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Concrete Mix AI is a free site for concrete professionals, civil engineers, construction contractors, and students: free concrete takeoffs from your plans, concrete calculators, ACI certification practice exams in English and Spanish, and technical articles about concrete construction.

Use it to work out a starting-point concrete mix design based on ACI 211 principles, estimate compressive strength from the water-cement ratio, rough out the material cost of a concrete pour, or prepare for your ACI Field Testing Technician Grade I certification exam.

The calculators use simplified versions of published methods, such as Abrams' law for strength and ACI 211 principles for mix design. Treat every result as a starting point and verify it with trial batches, testing and the code your project uses. The practice exams cover the ACI certification programs, with explanations that point to the ASTM test methods and ACI documents behind each answer.

Who Uses Our Tools?

• +Ready-mix sales teams sizing orders from a takeoff
• +Engineers looking up ACI 318 exposure categories and IBC Chapter 19 requirements
• +Contractors and estimators getting concrete, rebar and CMU quantities from their plans
• +QC technicians preparing for ACI certification exams
• +Concrete inspectors studying for ACI special inspector certification
• +Civil engineering students learning mix design and concrete technology
• +Spanish-speaking concrete professionals (all exams available in Spanish)

Concrete Mix Design Calculator

A simplified starting-point mix based on ACI 211 principles. Enter target compressive strength (MPa), slump (mm), maximum aggregate size and exposure condition; get the water-cement ratio and the cement, water, sand and coarse aggregate quantities per cubic meter. Verify with trial batches.

Compressive Strength Predictor

Estimate concrete compressive strength at any age from the water-cement ratio and cement type (OPC grades, PPC or PSC), using an Abrams' law approximation and an ACI 209 style age curve. A planning estimate for early strength and form stripping questions; cylinder tests decide.

Water-Cement Ratio Calculator

Find a water-cement ratio from your target strength (Abrams' law), then cap it for the exposure you choose: freezing and thawing, sulfate, low permeability or chloride classes in US units, or mild to extreme in metric. See the strength-based and durability-based values and which one governs. Check the limits against your project's code.

Concrete Cost Estimator

Rough out the material cost of a concrete volume in cubic meters: cement, sand, coarse aggregate and water for grades M15 to M40, at built-in typical prices for the United States, India, the United Kingdom or the Middle East. Use your supplier's prices for a bid.

Slump Test Calculator

Get a suggested slump range in millimeters for foundations, columns and walls, slabs, pavements or general work, by placement method: chute or wheelbarrow, pump, or tremie. Slump itself is measured with the ASTM C143 cone test.

Curing Time Calculator

Estimate how many days concrete takes to reach a target share of its 28-day strength from cement type and air temperature (a simplified maturity approach), with a strength timeline at 1, 3, 7, 14, and 28 days. ACI 308 covers how to cure; this estimates how long.

Testing Program Certifications

• ACI Concrete Field Testing Technician Grade I: Slump test (ASTM C143), air content (ASTM C231), unit weight (ASTM C138), making cylinders (ASTM C31), temperature (ASTM C1064), and sampling (ASTM C172)
• ACI Aggregate Testing Technician Level I: Sieve analysis (ASTM C136), specific gravity and absorption (ASTM C127/C128), moisture content (ASTM C566), and unit weight (ASTM C29)
• ACI Concrete Laboratory Testing Technician: Compression testing (ASTM C39), sulfur capping (ASTM C617), neoprene caps (ASTM C1231), moist room curing (ASTM C511)

Inspection and Specialty Certifications

• ACI Concrete Construction Special Inspector: Formwork, reinforcement, placement, consolidation, and curing per ACI 318 and ACI 301
• ACI Reinforcing Steel Inspector: Bar identification, tolerances per ACI 117, splice and development lengths, cover requirements per ACI 318
• ACI Shotcrete Inspector: Dry-mix and wet-mix shotcrete, ACI 506, nozzle technique, rebound, core testing per ASTM C1140
• ACI Concrete Flatwork Finisher: Screeding, floating, troweling, jointing, curing, F-numbers per ASTM E1155, ACI 302
• ACI 318 Concrete Design Professional: Flexural design, shear, columns, load combinations, strength reduction factors