Effect of carbon fibres on the mechanical properties and corrosion levels of reinforced portland cement mortars

The changes in mechanical properties of portland cement mortars due to the addition of carbon fibres (CF) to the mix have been studied. Compression and flexural strengths have been determined in relation to the amount of fibres added to the mix, water/binder ratio, curing time and porosity. Additionally, the corrosion level of reinforcing steel bars embedded in portland cement mortars containing CF and silica fume (SF) have also been investigated and reinforcing steel corrosion rates have been determined. As a consequence of the large concentration of oxygen groups in CF surface, a good interaction between the CF and the water of the mortar paste is to be expected. A CF content of 0.5% of cement weight implies an optimum increase in flexural strength and an increase in embedded steel corrosion.

Recolonization of mortars by endolithic organisms on the walls of San Roque church in Campeche (Mexico): A case of tertiary bioreceptivity

San Roque church (Campeche, Mexico) was built at the end of the 17th century with a micritic limestone and lime mortar in baroque style. In 2005 the church exhibited heavy biodeterioration associated with the development of extensive dark green phototrophic-based biofilms. Several cyanobacteria belonging to the order Chroococcales and lichenized fungi (Toninia nordlandica, Lobaria quercizans, Lecanora subcarnea, Cystocoleus ebeneus) were predominant in the dark biofilm samples, as revealed by DNA-based molecular techniques. In 2009, a cleaning and restoration intervention was adopted; however, after few months, microbial recolonization started to be noticeable on the painted church walls, representing an early phototrophic-based recolonization. According to molecular analysis, scanning electron microscopy observations and digital image analysis of cross sections, new phototrophic-based colonization, composed of cyanobacteria and bryophytes, developed mainly beneath the restored mortars. The intrinsic properties of the mortars, the tropical climate of Campeche and the absence of a biocide treatment in the restoration protocol influenced the recolonization of the church façades and enhanced the overall rate of deterioration in a short-term period.

Blending of industrial waste from different sources as partial substitution of Portland cement in pastes and mortars

Binary and ternary combinations of sewage sludge ash (SSA) with marble dust (MD), fly ash (FA) and rice husk ash (RHA) as replacement in Portland cement pastes, were assessed. Several tests were carried out at different curing ages: thermogravimetry, density, water absorption, ultrasonic pulse velocity and mechanical strengths. Pozzolanic effects of the mineral admixtures, densities similar to control sample and improved absorptions when combining waste materials were identified. In general, the compressive strength reaches or exceeds the cement strength class, and blending SSA, FA and RHA (30% cement replacement) increase of strength by 9%, compared to the control sample, was achieved.

Impedance spectroscopy study of the effect of environmental conditions in the microstructure development of OPC and slag cement mortars

In this work, the microstructure of mortars made with an ordinary Portland cement and slag cement has been studied. These mortars were exposed to four different constant temperature and relative humidity environments during a 180-day period. The microstructure has been studied using impedance spectroscopy, and mercury intrusion porosimetry as a contrast technique. The impedance spectroscopy parameters make it possible to analyze the evolution of the solid fraction formation for the studied mortars and their results are confirmed with those obtained using mercury intrusion porosimetry. The development of the pore network of mortars is affected by the environment. However, slag cement mortars are more influenced by temperature while the relative humidity has a greater influence on the OPC mortars. The results show that slag cement mortars hardened under non-optimal environments have a more refined microstructure than OPC mortars for the studied environmental conditions.

The royal atlas of England and Wales, reduced from the ordnance survey; a complete series of topographical maps, physical and statistical charts, town plans, and index of 35,000 names ..

Mode of access: Internet.

Catalogue of the maps and plans and other publications of the Ordnance Survey of England and Wales, and the Isle of Man, to 1st January 1894 ...

Supplemented by: Publications issued ... January, 1894[-June 1895]. [London : H.M.S.O., 1894-1895]. 18 no. Caption title. Number for April 1895 wanting. Bound with Catalogue of maps and plans ... of England and Wales, and the Isle of man, to 1st of Jan. 1888.

Explosive ordnance disposal unit operations /

Template in pocket.

Experimental researches on the constitution of hydraulic mortars,

Mode of access: Internet.

Cements, mortars and concretes, their physical properties,

Mode of access: Internet.

Operative masonry; or, A theoretical and practical treatise of building; containing a scientific account of stones, clays, bricks, mortars, cements, &c.; a description of their component parts, with the manner of preparing and using them. The fundamental rules in geometry, on masonry and stone-cutting, with their application to practice. Illustrated with forty copper-plate engravings.

Republished in 1846 with title: Practical masonry: or A theoretical and operative treatise of building ...

The Reigate sheet of the one-inch Ordnance survey; a study in the geography of the Surrey hills,

Maps in detached pocket.

Reports of experiments with small arms for the military services, by officers of the Ordnance Department, U.S. Army.

Mode of access: Internet.