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| Normal
Portland cement (NPC) is a high quality general purpose cement and is by far the most
widely used cement type in Ireland. |
| NPC is
made 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 fine powder - Normal Portland cement.
NPC 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 NPC 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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| NPC is
suitable for a wide range of applications where no special or unusual considerations
arise. |
| Typical
applications include use in general readymixed and site-mixed concrete, precast and
prestressed concrete, masonry, mortars, renders and grouts. NPC is also suitable for use
with a wide range of approved additives and admixtures. |
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NPC is suitable for a wide range of applications where no special or unusual considerations arise.
The requirements of Irish Standard I.S. EN 197-1 for CEM I Portland Cement are compared hereunder to typical performance data for class 32,5N and class 42,5N Normal Portland Cements. |
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| I.S. EN 197-1
requires a minimum initial setting time of 60 minutes for class 42,5N and 75 minutes for class 32,5N cements. The initial setting time for NPC
typically exceeds 90 minutes. |
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| Minimum
compressive strengths for standard mortar prisms of 10MPa at 2 days and 42.5MPa at 28 days
are stipulated in I.S. EN 197-1 for cement class 42.5N, in accordance with statistically based
compliance rules. For class 32.5N, the minimum requirements are 16MPa at 7 days and 32.5MPa
at 28 days. |
| Class
42.5N (bulk) typical mortar prism strengths are in the range 50-60 MPa at 28 days for NPC
from both Works, with approx. 75% of this strength being achieved at 7 days. |
| Class
32.5N (packed) typical mortar prism strengths are in the range 40-50 MPa at 28 days for NPC
from both Works, with approx. 75% of this strength being achieved at 7 days. |
| Users
are particularly interested in strength development and durability in concrete. Concrete
strength is significantly affected by mix constituents and proportions, ambient
temperature and the efficiency of 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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