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| Rapid Hardening Portland cement (RHPC) is a special purpose cement used in
concrete to ensure a higher rate of early age strength development than that typically
achieved using Normal Portland cement (NPC). The improved early age strength performance
of RHPC is principally achieved through increased product fineness. |
| RHPC is made - in the same manner as NPC - by fusing together a precisely
controlled blend of very finely ground limestone and shale at high temperatures to form
cement clinker. A small quantity of gypsum is added to this clinker before grinding to
produce the final, very fine powder - Rapid Hardening Portland cement. RHPC is
manufactured in modern dry process works at Castlemungret, Co. Limerick, and Platin Co.
Meath, and is supplied either in bulk or in bags. |
| The quality of all RHPC produced by the company is guaranteed to meet in full the requirements of I.S. EN 197-1 : 2001, 'Cement- Part 1: Composition, specifications and conformity criteria for common cements'. The product is independently certified to I.S. EN 197-1 by the National Standards Authority of Ireland and bears the CE mark in accordance with the requirements of the EU Construction Products Directive. |
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| Typical applications of RHPC include precast concrete production, the
manufacture of concrete masonry, urgent repair work and cold weather concreting. |
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Regular information is available on the performance aspects of RHPC which are of direct interest to specifiers and users.
The requirements of Irish Standard I.S. EN 197-1:2001 for CEM I Portland cement are compared hereunder to typical performance data for Rapid Hardening Portland Cement class 42,5R |
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| I.S. EN 197-1
requires a minimum initial setting time of 60 minutes. Initial
setting time for RHPC typically exceeds 75 minutes. |
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| Minimum compressive strengths for standard mortar prisms of 20 MPa at 2
days and 42.5 MPa at 28 days are stipulated in I.S. EN 197-1
for cement class 42.5R, in
accordance with statistically based compliance rules.
Class 42.5R typical mortar prism
strengths are in the range 28-32 MPa at 2 days and 55-62 MPa days for RHPC from both
Works.
Users are particularly
interested in strength development and durability of concrete. Concrete strength is
significantly affected by mix constituents and proportions, ambient temperature and the
efficiency of the site curing. A durable concrete requires an adequate cement content and
a low water/cement ratio. Guidance is available in Irish Standards for concrete and
concrete products and for all applications, directly from Irish Cement's Technical
Marketing Department. |
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| Portland cement clinker consists predominantly of compounds formed from calcium, silica, alumina and iron. Calcium sulfate is present in cement due to the gypsum addition to control setting time and up to 5% of minor additional constituents may be added in accordance with I.S EN 197-1. Typically, minor additional constituents are pfa (Limerick Works) and raw meal (Platin Works).
Specific chemical data (e.g. alkalis and chlorides) is provided regularly on test certificates.
Detailed information on chemical and compound composition is available on request. |
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