Accredited manufacturer of masonry blocks
Intercrete Midi Masonry Units
Lightweight, flexible masonry units under 20kg, with compressive strengths up to 40N/mm2, compliant with HSE guidelines and BS EN 771-3.
A general purpose, solid masonry unit produced using natural dense Class 2 aggregates. Designed to allow Architects and Designers to specify a 140mm wide unit, with a unit weight of less than 20 kg, making it suitable for single person repetitive lifting. Available in strengths of 7.3N/mm2 to 40N/mm2. Where greater load distribution is required Midi units can be laid flat to produce a wall of 215mm width.
Key Features
Key Features of High-Strength Masonry Blocks
- Low Unit Weight, less than 20kg
- Complies with HSE Guidelines on Manual Handling
- Design flexibility with 140mm width
- Wide range of compressive strengths 7.3 - 40N/mm2
- Performance characteristics similar to conventional solid Intercrete units
- Available as standard or close textured version
- Manufactured to BS EN 771-3 & associated test standards
Applications
Intercrete Midi units are intended for use in walls above and below DPC, including use in sulphate soil classes DS-1, DS-2 and DS-3. They are particularly suitable where high strength and acoustic sound requirements are specified. They can be plastered, rendered or drylined. Midi units are also available in a close textured version for walls to be built fair, left undecorated or paint finished.
The thermal conductivity values are based CIBSE Guide 1999.
THERMAL CONDUCTIVITY
CONCRETE DENSITY | W/mK (LAMDA VALUE) | |
3% 1.28 | 5% 1.37 | |
For a unit width of 140mm, the thermal resistance may be taken as 0.11m2W/K at 3% moisture content.
The wall ‘U’ value must be calculated using method in BS EN ISO 6946.
The sound reduction values for standard and close textured Midi units. This data is based on the Mass Law.
SOUND REDUCTION (VALUES IN dB)
WALL THICKNESS | 140mm | 215mm |
NO FINISH | 49 | 50 |
PAINTED | 50 | 51 |
LIGHTWEIGHT PLASTER* | 51 | 54 |
DENSE PLASTER* | 52 | 55 |
DRY LINED* | 51 | 54 |
For compliance with Building Regulations AD E Wall Type 1.1., Midi units laid to a 215mm width should provide similar performance to 100mm solid blocks laid flat.
140mm width solid units.
Face work size 290mm x 215mm.
Tolerances as EN 771-3, Tolerance category D1 .
Unit length and height +3, -5mm.
Unit width +3, -5mm.
Relationship of density / strength.
EN772-13 Gross Dry Density – Category II Materials.
7.3 N/mm2 -17.5 N/mm2, 2000 kg/m3.
22.5 N/mm2 – 40 N/mm2 , 2050 kg/m3.
EN 1745 Table A3 Water vapour diffusion coefficient μ 5/15.
As tested to EN 772-14 : 2002.
Total movement = 0.27mm/m.
Static modulus of Intercrete Midi is approximately 3-8kN/mm2.
Frost-resistance in accordance with PD 6697.
Declared Value 0.15N/mm2 in accordance with EN 998-2 Annex C.
Coefficients of linear expansion is 10 x 10-6/0C.
Lightweight plaster. Suitable undercoats include British Gypsum’s Thistle Bonding , Thistle Hardwall and Thistle Tough Coat. The finishing coat can include Thistle Multi-Finish.
Dense plaster. A backing coat of 1:1:6 cement: lime: sand or 1:5 to 6 cement: sand, with added plasticiser with a setting coat of gypsum plaster, e.g. Thistle Multi-Finish or similar.
Depending on exposure conditions, it may be necessary to treat the surface with a spatterdash coat of 1:1 cement: sand: followed when dry and hard with a backing coat 10mm thickness of 1:1:6 cement: lime: sand, ruled out, and lightly scratched.
A final or subsequent coat of 5 mm thickness using the same mix finished with a wood float, is applied. All types of paint finishes are satisfactory.
