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  1. HIGH-PERFORMANCE AEROGEL CONCRETE Guided By: Dr. Anupama Krishna D Assistant Professor, Department of Civil Engineering, MBCET, Trivandrum Presented By: Savinaj V Santhosh Roll Number: 53 CE – 2 ; Semester – 7 MBCET, Trivandrum MBCET 05/12/2022 01/48
  3. ➢ Requirements for the thermal insulation of residential and non- residential buildings have led to a number of developments in the field of building materials for massive outer walls. ➢ For thermal insulation it requires building materials with low thermal conductivity and high compressive strength. ➢ Most of the masonry blocks or concrete show either a low thermal conductivity with low compression strength or vice versa. ➢ Preferred Lightweight Aggregate Concrete (LWAC) over all other building materials for insulation. INTRODUCTION MBCET 05/12/2022 03/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  4. INTRODUCTION (Contd..) MBCET 05/12/2022 04/48 HIGH-PERFORMANCE AEROGEL CONCRETE Materials ρ (kg/m³) fk / fck (MPa) λ (W/(mK)) Light-weight Concrete Block 315-335 0.8 0.06 Aerated Cement Block 250 0.8 0.07 Proton Brick 810-900 4.2 0.09 Aerated Cement Block 400 1.8 0.10 Light-weight Concrete Block 600 2.5 0.14 Proton Plane Brick 710-800 4.7 0.16 Sand-lime Brick Silica 1210-1400 5.6 0.56-0.70 Light-weight Aggregate Concrete 1500-1600 35.0 0.89-1.00 Sand-lime Brick Silk 1810-2000 10.5 0.99-1.10 Normal weight Concrete 2200-2400 12.0 1.65-2.0 Reinforced Concrete 2300-2400 30.0 2.3-2.5 Table 1: Bulk Density, Compressive Strength and Thermal Conductivity of selected Wall Building materials. [1]
  5. INTRODUCTION ➢ Still LWAC had low thermal conductivity and comparatively low compressive strength. ➢ High-performance concrete (HPC) is concrete are stronger than LWAC. It has high compressive strength of above 80 MPa. ➢ But one of the major demerit of these concrete is its high thermal conductivity. ➢ The thermal conductivity can be reduced by introducing silica aerogels into high performance concrete mix instead of aggregates known as High- Performance Aerogel Concrete (HPAC) and thereby increasing its compressive strength. 05/12/2022 05/48 MBCET HIGH-PERFORMANCE AEROGEL CONCRETE INTRODUCTION (Contd..)
  6. OBJECTIVES ➢ By the development of High-Performance Aerogel Concrete the aim is to develop a building material, which has low bulk density, low thermal conductivity and higher compressive strength compared to LWAC. ➢ HPAC makes it suitable for the construction of single-leaf exterior walls of multi-storey buildings without any further thermal insulation. MBCET 05/12/2022 06/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  7. WHAT IS HPAC ? ➢ Prepared by embedding silica aerogel granules in a high strength cement matrix. ➢ HPAC is extremely water repellent and protects from moisture damage corrosion. ➢ HPAC is a High Thermal Insulating material with High Compressive Strength. ➢ HPAC retains its shape in high-temperature exposure and does not crack, clump, or sag like other insulating materials. ➢ The thermal conductivities are in the range 0.16 ≤ λ ≤ 0.37 W/(mK). ➢ The compressive strength is about 60 MPa, further could be increased by providing reinforcement for about 80 MPa or greater. MBCET Fig 1: Microstructure of HPAC. [1] 05/12/2022 07/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  8. MATERIALS USED IN HPAC 1.SILICA AEROGEL 2.HIGH PERFORMANCE CONCRETE 1. SILICA AEROGEL ➢ Created by SAMUEL STEPHENS KISTLER. ➢ Also called blue or frozen smoke. ➢ Traditional thermal insulating building material. ➢ Nano-porous material with remarkable properties: 1. High specific surface area (500–1200 m2/g). 2. High porosity (80–99.8%). 3. Low density (0.003 g/cm3). 4. Ultra-low dielectric constant (k = 1.0–2.0). 5. High thermal insulation value (0.005 W/(mK)). 6. Low index of refraction (1.05). Fig 2: Silica Aerogel. (Source: MBCET 05/12/2022 08/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  9. MATERIALS USED IN HPAC (Contd..) Synthesis of Silica Aerogel The synthesis of silica aerogels can be divided into 3 general steps: a. Gel Preparation b. Aging of Gel c. Drying of Gel Fig 3: Synthesis of Silica Aerogel.[3] MBCET 05/12/2022 09/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  10. 