scholarly journals Moisture behavior of external insulated precast concrete wall panels

2020 ◽  
pp. 174425912092585
Author(s):  
Pauli Sekki ◽  
Timo Karvinen ◽  
Juha Vinha
Keyword(s):  
Relative Humidity ◽  
Precast Concrete ◽  
Concrete Surface ◽  
Mineral Wool ◽  
Insulation Material ◽  
Concrete Wall ◽  
Building Stock ◽  
Interior Surface ◽  
Insulation Materials ◽  
Wall Panels

Excess moisture in concrete structures is a major problem in building industry. It is claimed that degradation of the finishing materials of concrete slabs is the largest source of volatile organic compound in the building stock in the Nordic countries. Considering concrete wall panels, the choice of the insulation material influences concrete drying considerably and causes a risk for moisture accumulation on the interior surface, if vapor tight finishing materials are used or if finishing materials are installed prematurely. Mineral wool insulation, which has predominately been used in Finland, is a vapor open material. However, vapor tight plastic foam insulation materials are nowadays more commonplace. Here we show that the overall rate of drying of the concrete panel with a vapor open insulation material is higher in comparison to the concrete panel with vapor tight insulation materials. However, relative humidity distribution near the inner surface of the concrete panel at the end of the drying phase is almost identical irrespective of the insulation material and the water vapor resistance of the interior surface material has a greater impact on the relative humidity level on the inner concrete surface. Moisture behavior of concrete panel walls is studied under a certain building schedule in Finnish environment and building conditions by numerical simulation. The model for drying of concrete is calibrated based on laboratory measurements. According to our study, self-desiccation and changing diffusivity due to the hydration process of the concrete cannot be ignored when evaluating the moisture behavior of the concrete wall panel structure with a low water binder ratio ( w/ b < 0.5). Measurements indicate that the early age humidity drop is by up to 10 percentage points.

scholarly journals PRODUCTION OF THERMAL INSULATION MATERIAL BASED ON VOLCANIC ASH DEPOSITS OF PRIMAGADANYA

2019 ◽  
Vol 10 (2) ◽  
pp. 78-91
Author(s):  
A. V Bolotin ◽  
S. M Sergeev ◽  
A. A Lunegova ◽  
E. A Kochetkova
Keyword(s):  
Thermal Insulation ◽  
Building Materials ◽  
Volcanic Ash ◽  
Mineral Wool ◽  
Raw Material ◽  
Thermal Calculation ◽  
Vapor Permeability ◽  
Insulation Material ◽  
Comparative Performance ◽  
Insulation Materials

Modern technologies are not standing still, and scientists are trying not only to invent new building materials, but also to find non-standard use of various raw materials that were previously considered unsuitable for use. Innovative technologies are actively used for modern construction of buildings, in particular, some types of new materials are used in the construction of various facilities. This is especially true in areas where it is not possible to import or use ordinary building materials for various reasons. Often, when designing a building, developers are wondering whether it is worth making the house warm during construction, and which insulation for the walls of the house is better to choose. This article addresses the question of which insulation for walls is most suitable for construction. The most common are mineral insulation, which are represented on the market today in the form of basalt slabs, fiberglass, etc. They have such advantages as low thermal conductivity, good thermal insulation and vapor permeability. The article presents a table with comparative performance characteristics of a mineral wool stone slab and a fiberglass slab. Stone or basalt wool has several advantages. It is able to withstand significant temperatures and temperature changes, the mats are easy to transport, convenient to install. In our opinion, a serious alternative to basalt in the production of thermal insulation materials is volcanic ash. One of the main features of volcanic ash are its building qualities, such as good thermal insulation and an environmentally friendly composition. Since here we are considering the possibility of producing insulation materials based on volcanic ash, we performed a thermal calculation of the enclosing structures. Also in the tables are the costs of transportation of volcanic ash from the field to the point of the proposed production of insulating material. Volcanic ash can be widely used in countries with high volcanic activity as an inexpensive raw material for the manufacture of building materials. It does not require additional processing and has a number of useful properties.

scholarly journals Hygrothermal conditions in ventilated attics with different air change rates and ceiling constructions

2020 ◽  
Vol 172 ◽  
pp. 07008
Author(s):  
Martin Morelli ◽  
Eva Møller ◽  
Thor Hansen
Keyword(s):  
Relative Humidity ◽  
Ventilation Rate ◽  
Mineral Wool ◽  
Insulation Material ◽  
Tracer Gas ◽  
Limited Effect ◽  
Hygroscopic Properties ◽  
Test House ◽  
Danish Study ◽  
Hygrothermal Behaviour

A recently Danish study reported that no vapour barrier is needed in ceilings, if the attic is well ventilated and the ceiling towards the dwelling is airtight. Based on that study, new investigations were initiated with focus on the hygrothermal behaviour in ventilated attics with different air change rates. A test house with three sets of four different ceiling constructions – all airtight – was used in this study. The ventilation rate was reduced in two of the sets with approx. 35 % and 50 %, respectively. Air change rates were measured with tracer gas. Furthermore, temperature and relative humidity was measured every hour. Measurements in similar ceilings with mineral wool or cellulose-based insulation material show that hygroscopic properties of the insulation have very limited effect on relative humidity. Furthermore, only at low ventilation rate the effect of a vapour barrier could be measured with minor impact. Based on the short-measured period the calculations of the risk of mould growth showed no risk. The results indicate that even when the ventilation is reduced by 50 %, the ventilated attic still performs well if the ceiling is highly airtight. However, the importance of vapour barriers becomes more important at lower air change rates.

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