This research program presents an experimental study on the mechanical and thermal properties of different types of concretes at very early ages, (i.e., during hydration). These properties are investigated for temperature-matched curing, sealed curing and air-dried curing. Three types of concretes are studied including normal-strength (30 MPa), medium-strength (70 MPa) and high-strength (100 MPa) concretes. About 300 cylinders and 175 flexural beams were tested to determine the early-age mechanical properties including compressive stress-strain responses, gain of compressive strength, change in elastic modulus and variation of tensile strength. Creep frames and measuring devices were built to enable the experimental determination of early-age creep, with unloaded, companion specimens giving the corresponding shrinkage strains. A temperature-matched curing bath was developed to measure the heat of hydration and to subject 15 cylinders and 12 flexural beams to temperature-matched curing. The thermal properties investigated included the heat of hydration, the thermal conductivity, the specific heat and the coefficient of thermal expansion. Expressions are proposed to predict the development of compressive strength, elastic modulus and modulus of rupture as a function of the type of concrete and the type of curing. / Sub-routines were developed for a finite element thermal analysis program "DETECT" to predict the variation of temperatures during hydration. Additional sub-routines, using the maturity concept, predicted the compressive strength, elastic modulus and tensile strength of each element, in the time domain. An experimental study was performed to observe the effect of different curing conditions and early-form stripping on the temperature and strain development in structural concrete members. Comparisons are made between the measured and predicted temperatures in large concrete columns and precast tee beams and slabs. / Sub-routines were developed to enable incremental stress analysis in the time domain to account for the rapidly changing material properties and the influence of creep. Predictions of the risk of cracking were made and compared with observations from experiments on concrete elements during hydration. Parametric analyses were carried out to determine the influence of key thermal properties, time of formwork removal, creep, and concrete strength on the thermal gradients developed and the risk of thermal cracking.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.29060 |
| Date | January 1995 |
| Creators | Khan, Arshad A. (Arshad Ahmad) |
| Contributors | Mitchell, Denis (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Civil Engineering and Applied Mechanics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001474934, proquestno: NN08120, Theses scanned by UMI/ProQuest. |
Page generated in 0.0023 seconds