In the last decade he has caused himself an increase of the education of the interior ambient conditions of the buildings caused by the appearing of numerous scientific reports that they relate them to serious diseases. Between these, the education of concentration of radon branded like carcinogen wilfully publicise one. The present article parses the concentrations of this gas that have taken place in a single-family housing and as the ventilation system in work has influence upon her. For it, two samples in three outbuildings of the house have been taken, (car park, dining room and bedroom). The first unaccomplished sample the ventilation of the spaces and the second with ventilation. The obtained peak concentrations when the ventilation system does not find itself in operation evidence values from among 391 and 94 Bq/ m3 coming right across over the doorsteps established in the standard 2013/59 EURATOM. On the contrary, the peak concentrations of radon decrease to values from among 71 and 29 Bq/ m3 interveningventilation. In this sense, it is confirmed that the ventilation system in work is determining to decrease the concentration of the gas in the analysed sojourns getting an average efficacy from the 62 %.

In recent years, chemical admixtures have become one of the main components of concrete alongside aggregate, cement and water. In this study, the plasticizer and the antifreeze were used. The concrete specimens (the reference concrete without an admixture, concrete with plasticizer, concrete with antifreeze and concrete with plasticizer+antifreeze) were exposed to elevated temperatures (200, 400, 550 and 700 oC) and cooling via air and water. Water absorption, ultrasonic pulse velocity and compressive strength tests were performed on the specimens. The concrete specimens were also analyzed using X-ray diffraction. The test results indicated that at the temperatures of 550 and 700 oC and against both of the cooling regimes the plasticizer+antifreeze concrete showed a maximum strength loss. When the air cooled specimens were examined, the lowest strength loss was this obtained for reference concrete at 550 and 700 oC. The lowest strength loss at these temperatures for the water cooled specimens was observed in the concrete with antifreeze. After being exposed to 700 oC and the cooling regimes, no portlandite peaks were observed in the concrete mixtures was when they were compared at with the control specimen exposed to 20 oC in the X-ray diffraction analysis.

The discussion on fire safety is necessary in Brazilian buildings. Current legislation requires construction with compartmentalized areas separated by walls with structural ceramic blocks capable of resisting fire for an amount of time pre-determined in norm NBR 14432 (ABNT, 2001). However, a lack of building standards requires experimental tests according to NBR 5628 (ABNT, 2001) to determine the necessary configuration to achieve fire resistance. For this purpose, this study analyzed the effect of fire on structural walls covered with a mortar coating. Experiments were conducted in real scale in a standardized vertical oven and the fire growth curve of ISO 834 (ISO, 1999). Three types of walls were tested, each with a different mortar coating: (a) lime; (b) 0.6 kg/m³ polypropylene fiber and 1.2 kg/m³ polypropylene fiber. The mortar coatings were 1.5 cm thick on the side facing the fire and 2.5 cm thick in the outside. The wall was composed of structural blocks measuring 14 cm x 19 cm x 29 cm. Fire experiments evaluated the structure stability, impermeability to hot gases and smoke and thermal insulation of each sample. Results showed that the structural system with 1.2 kg/m³ polypropylene fiber mortar coating obtained the best thermal insulation effect with the longest fire resistance time of 176 min.

Laterite, due to its wide availability and low cost, is considered as a societal building material in tropical and sub-tropical regions of the world. Excavation of the laterite leaves laterite stones as scrap which accounts for around 25-30%. These scraps being a hindrance for the further excavation of the laterite in the quarries can be crushed and used to meet the demand of fine aggregates in the construction industry. Performance indicators such as workability, compressive, split-tensile and flexural strength are measured to evaluate the suitability. M30 grade of concrete specimens were produced with these crushed scraps by replacing M-sand at the intervals of 25% ranging from 0% to 100%. Laterite replacement of 25% could enhance the performance after 28 days. Not limiting only to strength characteristics, its morphological features were also understood by conducting Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) for the optimum mixes. Laterite, due to its wide availability and low cost, is considered as a societal building material in tropical and sub-tropical regions of the world. Excavation of the laterite leaves laterite stones as scrap which accounts for around 25-30%. These scraps being a hindrance for the further excavation of the laterite in the quarries can be crushed and used to meet the demand of fine aggregates in the construction industry. Performance indicators such as workability, compressive, split-tensile and flexural strength are measured to evaluate the suitability. M30 grade of concrete specimens were produced with these crushed scraps by replacing M-sand at the intervals of 25% ranging from 0% to 100%. Laterite replacement of 25% could enhance the performance after 28 days. Not limiting only to strength characteristics, its morphological features were also understood by conducting Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-Ray Diffraction (XRD) and Thermogravimetric analysis (TGA) for the optimum mixes.

