# Experimental Evaluation of Thermal Performance and Durability of Thermally-Enhanced Concretes
## 1 Introduction  
Global efforts are focusing on reducing the greenhouse gas emission since it causes the significant environmental and economic problems with climate change. Korean government has also decided to reduce greenhouse gas emissions by 37% from business-as-usual (BAU) level in 2015 to BAU level in 2030 and submitted the plan to the U.N. in August 2015 [1]. Korea recorded 18 barrels oil consumption per capita in 2014, which corresponded to the fifth largest consumption country in the world [2]. Although Korean government has tried to develop new energy business and innovative industrial sectors, one of the feasible solutions might be to decrease heating energy consumption by increasing the thermal insulation of houses and buildings, such as passive houses and zero-energy buildings, since the main energy consumption sectors in Korea shifted from industrial sectors to residual sectors. According to the report on the annual energy consumption in 2014 in Korea, the residual sectors are responsible for 27.6% of total energy consumption, which increased by 5.4% comparing to previous year [3]. The energy regulations for buildings and houses have been continuouslystrengthened to reduce the energy losses around the world. For example, Denmark has implemented the project for energy renovation, since heating energy occupied 40% of the total Danish energy consumption [4]. While an increase in the insulator thickness can improve the thermal insulation of buildings, it also increases construction cost and weight. Therefore, the development of advanced and lightweight insulation materials are currently underway to decrease the insulator thickness [5; 6]. Thermally insulated structural concrete including various materials have been recently studied and brought great attentions, as an alternative to reduce energy consumption and increase the heating efficiency of buildings and houses [7; 8]. [PERSON] et al. [9] investigated the thermal performance of concrete using recycled glass screed. [PERSON] et al. [10] gave an overview of the various kinds of phase change materials (PCMs) and possibilities for building applications. [PERSON] et al. [11] developed multi-scale composite models for PCM concrete to estimate the effective thermal conductivity. [PERSON] et al. [12] experimentally studied on the lightweight aggregate concrete using silica aerogel particles to increase the thermal insulating capacity. In addition, there are several researches relating to diatomic powder to try to improve mechanical properties of cement mortar and concrete, as a replacement of cement [13]. [PERSON] et al. [14] recently studied lightweight aggregate concrete to enhance energy efficiency in the field of building in Germany. Several available testing methods for thermal properties are proposed and adopted by ASTM and ISO. The measurement methods by means of guarded hot plate, contact hot wire, and thermal needle have been widely used to evaluate the thermal conductivity [15; 16; 17; 18; 19]. However, the evaluation or measurement of the exact thermal properties of new materials-incorporated concrete become more difficult and inaccurate as insulating materials in concrete are getting more diverse and irregular. To enhance the accuracy and credibility of thermal properties measurement, more than two methods should be conducted. Furthermore, to accurately evaluate the heat flows and the actual thermal properties of composite or hybrid components, hot box facilities are recommended [7]. Since thermally-enhanced concrete is usually mixed with diverse materials, the durability performance of the concrete should be verified under the harmful environmental conditions for its expected life [20; 21]. Considering the seasonal change of ambient temperature in Korea, the resistance on cyclic freeze-thaw should be verified. Also, there is a higher risk to the carbonation of the concrete, since atmospheric CO\({}_{2}\) concentration is increasing as increasing greenhouse gas emission.