Mortar

About: Mortar is a research topic. Over the lifetime, 25024 publications have been published within this topic receiving 218739 citations.

Longitudinal guided waves for monitoring corrosion in reinforced mortar

Abstract: Guided longitudinal modes in both low (<200 kHz) and high (2–8 MHz) frequency ranges were invoked to monitor damage in reinforced mortar specimens undergoing accelerated uniform corrosion. The fundamental longitudinal mode, i.e. L(0, 1), and the L(0, 9) mode were invoked for low- and high-frequency testing, respectively. Because of the significant amount of axial displacement at the steel/mortar interface, the L(0, 1) mode was so appreciably attenuated for the particular specimen size used that it is was not detected until after corrosion had initiated and corrosion product accumulation caused mortar cracking. Once detected, the L(0, 1) mode was sensitive to the combined effects of bond deterioration and mortar stiffness reduction. The L(0, 9) mode has negligible radial and axial displacement at the steel/mortar interface. As a result, the L(0, 9) mode is relatively insensitive to the surrounding interface conditions at high frequencies. This allows for changes in the steel cross-sectional area and bar topography to be isolated and monitored from the onset of corrosion up to severe pitting.

Effect of polyacrylamide on the different properties of cement and mortar

Abstract: The effect of polyacrylamide (PAA) addition in the ordinary cement and mortar, on the properties, such as setting time, heat of hydration, compressive and tensile strength has been studied by adding 0.5–5.0% additive by weight of cement. While hardness was determined using the Vickers indentation method, the fracture toughness of cementitious bond and flexural strength have been determined using three point bending system. Corrosion resistance of resulting products was tested against each of 0.1 and 1.0N of HCl and H 2 SO 4 and seawater. FT-IR and X-ray diffraction techniques have been employed to determine the phase compositions of the material. Polymeric phase is interspersed in cement causing decrease in water absorption and also its interaction with hydrating cement resulting additional bond formation leading to the increase in strength.

Reduction in Mortar and Concrete Expansion with Reactive Aggregates Due to Alkali Leaching

Abstract: Mortar bar expansion tests for evaluating alkali-silica reactive aggregates are not always reliable. Containers with efficient wick systems may cause excessive leaching of alkalies out of mortar bars, thus reducing the expansion. This problem has become more apparent since the introduction in 1987 of a new recommended container for the ASTM C 227 mortar bar test. It is believed that the use of this container can result in deleteriously expansive aggregates appearing to be innocuous in laboratory testing. Similar effects were found with concrete prisms made with alkali-carbonate reactive aggregate. If laboratory expansion tests are to be reliable, it is necessary to calibrate the severity of the storage condition by conducting calibration tests with known alkali-reactive aggregates as reference materials. The use of Pyrex glass is not satisfactory for calibrating storage conditions because it contributes alkalies to the reaction.