Sodium phosphate-derived calcium phosphate cements

Journal Article · Sun Jan 01 00:00:00 EST 1995 · Cement and Concrete Research; (United States)

DOI:https://doi.org/10.1016/0008-8846(94)00117-H· OSTI ID:6494311

Sugama, T; Carciello, N R ^[1]

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1. Brookhaven National Lab., Upton, NY (United States)

Calcium phosphate cements (CPC) were synthesized by the acid-base reaction between sodium phosphate, NaH[sub 2]PO[sub 4] or -(-NaPO[sub 3]-)-[sub n], as the acid solution, and calcium aluminate cements (CAC) as the base reactant at 25 C. The extent of reactivity of -(-NaPO[sub 3]-)-[sub n] with CAC was much higher than that of NaH[sub 2]PO[sub 4], thereby resulting in a compressive strength of > 20 MPa. Sodium calcium orthophosphate (SCOP) salts as amorphous reaction products were responsible for the development of this strength. When this CPC specimen as exposed in an autoclave, in-situ amorphous [r arrow] crystal conversions, such as SCOP [r arrow] hydroxyapatite (HOAp), and Al[sub 2]O[sub 3] [center dot] xH[sub 2]O [r arrow] [gamma]-AlOOH, occurred at [approx] 100 C, while the rate of reaction of the residual CAC with the phosphate reactant was increasingly accelerated by hydrothermal catalysis. Based upon this information, the authors prepared lightweight CPC specimens by hydrothermally treating a low-density cement slurry (1.28 g/cc) consisting of CAC powder, -(-NaPO[sub 3]-)-[sub n] solution, and mullite-hollow microspheres. The characteristics of the autoclaved lightweight specimens were a compressive strength of > 9.0 MPa, water permeability of [approx] 5.0 [times] 10[sup [minus]3] milli darcy, and a low rate of alkali carbonation. The reasons for such a low carbonation rate reflected the presence of a minimum amount of residual CAC, in conjunction with the presence of HOAp and [gamma]-AlOOH phases that are unsusceptible to wet carbonation.

• OSTI ID: 6494311
• Journal Information: Cement and Concrete Research; (United States), Vol. 25:1; ISSN 0008-8846
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALCIUM PHOSPHATES
SYNTHESIS
CEMENTS
COMPRESSION STRENGTH
PERMEABILITY
CRYSTAL-PHASE TRANSFORMATIONS
PHASE STUDIES
ALKALINE EARTH METAL COMPOUNDS
BUILDING MATERIALS
CALCIUM COMPOUNDS
MATERIALS
MECHANICAL PROPERTIES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHOSPHATES
PHOSPHORUS COMPOUNDS
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