FOAMED CONCRETE

1. INTRODUCTION
2. TERMS OF REFERENCE
3. WHY USE FOAMED CONCRETE?
4. DISADVANTAGES OF FOAMED CONCRETE/MORTARS
5. FOAM GENERATION OVERVIEW
6. METHODS OF FOAM UTILISATION
7. DESIGNING WITH LIGHTWEIGHT CONCRETE
8. LIGHTWEIGHT CONCRETE PRODUCTS & SERVICES
9. FOAMED CONCRETE MIX, STARTING POINT FORMULATIONS
10. SUMMARY OF FOAMED/LIGHTWEIGHT CONCRETE BENEFITS
11. TYPICAL THERMAL INSULATION VALUES OF FOAMED CONCRETE
12. TYPES OF FOAMING EQUIPMENT PRODUCED

INTRODUCTION

1. In the context of this article we refer to foam as it may be utilised within mortar and concretes.
2. Foaming agent is supplied as a liquid concentrate.
3. One litre of concentrate produces nom 1000 litres foam.
4. Mixing of compressed air and diluted concentrate produces foam very similar to shaving cream.
5. If foam is split or left in an open container it reverts back to a liquid in minutes or hours depending on volume.
6. Very mildly corrosive having a PH of 6.5-7.
7. When immediately introduced and mixed with mortar does not revert to water as per point 5 (above).

TERMS OF REFERENCE

There are many terms descriptive of foamed concrete or mortars – to name a few: Cellular Concrete – Lightweight Concrete – Aerated Concrete etc, plus proprietary product names/terms.

WHY USE FOAMED CONCRETE?

There are many varied justifiable reasons one may specify foamed concrete/mortars:

1. Cost reduction – nom ten percent of the cost of the cements and aggregates replaced
2. Far superior thermal insulation (varies with product density)
3. Will not spall under the influence of directly applied intense flame (at SG 1.4 or less)
4. Acoustically superior to dense weight product due to sound absorption rather than sound reflection.
   
   NOTE There are many variables that influence acoustic test results – product density; sound frequency spectrum; coatings if any etc
   
   
5. Does not give off toxic gases under the influence of flame
6. Totally environmentally friendly – both in the production process and of product

DISADVANTAGES OF FOAMED CONCRETE/MORTARS

When proposing to utilise foamed concrete it is important to consider all design criteria particularly in the following areas

1. Compressive and Flexural strength will degrade typically as a function of density
2. Retention values of attachment fixtures – again this is a function mainly of density. Particular attention needs to be given to those areas where continuous impact may occur – door jambs etc
3. Unless purpose designed equipment is used mixing may be a problem as the foam tends to float at the surface of the mix and thus its effectiveness is diminished. Issue readily addressed be injecting foam into rather than on to mix in the case of an open mixer, or in the case where foam is introduced into a flowing product line it is not a problem.

FOAM GENERATION OVERVIEW

1. Foam concentrate – Condor CA300 – is poured into a container – 1 percent of container volume and the container then filled with clean water. (Referred to as foaming agent dosing water).
2. Dosing water is then metered into a compressed air stream prior to the introduction into a static generator.
3. Resultant foam from generator discharge has volume of nom 10 times that of the dosing water.
4. Conversion factors:
   
   • Concentrate diluted with water – 100:1
   • Dosing water to foam – 10:1
   • Therefore the conversion factor from concentrate to foam = 100 x 10 = 1000. That is to say that one litre on concentrate (Condor CA300) yields 1000 litres of foam.

METHODS OF FOAM UTILISATION

1. In the case of ready mixed agitator application, all the raw materials are metered into the agitator (according to design specs) and with the agitator turning at a high speed, a predetermined electronically batched volume of foam is shot into agitator.
   
   • Typically the batching both of raw materials and foam are done at the Ready Mixed Concrete batching plant and then to travel to site.
   • A preferable procedure is to batch all the raw materials at the R.M.C. plant and then to have the foam introduced at the job site.
   
   NOTE: A. Since the lower density light weight has a very high slump, one would benefit from a larger payload per trip should the foam volume be applied at the site.
   B. With continual mixing over a long period of time will cause some loss of the foam from within the mix and thus increase the SG of product.
   
   
2. Site mixing of all the raw materials plus precisely metered foam can be routinely achieved with suitably designed equipment. The Condor MPS303B fitted with the foam generation option routinely produces lightweight mortars to any desired and consistent density at the rate of nom 110 litres per 5 minutes. IE about 1.3m3 per hour.
3. A further more recent development is that of producing foam at a rate directly proportional to the flow rate of premixed raw materials. A hydraulically driven positive displacement product pump pumps the premixed product – a second hydraulic motor drives the foam generation equipment and is in series with the product pumps hydraulic motor. With the foam and product entering an inline powered mixer the process is complete, resulting in a foamed product of consistent density regardless of pumping rate.

We believe that this is a world first development and having great potential. The technology we employ is freely available to any of our overseas competitors and in the interest of promoting better applications through the use of foamed concrete.