2. HIGH PERFORMANCE CONCRETE ➢ HPC possesses high workability, high strength and high durability. ➢ Gives excellent performance in the structure in which it will be placed. ➢ Compressive strength > 80 MPa. ➢ Main characteristic properties are: 1. Low porosity. 2. It has very low permeability. 3. High resistance to chemical attack. 4. Low heat of hydration. 5. High early strength. 6. Low Bleeding. MATERIALS USED IN HPAC (Contd..) MBCET 05/12/2022 10/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  11. MIXTURES FOR HPAC ➢ Silica Aerogel granules used : - amount varies from 45 to 70 %. - particle size from 0.01 mm to 4.0 mm. - a thermal conductivity of ≤0.02 W/(mK). - porosity > 90%. ➢ Flow behaviour is adjusted by the amount of superplasticizers used (e.g., sulphonated melamine formaldehyde (SMF), sulphonated naphthalene formaldehyde (SNF) etc.) Portland Cement kg/m3 541.0 Silica Aerogel Granule vol% 61.4 Silica Suspension wt% * 13.0 Superplasticizer wt%* 3.6 Organic Stabilizer wt%* 0.5 w/c based on the amount of - - the cement used. MBCET Table 2: Reference mixture of HPAC. [4] 05/12/2022 11/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  12. 01 02 03 04 Add water-silica mixture, water-plasticizer mixture and the stabilizer After restarting the mixing, add the remaining water and continuing to mix Add the inorganic binder during a suspension of mixing Mixing aerogel and any lightweight aggregates MIXTURES FOR HPAC (Contd..) MBCET 05/12/2022 12/48 HIGH-PERFORMANCE AEROGEL CONCRETE Fig 4: Preparation of HPAC. (Source:
  13. PROPERTIES OF HPAC 1. Dry Bulk Density ▪ Due to the absence of sand and coarse aggregate the solid content of HPAC is reduced resulting in lower dry bulk density. MBCET Fig 5: Relation between the Aerogel amount and the Dry Bulk Density of High-Performance Aerogel Concrete compared to Aerogel Concrete. [4] 05/12/2022 13/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  14. 2. Compressive Strength ▪ Performed using Universal Testing Machine with constant load speed set to 9 kN/s. ▪ Compressive strength of HPAC was higher than 600 kg/m3, which is equal to 60 MPa. ▪ Compressive strength of HPAC is higher than that of the Aerogel Concrete. PROPERTIES OF HPAC (Contd..) MBCET Fig 6: Relation between Dry Bulk Density and Compressive Strength of HPAC compared to Aerogel Concrete. [4] 05/12/2022 14/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  15. 3. Flexural Tensile Strength ▪ Flexural tensile strength of HPAC was determined for eight mixtures with an amount of aerogel granule between 45% to 70% volume. ▪ Four-point bending tests performed on the samples with dimensions: 700mm x 150 mmx150 mm. ▪ Flexural tensile strength of HPAC is slightly lower than that of LWAC. PROPERTIES OF HPAC (Contd..) MBCET Fig 7: Four-point bending test (Source: 05/12/2022 15/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  16. 3. Flexural Tensile Strength (Contd..) PROPERTIES OF HPAC (Contd..) MBCET Fig 8: Relation between Compressive Strength and Tensile Strength of HPAC in comparison to Lightweight Aggregate Concrete.[4] 05/12/2022 16/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  17. 4. Young’s Modulus ▪ Standard cylinders with dimensions of 150mm x 300mm are used to determine the Young’s Modulus of the mixtures. ▪ Young’s modulus of HPAC is slightly lower than that of LWAC. PROPERTIES OF HPAC (Contd..) MBCET Fig 9: Relation between the Compression Strength and Young’s Modulus in comparison to Lightweight Aggregate Concrete.[4] 05/12/2022 17/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  18. 5. Thermal Conductivity ▪ Thermal conductivity is determined using the Heat Flow Meter Method. ▪ 14 days after concreting cubes with an edge length of 150 mm were cut into slices of 30 mm thickness and stored in a drying cabinet at 100°C for 24 hrs before testing. ▪ Thermal conductivity of HPAC is very much lower compared to Aerogel concrete. PROPERTIES OF HPAC (Contd..) MBCET 05/12/2022 18/48 HIGH-PERFORMANCE AEROGEL CONCRETE Fig 10: Heat Flow Meter Method (Source:
