Ready-mix and site concrete plants · Batching tolerances by material, scale checks and moisture probes, plant certification, output and layout (hopper or belt feed)
A concrete batching plant stores cement, supplementary cementitious materials (SCMs), aggregates, water and admixtures, weighs each to a mix design and mixes or loads them into trucks, so each batch has the proportions the engineer specified. Ask three things first: which batching tolerances the plant must hold under the project specification, how scales, water meters, admixture dispensers and moisture probes will be checked, and what output, layout and certification the job needs.
Stationary, mobile and fast-setup concrete batching plants with weigh batchers, for wet (central mix) or dry (truck mix) batching. Volumetric mixer trucks, asphalt plants, dry mortar plants and individual silos, conveyors or mixers sold separately are outside this page except where compared.
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01
Texas DOT's 2024 specification Item 421 (Hydraulic Cement Concrete), Table 12, sets batching tolerances for non-volumetric mixers: cement, SCM and cement plus SCM weighed cumulatively at −1% to +3%; water by weight or volume at ±3% (not counting water withheld or aggregate moisture); fine and coarse aggregate each at ±2%, or ±1% when weighed cumulatively; and chemical admixtures at ±3%. Cement and SCMs must be weighed in a hopper on a separate scale from other materials, with cement first when weighing cumulatively, and aggregate batch weights corrected for moisture. [1]
When cementitious materials are weighed at under 30% of scale capacity, the quantity must be no less than required and no more than 4% over; for cumulative aggregate weighing below 30% of capacity the tolerance is ±0.3% of scale capacity or ±3% of the required weight, whichever is less. [1]
Editorial calculation: for a mix with 350 kg of cement per cubic metre (an assumed figure), the −1% to +3% tolerance allows 346.5–360.5 kg; on a 3 m³ batch that is 1,039.5–1,081.5 kg. Ask the supplier for the scale capacities and divisions so small batches stay above the 30%-of-capacity limit or meet the tighter low-load rule. [1]
Give the supplier the concrete classes and mix designs, required output per hour and per day, wet or dry batching, number of aggregate and cementitious materials, admixture types, scale capacities, moisture probes, site space and foundations, climate (hot or cold weather concreting), power supply, dust control, and the specification and certification required.
02
Item 421 requires each plant and truck mixer to be certified by NRMCA or to have an inspection report signed and sealed by a licensed professional engineer showing that measuring, mixing and delivery equipment meets ASTM C94, renewed whenever a plant is moved (and every two years for engineer inspections). Scales must be checked before operations, after each move and at least every 6 months; volumetric water devices at least every 90 days; admixture dispensers at least every 6 months; and electronic aggregate moisture probes at least every 90 days, accurate to within 1.0% of actual moisture. Mixer blades and fins with 10% or more wear must be repaired. [1]
Aimix lists hopper-type and belt-type stationary plants (AJ-60 to AJ-270 belt-type) and fast-setup AJQ50, AJQ70, AJQ100 and AJQ150 plants with actual outputs of 45, 56, 90 and 135 m³/h, a foundation-free modular chassis and weighing with automatic compensation stated to hold batching accuracy up to ±1%. [2]
Editorial note: a supplier's stated weighing accuracy is not the same as meeting a project's batching tolerance at all batch sizes; ask for scale capacities, divisions and calibration procedure, and plan the certification the specification requires.
US EPA's AP-42 Section 11.12 (Concrete Batching, June 2006) says about 75% of US concrete is made at plants that store, convey, weigh and discharge the materials into trucks, where, at “most of these plants”, sand, aggregate, cement and water are gravity fed from the weigh hopper into truck mixers and mixed on the way to site; some plants mix in a central drum first. Its only point sources are cement and pozzolan transfers to silos, which it says are “usually vented to a fabric filter or ‘sock’”; the rest — sand and aggregate transfer, truck and mixer loading, traffic and stockpile wind erosion — are fugitive, and depend on the surface moisture of the materials. Its per-yard factors assume what it calls a “typical concrete formulation of 564 pounds of cement and cement supplement” (491 lb cement, 73 lb supplement) in 4,024 lb of material. [3]
Editorial calculation: AP-42's “typical” 564 lb of cementitious material per yd³ is about 335 kg/m³ (564 × 0.4536 ÷ 0.7646), close to the 350 kg/m³ assumed earlier on this page [3]. Dust control at the silos and truck-loading point should be specified with the plant, not added later.
