the wet density has been determined on 22 specimens from the ONKALO drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226, Olkiluoto, Finland. The coefficient of thermal expansion has been determined in the temperature interval 20-60 ºC. The results indicated that the thermal expansion was almost linear, and the coefficient of thermal expansion for the investigated specimens range between 3.2 and 14.4 x 10-6 mm/mm ÛC, and the wet density between 2,610 and 2,820 kg/m3. The granite pegmatite has slightly lower coefficient of thermal expansion and wet density than gneissic rocks. Keywords: Coefficient of thermal expansion, Olkiluoto, laboratory measurements, rock core samples, wet density. Kiven lämpölaajenemiskertoimen laboratoriomääritykset Olkiluodon kairasydännäytteistä TIIVISTELMÄ Kiven lämpölaajenemiskerroin ja märkätiheys on määritetty Olkiluodon 22 kairasydännäytteistä. Näytteet ovat ONKALOn tutkimusrei’istä ONK-PP167, ONKPP199, ONK-PP224, ONK-PP225 ja ONK-PP226. Lämpölaajenemiskerroin on määritetty lämpötilaväliltä 20 - 60 °C. Tulokset kertovat, että lämpölaajeneminen on lähes lineaarista ja lämpölaajenemiskerroin tutkituilla näytteillä vaihtelee välillä 3,2 – 14,4 x 10-6 mm/mm ÛC ja märkätiheys välillä 2610 2820 kg/m3. Pegmatiitti-graniiteilla on hieman alhaisempi lämpölaajenemiskerroin ja märkätiheys kuin gneisseillä. Avainsanat: Lämpölaajenemiskerroin, Olkiluoto, laboratoriomittaus, kairasydännäyte, märkätiheys 1 TABLE OF CONTENTS ABSTRACT TIIVISTELMÄ 1 INTRODUCTION ................................................................................................... 2 2 EQUIPMENT ......................................................................................................... 3 3 EXECUTION ......................................................................................................... 4 3.1 Description of the specimens ....................................................................... 4 3.2 Testing ......................................................................................................... 5 4 RESULTS .............................................................................................................. 6 4.1 Description of the specimens and presentation of the results ...................... 6 4.2 Summary of results .................................................................................... 29 REFERENCES ............................................................................................................. 31 2 1 INTRODUCTION The purpose of this report was to determine the coefficient of thermal expansion and the wet density of intact rock cores from the Olkiluoto drillcore samples. The testing comprised of 22 rock specimens from the ONKALO drillholes ONKPP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226. The locations of the drillholes are shown in Figure 1-1. The specimens were sampled by Posiva Oy, and sent to the Swedish Cement and Concrete Research Institute in Borås, Sweden who performed the test. Testing commenced in April 2010 and was completed in May 2010. ONK-PP167 ONK-PP199 ONK-PP224 ONK-PP225 ONK-PP226 -290 m -437 m Figure 1-1. The locations of the ONKALO drillholes for determination of thermal expansion coefficients. 3 2 EQUIPMENT The following equipment has been used for the laboratory measurements: x Extensometer (DEMEC inv no 102266) for measurement of the thermal expansion. The uncertainty of the extensometer is ± 3.97 x 10-6 mm/mm (strain), which equals an uncertainty of a single measurement of the coefficient of thermal expansion of ± 0.2 x 10-6 mm/mm oC for a temperature difference of 20 degrees C. x Reference bar in invar steel for calibrate the extensometer. x Heating chamber (inv no 102284) with an accuracy of ± 0.7 ºC at 80 ºC for heating up the specimens. x A covered plastic box filled with water for keeping the specimens water saturated. The equipment was same as used for SKB’s thermal expansion property measurements at Oskarshamn and Forsmark sites (see e.g. Åkesson 2007). 