  19. 5. Thermal Conductivity (Contd..) PROPERTIES OF HPAC (Contd..) MBCET Fig 11: Relation between Compressive Strength and Thermal Conductivity of HPAC compared to Aerogel concrete. [4] 05/12/2022 19/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  20. ADVANCEMENTS IN HPAC ➢REINFORCED HPAC ▪ The comparatively low flexural tensile strength of HPAC result in the need for reinforcement if HPAC is intended to use for construction members subjected to bending. ▪ GFRP reinforcement bars were used in order to avoid negative effects on the thermal conductivity of HPAC and problems resulting from different thermal expansion coefficients which may be caused by steel reinforcement. Fig 12: Test Set Up for the Pull-Out tests.[6] 05/12/2022 20/48 HIGH-PERFORMANCE AEROGEL CONCRETE MBCET
  21. ➢GRADED HPAC ▪ Thermal insulating properties of HPAC is achieved by the realization of graded HPAC members. ▪ It consists of: i) load carrying layer with a high compression strength. ii) an insulating layer with a low thermal conductivity ▪ The bond strength or shear strength, respectively, and the adhesive tensile strength is very much higher. MBCET ADVANCEMENTS IN HPAC (Contd..) Fig 13: Graded HPAC. Above: heat-insulating layer, Below: load carrying layer.[6] 05/12/2022 21/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  22. ➢3D PRINTABLE AEREOGEL CONCRETE ▪ Aerogel incorporated concrete is suitable for 3D printing. ▪ The optimal replacement range for sand by silica aerogel in a cementitious mixture was about 0% – 20% by volume. ▪ The thermal conductivity of the cast and printed specimens decreased gradually with an increase in the aerogel content. MBCET ADVANCEMENTS IN HPAC (Contd..) Fig 14: 3D Printed Aerogel Concrete.[6] 05/12/2022 22/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  25. INTRODUCTION ➢ Tunnel fire that occurred during the past decades increased the interest in structural fire safety of large underground facilities and have highlighted the importance of increasing the fire resistance in materials and structural design of tunnels. ➢ During tunnel fires HPC results in explosive spalling, causing devastating damage of the tunnel structure, which threatens both, civilians and emergency response units. ➢ Solution to this problem is to make use of a highly-insulating layer. MBCET 05/12/2022 25/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  26. OBJECTIVE OF THE STUDY ➢ Aim of making use of highly-insulating layer to delay the heating of the HPC and extending the performance of the main concrete structure of the tunnel under fire. ➢ Uses silica aerogel in the protection of concrete linings by coating with a layer of High-Performance Aerogel Concrete. MBCET 05/12/2022 26/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  27. EXPERIMENTAL INVESTIGATION ➢THERMAL CONDUCTIVITY ▪ Small cylindrical aerogel-cement mortar samples (ϕ 60 mm × 15 mm) were measured on a custom-built guarded hot plate device with guarded zone: 50 × 50 mm2, measuring zone: 25 × 25 mm2 having a 15°C temperature difference, which was originally designed for small samples of low thermal conductivity materials. MBCET 05/12/2022 27/48 HIGH-PERFORMANCE AEROGEL CONCRETE Fig 15: Guarded Hot Plate Device (Source:
  28. INFERENCE: For avoiding or delaying the explosive spalling of HPC tunnel linings, the thermal conductivity of the aerogel mortars used is the essential parameter to be controlled.. ● without aerogels-thermal conductivity 1.7 W/(mK), ● With the addition 33% in volume of silica aerogels, thermal conductivity was about 0.4 W/(mK) With increasing amounts of aerogels in the mortar, proportionally smaller decrease of thermal conductivity is observed. MBCET EXPERIMENTAL INVESTIGATION (Contd..) 05/12/2022 28/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  29. ➢EVALUATION OF EXPLOSIVE SPALLING ▪ Thermal loading was performed from one side of the specimens (corresponding to the side coated with aerogel mortar and uncoated HPC) using a heating plate. ▪ The heating process started from room temperature and the temperature of the plate was increased uniformly up to a maximum temperature of 600 °C within about 40 min. ▪ The maximum temperature was kept for 2h, followed by free cooling down on the heating plate in ambient air. MBCET EXPERIMENTAL INVESTIGATION (Contd..) 05/12/2022 29/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  30. EXPERIMENTAL INVESTIGATION (Contd..) MBCET Fig 16: Modelling method of Tunnel and Lining.[7] Fig 17: Design method of Silica Aerogel Coating.