DESIGNING WITH LIGHTWEIGHT CONCRETE

Designing structures using lightweight concretes requires engineering input just as applies to steel timber etc. There are many consultants who are quite capable of guiding you in achieving the optimum benefits of this technology. You would be strongly advised to take advantage of their services – which whilst being an expense – in the longer term would yield significant benefits – be it cost saving – or better product performance.

LIGHTWEIGHT CONCRETE PRODUCTS & SERVICES

1. Site mixing and production equipment
2. Precision foam production and batching equipment
3. Proportional foam/product production equipment
4. Foam generating liquid concentrate
5. Equipment design consultation to foreign equipment manufacturers
6. Referral service – consultants, builders, specifying bodies
   

FOAMED CONCRETE MIX, STARTING POINT FORMULATIONS

1. Volumes stated relate to 1 cubic metre of final product
2. Sand = clean washed dune sand of nominally 0.75mm grain size maximum
3. Cement – Ordinary Portland Cement
4. Foam Volume = Foam generated using Condor CA300 concentrate
5. One litre of CA300 produces 1000Ltrs of foam

Density kg/m3	Sand kg	Cement kg	Ltrs Base Mix	Foam Ltrs*	MPA 7 days	MPS 28 days
1600 1600 1400 1400 1200 1100 1100 1000 900 900 800 700 700 600 600 500 400 300	1235 1145 1080 995 860 785 690 630 560 410 365 320 0 275 0 0 0 0	310 385 270 330 290 265 345 315 280 410 365 320 580 275 495 415 330 250	583 572 510 496 430 393 381 348 309 292 260 228 185 196 158 133 105 80	417 428 490 505 570 608 620 653 691 709 741 773 815 805 842 868 895 920	9.5 12 6 8 4 3 3.8 2.2 1.4 3.5 2.5 1.4 2.2 0.8 3.5 2 0.8 0.3	19 18 13 16 10 7 8.5 5.2 3.2 8 6 3.5 4.3 2 8 4.5 1.5 0.7

*Divide by 1000 for foam concentrate volume.

NOTE: Due to sand and cement variables it is advisable where possible
to carry out tests to confirm that specification values are achieved.

• Water – Cement Ratio- Typically allow 40-45 litres water per 100KG cement
• Batch up appropriate quantities of sand and cement – add water to suit and mix thoroughly
• Adjust water to compensate for moist or wet sand
• Depending on target density the mix should be quite fluid
• Add foam preferably into mix rather than on to mix and continue mixing (foam being very light will float – hence the preference for injecting into mix)

SUMMARY OF FOAMED/LIGHTWEIGHT CONCRETE BENEFITS

• Lower cost
• Better thermal insulation
• Will not spall under the influence of direct flame (typically at 1400KG/m3 or less)
• Minimises bleed water
• Improved pumping characteristics
• Reduced sound transmission
• Lower transportation costs- 1000 ltrs from 1 ltr of concentrate

TYPICAL THERMAL INSULATION VALUES OF FOAMED CONCRETE

THERMAL TRANSMISSION COEFFICIENT BY THICKNESS OF PANEL

Concrete Density kg/m3	Conductivity Co-efficient	50mm	80mm	100mm	120mm	150mm	180mm	200mm
300 400 400 600 700 800 900 1000 1100 1200 1400 1600	0.65 0.075 0.097 0.116 0.135 0.155 0.17 0.2 0.22 0.275 0.348 0.439	1.02 1.2 1.37 1.58 1.24 1.38 1.53 1.7 1.83 2.01 2.3 2.05	0.75 0.84 0.95 1.13 1.02 1.16 1.35 1.45 1.58 1.76 2.05 2.34	0.58 0.7 0.79 0.94 0.9 1 1.14 1.28 1.4 1.56 1.84 2.15	0.5 0.6 0.7 0.82 0.75 0.84 0.95 1.08 1.18 1.33 1.59 1.05	0.42 0.49 0.55 0.67 0.64 0.72 0.82 0.95 1.03 1.16 1.4 1.64	0.33 0.42 0.49 0.58 0.59 0.65 0.76 0.85 0.95 1.05 1.29 1.53	0.31 0.38 0.44 0.53 0.48 0.55 0.62 0.69 0.78 0.99 1.09 1.3

**IMPORTANT**

1/ the above values are presented as starting point values only.

2/ foam volume accuracy is most critical for consistent

** our company policy does not allow the supply of foam generation equipment unless output volumes may be calibrated and accuracy repeatable.

TYPES OF FOAMING EQUIPMENT PRODUCED

• Site mixing and pumping units fitted with precision foam generation and injection to any density.
• Stand alone generators for the Ready Mixed Concrete industry. Precision batching using electronic flowmeters with rotary digital volume selection to nominally 1500Ltrs/min.
• Proportional in line generation, i.e. pre-mixed ingredients are fed through a foam generator mixed and then fed into pump intake. Any required density or flow rate.