4 3 EXECUTION Determination of the coefficient of thermal expansion was made in accordance with SKB’s method description SKB MD 191.002-version 2.0 (SKB internal controlling document). The Swedish Cement and Concrete Research Institute performed the tests. 3.1 Description of the specimens The specimens from the drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONKPP225 and ONK-PP226 were sampled on various depths in the drillholes. Table 3-1 shows the identification mark, sampling level and rock type description of each specimen. Table 3-1. Identification mark, drillhole ID, sampling position and rock type of each specimen. Rock type abbreviations: VGN is veined gneiss, DGN is diatexitic gneiss and PGR pegmatitic granite. The veined gneisses are divided in two groups by the foliation angle; parallel (foliation 0) and perpendicular (foliation 90) to the core axis. Sample ID Drillhole ID Drillhole depth (m) Rock type code 3784 ONK-PP167 1.95-2.49 VGN (foliation 90) 3785 ONK-PP167 4.42-4.98 VGN (foliation 90) 3786 ONK-PP199 10.33-10.75 PGR 3787 ONK-PP199 47.45-48.03 PGR 3788 ONK-PP224 1.93-2.46 DGN 3789 ONK-PP224 3.64-4.15 DGN 3790 ONK-PP224 5.00-5.48 DGN 3791 ONK-PP224 7.42-8.07 PGR 3792 ONK-PP224 9.24-9.85 PGR 3793 ONK-PP224 13.39-13.75 VGN (foliation 0) 3794 ONK-PP224 16.75-17.3 VGN (foliation 0) 3795 ONK-PP224 27.97-28.50 VGN (foliation 0) 3796 ONK-PP225 0.83-1.46 DGN 3797 ONK-PP225 3.54-4.05 DGN 3798 ONK-PP225 4.70-5.26 DGN 3799 ONK-PP225 9.62-10.22 PGR 3800 ONK-PP225 19.26-19.72 VGN (foliation 0) 3801 ONK-PP225 19.72-20.18 VGN (foliation 0) 3802 ONK-PP225 29.00-29.56 PGR 3803 ONK-PP226 2.93-3.50 VGN (foliation 90) 3804 ONK-PP226 20.56-21.03 VGN (foliation 90) 3805 ONK-PP226 23.45-23.88 VGN (foliation 90) 5 3.2 Testing The execution procedure followed the prescription in SKB MD 191.002 and the following steps were performed: Item 1 2 3 4 5 6 Activity The specimens were cut according to the marks on the rock cores. Two measuring points with a distance of 200 mm were glued on the specimens. The specimens were photographed in JPEG format. The specimens were water saturated for seven days. The wet density was determined. The coefficient of thermal expansion was determined. The thermal expansion measured at 20, 40 and 60 ºC. On each temperature level was three to measurements done with 24 h intervals in order to know that the expansion completed for each temperature level. The coefficient of thermal expansion determined between 20-60 ºC. was five was was 6 4 RESULTS The results of the coefficient of thermal expansion and wet density determinations of core samples from the drillholes ONK-PP167, ONK-PP199, ONK-PP224, ONK-PP225 and ONK-PP226 are presented here. The temperature of the water used for the water saturation was 21.5 ºC and the density of the water was 997 kg/m3. The coefficient of thermal expansion was determined between +20- +60 ºC to cover the rock temperature range equivalent to the disposal process. 4.1 Description of the specimens and presentation of the results Specimen 3784 Thermalexpansion(mm/mm) 3784 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-1. Diagram showing the thermal expansion of specimen 3784 between 20 and 60 ºC, mean values plotted. Figure 4-1 shows a picture of the specimen 3784 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3784 was measured to be 13.2 x 10-6 mm/mm ºC and the specimen had a wet density of 2,780 kg/m3. 7 Specimen 3785 Thermalexpansion(mm/mm) 3785 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-2. Diagram showing the thermal expansion of specimen 3785 between 20 and 60 ºC, mean values plotted. Figure 4-2 shows a picture of the specimen 3785 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3785 was measured to be 8.4 x 10-6 mm/mm ºC and the specimen had a wet density of 2,720 kg/m3. 8 Specimen 3786 Thermalexpansion(mm/mm) 3786 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-3. Diagram showing the thermal expansion of specimen 3786 between 20 and 60 ºC, mean values plotted. Figure 4-3 shows a picture of the specimen 3786 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3786 was measured to be 3.2 x 10-6 mm/mmº C and the specimen had a wet density of 2,610 kg/m3. Clear non-linear behaviour was noticed in the results. 