Now showing 1 - 10 of 11
  • Publication
    Soundless chemical demolition agents performance under cold and cool temperatures in concrete and masonry structures
    (University College Dublin. School of Civil Engineering  , 2017) ;
    There are several commonly used traditional demolition methods such asjackhammers, explosives, controlled blasting and diamond wire saws.Unfortunately, these traditional methods produce high levels of noise, vibration anddust. As such, demolition of rocks, existing concrete structures, historic structuresand densely populated areas always raises concerns. In such cases, SoundlessChemical Demolition Agents (SCDAs) offer a reliable alternative. This PhD thesisfocuses on SCDA performance under cold and cool temperatures by means of foursets of experimental work. Across these tests, the relationship between ambienttemperature, heat of hydration, volumetric expansion, calcium hydroxide Ca(OH)2and calcium carbonate (CaCO3) were monitored under different ambienttemperatures and conditions. As a part of these tests, the impact of the thermaltransfer likely to be present during concrete demolition and its effect on thehydration heat development and pressure generation was considered. Resultsindicate that higher ambient temperature results in higher heat of hydration andhigher expansive pressure development. The relationship between ambienttemperature, volumetric expansion and calcium hydroxide Ca(OH)2 generation wasalso investigated. In the last part of this thesis, SCDAs were used for selective andpartial removal of masonry units. The experimental results show that partialremoval was successful, although selective targeted removal of individual masonryunits removal was not possible by hand, despite significant cracking in the area.
  • Publication
    Chemical Demolition of Unit Masonry: A Preparatory Study
    Chemical demolition of concrete and rock has been conducted on a commercial basis since the 1970s, although not widely adopted. Furthermore, to date there have been no publications on the application of this class of products to unit masonry. To begin to fill this gap, this paper documents a laboratory study on the insertion of a soundless chemical demolition agent into a series of unit masonry wallettes. The paper introduces initial steps towards developing a procedure for the non-percussive demolition of such a wall and observations on the progressive nature of cracking in such arrangements. Although neither the assembled units nor the mortar in these tests were of historic material, the paper provides critical insight into the application of this technology into a building configuration in which it is not usually seen. The results show the promise this technology holds for highly selective material removal, without endangering the surrounding material for historic brick and stone buildings.
  • Publication
    Ecostructure: Concrete design for improved marine biodiversity
    In some parts of the world artificial marine structures now cover more than half of the available natural shoreline. Due to the impact of climate change and the need for improved coastal defences this number is set to increase, and these will inevitably have a significant impact on the local marine ecosystem. As an indicator of this impact, research in the UK has shown the epibiotic diversity to be significantly reduced on submerged artificial structures. The Ecostructure project is part funded by the Ireland Wales Cooperation Programme and has the objective of addressing climate change adaptation through ecologically sensitive coastal infrastructure. The approach under development is to increase the ecological value of artificial coastal infrastructure in the Irish Sea through careful design of pre–fabricated ecological engineering units. A key parameter in the design of these units is material selection. Reinforced concrete plays an important role in the design of these units, due to its ease of production, relatively low cost and its suitability for mass construction. However when assessing concrete mixes for use in this application, a key issue is how easily the local marine organisms can colonise the hard concrete substrate. It is considered that key parameters can include binder composition, aggregate type, texture, colour etc. To assess these parameters, a testing programme has been developed that is focusing on 9 different concrete designs. These are assessed for key engineering parameters (strength, chloride diffusion coefficient etc.), as well their ecological colonisation performance. This is determined by placing concrete samples in marine environments in Ireland and measuring the ecological diversity through quadrat sampling at a number of time intervals. This testing is taking place in Dublin and initial results are presented.
  • Publication
    Using Chemicals as Demolition Agents Near Historic Structures
    When selective demolition of rock and existing concrete is required near historic structures, there are always concerns about vibration-induced damage from either explosives or other percussive means, such as jackhammers. Soundless chemical demolition agents (SCDAs) offer an alternative.  Although not widely applied, this non-percussive approach can be highly effective. The following paper outlines a set of usage considerations for SCDAs near historic structures.  As part of this, the relative advantages and disadvantages are discussed including appropriate environmental conditions, and the quantity of material needed (along with the affiliated costs). Performance information related to the timing and extent of cracking is also provided. Furthermore, critical portions of this paper relate to the necessary preparatory work, training, safety precautions, and storage requirements needed when using this class of products, including emergency precautions. Finally, this paper briefly summarizes the application of one SCDA product as part of the 2001 Carnegie Hall expansion.