In housing where walls are often plastered, ceramic tiling is fixed with proprietary adhesive. In buildings other than housing, the wall is rendered using a mix of 1:4 cement: sand, ruled out level, and the tiles are fixed using an adhesive. Adequate drying time should be given to the render coat before tiling commences.
Midi Close Textured units can be painted directly using cement or water-based paints. An economic finish can be achieved using a mist coat (diluted emulsion) followed by 2 coats of emulsion. The paint can be brush or spray applied. The opacity will depend upon the quality of the paint and the number of coats applied.
Drylining using Gypsum Wallboard or similar, fixed either by adhesive dabs, or screw fixing to metal firrings, or nailing to timber battens. If required, thermal laminate plasterboards can be used, fixed in accordance with the manufacturer’s recommendations.
Mechanical cutting is recommended and essential for masonry units built fair and reduces wastage.
Chasing dense concrete material is laborious and should be avoided whenever possible.
If unavoidable it should be carried out using mechanical means.
Fixings for domestic fittings can be made using traditional plugs and screws. Refer to Interfuse Design Guide for further information.
Interfuse Ltd operates a formalised Quality Assurance system at both Syston and Gainsborough plants. All masonry units are subject to stringent quality control checks and are tested daily in our
own laboratory.
A documented factory production control system is in operation with regular checks made on raw materials, production and finished units. A stock control system is in operation with written procedures for non-conforming products. All products are produced to the current European Standards.
Each pack is marked for traceability of product and unit clarification as given on the delivery ticket.
Interfuse Ltd is certified to BRE’s Standard for Responsible Sourcing of Construction Products, BES 6001, obtaining a “Very good” performance rating.
The environmental impact of Midi constructions can be assessed by referring to BRE’s Green Guide to Specification, with many constructions achieving the highest A or A+ rating.
At the end of the life of the building, Midi units, which are inert, can be crushed down and recycled. Their use in buildings will far exceed the usual 60-year design life expectancy, making Intercrete Midi a very sustainable material.
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UNIT AND LAID WEIGHTS
UNIT WEIGHT (kg) | LAID WEIGHT INC. MORTAR | LAID WEIGHT INC. MORTAR | |
Midi 7.3, 10.5, 17.5 – 40N/mm2 | 18.0 | 280 | 430 |
The following Fire Resistance table is based upon EN 1996–1–2: 2005, Table NA.3.1 and NA.3.2. These are valid for walls without finishes, designed to EN 1996.
FIRE RESISTANCE (HOURS)
| BLOCK THICKNESS (mm) | ||
| (CRITERIA) | 140 | 215 |
MIDI UNITS – ANY STRENGTH | |||
NON-LOADBEARING | (E1) | 4 | 4 |
LOADBEARING | (RE1) | 3 | 4 |
Suitable mortar mixes for use with Midi blocks are shown in Table 5. The thickness of mortar joints should be approximately 10mm.
RECOMMENDED MORTAR MIXES
LOCATION | MORTAR DESIGNATION | COMPRESSIVE STRENGTH CLASS | PRESCRIBED MIX |
WORK ABOVE DPC | (iii) | M4 | 1:1:6 cement: lime: sand, or 1:5 to 6 cement: sand* |
WORK BELOW DPC | (iii) | M4 | 1:1:6 cement: lime: sand, or 1:5 to 6 cement: sand* |
(ii) | M6 | 1½: 4 to 4½ cement: lime: sand or 1:3 to 4 cement: sand* | |
| * Mixes can be used with or without air entrainment. Plasticisers should be used only with the designer’s approval and should be gauged in accordance with the manufacturer’s written instructions. | |||
Prices quoted per 10 units. 15 units to m2 of wall. All prices include mechanical off-loading and apply to full loads. Load sizes may vary between 19 tonne Rigids, 20 – 27 tonne Artics.
Part Loads are subject to special quotations.
Units per pack – 72 Weight per pack – 1.27 tonne.
19 tonne load Approx no of units per load – 1008.
Artic load.
Approx no of units per load – 1512.
Units should be stored on firm, level ground no more than 2 packs high.