What weigh batching means, and what it is set against
Weigh batching means the ingredients are proportioned by mass. Volume batching means they are proportioned by the size of the thing that carries them — a bucket, a gauge box, a barrow. Indian Standard 456:2000, the code of practice for plain and reinforced concrete, is direct about which it expects. Under clause 10.2 the quantity of both cement and aggregate shall be determined by mass, solid admixture by mass, liquid admixture by volume or mass, and water shall be weighed or measured by volume in a calibrated tank. Clause 10.2.3 adds that all ingredients of the concrete should be used by mass only. Volume batching is not forbidden, but clause 10.2.4 permits it only where weigh batching is not practical, and only where accurate bulk densities of the materials actually to be used have been established beforehand, with an allowance made for bulking.
That last condition is the one a self-loading mixer walks straight into. The machine fills its own bucket from a stockpile that has been rained on, and damp sand occupies more volume than dry sand of the same mass, which is the bulking the code requires an allowance for. The same code puts numbers on the measuring equipment itself: accuracy within plus or minus 2 per cent of the quantity of cement being measured, and within plus or minus 3 per cent for aggregate, admixtures and water. Those figures show what the question is; they do not answer it. No machine described on this site has been shown to meet them, because no plant has given us a stated accuracy for any weighing device on any model, and a tolerance nobody has measured against is not a compliance claim.
Source: IS 456:2000, Plain and Reinforced Concrete — Code of Practice, Bureau of Indian Standards, clauses 10.2, 10.2.2, 10.2.3 and 10.2.4, read from the standard's own published text. The 2 and 3 per cent figures are the code's requirement on measuring equipment and are applied to no machine on this site.
The one machine where the scale is standard equipment
Exactly one model in the published range has an electronic hydraulic weighing device on its standard equipment list. It sits there alongside the automatic lubrication system, air conditioning and heating, the reversing and drum-monitoring camera, the automatic water-fill controller and a drum that lifts and rotates through 270 degrees. Across the sixteen mixer records behind that range, the device appears in exactly one standard configuration list and in no other. That is the whole of the good news, and it is worth saying plainly what it does and does not settle. It settles that the device is fitted as built on one machine we publish. It settles nothing about the other five, because a model whose standard list does not name the device is a model that leaves the plant without it unless somebody orders it on. Weigh batching, across this range, is one machine's standard equipment and everybody else's purchase decision.
Source: the plant's standard-equipment configuration sheet, where the entry appears once across the sixteen mixer records we hold.
The models that list it as an option, and what a line-wide list proves
On the SLM-18 the weighing device appears under optional equipment and not under standard, next to air conditioning, a high-pressure wash-down pump, a cement hopper and the automatic lubrication system. Four more models in the published range carry the same option entry, and one of those four is the machine where the device is already standard. That duplication is the detail that tells you what kind of list this is. Behind those five published models sit seven records from one supply line, and all seven carry an identical option list. The repetition is the finding: this is a line-wide option catalogue, not a per-machine build sheet. It is good evidence that the device exists and can be fitted to that line. It is no evidence at all about how an individual machine was built, and it should not be read as a tick against the model you are quoting.
What the option list does not contain matters as much as what it does. There is no accuracy, no calibration interval, no service life, no indication of whether the device weighs cement separately from aggregate or simply reports what is already in the bucket, and no statement of how it behaves when the machine is standing on a slope. The record holds a name and nothing else. None of those omissions is unusual in an option catalogue; the mistake would be to read one as though the missing lines had been filled in somewhere else. So this page will not call a model suitable for weigh-batched work on the strength of an option entry, and it will not convert a catalogue that covers a whole line into a specification for the machine on your order. That question goes to the plant instead, in writing, against the model number actually being bought.
Source: the optional-equipment list published on the SLM-18 model page, and the plant's line-wide option list behind it, which is identical on all seven records of that supply line, the machine where the device is standard included. The list names the device and records nothing else about it.
Nine mixer records where the answer is unknown, not no
One model in the published range has an empty optional-equipment list, and that emptiness means one thing only: the second supply line has given us no option list, so there is nothing to publish. Nine of the sixteen mixer records sit in that position, and none of their standard equipment lists names a scale of any kind. The correct answer for that model is therefore that we do not know whether a weighing device can be had on it, not that it cannot. Those are different answers and a buyer is entitled to have them kept apart, because one of them can be changed by a phone call and the other cannot. An empty option list is not a finding about the machine. It is a finding about what has reached us. Name the model in an enquiry and the question goes to the plant in writing, and the written reply is what gets quoted back.
Source: the second supply line's configuration sheets; it has supplied no option list for any of its nine mixer records, and none of those nine standard equipment lists names a weighing device of any kind.
What the machines do carry, on the record rather than by assumption
Fifteen of the sixteen mixer records carry an on-board water system, in two different forms that should not be collapsed into one. The five published models from the first supply line list an automatic water-fill controller together with an external suction pump, which is what lets the machine draw its own water from a drum, a tank or a stream rather than depending on water being delivered to the pour. The sixth, from the second supply line, lists a high-capacity water tank with a self-priming fill system. Both are ways of getting water aboard and carrying it. Neither is described in our record as calibrated or metered, while IS 456 clause 10.2 asks for water to be weighed, or measured by volume in a calibrated tank. On the evidence we hold, the water on these machines is carried rather than measured, and we will not write it up as batching.
The same distinction applies to what the operator can see. Five published models list a camera system described as reversing and drum monitoring. The sixth lists a high-definition LCD driving display, which does not say what it displays, so it is not counted here as a drum camera; across the sixteen mixer records those two entries stand at seven and eight respectively, and they are kept apart for exactly that reason. Five published models carry a drum that lifts and rotates through 270 degrees, which is what puts the chute where the pour is rather than where the machine can park. That is the honest inventory: a machine that loads itself, mixes while it travels and discharges through a swivelling drum, with a weighing device as standard on one published model and an open question on another.
Source: the plant configuration sheets behind the range, the SLM-18's own list also published on its model page — a water item on fifteen of the sixteen mixer records we hold, the sixteenth record's own list being incomplete; a reversing and drum-monitoring camera on seven of those records and a driving display on eight, counted separately because the two entries describe different things. The five crawler dozers on this site carry no equipment list at all and are not counted here. The water requirement is IS 456:2000, clause 10.2.
The question to put to any seller, including us
Three questions, and all three deserve a written answer before a deposit moves. Does this exact model carry the weighing device on the machine you will ship me, standard or fitted as an option? What is its stated accuracy, and against which quantity is that percentage measured? Is the water on board measured into the mix, or only carried to the site? A seller who answers the second with a number should be asked where that number comes from — a plant declaration, a calibration certificate, or the person typing the reply. In our own case the answers today are: standard on one published model, listed as an option on four more, unknown on one, and no stated accuracy anywhere in our record for any of them. We would rather publish that than a cleaner sentence we cannot stand behind.
When a buyer names a model we put the accuracy question to the plant and quote the written reply, which is the sequence set out on the How We Work page and the reason several rows in the published mixer range are blank rather than filled. A blank row is a question that has been asked and not yet answered, and to a buyer it is worth more than a filled one that cannot be traced back to a document. If weigh batching is a hard requirement in your specification, treat it as the question that chooses the model rather than a detail settled once the model is already chosen, and keep every part of the answer on paper, against a model number, before any money moves. That is the discipline this page has tried to apply to itself: one model named, four qualified, one left open, and no accuracy figure attached to any of them.
Source: the three questions restate the gaps named in the sections above and introduce no new figures. Our record holds no accuracy, calibration or metering figure for the weighing device, or for any water system, on any machine.