  • Publication
    A concrete home for marine micro inhabitants
    (RILEM Publications S.A.R.L., 2018-10-24) ;
    In the last decades, the prevalence of artificial marine structures along natural shorelines has increased significantly. In some parts of the world, more than half of the available natural shoreline has been covered by these structures. Epibiotic diversity has been shown to decrease significantly on submerged artificial structures due to the reduced environmental heterogeneity of artificial environments. Natural rocky shores provide microhabitants through their rough surfaces, pits, rock pools and crevices. In contrast, modern building materials typically fail to provide many of these features. The ecological value of artificial coastal infrastructure could be increased through careful design of pre–fabricated ecological engineering units. Material selection is a crucial parameter in the design of these units. Reinforced concrete plays an important role in the design process due to its ease of production, relatively low cost and its suitability for mass construction. To maximise the potential of concrete to support biodiversity and natural capital, binder composition, aggregate type, and texture are considered to be important parameters. To investigate these parameters, an experimental programme has been developed which is focusing on a number of different concrete designs. Key engineering parameters, such as strength, chloride diffusion coefficient, and their ecological colonisation performance are evaluated.
  • Publication
    Three-dimensional building façade segmentation and opening area detection from point clouds
    Laser scanning generates a point cloud from which geometries can be extracted, but most methods struggle to do this automatically, especially for the entirety of an architecturally complex building (as opposed to that of a single façade). To address this issue, this paper introduces the Improved Slicing Method (ISM), an innovative and computationally-efficient method for three-dimensional building segmentation. The method is also able to detect opening boundaries even on roofs (e.g. chimneys), as well as a building’s overall outer boundaries using a local density analysis technique. The proposed procedure is validated by its application to two architecturally complex, historic brick buildings. Accuracies of at least 86% were achieved, with computational times as little as 0.53 s for detecting features from a data set of 5.0 million points. The accuracy more than rivalled the current state of the art, while being up to six times faster and with the further advantage of requiring no manual intervention or reliance on a priori information.
      1050Scopus© Citations 40
  • Publication
    Temperature-induced Chemical Changes in Soundless Chemical Demolition Agents
    This paper explored the relationship between ambient temperature, calcium oxide (CaO) hydration, and calcium carbonate (CaCO3CaCO3) generation in cold and moderate ambient temperatures (2°C–19°C). A total of 22 samples from 2 commercial soundless chemical demolition agents (SCDAs) were tested in 36-mm-diameter×170-mm-long36-mm-diameter×170-mm-long steel pipes. The raw powder and materials resulting from hydration were subjected to X-ray diffraction analysis, derivative thermogravimetric analysis, and thermogravimetry analysis. Raw and hydrated specimens proved chemically distinctive. Experimental results showed that (1) the unconfined portions of hydrated specimens contained more CaCO3CaCO3 due to carbonation of Ca(OH)2Ca(OH)2, and confined portions had higher Ca(OH)2Ca(OH)2concentrations; (2) all materials tested at 19°C ambient temperature had Ca(OH)2Ca(OH)2concentrations nearly 10% greater than those tested at 2°C; and (3) the higher Ca(OH)2Ca(OH)2 concentrations formed at 19°C generated 350% greater expansive pressure than did those that formed at 2°C.
      165Scopus© Citations 9
  • Publication
    The effect of angles and distance on image-based, three-dimensional re-constructions
    This paper introduces a three-dimensional reconstruction experiment based on a physical laboratory-based experiment on a brick wall. Using controlled shooting distances and angles, different images sets were captured and processed with a structure from motion based technique, which can reconstruct 3D models based on multi-view, two-dimensional (2D) images. Those 2D geometries are shown to generate significant deformations within the resulting point cloud, especially where there were large angles (with respect the camera position and the wall's normal direction) and at close distances to the wall's surface. This paper demonstrates that by overlapping different flawed image sets, the deformation problem can be minimised. 
      266Scopus© Citations 7
  • Publication
    Impact of thermal transfer on hydration heat of a Soundless Chemical Demolition Agent
    This paper explores thermal transfer effects in Soundless Chemical Demolition Agents (SCDA). In a 10°C water bath, quadrupling the volume of SCDA in a pipe accelerated peak hydration onset and resulted in a 700% increase in expansive pressure and a 20% increase in volumetric expansion. An equivalent sample in a constant temperature chamber showed an almost 5°C greater hydration heat than in the water bath, which resulted in a six-fold expansive pressure difference after 4 days of testing and an order of magnitude more pressure in the first 24 h, thereby demonstrating limitations of previous SCDA experimental work and providing a temperature-based reason for discrepancies between large-scale testing and manufacturers’ predictions. Since most construction projects have scheduling requirements, understanding how to achieve sufficiently high pressures within a single work shift is important for evaluating the field viability of SCDAs on a particular project.
      436Scopus© Citations 28
  • Publication
    Cold and moderate ambient temperatures effects on expansive pressure develop-ment in soundless chemical demolition agents
    This paper explores cool and moderate temperature (2–19 °C) impacts on hydration heat and expansive pressure development in two commercial soundless chemical demolition agents (SCDAs). Experimental results showed (1) product-specific, linear relationships between the ambient temperature and time to peak hydration heat; (2) peak hydration heats to be consistently 1.5 times the ambient temperatures at 10–19 °C; outside of this range the factor was greater; (3) a linear relationship between peak hydration heat time and the onset of expansive pressure development; (4) a largely proportional relationship between ambient temperature and volumetric expansion of 1.1–1.4 times the original volume.
      452Scopus© Citations 54