Contribution Of Building Materials Research Articles

A Preliminary Study of the Characteristics of Radon Data from Indoor Environments and Building Materials in the Campania Region Using PCA and K-Means Statistical Analyses

For a healthy indoor environment, it is important to understand which materials and factors favor the generation of high levels of indoor radon. A preliminary multivariate statistical analysis was carried out on two datasets concerning indoor radon and building materials in the Campania Region using Principal Component Analysis (PCA) and the k-means partitional analysis technique. A total of 13 parameters related to building materials were used. The results show the greater contribution of building materials of volcanic origin to the concentration of indoor radon and thoron activity and the different influence of the parameters of the 31 materials analyzed. The same analyses applied to the indoor radon values of 694 rooms in the Campania Region were equally effective in assessing the structural characteristics of indoor environments that most influence indoor radon levels. The study provided an effective assessment of the influence on radon activity of several environmental parameters, which are often not adequately considered.

USE OF COMMERCIAL RADON MONITORS FOR LOW LEVEL RADON MEASUREMENTS IN DYNAMICALLY OPERATED VOC EMISSION TEST CHAMBERS.

Compared to the intended EU reference level of 300 Bq m-3 for indoor radon concentrations, the contribution of building materials appears to be low. Considering the recommended limit of 100 Bq m-3 by WHO, their contribution is supposed to be relevant, especially at low air exchange rates. This study as part of a two-part research project investigated the suitability of direct low level 222Rn measurement under simulated indoor conditions with commercial radon monitors and dynamically operated emission test chambers. Active measuring devices based on ionisation or scintillation chambers with 1-σ uncertainties below 8.6% at 20 Bq m-3 were found to be best suitable for a practical test procedure for the determination of radon exhalation rates of building materials. For the measurement of such low concentrations, the knowledge of the accurate device background level is essential.

Recent update on the environmental impact of geopolymers

The contribution of building materials’ production to environmental impacts becomes significant in the new energy efficient buildings that are currently built. Among those materials, cement represents a major part of the embodied carbon footprint of buildings. Development of alternatives to traditional Portland cement have emerged over the last decades; however, their environmental assessment over their life cycle have resulted in conflicting results, which give a confusing picture of the strategic path to be followed. This paper focuses on the alkali-activated cement and concrete and points out the variability linked with the choice of energy source for the production of the activators and precursors. A review of existing studies is then performed in order to highlight the main benefits of these alternative cements in terms of reduction of greenhouse gas emissions. Finally, the results presented here highlight further research trends for new cements and concrete.

Recent update on the environmental impact of geopolymers

The contribution of building materials’ production to environmental impacts becomes significant in the new energy efficient buildings that are currently built. Among those materials, cement represents a major part of the embodied carbon footprint of buildings. Development of alternatives to traditional Portland cement have emerged over the last decades; however, their environmental assessment over their life cycle have resulted in conflicting results, which give a confusing picture of the strategic path to be followed. This paper focuses on the alkali-activated cement and concrete and points out the variability linked with the choice of energy source for the production of the activators and precursors. A review of existing studies is then performed in order to highlight the main benefits of these alternative cements in terms of reduction of greenhouse gas emissions. Finally, the results presented here highlight further research trends for new cements and concrete.

Modeling of indoor radon concentration from radon exhalation rates of building materials and validation through measurements

Building materials are the second major source of indoor radon after soil. The contribution of building materials towards indoor radon depends upon the radium content and exhalation rates and can be used as a primary index for radon levels in the dwellings. The radon flux data from the building materials was used for calculation of the indoor radon concentrations and doses by many researchers using one and two dimensional model suggested by various researchers. In addition to radium content, the radon wall flux from a surface strongly depends upon the radon diffusion length (L) and thickness of the wall (2d). In the present work the indoor radon concentrations from the measured radon exhalation rate of building materials calculated using different models available in literature and validation of models was made through measurement. The variation in the predicted radon flux from different models was compared with d/L value for wall and roofs of different dwellings. The results showed that the radon concentrations predicted by models agree with experimental value. The applicability of different model with d/L ratio was discussed. The work aims to select a more appropriate and general model among available models in literature for the prediction of indoor radon.

Determination of radon level and radon effective dose rate using SSNTD in dwellings in the Bathinda district of Punjab, India

The problem of indoor radon has attracted a great deal of attention worldwide as radon is the largest contributor to the total natural radiation dose. The dwellings belonging to the Bathinda district of Punjab, India, are investigated for the yearly average of indoor radon concentrations using solid-state nuclear track detectors. The annual average indoor radon values in the study area vary from 122.30 to 147.10 Bq m(-3), which is well within the recommended action level given by the International Commission on Radiological Protection. The calculated lifetime fatality risk values vary from 1.61 to 1.94. The seasonal variations and the contribution of building materials and ventilation conditions to the indoor radon in dwellings are also discussed.

Estimating the importance of factors influencing the radon-222 flux from building walls

Radiation hazard in dwellings is dominated by the contribution of radon-222 released from soil and bedrock, but the contribution of building materials can also be important. Using a simple air mixing model in a 2-story house with an attic and a basement, it is estimated that a significant risk arises when the Wall Radon exhalation Flux (WRF) exceeds 10×10−3Bq·m−2·s−1. WRF is studied using a multiphase advection–diffusion 3-layer analytical model with advective flow, possibly induced by a pressure deficit inside the house compared with the outside atmosphere. To first order, in most circumstances, the WRF is proportional to the wall thickness and to the radon source term, the effective radium concentration ECRa, which is the product of the radium-226 concentration by the emanation coefficient E. The WRF decreases with increasing material porosity and exhibits a maximum for water saturation of about 50%. For ECRa=10Bq·kg−1, in many instances, WRF is larger than 10×10−3Bq·m−2·s−1 and, therefore, ECRa=10Bq·kg−1 can be considered as the typical limit not to be exceeded by building materials. An upper limit of the WRF is obtained in the purely advective regime, independent of porosity or moisture content, which can thus be used as a robust safety guideline. The sensitivity of WRF to temperature, due to the temperature sensitivity of ECRa or the temperature sensitivity of radon Henry constant can be larger than 5% for the seasonal variation in the presence of slight pressure deficit. The temperature sensitivity of ECRa is the dominant effect, except for moist walls. Temperature and moisture variation effects on the WRF potentially can account for most observed seasonal variations of radon concentration in houses, in addition to seasonal changes of air exchange, suggesting that the contribution of walls should be considered when designing remediation strategies and studied with dedicated experiments.

Passive integrating radon studies for environmental monitoring in Sirsa district, Haryana, India using solid state nuclear track detectors

Indoor radon studies have been carried out in the environs of some areas of Sirsa district, Haryana, India using LR-115 type II plastic track detectors. LR-115 Type II films in the bare mode were exposed for one year on three month basis to cover all seasons for the measurement of indoor radon levels. The work has been undertaken for health risk assessment. The average radon concentration in dwellings in most of the villages falls in the action level (200–600 Bq m−3) recommended by International Commission on Radiological Protection. The radon values in some of the dwellings exceed the action level and may be unsafe from the health hazard point of view. The variation due to the ventilation conditions and contribution of building materials to the indoor radon in dwellings are also discussed. The positive values of winter-summer ratio of radon concentration also confirm that level of radon concentration is high in winters as compared to the summers.