Verifi LLC's US patent 11,320,415 B2 (Minimizing variation due to construction aggregate moisture probes) puts numbers on a probe error: a 1-percentage-point moisture error in sand used at 1,800 lb per cubic yard in a 3,000 psi mix adds 18 lb of water per cubic yard, which the patent says is more than 2 gallons; it takes each extra gallon per cubic yard as lowering compressive strength by approximately 250 psi, so the delivered concrete could lose up to 500 psi, and the inventors estimate a miss on the strength target of as much as 17%. The patent notes that probes sit near the bottom of hoppers, where aggregate may have been exposed to heat or rain earlier in storage, so a probe calibrated against material loaded at the top can read wrong; it proposes comparing slump measured in the truck drum with the slump predicted from the probe reading and raising an alarm when the probe needs calibration. [4]
Editorial calculation: 18 lb of water at 8.34 lb per US gallon is about 2.2 gallons per cubic yard, consistent with the patent's "more than 2 gallons". Set against the TxDOT rule above (probes within 1.0% of actual moisture, checked at least every 90 days), a probe right at the 1.0% limit can still shift water by this amount, so ask the supplier how the plant control system logs probe readings and supports calibration between scheduled checks. [1] [4]
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The suppliers reviewed list stationary, mobile and precast batching plants; ask each for actual (not only theoretical) output, mixer type and size, scale capacities and accuracy, aggregate and silo storage, control system and batch records, and installation needs.
04
TxDOT Item 421 sets the separate cement scale and moisture correction in these rows; Aimix supplies the feed and control rows.
| Part | Role | Fix in the order |
|---|---|---|
| Aggregate bins and feed (hopper or belt) | Store and deliver aggregates. [2] | Bins; feed type. |
| Cement and SCM silos and scale | Store and weigh separately; silo transfer “usually vented to a fabric filter” (AP-42). [1] [3] | Silos; scale. |
| Aggregate weigh batcher | Weigh, correct for moisture. [1] | Capacity; probes. |
| Water and admixture dosing | Meter liquids. [1] | Meters; dispensers. |
| Mixer (central mix) | Mix batches. [1] [2] | Type; size. |
| Control system | Batch to recipe and record. [2] | Records; compensation. |
05
Three of the thirteen rows carry source values — Aimix's AJQ output, TxDOT's cement tolerance and AP-42's silo venting; mixer size, storage, power, weight and footprint must come from the supplier.
| Field | What it means and published values | Ask the supplier for |
|---|---|---|
| Production Capacity (m³/h) | E.g. 45–135 m³/h actual (AJQ series). [2] | Actual and theoretical. |
| Mixer Capacity (m³) | Batch size. | Mixer type; size. |
| Aggregate Storage Capacity (m³) | Bins. | Number; volume. |
| Cement Silo Capacity (tons) | Cementitious storage. [1] | Silos; separate SCM. |
| Water Tank Capacity (m³) | Supply buffer. | Volume. |
| Power Consumption (kW) | Installed power. | Total kW. |
| Mixing Accuracy (%) | Batching tolerance, e.g. cement −1/+3%. [1] [2] | Accuracy per material. |
| Discharge Height (m) | Truck clearance. | Height. |
| Operating Temperature (°C) | Hot and cold weather. | Range; heating. |
| Noise Level (dB(A)) | Site limits. | Value. |
| Total Weight (t) | Transport and foundations. | Weight. |
| Footprint Area (m²) | Layout. | Layout drawing. |
| Dust control | Silo filling “usually vented to a fabric filter”; loading points fugitive. [3] | Filters, enclosures, sprays. |
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Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Mixes: [classes; cement; SCMs; admixtures] Output: [m³/h; m³/day] Batching: [wet or dry; tolerances; scales] Moisture: [probes; testing] Site: [space; foundations; power] Compliance: [specification; certification] Records: [batch tickets; data export]
12 companies list this product among what they make. Company figures are quoted from each company's own website; every card states where the relationship came from.
Lists stationary, mobile and fast-setup concrete batching plants.
Product scope checked 2026-10-11
Lists concrete batching plants with asphalt and dry mortar plants.
Product scope checked 2026-10-11
Lists stationary and precast concrete batching plants.
Product scope checked 2026-10-11
Lists stationary concrete batching plants such as the HZS25.
Product scope checked 2026-10-11
Lists concrete batching plants with block-making machines.
Product scope checked 2026-10-11
Lists concrete batching plants with block and wall-panel machines.
Product scope checked 2026-10-11
Lists concrete batching plants with concrete pumps and mixers.
Product scope checked 2026-10-11
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
Texas DOT Item 421 (2024) sets −1% to +3% for cement and SCM by weight. [1]
Under TxDOT Item 421, before operations, after each move and at least every 6 months. [1]
Within 1.0% of actual moisture, checked at least every 90 days (TxDOT Item 421). [1]
AP-42 Section 11.12 lists cement and pozzolan silo filling as the only point sources, “usually vented to a fabric filter or ‘sock’”; aggregate transfer, truck loading and stockpiles are fugitive sources. [3]
Verifi's US patent 11,320,415 B2 works through a 3,000 psi mix with 1,800 lb of sand per cubic yard: a 1-point moisture error adds 18 lb (more than 2 gallons) of water per cubic yard and could cut strength by up to 500 psi. [4]
Sources checked 2026-10-12. TxDOT's Item 421 is a state highway specification; other agencies and ASTM C94 may apply to your project. Aimix describes its own plants. US EPA's AP-42 Section 11.12 describes how plants feed trucks and where they emit dust. Verifi's US patent 11,320,415 B2 quantifies how an aggregate moisture probe error carries through to batch water and strength.
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