This paper presents results of an experimental study of a residue of masonry (RM), sampled from a construction and demolition waste (CDW), added as a supplementary cementitious material (SCM) to partially replace up to 50% of Portland cement in the preparation of mortars. The pozzolanic activity (fixed lime and strength activity index), setting time, heat of hydration, the (autogenous and drying) shrinkage and compressive strength tests were carried out. The results show how the RM has a positive activity because the increase of RM replacement level in the mortars generates a lower heat of hydration and autogenous and drying shrinkage. The fixed lime at 28 and 180 days, indicating that the RM exhibits in some degree pozzolanic activity and the Strength Activity Index (SAI) was 77.13% and 84.36% of the compressive strength of 100% OPC mortar at the 7 and 28 days respectively, which conformed to ASTM C311. These results indicate that RM should be considered appropriated for using as a supplementary cementitious material.

Soils are made stronger and more durable by mixing additive materials. In particular, the use of waste provides environmental and economic advantages for this case. Wastes form in large quantities, however, which creates storage problems. To objective of this study is to research the availability of industrial wastes for soil stabilization. An experimental study was conducted on granular soil specimens mixed with industrial wastes such as marble and granite dust, boron waste, and fly ash in different ratios. Each mixture used two waste materials together. Specifically, fly ash was used with three additional waste materials because of its pozzolanic characteristics. The tests performed included freezing-thawing, unconfined compression strength, and California bearing ratio. The results of the study show that the strength of a specimen is dependent on the additive ratio, curing period, and the number of freeze-thaw cycles. Generally, unconfined compressive strength and California bearing ratio increased with additive materials and curing times. After freezing and thawing, unconfined compressive strength (except granite dust) decreased, whereas weight loss increased due to increasing additives and increasing freeze-thaw cycles.

The 3300-year-old Chogha Zanbil is the largest and best-preserved five levelled pyramidal earth ziggurat outside Mesopotamia, which was inscribed on UNESCO’s World Heritage List. Underground tombs of Chogha Zanbil are accepted as outstanding instances in Iran and consist of vaults, which are built with special methods by Elamite architects. In this context, the main purpose of this paper is to contribute to sustain the outstanding universal value of the Chogha Zanbil. For that purpose, this paper puts forward a structural analyse of the vaults of five Chogha Zanbil underground tombs, which were built inside the ground by brick, lime mortar, plaster and bitumen materials. Data for underground tombs and vaults were collected upon field observations and literature study. Finite-element methodology was used for structural analysis and SAP software was utilized to determine the way the forces are transmitted through the vaults, the conditions of bending moments, the shear forces. As a result, it has been observed that the bending in the vaults turns into pressure force that is perfectly resisted by bricks. In conclusion, it was ascertained that the vaults of the Chogha Zanbil underground tombs were built with the right techniques at that time, so that the vaults still have solid behaviour after thousands of years and remained completely healthy to this day.

DOI: 10.7764/RDLC.18.1.134 In the present work it is explained how the architect Felix Candela got to analyse the roof long cylindrical shells in reinforced concrete using an method based simply on equilibrium equations. All this, in a moment in which the elastic theory of shells becomes practically impossible to apply due to the involvement of eighth-order differential equations. Felix Candela ‘objective was to get a safely and easily calculation method, respecting the assignment of reinforced concrete and, therefore, obviating the considerations of compatibility and deformation that could undergo the structure. This method, developed previously by other engineers, is explained mathematically choosing an example of work of Felix Candela, done by roof long cylindrical shells, and making the necessary structural calculations proposed.

This paper studies the possibility of using the following occupational risk assessment methods for construction works: INSHT, ANACT, THREP, SHERPA, RNUR, EVENT TREE, LEST, FINE, ERGONOMIC ANALYSIS and PSYCHOSOCIAL FACTORS. Of these methods, INSHT, ANACT, RNUR and FINE have been selected with the objective of applying them to real building works, in order to determine the discrepancies in the results obtained compared to the risks analyzed. The results make it possible to ascertain the types of risk which each method most reliably detects, there being methods which are not able to detect extreme or very low risks. It is concluded that if a single risk assessment method is used, the results do not entirely reflect reality, as such it is necessary to establish a new risk assessment methodology for construction works.