Mortar

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

Non-destructive testing of hardened cement specimens at microwave frequencies using a simple free-space method

Abstract: In this research paper, we show microwave reflection and transmission properties measured from various sides of hardened mortar and concrete specimens with different water-to-cement ratios. These properties are important in predicting/measuring accurate electrical properties of cement-based materials which can eventually be utilized in structural health monitoring, public safety, and propagation-related research. Measurements are carried out by a simple and relatively inexpensive non-destructive free-space set-up with its newly developed calibration technique at X-band (8–12 GHz) during 3–36 months after samples’ preparation. A new approach (relative difference approach) is introduced for transmission properties to predict the state and degree of hydration inside specimens. It is shown that concrete specimens will complete the hydration sooner than mortar specimens with the same water-to-cement ratio (w/c) ratio due to heavy aggregates. In addition, among the specimens, while the concrete specimen with a higher w/c ratio will exhibit faster hydration during approximately 3–6.1 months, the mortar specimen with a lower w/c ratio will display rapid hydration during approximately 6.1–30 months. Besides, it is demonstrated that the magnitude of transmission properties for the top (or bottom) is less than those for the right (or left) side due to the effect of gravels and sand particles in specimens. Measurement results indicate that a varying electrical property depending on height should be used for cement-based materials in the predicting the channel properties in propagation-related researches.

Interaction of TEOS with cementitious materials: Chemical and physical effects

Abstract: This study explored the effectiveness of tetraethyl orthosilicate (TEOS) as a Portland cement mortar consolidant to verify whether it meets the requirements for use in cultural assets. TEOS was found to raise cement mortar strength, lower its porosity and permeability and occasion minimal alteration in its appearance, an indication of its suitability to conserve heritage mortar works. FTIR and 29Si MAS NMR studies supported the notion that TEOS interacts with the hydrated phases of the cement, portlandite and C–S–H gel. The reaction product between portlandite and TEOS was C–S–H gel and between TEOS and C–S–H gel was a gel with longer chain.

Diagonal compression tests on masonry walls strengthened with a GFRP mesh reinforced mortar coating

Abstract: The paper presents the results of a broad experimental investigation conducted through diagonal compression tests on masonry specimens strengthened with a mortar coating applied on both surfaces of the wall and reinforced with a glass fiber reinforced polymer (GFRP) mesh. Four types of masonry, three different types of masonry mortar and five diverse GFRP meshes for the reinforcement were considered. In particular, solid brick masonry 250 and 380 mm thick, two-leaf brick masonry with rubble conglomerate infill and rubble stone masonry were tested. The diagonal compression tests, performed on 60 square masonry specimens with loading-unloading cycles up to the collapse, evidenced a good effectiveness of the strengthening technique in terms of both resistance and ductility. Results also showed the resistance increment in reinforced samples is generally greater for weaker masonry types and, referring to a single masonry type, for specimens built with a weaker mortar. Furthermore, the different GFRP meshes influenced very little the resistance of specimens, but higher reinforcement contents induced a lower decrease of the diagonal load after the cracking.