Μελέτη Σταθεροποίησης Πηλοκονιαμάτων [article]

Konstantinos Stathopoulos, National Technological University Of Athens, National Technological University Of Athens
2015
During the past few years the construction industry is looking to expand the use of ecological materials, in order to create environmentally friendly buildings, contributing to the sustainability of the cities and limiting the waste of energy. Following this direction, clay is reconsidered as a possible structural material of extensive use. Clay presents several advantages, such as big thermal mass, through which it manages to provide thermal comfort, in warm and dry climate conditions, while
more » ... multaneously it succeeds to control the levels of humidity of indoor spaces, contributing to the maintenance of good air quality. Moreover, clay is considered a recyclable material and containing extremely low levels of embodied energy. However, one of the major disadvantages of clay is its reduced resistance against water corrosion. This thesis explores the potential stabilization of clay mortars, with the addition of either natural hydraulic lime or ladle furnace slag originated from the steel production process. In both cases the effectiveness of the each additive is tested by its use in two different percentages and its assessment in comparison to a non-stabilized reference clay mortar. The clay used was analyzed according to the soil mechanics practice, particle size distribution and Atterberg limits were determined. The clay was classified as a Silt Sand (SM), according to the Unified Soil Classification System (USCS). The concentration of the material's total soluble salts, moisture content and organic material content were also examined. All of the above tests revealed that the clay is suitable for the production of mortars. The river sand 0-4mm that was selected as aggregate, was tested through sieve analysis in order to examine its particle size distribution. All of the raw materials used for the production of the mortar samples were examined by X-ray diffraction (XRD) and Thermal Analysis (DTA/TG). Five different design mixes were selected for the mortar tests. The first one contains 80% clay and 20% sand and is used as the reference clay mortar. The ratio of clay to sand is kept constant for all mortar mixes, so as to obtain comparable results. The tests of the fresh mortars include the determination of consistency by flow table, bulk density, air content and water retentivity. The mortar for each mix design was moulded in 4x4x16 cm moulds, the samples were cured for a few days in the conservation chamber and then they were left in a room with fixed humidity and temperature conditions until the testing date. For the physical, chemical and mechanical evaluation of the set and hardened mortars, the following techniques were applied: Fiber Optics Microscopy (FOM), Colorimetry, Thermal Analysis (DTA/TG), Mercury Intrusion Porosimetry (MIP), determination of Volume Loss, Ultrasonic Testing, determination of Flexular and Compressive strength, determination of Water Absorption Coefficient due to capillary action and Wetting-Drying cycles, by both capillary action and immersion. The tests have revealed an obvious improvement of the microstructure and the mechanical properties of the stabilized mortars, in comparison to the reference mortar. The mechanical properties of the mortars that have been stabilized by the addition of natural hydraulic lime are slightly better than all others. Regarding the assessment of the stabilized mortar samples behavior to water corrosion, the results are extremely promising, as both natural-hydraulic-lime and ladle-slag stabilized mortars presented excellent behavior in comparison to the reference mortar. Σχήμα 1.1 Κύκλος ζωής δομικού υλικού [1]. Το κάθε δομικό υλικό ακολουθεί έναν κύκλο ζωής (Σχήμα1.1.) από τη συλλογή ή την εξόρυξη, στην επεξεργασία, τη μεταφορά, την κατασκευή, τη χρήση της κατασκευής, την κατεδάφιση και την πιθανή επανάχρηση, την ανακύκλωση ή τη δυνατότητα βιοδιάσπασης. Συνεπώς στην επιλογή του υλικού δεν παίζουν ρόλο μόνο τα πλεονεκτήματά του κατά τη χρήση της κατασκευής, αλλά μπαίνουν και παράγοντες κόστους, υγιεινής και φιλικότητας προς το περιβάλλον.
doi:10.26240/heal.ntua.4596 fatcat:6ilpavcj2nb75k3rsd3huujvh4