Focus on quality and efficiency in mortar production on construction sites
Forced-action mixer or conventional Concrete Mixer - which is the right choice?
Which machine type makes sense for which material applications?
Mixing mortar and concrete directly on the construction site is still a central component of many construction projects – especially where flexibility, smaller quantities or special formulations are required. It is not just a question of the right mixing ratios, but also of choosing the right mixing system. Two fundamentally different mixer types are available: Concrete Mixers (drum-style mixers) and Forced-action Mixers (pan or trough mixers)
Ready-mixed material or self-produced mortar
The use of factory-made dry mortar – i.e. ready-mixed mortar in sacks – is widespread on construction sites today. These materials offer many advantages in terms of quality assurance, shelf life and ease of processing. Nevertheless, when mixing on the construction site – especially with free-fall mixers or forced-action mixers – there are a few important points to bear in mind to ensure the full performance of the material. In any case, the material manufacturer's specifications for the material must be observed.
If you want to producemortar yourself on the construction site – i.e. without using factory-made dry mortar or ready-mixes – there are several aspects to consider in order to ensure a durable, workable and standard-compliant mixture.
Binders
Lime (air or hydraulic), cement or mixed forms.
Must be dry and lump-free.
For cement: ensure freshness (max. 6 months storage time).Aggregates (sand, possibly gravel)
Grain size suitable for the intended use (e.g. 0-4 mm for masonry mortar).
Free of organic components, clay, silt or salts.
Use washed sand if possible.Water
Drinking water quality is mandatory.
No contaminated sources (e.g. rainwater from containers).Mixing ratio
Must correspond to the intended use (e.g. 1 part cement : 4 parts sand for masonry mortar).
For lime mortar: Ratio dependent on air or hydraulic lime.
Add water precisely – too much water reduces strength and increases shrinkage cracks.Freshness and pot life
Mortar must be applied promptly – do not store for hours.
With hydraulic binders, hardening begins immediately after mixing.Consistency check
Mortar must be workable but stable.
Fist test or trowel test for inspection.Weather influences
Do not mix or process in frost or extreme heat.
Protect fresh mortar from drying out or rain.Mixing technology
The choice of mixing system depends heavily on the type of material, the quantity required and the quality standards:
- For quantities of up to approx. 32 gal., e.g. for repairs, interior work, floor work or masonry work, pan mixers are particularly efficient, offering a good balance between output and mobility.
- Free-fall mixers are useful for coarse concrete quantities of approx. 20 gal. or more – but only if a high mixing quality is not required.
Special features when mixing factory-made dry mortar on the construction site
- Precise addition of water: The formulation is adjusted to a defined water/material ratio. Deviations lead to loss of strength or processing problems.
- Homogeneous mixing: The mortar will only develop its full properties, such as adhesion and compressive strength, if all of the components are evenly distributed.
- Processing within the pot life: After mixing, the mortar must be processed quickly as the reaction time is limited. It is essential to avoid rewatering the mixture.
Drum Style Concrete Mixers
Drum style mixers, often known as classic concrete mixers, work with a rotating drum in which the material is mixed by gravity. They are particularly suitable for coarse concrete mixes with aggregates such as gravel or chippings.
- Advantages:
- Easy to use and robust
- Low-maintenance
- Cost-effective to purchase and operate
- Disadvantages:
- Unsuitable for fine-grained or viscous materials such as mortar or levelling compound
- Mix quality often uneven
- Higher material loss due to incomplete mixing
- Longer mixing times for demanding formulations
- Recommendation:
- First add the dry mixture, then gradually add water.
- Allow for a longer mixing time.
- Regularly check the consistency
Forced-Action Mixers
- Suitable for: All ready-mixed dry mortars, especially fine-grained and viscous materials such as cement screed, lime-cement plaster, grout, natural stone mortar, drainage mortar, renovation mortar, epoxy resin mortar and much more.
- Advantages:
- Very good homogeneity of the mixture.
- Fast and even water distribution.
- Low material losses.
- Shorter mixing times.
- Disadvantages:
- Higher acquisition costs
- Recommendation:
- Observe the mixing time according to the manufacturer's instructions.
- Clean mixing tools after use.
- Do not overfill the mixing bucket – observe the optimum mixing quantity.
Practical tips for the construction site
- Dose water precisely – ideally with a measuring container or dosing device.
- Document the mixing time – e.g. with a timer or mixing log.
- Check material before mixing – do not use lumpy or moist prebagged material.
- Clean the mixer regularly – residues can have a negative impact on the next mixture.
- Select a mixing system to suit the type of material – not every mortar is suitable for every mixer.
Ready-mixed dry mortars offer high quality and processing reliability – but only if they are prepared professionally. The characteristics of the mixer play a decisive role here: while free-fall mixers are still acceptable for coarse materials, the use of a forced-action mixer is strongly recommended for demanding mortars. This prevents processing errors, material losses and quality defects.
Self-produced mortar offers flexibility and cost savings, but requires expertise, care and control.
For professional construction site use, especially when processing mortar and cementitious materials, forced-action mixers have a clear advantage. They offer consistently high quality, save time and material and therefore also make economic sense, despite higher acquisition costs. Free-fall mixers remain a good solution for simple concrete mixes, but should be avoided for quality-orientated applications.
Collomix Mortar Mixers
TMX 1000
TMX 1500
AOX-S
oneMIX 340
AQiX