9 Specimen 3787 Thermalexpansionmm/mm 3787 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-4. Diagram showing the thermal expansion of specimen 3787 between 20 and 60 ºC, mean values plotted. Figure 4-4 shows a picture of the specimen 3787 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3787 was measured to be 7.8 x 10-6 mm/mm ºC and the specimen had a wet density of 2,650 kg/m3. 10 Specimen 3788 Thermalexpansionmm/mm 3788 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-5. Diagram showing the thermal expansion of specimen 3788 between 20 and 60 ºC, mean values plotted. Figure 4-5 shows a picture of the specimen 3788 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3788 was measured to be 8.3 x 10-6 mm/mm ºC and the specimen had a wet density of 2,690 kg/m3. 11 Specimen 3789 Thermalexpansionmm/mm 3789 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-6. Diagram showing the thermal expansion of specimen 3789 between 20 and 60 ºC, mean values plotted. Figure 4-6 shows a picture of the specimen 3789 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3789 was measured to be 8.7 x 10-6 mm/mm ºC and the specimen had a wet density of 2,720 kg/m3. 12 Specimen 3790 Thermalexpansionmm/mm 3790 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-7. Diagram showing the thermal expansion of specimen 3790 between 20 and 60 ºC, mean values plotted. Figure 4-7 shows a picture of the specimen 3790 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3790 was measured to be 8.6 x 10-6 mm/mm ºC and the specimen had a wet density of 2,710 kg/m3. 13 Specimen 3791 Thermalexpansionmm/mm 3791 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-8. Diagram showing the thermal expansion of specimen 3791 between 20 and 60 ºC, mean values plotted. Figure 4-8 shows a picture of the specimen 3791 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3791 was measured to be 8.3 x 10-6 mm/mm ºC and the specimen had a wet density of 2,640 kg/m3. 14 Specimen 3792 Thermalexpansionmm/mm 3792 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-9. Diagram showing the thermal expansion of specimen 3792 between 20 and 60 ºC, mean values plotted. Figure 4-9 shows a picture of the specimen 3792 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3792 was measured to be 10.8 x 10-6 mm/mm ºC and the specimen had a wet density of 2,630 kg/m3. Minor non-linear behaviour was noticed in the results. 15 Specimen 3793 Thermalexpansionmm/mm 3793 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-10. Diagram showing the thermal expansion of specimen 3793 between 20 and 60 ºC, mean values plotted. Figure 4-10 shows a picture of the specimen 3793 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3793 was measured to be 10.8 x 10-6 mm/mm ºC and the specimen had a wet density of 2,750 kg/m3. Minor non-linear behaviour was noticed in the results. 16 Specimen 3794 Thermalexpansionmm/mm 3794 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-11. Diagram showing the thermal expansion of specimen 3794 between 20 and 60 ºC, mean values plotted. Figure 4-11 shows a picture of the specimen 3794 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3794 was measured to be 14.4 x 10-6 mm/mm ºC and the specimen had a wet density of 2,790 kg/m3. Minor non-linear behaviour was noticed in the results. 17 Specimen 3795 Thermalexpansionmm/mm 3795 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-12. Diagram showing the thermal expansion of specimen 3795 between 20 and 60 ºC, mean values plotted. Figure 4-12 shows a picture of the specimen 3795 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3795 was measured to be 11.0 x 10-6 mm/mm ºC and the specimen had a wet density of 2,820 kg/m3. 