Compressive mortars

Pipelines in the ground can be mortar lined in situ by the use of travelling devices. Epoxy resin paints for long welded pipelines already laid have been applied in situ by placing two plugs in the pipeline with the paint between them, and then forcing them to travel through the pipeline by the use of compressed air. 

In theory, increased quantities of the organic compound finely ground with constant quantities of potassium bromide should give infrared spectra of increasing intensity. However, good quantitative results by this direct procedure are difficult to obtain due to problems associated with the non-quantitative transfer of powder from the small ball-mill grinder (or pestle and mortar) into the compression die. These are only partially overcome by using a micrometer to measure the final disc thickness. 

The addition of STPP (1-7%) acted as a retarder and increased compressive strength (mortar II). Less heat and ammonia were evolved and the cement set more slowly in 10 minutes. The paste hardened in 30 to 60 minutes. Traces of ADP persisted for 30 minutes but no STPP was detected in the reaction products. Struvite, the main hydration product, schertelite and dittmarite all appeared within 5 minutes. Struvite continued to increase in amount as the cement aged schertelite disappeared after 3 hours and dittmarite after a week. Stercorite was found only during the first 7 hours. 

The addition of STPP improved the compressive strength of the mortar which reached 19-5 MPa in 24 hours. The total pore volume was reduced to 70-4 mm g and the coarse pore volume to 55-4 mm g L... 

Current research related to biological additives is focused particularly on their influence on the properties of mortars, namely on porosity, tensile strength, compressive strength, drying shrinkage, etc. [23, 24, 26], The identification of proteinaceous additives used in historical buildings has been marginal for many years and no reliable methods are properly described in the literature. 

The blast capacity and ductility of reinforced masonry walls is much lower than the capacity that can be achieved with reinforced concrete of comparable dimensions. The lower capacities are due to the limited available space for placing steel reinforcing, the lower compressive strength of the masonry, and the limited mortar bond strength. 

In addition, compression methods that utilize hydraulics and levers may be used. These sometimes have pressure gauges that allow the analyst to apply a certain optimal force in order to maximize the chances of making a quality pellet. To make a quality pellet, in addition to using the optimum pressure, it is important for the KBr and the sample to be dry, finely powdered, and well mixed. An agate mortar and pestle is recommended for the grinding and mixing of the KBr and sample prior to compression. See Workplace Scene 8.3. 

C 531 Test Method for Linear Shrinkage and Coefficient of Thermal Expansion of Chemical-Resistant Mortars, Grouts, and Monolithic Surfacings C 579 Test Methods for Compressive Strength of Chemical-Resistant Mortars and Monolithic Surfacings... 

C 579 Standard Test Method for Compressive Strength of (Method B) Chemical Resistant Mortars and Monolithic Surfacings C 882-87 Standard Test for Bond Strength of Epoxy-Resin Systems Used with Concrete C 884-87 Standard Test Method for Thermal Compatibility between Concrete and an Epoxy-Resin Overlay... 

Alkyl alkoxy silanes have been found to be very effective in reducing alkali-aggregate expansion [11] (Fig. 6.4). Of the silanes used in the study, hexyl trimethyl siloxane and decyl trimethoxyl silane were found to be more effective in decreasing the expansion than the others. In the same study, Ohama et al. [11] investigated the effect of sodium silicofluoride, alkyl alkoxy silane, lithium carbonate, lithium fluoride, styrene-butadiene rubber latex and lithium hydroxide on compressive strength and the expansion of mortar containing cement with 2% equivalent Na20. The reduction of the level of expansion shown in Fig. 6.4 with the siloxanes was attributed to... 

Surfactants enable the polymer particles to disperse effectively without coagulation in the mortar and concrete. Thus, mechanical and chemical stabilities of latexes are improved with an increase in the content of the surfactants selected as stabilizers. An excess of surfactant, however, may have an adverse effect on the strength because of the reduced latex film strength, the delayed cement hydration and excess air entrainment. Consequently, the latexes used as cement modifiers should have an optimum surfactant content (from 5 to 30% of the weight of total solids) to provide adequate strength. Suitable antifoamers are usually added to the latexes to prevent excess air entrainment increased dosages causes a drastic reduction in the air content and a concurrent increase in compressive strength [87, 92-94]. 

Such effects increase with an increase in the polymer content or the polymer-cement ratio (the weight ratio of total solids in a polymer latex to the amount of cement in a latex-modified mortar or concrete mixture). However, at levels exceeding 20% by weight of the cement in the mixture, excessive air entrainment and discontinuities form in the monolithic network structure, resulting in a reduction of compressive strength and modulus [87, 94, 95]. 

Mortar (Vol 1, p XIX) [Barnett (1919), 181-82] Note Accdg to L.V.Clark, IEC 25, 1388 (1933), the relative propulsive strength can be determined either by Ballistic Pendulum Test or Trauzl Test, usual trsts for power determination. The Pb block compression value is regarded as a measure of relative brisance while Fragmentation tests in hand-grenade bodies measure relative shattering power... 

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