Compressive strength mortar

The effects of sodium, potassium, and magnesium oxides on the strength of mortar were investigated by Ono, Hidaka, and Shirasaka (1969) and optimum percentages were established. These authors concluded that mortar compressive strength was related to abundances of alpha and alpha-prime belite. 

Mortar compressive strength [MPa] at the different time points ... 

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. 

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]. 

Figure I. Variation in compressive strength of sulfur mortars with hydrogen sulfide content before mixing (18)...

The compressive strength depends on water content and curing time. Mortars with less water showed higher strength. For example, a solid-to-water ratio of 8 gave a compressive strength of 19.5 MPa (2790 psi) in 24 h, while the mortar made with a solid-to-water ratio of 16 attained a strength of 27.4 MPa (3910 psi). 

American Society for Testing of Materials, Standard test for compressive strength of hydraulic cement mortars, C109/C109M-02, (2003). 

The test material was a cementitious mortar made of a Portland cement CEM142.5 and sand with maximum grain size of 4 mm. The blend ratio was 1 3 cement to sand by mass. The water/cement ratio was 0.44. Five 140 x 140 x 560 mortar prisms were produced. After demolding they were stored under water for 90 days. The mortar is characterized by a compressive strength of 61.9 N mm , a bending strength of 8.83 N mm and a bulk density of 2.37 g cm (determined according to DIN-EN 196-1 [8] at 28 days). 

Concretes and mortars rapid cure early, high compressive strength even at low temperatures Galvanic protection of bridge decks Filling cable slots Areas where rapid cure and early strength are required... 

C-579 Compressive strength of chemical-resistant mortars, grouts, monolithic surfacing and polymer concrete (based on resin, silicate, silica and sulphur binders). 

Brick and mortar materials should only be used alone where the fact that gas and liquid can penetrate, though slowly, through them is not important, but where their considerable compressive strength (load bearing ability), combined with their resistance to chemical attack can be useful. Examples of these types of structures are self-supporting chimney liners (some of them 800+feet tall), foundations set in acid contaminated soil, and supports for chemical equipment subject to splash or spill. 

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