18 Specimen 3796 Thermalexpansionmm/mm 3796 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-13. Diagram showing the thermal expansion of specimen 3796 between 20 and 60 ºC, mean values plotted. Figure 4-13 shows a picture of the specimen 3796 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3796 was measured to be 8.6 x 10-6 mm/mm ºC and the specimen had a wet density of 2,740 kg/m3. 19 Specimen 3797 Thermalexpansionmm/mm 3797 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-14. Diagram showing the thermal expansion of specimen 3797 between 20 and 60 ºC, mean values plotted. Figure 4-14 shows a picture of the specimen 3797 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3797 was measured to be 8.5 x 10-6 mm/mm ºC and the specimen had a wet density of 2,750 kg/m3. 20 Specimen 3798 Thermalexpansionmm/mm 3798 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-15. Diagram showing the thermal expansion of specimen 3798 between 20 and 60 ºC, mean values plotted. Figure 4-15 shows a picture of the specimen 3798 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3798 was measured to be 6.8 x 10-6 mm/mm ºC and the specimen had a wet density of 2,750 kg/m3. 21 Specimen 3799 Thermalexpansionmm/mm 3799 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-16. Diagram showing the thermal expansion of specimen 3799 between 20 and 60 ºC, mean values plotted. Figure 4-16 shows a picture of the specimen 3799 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3799 was measured to be 8.7 x 10-6 mm/mm ºC and the specimen had a wet density of 2,630 kg/m3. 22 Specimen 3800 Thermalexpansionmm/mm 3800 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-17. Diagram showing the thermal expansion of specimen 3800 between 20 and 60 ºC, mean values plotted. Figure 4-17 shows a picture of the specimen 3800 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3800 was measured to be 8.5 x 10-6 mm/mm ºC and the specimen had a wet density of 2,710 kg/m3. 23 Thermalexpansionmm/mm Specimen 3801 3801 0,00035 0,0003 0,00025 0,0002 0,00015 0,0001 0,00005 0 20 40 60 TemperatureC Figure 4-18. Diagram showing the thermal expansion of specimen 3801 between 20 and 60 ºC, mean values plotted. Figure 4-18 shows a picture of the specimen 3801 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3801 was measured to be 7.1 x 10-6 mm/mm ºC and the specimen had a wet density of 2,740 kg/m3. 24 Specimen 3802 Thermalexpansionmm/mm 3802 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-19. Diagram showing the thermal expansion of specimen 3802 between 20 and 60 ºC, mean values plotted. Figure 4-19 shows a picture of the specimen 3802 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3802 was measured to be 4.6 x 10-6 mm/mmº C and the specimen had a wet density of 2,620 kg/m3. Non-linear behaviour was noticed in the results. 25 Specimen 3803 Thermalexpansionmm/mm 3803 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-20. Diagram showing the thermal expansion of specimen 3803 between 20 and 60 ºC, mean values plotted. Figure 4-20 shows a picture of the specimen 3803 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3803 was measured to be 12.3 x 10-6 mm/mm ºC and the specimen had a wet density of 2,740 kg/m3. Non-linear behaviour was noticed in the results. 26 Specimen 3804 Thermalexpansionmm/mm 3804 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-21. Diagram showing the thermal expansion of specimen 3804 between 20 and 60 ºC, mean values plotted. Figure 4-21 shows a picture of the specimen 3804 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3804 was measured to be 9.5 x 10-6 mm/mm ºC and the specimen had a wet density of 2,750 kg/m3. 27 Specimen 3805 Thermalexpansionmm/mm 3805 0,0006 0,0005 0,0004 0,0003 0,0002 0,0001 0 20 40 60 TemperatureC Figure 4-22. Diagram showing the thermal expansion of specimen 3805 between 20 and 60 ºC, mean values plotted. Figure 4-22 shows a picture of the specimen 3805 and a diagram for the thermal expansion in the interval 20, 40 and 60 ºC. The coefficient of thermal expansion for specimen 3804 was measured to be 10.6 x 10-6 mm/mm ºC and the specimen had a wet density of 2,760 kg/m3. Minor non-linear behaviour was noticed in the results. 