**Preparation and Numerical Modelling of Ceramic Foam Insulation for Energy Saving in Buildings Insulation for Energy Saving in Buildings**

**Preparation and Numerical Modelling of Ceramic Foam** 

DOI: 10.5772/intechopen.71393

Ru Ji, Xidong Wang and Yang He Additional information is available at the end of the chapter

Ru Ji, Xidong Wang and Yang He

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.71393

#### **Abstract**

For the purpose of energy saving in buildings, a foam ceramic insulation (FCI) was prepared by using fly ash (FA) and ceramic waste (CW) as the main raw materials for its matrix part and foam part, respectively. The effects of the sintering temperature and the additive agent on the macroscopic performances were systematically measured and investigated. The experiment results indicate that for the matrix sample 5% quartz addition makes the rupture modulus at 1200°C reach high to 34.28 MPa, while the corresponding water absorption capacity is only 0.83%. In addition, for the foam sample with 1 wt% silicon carbide, the lowest measured bulk density and thermal conductivity at 1200°C are 0.471 g/cm3 and 0.1184 W/(m•K), respectively. Furthermore, the proposed simulation model predicts that the effective thermal conductivity of FCI decreases with the decrease of the bulk density. Moreover, the simulation results calculated by EnergyPlus software indicate that the synthetic FCI can efficiently reduce the building's heating and cooling loads and exerts excellent energy conservation effect.

**Keywords:** ceramic foam insulation, solid waste, numerical modelling, thermal conductivity, energy saving in buildings

## **1. Introduction**

It is well known that as the society and economy is developing at a high rate, about 35% of the total energy is consumed by buildings [1–4]. For the sake of energy saving in buildings, all over the world, there are many different concepts of energy-efficient buildings, such as passive houses, near-zero-energy buildings, and even active houses [5]. According to the requirements of these houses' design, the energy use in these buildings needs to be strictly reduced to a very certain small range. Therefore, an appropriate thermal insulation material is necessary to

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

realise the energy saving in buildings [6]. As ceramic foam insulation (CFI) is one of the notable methods to reduce the energy use in buildings, it has been widely developed in recent years.

FA, clay, feldspar, and quartz, which were all driven from the same region in China. Secondly, the foam raw materials included CW and other additives. Here, CW was used as a main raw material and SiC was applied as a foaming agent. The chemical characteristics of the main raw materials were measured by X-ray fluorescence (XRF) scan and are shown in **Table 1**. It can be

and Al<sup>2</sup>

O and Na2

. Moreover, for CW, the main structure is quartz.

the total proportion of 81.87, 71.53, 86.10, 95.77 and 84.01 wt%. It is interesting to note that for

In addition, the crystalline phases of the raw materials are determined by X-ray diffraction (XRD) (D/MAX-PC 2500, Rigaku), and the XRD patterns are presented in **Figure 1**. It can be seen that FA is a heterogeneous material. Firstly, the major crystalline phases of FA are quartz and mullite with a small amount of gypsum. Secondly, it is interesting to note that parts of FA belong to the amorphous phase due to the observed low and broad diffraction bands in the

In this research, for the matrix part, 50 wt% FA will be used as the main raw material in all batches. While, for the foam part, only CW will be utilised as the raw material with only 1% SiC. In this study, according to the previous work, the detailed steps of the preparation are

Firstly, all raw materials were thoroughly mixed and milled in the proportion as shown in **Table 2**. Here, quartz content in the batches 1–5 varied from 0 to 20 wt%. Then, mixtures were wet ground in two ball mills for 15 h to obtain the homogeneous slurries. The slurries were sieved to pass through a 200-mesh screen and dried at 110°C for 12 h. Subsequently, the two mixtures were granulated in a moist condition and samples were hydraulically compacted using uniaxial pressing at 10 MPa. Finally, the shaped samples were dried at 105°C for 3 h, followed by calcination in a muffle furnace at the preset sintering temperature, and the sintered

For the matrix part, the obtained samples were measured for moisture absorption (MA)

**O CaO Fe2**

**O3 K2**

**O Na2**

Fly ash 41.97 39.90 0.50 0.20 6.41 1.96 0.60 1.20 3.15 3.64 Clay 34.96 36.57 0.39 0.09 0.49 0.82 0.22 1.47 — 24.38 Feldspar 68.60 17.50 7.74 3.98 0.53 0.41 0.17 0.04 — 0.83 Quartz 91.30 4.47 1.76 1.19 0.42 0.17 0.15 0.01 — 0.44 Ceramic waste 65.18 18.83 1.61 4.10 1.61 0.45 3.22 0.21 — 4.13

O3

O are high: 11.72 wt%.

Preparation and Numerical Modelling of Ceramic Foam Insulation for Energy Saving in Buildings

possess the dominating proportions with

http://dx.doi.org/10.5772/intechopen.71393

131

**O3 MgO TiO2 S LOI**

seen that for all main raw materials, SiO2

feldspar the total contents of K<sup>2</sup>

range of 20–30o

**2.2. Preparation**

shown as follows.

samples were cooled naturally.

capacity and rupture modulus.

**Content (wt%) SiO2 Al2**

**Table 1.** Chemical composition of main raw materials.

**2.3. Characterisation**

As we all know, the building insulation materials are generally sorted into two groups, organic insulation materials and inorganic insulation materials. Organic insulation materials, such as polystyrene foam, often lead to a series of problems related to combustion, environmental toxicity, and adhesive incompatibility with cement and ceramic structures. In addition, organic insulation materials usually exert short working life, for instance, foam plastic only can ensure the required heat resistance in about 8 years. However, inorganic materials, such as CFI, are excellent building insulation materials, which have many advantages compared with other thermal insulation materials, including chemically inactive, noncombustible, low moisture absorption, chemically stable, long-time stable in physical properties, environmental friendly, and long use life [7]. For the above reasons, this study is motivated to propose a novel FCI for saving energy in buildings.

On the other hand, according to the investigation in literature, it is known to us that the traditional manufacture of ceramic materials often requires massive amount of natural raw materials, such as clay and feldspar [8–10]. However, recently, taking into consideration the big challenges in environmental protection and energy saving, nontraditional raw materials are needed in the synthesis process of the ceramic materials. Therefore, the development of innovative ceramic materials by using huge amounts of alternative raw materials, especially solid waste, will be important to the environmental protection.

Hence, in this research, according to our previous work [11–13], two solid wastes were applied as the main raw materials for the synthesis of FCI. Firstly, fly ash (FA), a by-product of thermal generation in coal power stations, is used as the main raw material in the matrix part of the FCI [14]. According to the statistics, more than 750 million tonnes of FA are generated each year, but only less than 50% of FA is utilised. In China, the annual output of FA reached almost 600 million tonnes, which results in very serious environmental pollution, such as groundwater contamination [15–17]. Secondly, the reclaimed waste is the ceramic waste (CW). Statistics show that in the ceramic industry about 30% of the daily production will turn into solid waste. As we all know, CW is not recycled in any form at present [18]. Therefore, both solid wastes will cause serious environmental pollution [19–20]. So it is necessary to develop an effective way to recycle FA and CW.

Based on the previous work of our research [11–13], we are therefore motivated to prepare FCI by using FA and CW as the main raw materials. Moreover, since the study of heat transfer behaviour of FCI and its energy-saving function in buildings was important to guide the synthesis process of FCI, in this study, the foaming behaviour, the thermal conductivity, and its energysaving function were investigated experimentally and were modelled by simulative method.
