Livingston Rose, Jeffryd Rose (2018-05). Mechanics of Accelerated Autogenous Healing of Concrete Water Distribution Systems Damaged by Cracking and Decalcification. Doctoral Dissertation. Thesis uri icon

abstract

  • The research discussed herein contains details about exploring a method for healing damaged drinking water pipe distribution systems. Two types of damage in the systems were considered, namely cracking and decalcification. Radial permeability of the pipes was considered as the metric to measure the damage in the pipe systems. Highly scaled down miniaturized samples were used to study the effects. The effects of different types of flow in the permeability measurement were studied first. The difference in the types of permeability measurement, namely poromechanical method (Hollow Dynamic Pressurization) and accelerated flow through method (Radial Flow Through), showed that for cement paste having a unimodal pore network there is no measured difference. For materials with multimodal pore network distribution, namely cement mortar and concrete, there is a significant difference in permeability measurement between the two methods. The Radial Flow Through measures the flux of fluid across the cross-section of a material while the Hollow Dynamic Pressurization measures the flux of fluid into the smallest pore network of the material. Thus, the Radial Flow Through is primarily influenced by the largest pores in the cross section while the smaller pores primarily influence the Hollow Dynamic Pressurization. The Radial Flow Through method was chosen as the testing method for damage caused by cracking and Hollow Dynamic pressurization was chosen as the method for measuring permeability in damaged specimens caused by decalcification. The hollow cylindrical pipe section specimens were damaged in a controlled manner by cracking and decalcification. The damaged samples were healed by a healing solution that was seeded with calcium and carbonate ions to help accelerate the autogenous healing process in the samples. The effect of the healing was determined by measuring the permeability of the samples before and after healing. The results showed a permeability decrease of up to a factor of 4 for decalcified samples and up to a factor of 12.5 in the case of cracked samples. It was also determined that permeability loss due to cracking was significantly higher that caused by decalcification. The healed samples were imaged using X-ray Computed Tomography to provide more details of the healing precipitation. The resulting images were too sensitive to thresholding effects to provide a clear result. Scanning Electron Microscope assisted Energy Dispersive Spectroscopy was used to isolate the precipitation location of the healing precipitates in the samples. The precipitation was primarily determined to be present along the inner surface of the hollow cylindrical pipe section specimen covering up the crack mouth of the damaged specimen and healing the sample.
  • The research discussed herein contains details about exploring a method for healing damaged drinking water pipe distribution systems. Two types of damage in the systems were considered, namely cracking and decalcification. Radial permeability of the pipes was considered as the metric to measure the damage in the pipe systems. Highly scaled down miniaturized samples were used to study the effects. The effects of different types of flow in the permeability measurement were studied first. The difference in the types of permeability measurement, namely poromechanical method (Hollow Dynamic Pressurization) and accelerated flow through method (Radial Flow Through), showed that for cement paste having a unimodal pore network there is no measured difference. For materials with multimodal pore network distribution, namely cement mortar and concrete, there is a significant difference in permeability measurement between the two methods. The Radial Flow Through measures the flux of fluid across the cross-section of a material while the Hollow Dynamic Pressurization measures the flux of fluid into the smallest pore network of the material. Thus, the Radial Flow Through is primarily influenced by the largest pores in the cross section while the smaller pores primarily influence the Hollow Dynamic Pressurization. The Radial Flow Through method was chosen as the testing method for damage caused by cracking and Hollow Dynamic pressurization was chosen as the method for measuring permeability in damaged specimens caused by decalcification.
    The hollow cylindrical pipe section specimens were damaged in a controlled manner by cracking and decalcification. The damaged samples were healed by a healing solution that was seeded with calcium and carbonate ions to help accelerate the autogenous healing process in the samples. The
    effect of the healing was determined by measuring the permeability of the samples before and after healing. The results showed a permeability decrease of up to a factor of 4 for decalcified samples and up to a factor of 12.5 in the case of cracked samples. It was also determined that permeability loss due to cracking was significantly higher that caused by decalcification. The healed samples were imaged using X-ray Computed Tomography to provide more details of the healing precipitation. The resulting images were too sensitive to thresholding effects to provide a clear result. Scanning Electron Microscope assisted Energy Dispersive Spectroscopy was used to isolate the precipitation location of the healing precipitates in the samples. The precipitation was primarily determined to be present along the inner surface of the hollow cylindrical pipe section specimen covering up the crack mouth of the damaged specimen and healing the sample.

publication date

  • May 2018