[7] 05/12/2022 30/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  31. INFERENCE: ● The HPC cube without aerogel protection spalled after 25 min of thermal loading, confirming the susceptibility of HPC to explosive spalling when exposed to high temperatures . ● In the case of the HPC samples protected by a aerogel layer, explosive spalling occurred later on samples with thinner mortar layer at 68 and 148 min after the start of loading. ● On samples with thicker layers, spalling did not occur during the testing period. MBCET EXPERIMENTAL INVESTIGATION (Contd..) 05/12/2022 31/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  32. CONCLUSION OF THE STUDY ➢ In this study, a strategy for protecting tunnel shield high performance concrete (HPC) from explosive spalling was suggested, consisting in coating the surface with High-Performance Aerogel Concrete of low thermal conductivity. ➢ In a series of preliminary tests, layers of 40–50 mm of such aerogel mortars were able to prevent fire spalling of high-performance concrete cubes. MBCET 05/12/2022 32/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  33. CASE STUDY 2 10/30/2022 STUDY ON THE THERMAL PERFORMANCE OF EXTERIOR WALLS COVERED WITH SILICA-AEROGEL-BASED INSULATING COATING. ▪ Domestic Buildings in Switzerland. ▪ Buildings in cities of Basel and Zurich. (Authors: Mohamad Ibrahim, Pascal Henry Biwole and Etienne Wurtz) MBCET 05/12/2022 33/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  34. INTRODUCTION ➢ The building's external fabric is in continuous interaction with the outside environment. ➢ The outside surface temperature of the walls/roof is greatly affected by the outer air temperature and solar radiation leading to fluctuations in the heat flux passing through them to the inside. ➢ The lower the energy consumption, the better is the wall. ➢ Solution to this problem is make use of an insulating layer with low thermal conductivity. MBCET 05/12/2022 34/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  35. OBJECTIVE OF THE STUDY ➢ Aims at examining the energy behaviour of the buildings multi-layer exterior wall structures. ➢ To find the best wall structure and best position of insulation layers within exterior walls for continuous heating, intermittent heating, and no heating operation modes using HPAC. MBCET Fig 18: Silica-Aerogel-Based Coating.[9] 05/12/2022 35/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  36. EXPERIMENTAL INVESTIGATION ➢ Done on test-cell of a small-scale building composed of three cells (current test cell, adjacent cell, and acquisition cell). ➢ The test-cell is composed of two external walls having orientations south and east, and two internal walls (partitions with the other cells). ➢ The volume of the test cell is 30 m3. ➢ The south wall is taken as the test wall, composed of concrete (external layer), glass wool & plaster. ➢ Then, added a 4 cm layer of the HPAC coating on its external surface. MBCET Fig 19: Test Cell (and Adjacent Cells) [9] 05/12/2022 36/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  37. Material Thickness (cm) Thermal conductivity (W/(mK)) Specific heat (J/(kg.K)) Density (kg/m3) Plaster (inside layer) 1.3 0.32 800 790 Glass wool 16 0.041 840 12 Concrete 5 2.1 800 2400 Aerogel coating 4 0.027 1100 200 EXPERIMENTAL INVESTIGATION (Contd..) Table 3: Thermo-Physical properties for South Wall construction materials in the Test Cell. [9] MBCET 05/12/2022 37/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  38. ➢ Temperatures are measured using K-type Thermo-couples with a precision of ±0.3 C. ➢ They are placed: i) at the exterior surface of the coating, ii) at the interface between the coating and the concrete, iii) at the interface between concrete and internal insulation (glass wool), and iv) at the interior surface of the plaster layer. EXPERIMENTAL INVESTIGATION (Contd..) MBCET Fig 20: Temperature Sensors Within the South Wall.[9] 05/12/2022 38/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  39. INFERENCE ➢ Placing the insulation at the middle of the wall and at the interior surface provides the best performance. ➢ Placing the insulation at the interior wall surface is the best solution when considering the discomfort hours during the occupied period. ➢ Exterior insulation is the worst of all cases when considering the discomfort hours during the occupied period. MBCET 05/12/2022 39/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  40. MBCET CONCLUSION OF THE STUDY In this study, a strategy for understanding which layer of the wall would provide better insulation while coating with High-Performance Aerogel Concrete was undertaken. Results revealed that placing the insulation at the interior wall surface is the best solution. 