28 In order to investigate the non-linearity the specimen 3802 was remeasured. This time additional measuring points were glued on the specimen approximately at 120 degrees angles (see Figure 4-23). Figure 4-23. Photograph showing how the measuring points were placed on specimen 3802. The results of the measurements are shown in Figure 4-24, which indicates that the nonlinear phenomenon is partly due to bending of the drill core. The coefficients of thermal expansion for the measuring points were: 3802:1 5.0 x 10-6, 3802:2 4.8 x 10-6 and 3802:3 8.0 x 10-6 mm/mm ºC. 3802 0,0006 Thermalexpansionmm/mm 0,0005 0,0004 3802;1 0,0003 3802;2 0,0002 3802;3 0,0001 1,8EͲ18 20 40 60 Ͳ1EͲ04 Figure 4-24. Diagram showing the thermal expansion of specimen 3802 between 20 and 60 ºC, measured from three different sides of the specimen. Mean values are plotted. 29 4.2 Summary of results All the results are shown in Table 4-1 and Figure 4-25. Range of the coefficient of thermal expansion of all specimens is between 3.2 – 14.4 x 10-6 mm/mm qC with mean value being 9.0 x 10-6 mm/mm qC. Pegmatitic granite (range 3.2 – 10.8 x 10-6 with mean value of 7.2 x 10-6 mm/mm qC) has slightly lower values than gneissic rocks (range 7.1 – 14.4 x 10-6 with mean value of 9.7 mm/mm qC) (Figure 4-25). The foliation does not seem to affect the expansion properties, since the mean values are practically the same; VGN perpendicular foliation 10.8 x 10-6 mm/mm qC vs. VGN parallel foliation 10.4 x 10-6 mm/mm qC. The results are also in good agreement with the results presented in Huotari & Kukkonen (2004). They concluded that the linear thermal expansion coefficient of the Olkiluoto gneiss is 7-10 (10-6/°C) in the temperatures between 20-60 °C and this study states the value for gneissic rocks are 7-14 (10-6/°C). Table 4-1. Summary of the results for the coefficient of thermal expansion (mean values) and wet density of the tested specimens. Rock type abbreviations: VGN is veined gneiss, DGN is diatexitic gneiss and PGR pegmatitic granite. The veined gneisses are divided in two groups by the foliation angle; parallel (foliation 0) and perpendicular (foliation 90) to core axis. Drillhole ID Specimen Rock type code ONK-PP167 ONK-PP167 ONK-PP199 ONK-PP199 ONK-PP224 ONK-PP224 ONK-PP224 ONK-PP224 ONK-PP224 ONK-PP224 ONK-PP224 ONK-PP224 ONK-PP225 ONK-PP225 ONK-PP225 ONK-PP225 ONK-PP225 ONK-PP225 ONK-PP225 ONK-PP226 ONK-PP226 ONK-PP226 3784 3785 3786 3787 3788 3789 3790 3791 3792 3793 3794 3795 3796 3797 3798 3799 3800 3801 3802 3803 3804 3805 VGN (foliation 90) VGN (foliation 90) PGR PGR DGN DGN DGN PGR PGR VGN (foliation 0) VGN (foliation 0) VGN (foliation 0) DGN DGN DGN PGR VGN (foliation 0) VGN (foliation 0) PGR VGN (foliation 90) VGN (foliation 90) VGN (foliation 90) Coefficient of thermal expansion between 20 and 60 ºC (mm/mmºC) 13.2 x 10-6 8.4 x 10-6 3.2 x 10-6 7.8 x 10-6 8.3 x 10-6 8.7 x 10-6 8.6 x 10-6 8.3 x 10-6 10.8 x 10-6 10.8 x 10-6 14.4 x 10-6 11.0 x 10-6 8.6 x 10-6 8.5 x 10-6 6.8 x 10-6 8.7 x 10-6 8.5 x 10-6 7.1 x 10-6 4.6 x 10-6 12.3 x 10-6 9.5 x 10-6 10.6 x 10-6 Wet density (kg/m3) 2,780 2,720 2,610 2,650 2,690 2,720 2,710 2,640 2,630 2,750 2,790 2,820 2,740 2,750 2,750 2,630 2,710 2,740 2,620 2,740 2,750 2,760 30 The wet density of gneissic rocks 2,745 kg/m3 (mean value) is higher than for pegmatitic granite 2,630 kg/m3 (mean value). 2,850 2,800 Wetdensity(kg/m3) VGNfol90° PGR 2,750 DGN VGNfol0° 2,700 2,650 2,600 2,550 0,00E+00 2,00EͲ06 4,00EͲ06 6,00EͲ06 8,00EͲ06 1,00EͲ05 1,20EͲ05 1,40EͲ05 1,60EͲ05 Coefficientofthermalexpansionbetween20and60qC(mm/mmqC) Figure 4-25. The results for the coefficient of thermal expansion (mean values) and wet density of the tested specimens. 31 REFERENCES Huotari, T. & Kukkonen I. 2004. Thermal expansion properties of rocks: Literature survey and estimation of thermal expansion coefficient for Olkiluoto mica gneiss. Posiva Oy, Working Report 2004-04. Åkesson, U. 2007. Forsmark site investigation, Boreholes KFM05A and KFM06A, Extensometer measurement of the coefficient of thermal expansion of rock. SKB Report P-07-33.