FAQ

UHP.x is a native iOS app for Ultra-High Performance Concrete (UHPC) mix design. It implements the Absolute Volume Method to precisely proportion binder, SCMs, water, superplasticizer, fibers, and aggregates — all guaranteed to sum to exactly 1000 L/m³.

UHP.x is designed for structural engineers, material scientists, researchers, and lab technicians working with ultra-high performance concrete. It's a professional-grade tool intended for users with a background in concrete technology.

UHP.x requires iOS 17 or later and runs on iPhone and iPad. The app has optimised layouts for both screen sizes. It is not available on Android or as a web app.

UHP.x is free to download. The free tier gives you full calculation access, one saved mix, the Sample Library, and watermarked PDF export. A one-time unlock at $14.99 removes all limits — unlimited saves, custom libraries, clean PDF reports, and unlimited curing pins.

UHP.x uses the Absolute Volume Method. Each constituent is converted from mass to volume using its specific gravity. Aggregate volume is always computed as the remainder:

• V_agg = 1000 − Σ(Vc + Vs1 + Vs2 + Vw + Vsp + Vf + Vair)

This guarantees the total always equals exactly 1000 L/m³ by construction — no rounding errors.

By design. Aggregate volume is the remainder after all other constituents are placed. When you increase the binder, water, or fiber content, the aggregate volume decreases to maintain the 1000 L/m³ total. This is fundamental to the Absolute Volume Method.

It confirms that all constituent volumes sum exactly to 1000 L/m³. UHP.x guarantees this by computing aggregate as the remainder, so this check always passes as long as inputs are physically valid (no negative volumes).

If your aggregates are set to Oven Dry mode in the Material Library, UHP.x adds absorption water to the free water quantity automatically. This correction appears in the results and PDF report. If aggregates are set to SSD, no correction is applied.

UHP.x accepts fiber input in vol% only, which is the standard for UHPC design. To convert: vol% = (mass / (SG × 1000)) × 100. For example, 156 kg/m³ of steel fiber (SG 7.8) = 2.0 vol%.

Yes, with the unlocked version. Tap Save As New Library in the Materials tab to create a copy. You can have as many libraries as you need — one per project, supplier, or material source. Switch the active library from the Design tab or the library list.

No. The Sample Library is the default and is protected from deletion to ensure the app always has a working baseline. You can reset it to default values at any time. Create your own libraries and delete those freely.

Any fiber type can be added with a custom name and specific gravity. Common reference values:

• Steel fiber: SG ≈ 7.8
• PP fiber: SG ≈ 0.91
• Basalt fiber: SG ≈ 2.7
• PVA fiber: SG ≈ 1.3
• Glass fiber: SG ≈ 2.5

Set a casting date on any saved mix from the History tab. Pin the mix to your Home screen to see a live curing ring showing progress toward the 28-day milestone. You can also set Apple Reminders for Day 7 and Day 28 directly from within the app.

Yes. In the History detail view for any mix, scroll to the Test Results section. Tap + to add compressive, split tensile, or flexure results. Enter specimen values for each test age — the app calculates average and standard deviation automatically. Results are also included in the PDF export.

No. All data — mix designs, material libraries, your name — is stored entirely on your device. UHP.x has no server, no account system, and no analytics. Nothing leaves your phone.

Go to Settings → Data → Clear All within the app. This permanently removes all saved mixes and material libraries. Alternatively, deleting the app removes all data from your device.

If you have iCloud Backup enabled in iOS Settings, your UHP.x data is included in your regular device backup. This is standard iOS behaviour and is not controlled by UHP.x. We do not provide cloud sync between devices.