What to Pay Attention to in UHPC Construction? Key Control Points and Qinglong Group's Full-Process Construction Guide

The success of UHPC construction depends on strict control of a series of key control points. Negligence at any stage may prevent its exceptional performance from being achieved, or even cause engineering accidents. Based on 28 years of project experience, Qinglong Group has summarized the core considerations of UHPC construction into six aspects—"Man, Machine, Material, Method, Environment, Measurement"—forming a complete full-process construction control guide. In major projects such as the roof of the Hainan International Convention and Exhibition Center, it was the strict implementation of these key points that ensured the final quality of the project. The most critical points are detailed below.

1. Absolute Precision of Raw Materials and Mix Proportion

This is the "constitution" of construction, and no arbitrary changes are allowed. All raw materials (especially silica fume, fibers, and superplasticizers) must exactly match the types and specifications specified in the design mix proportion. Metering equipment must be calibrated regularly, and batching errors should be kept within ±0.5%. Adding water arbitrarily on site is strictly prohibited! Qinglong Group recommends that important projects use factory-premixed UHPC dry-mix or dedicated admixtures to minimize on-site variables.

2. Strict Control of the Mixing Process

A high-shear forced-action mixer must be used. Mixing time and feeding sequence must strictly comply with process requirements. Typically, cementitious materials and aggregates are dry-mixed first, followed by the addition of water solution containing superplasticizer. Material temperature must be monitored during mixing, and cooling water or ice chips should be used to control temperature when necessary. Both uneven mixing and over-mixing will lead to performance degradation.

3. One-Time Success of Casting and Compaction

Before casting, molds must be clean and coated with dedicated release agent. UHPC has good fluidity, but segregation caused by casting from excessive height must also be prevented. For areas with dense reinforcement or complex structures, casting points and flow paths need to be carefully designed. The compaction process is crucial: insufficient vibration will produce air bubbles, while excessive vibration will cause fibers to settle. For UHPC with an ultra-low water-binder ratio, vibration tables and surface vibrators are often used in combination, or vacuum-assisted degassing is adopted.

4. Timeliness and Precision of the Curing Regime

Curing is the "catalyst" for UHPC strength development. After casting, plastic film must be applied immediately for moisture retention to prevent surface moisture evaporation and cracking. Depending on the mix proportion and ambient temperature, wet curing or steam curing should begin at the appropriate time after initial setting. The heating and cooling rates of steam curing (usually ≤15°C/h), the constant temperature, and duration must be precisely controlled. After demolding, wet curing is still required for a period of time.

5. Professional Training of Construction Personnel

All workers and technicians involved in UHPC mixing, casting, and curing must undergo special technical briefing and training to understand the significance and consequences of each operation step. While providing materials, Qinglong Group always provides detailed work instructions and on-site technical guidance services—this is the key soft power that safeguards construction quality.

By following the above key points, UHPC construction can transform from "high-risk" into a standardized process of "high quality and repeatability". Qinglong Group is willing to share these experiences with all partners to jointly promote the successful application of UHPC technology.