05/12/2022 40/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  41. ADVANTAGES OF HPAC ➢ Low Thermal Conductivity. ➢ High Stability of Aerogel in Concrete. ➢ Highly Durable. ➢ Low Density. ➢ Light Weight. ➢ High Frost Resistance. ➢ Energy Efficient. ADVANTAGES AND LIMITATIONS OF HPAC MBCET 05/12/2022 41/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  42. LIMITATIONS OF HPAC ➢ Highly Expensive ➢ Low Modulus of Elasticity ➢ High Tendency to Shrink. ➢ Low Bond Stress compared to HPC. ➢ Requirement of reinforcement. MBCET 05/12/2022 42/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  43. CONCLUSION ➢ HPAC shows an improved correlation between dry bulk density and compressive strength as well as compressive strength and thermal conductivity. ➢ HPAC shows an improved performance over the full spectrum of investigated compressive strength in the range 25MPa ≤ fcm ≤ 60MPa. ➢ Due to low flexural and tensile strength of HPAC, reinforcement is required if HPAC is intended to be use for construction members subjected to bending. ➢ HPAC can be used to avoid exposure spalling during tunnel fires. ➢ Layer of 40-50 mm of silica aerogel were able to prevent fire spalling. MBCET 05/12/2022 43/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  44. ➢ Lower thermal conductivity, high sound absorption and high fire resistance of HPAC allows the production of load-carrying, single-leaf exterior walls without any further thermal insulation. ➢ HPAC with 50 vol% aerogel content showed the sound absorption capacity of µ = 0.309, which was about 38 % better than normal-weight concrete. ➢ The HPAC achieved a thermal conductivity of λ = 0.26 that is approx. 25.7 % lower as the LWAC’s thermal conductivity by the same density. ➢ The modulus of elasticity of HPAC with 50 vol% aerogel content was about 8000-10,000 MPa and is comparable to LWAC with the same bulk density. MBCET CONCLUSION (Contd..) 05/12/2022 44/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  45. REFERENCES [1] Fickler, S., Milow, B., Ratke, L., Schnellenbach-Held, M. and Welsch, T. (2015), “Development of High-Performance Aerogel Concrete”, Energy Procedia 78, 406-411. [2] Shah, S. N., Mo, H. K., Yap, S.P. and Radwan, M., K.H. (2021), “Towards an Energy Efficient Cement Composite Incorporating Silica Aerogel: A State-of- the-Art Review”, Journal of Building Engineering 44, 103227. [3] Lamy-Mendes, A., Pontinha, A. D. R., Alves, P., Santos, P. and Duraes, L. (2021), “Progress in Silica Aerogel-Containing Materials for Building’s Thermal Insulation”, Construction and Building Materials 286, 122815. MBCET 05/12/2022 45/48 HIGH-PERFORMANCE AEROGEL CONCRETE
  46. [4] Welsch, T. and Schnellenbach-Held, M. (2018), “High Performance Aerogel Concrete”, High Tech Concrete: Where Technology and Engineering Meet, 117-124. [5] Wang, Y., Huang, J., Wang, D., Liu, Y., Zhao, Z. and Liu, J. (2019), “Experimental Investigation on Thermal Conductivity of Aerogel Incorporated Concrete Under Various Hygrothermal Environment”, Energy Procedia 188, 115999. [6] Schnellenbach-Held, M. and Welsch, T. (2016), “Advancements in High Performance Aerogel Concrete”, Structural Engineering, Mechanics and Computation, 1577-1582. MBCET 05/12/2022 46/48 HIGH-PERFORMANCE AEROGEL CONCRETE REFERENCES (Contd..)
  47. [7] Liu, S., Zhu, P. and Li, X. (2020), “Design Approach for Improving Fire- Resistance Performance of Tunnel Lining Based on SiO2 Aerogel Coating”, Journal of Performance of Constructed Facilities 34 (3), 0402003. [8] Zhu, P., Brunner, S., Zhao, S., Griffa, M., Leemann, A., Toropovs, N., Lura, P., Malekos, A. and Koebel, M. M. (2019), “Study of Physical Properties and Microstructure of Aerogel Cement Mortars for Improving the Fire Safety of High-Performance Concrete Linings in Tunnels”, Cement and Concrete Composites 104, 103414. [9] Ibrahim, M., Biwole, H. P., Wurtz, E. and Achard, P. (2014), “A Study on the Thermal Performance of Exterior Walla Covered with Silica-Aerogel-Based Insulating Coating”, Building and Environment 81, 112-122. MBCET 05/12/2022 47/48 HIGH-PERFORMANCE AEROGEL CONCRETE REFERENCES (Contd..)