Compressive strength effect

Reeder, J.R. (1995). Stitching vs a toughened matrix compression strength effects. J. Composite Mater. 29, 2464-2487. 

Density and polymer composition have a large effect on compressive strength and modulus (Fig. 3). The dependence of compressive properties on cell size has been discussed (22). The cell shape or geometry has also been shown important in determining the compressive properties (22,59,60,153,154). In fact, the foam cell stmcture is controlled in some cases to optimize certain physical properties of rigid cellular polymers. 

A 2.54-cm Styrofoam plastic foam with thermal conductivity of ca 0.03 W/ (m-K) (0.21 (Btu-in.)/(ft-b°F)) is equivalent to 61 cm of gravel. Any synthetic foam having compressive strength sufficiently high and thermal conductivity sufficiently low is effective. However, the resistance of PS-type foams to water, frost damage, and microorganisms in the sod makes them especially desirable. An interesting and important appHcation of this concept was the use of Styrofoam in the constmction of the Alaska pipeline. In this case, the foam was used to protect the permafrost. 

Fig. 5. The immediate effect of temperature on strength properties of clear wood, expressed as percentage of value at 20°C. Trends illustrated are composites from studies on three strength properties modulus of mpture in bending, tensile strength perpendicular to grain, and compressive strength parallel to grain. VariabiUty in reported results is illustrated by the width of the bands. MC = moisture content.

Jones, O.E. and Graham, R.A., Shear Strength Effects on Phase Transition Pressures Determined from Shock Compression Experiments, in Accurate Characterization of the High Pressure Environment (edited by Lloyd, E.C., National Bureau of Standards Special Publication 326, US Government Printing Office, Washington, DC, 1971, pp. 229-242. 

Table 4-158 shows the effect of silica flour on the compressive strength of Class G cement cured at 700°F. 

Effect of Silica Flour on the Compressive Strength of Class G Cement Cured at Pressure... 

Hematite. This additive can be used to increase the specific weight of a cement slurry to as high as 19 Ib/gal. This is an iron oxide ore with a specific gravity of about 5.02. Hematite requires the addition of some water when it is used as an additive. Hematite has minimal effect on thickening time and compressive strength of the cement. 

Ilmenite. This additive has a specific gravity of about 4.67. It is a mineral composed of iron, titanium and oxygen. It requires no additional water to be added to the slurry thus, it can yield slurry specific weights as high as the hematite additive. Ilmenite also has mineral effect on thickening time and compressive strength of the cement. 

Attempts have been made to improve the mechanical properties of these cements by adding reinforcing fillers (Lawrence Smith, 1973 Brown Combe, 1973 Barton et al, 1975). Lawrence Smith (1973) examined alumina, stainless steel fibre, zinc silicate and zinc phosphate. The most effective filler was found to be alumina powder. When added to zinc oxide powder in a 3 2 ratio, compressive strength was increased by 80 % and tensile strength by 100 % (cements were mixed at a powder/liquid ratio of 2 1). Because of the dilution of the zinc oxide, setting time (at 37 °C) was increased by about 100%. As far as is known, this invention has not been exploited commercially. 

Figure 5.9 The effect of SiOj/AljOj mass ratio on setting time, compressive strength and opacity (Hill Wilson, 1988a).

Table 5.13. Effect of fluorides on glass polyalkenoate cement compressive strength, MPa (Crisp, Merson < Wilson, 1980)...

Figure 6.21 The effect of powder/liquid ratio on setting time and compressive strength of a dental silicate cement (Wilson Batchelor, 1967b).

Brauer, Stansbury Flowers (1986) modified these cements in several ways. The addition of various adds - acetic, propionic, benzoic etc. -accelerated the set. The use of zinc oxide powders coated with propionic add improved mixing, accelerated set, reduced brittleness and increased compressive strength from 63 to a maximum of 72 MPa. The addition of plasticizing agents such as zinc undecenylate yielded flexible materials. Incorporation of metal powders had a deleterious effect and greatly increased the brittleness of these cements. The addition of fluorides was not very successful, for fluoride release was not sustained. 

Ilmenite has a specific gravity of 4700 kg/m. It requires no addition of water when added to the slurry. Ilmenite has a minimal effect on the thickening time and compressive strength. Barite requires more water then hematite when added to the cement. This results in a decrease of the compressive strength of the set cement. 

Proppants are solid particles used to hold open the fracture after conclusion of the well treatment. Criteria to choose the economically most effective proppant for a given set of formation conditions have been discussed (7 6). While sand is the most commonly used proppant because of its low cost, resin-coated sand, sintered bauxite, and A O particles have also been used because of their greater compressive strength and resistance to dissolution at high temperature and pH (55). While epoxy resins are most commonly used, the use of other resins such as phenol-formaldehyde has been described. 

Shih, G.C. and Ebert, L.J. (1986). Interface strength effects on the compressive-flexure/shear failure mode transition of composites subjected to four-point bending. J. Mater. Sci. 21, 3957-3%5. 

Waas, A.M. (1992). Effect of interphase on compressive strength of unidirectional composites. J. Appl. Mech. 59, S183-S188. 

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