Ontario Ministry of Transportation

About: Ontario Ministry of Transportation is a government organization based out in Toronto, Ontario, Canada. It is known for research contribution in the topics: Poison control & Asphalt. The organization has 4652 authors who have published 3882 publications receiving 59011 citations.

Failure Evolution Law of Reinforced Anchor System under Pullout Load Based on DIC

Abstract: To obtain the failure evolution law, a pullout test model of the anchor system is proposed based on the digital image correlation (DIC) measurements. By the study of the displacement field, the strain field, and the force transfer law of the anchor system under the pulling load, the failure law of the anchor system is revealed. The results show that (1) the failure mode and the ultimate bearing capacity of the anchor system are related to the thickness of the anchor agent; (2) in the anchor system, the pulling force is gradually transferred from the loading end to the free end along the steel bar, and the greater the thickness of the anchoring agent, the deeper the transfer range; (3) during the loading, the deformation of the anchoring system is mainly concentrated at the interface between the anchoring agent and the concrete and expands to the depth along the steel bar; and (4) the failure evolution rate of the anchorage system is related to the loading stage. The failure evolution of the anchor system can be divided into the elastic phase, the plastic phase, and the deformation rebound phase.

Variation of Wave Velocity and Porosity of Sandstone after High Temperature Heating

Abstract: This paper reports the variations of mass, porosity, and wave velocity of sandstone after high temperature heating. The range of temperature to which the sandstone specimens have been exposed is 25–850°C, in a heating furnace. It has been shown that below 300°C, porosity and wave velocity change very little. Above 300°C, there is a rapid increase in porosity, but the wave velocity decreases significantly. The results of thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC) and mercury intrusion porosimetry (MIP) suggest that a series of changes occurred between 400 and 600°C in sandstone could be responsible for the different patterns of variation in porosity and wave velocity.

Occurrences of thaumasite in laboratory and field concrete

Abstract: The mineral thaumasite (CaSiO 3 · CaCO 3 · CaSO 4 · 15H 2 O) has been observed by the authors in a number of concrete samples including (i) an 80 year-old aqueduct in Manitoba, (ii) a 33 year-old pavement in Ontario, (iii) test samples exposed to marine (tidal) conditions, and (iv) laboratory samples exposed to wet–dry cycles in sulphate solution. The source of carbonate differed for these cases being variously derived from de-dolomitization of dolostone aggregate, carbonate ions in the seawater, or atmospheric CO 2 through the process of carbonation. In some cases the thaumasite mineral was found in close association with the mineral ettringite (3CaO · Al 2 O 3 · 3CaSO 4 · 31H 2 O). The paper discusses the results of detailed analyses using optical and electron microscopy. Although the mineral thaumasite can be readily identified by these techniques, it is possible that the thaumasite form of sulphate attack is frequently misdiagnosed as conventional sulphate attack due to the similarities in crystal structure and appearance of the minerals thaumasite and ettringite.