Mortar

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

Measuring the fracture toughness of cement paste and mortar

Abstract: Synopsis This paper describes two methods that have been used to measure the effective fracture toughness of cement pastes and mortars. The first is a notched-beam technique, combined with compliance measurements to measure the slow crack growth prior to instability. The change of toughness is measured for separate increments of crack growth as the crack propagates. The second method, using a double-cantilever beam, avoids the slow crack growth problem by making a specimen of variable web width such that the length of crack front increases with and exactly compensates for the effect of crack growth. Tests of both pastes and mortars show that the fracture toughness of cement paste is independent of crack growth but that the toughness of mortar increases as the crack propagates. For both materials, the stress intensity required to initiate crack growth was less than that to maintain crack growth at the loading rates used.

Laboratory investigation of carbonated BOF slag used as partial replacement of natural aggregate in cement mortars

Abstract: Direct mineral carbonation produces a material rich in carbonates and with reduced quantities of free oxides. The aim of this work was to show that such materials can be used in the construction domain. Basic Oxygen Furnace (BOF) slag from the steelmaking process has been traditionally seen as unfit for bounded applications due to its propensity to swelling, resulting from hydration of its high free lime content. Here, BOF slag was crushed to suitable particle sizes, carbonated in an aqueous solution of carbonic acid, and utilized to replace 50% of natural sand aggregate in cement mortars. The mechanical and chemical properties of these mortars were compared to mortars containing non-carbonated slags, and a standard cement mortar as a reference. Tests were conducted to determine mortar paste consistency and soundness, and cured mortar compressive strength and leaching tendencies. The results showed a satisfactory performance for all considered aspects (comparable with the reference) of the mortar sample containing 37.5 wt% (1.5 in 4 parts solids) carbonated BOF slag of

The reuse of municipal solid waste incinerator fly ash slag as a cement substitute

Abstract: The results of the treatment of fly ash from a municipal solid waste incinerator (MSWI) by melting are described, and the safety and the effectiveness of using the slag produced by this melting treatment are studied. The properties of the MSWI fly ash slag were analyzed, to evaluate the feasibility of its reuse as a substitute for part of the cement required in mortar preparation. This MSWI fly ash slag was found to be comprised mainly of SiO2 and CaO, which can be substituted for up to 20% of the cement content in mortar, without sacrificing the quality of the resultant concrete. In fact, the concrete thus produced has greater compressive strength, 10% higher than that without the substitution. The setting time of the fresh mortar becomes lengthens as increasing amounts of cement are replaced; while the spread flow value increases with the increasing percentage of cement substitution. X-ray diffraction analysis reveals that when the W/C=0.38 and the curing age=28 days, the crystal patterns in the mortar samples, prepared with different amounts of cement having been replaced by MSWI fly ash slag are similar. According to the results of the toxic characteristic leaching procedure analysis, MSWI fly ash slag should be classified as general non-hazardous industrial waste, that meets the effluent standard. Therefore, the reuse of MSWI fly ash slag is feasible, and will not result in pollution due to the leaching of heavy metals.

AMS 14C dating of lime mortar

Abstract: A method for refining lime mortar samples for 14 C dating has been developed. It includes mechanical and chemical separation of mortar carbonate with optical control of the purity of the samples. The method has been applied to a large series of AMS datings on lime mortar from three medieval churches on the Aland Islands, Finland. The datings show convincing internal consistency and confine the construction time of the churches to AD 1280–1380 with a most probable date just before AD 1300. We have also applied the method to the controversial Newport Tower, Rhode Island, USA. Our mortar datings confine the building to colonial time in the 17th century and thus refute claims of Viking origin of the tower. For the churches, a parallel series of datings of organic (charcoal) inclusions in the mortar show less reliable results than the mortar samples, which is ascribed to poor association with the construction time.