Is the Impermeability of UHPC Manufacturer Products Good? Core Influencing Factors and Testing Verification Methods

Water impermeability is an important functional indicator of UHPC (Ultra-High Performance Concrete) products. Especially for exterior wall decoration, landscape components, and components used in humid environments, good impermeability can effectively prevent water penetration, avoiding problems such as internal structural damage, surface sanding, and mildew, ensuring long-term stable use of the product. Impermeability varies among products from different UHPC manufacturers; understanding its core influencing factors and verification methods can help accurately judge product quality.

The high density of UHPC is the natural basis of its impermeability, but premium impermeability still needs to be guaranteed through scientific formulation, refined processes, and strict testing.

I. Core Evaluation Standards for UHPC Impermeability

The impermeability of UHPC is usually expressed by its impermeability grade; the higher the grade, the better the impermeability. According to industry standards, the impermeability grade of UHPC products should not be lower than P12 (i.e., able to withstand 1.2MPa of water pressure without any seepage). Premium products can reach P15 or above, and some high-end products can even reach P20, far exceeding ordinary concrete (whose impermeability grade is usually P6-P8). Core evaluation indicators of impermeability also include water penetration height and permeability coefficient. Premium UHPC should have a water penetration height of ≤5mm and a permeability coefficient of ≤1×10⁻¹²m/s, effectively preventing water from penetrating and diffusing inside the material. Qinglong's UHPC products maintain a stable impermeability grade of P15 or above, with a water penetration height of ≤3mm, fully meeting the high impermeability requirements of exterior walls, underground spaces, humid environments, and more.

II. Three Core Factors Affecting UHPC Impermeability

The impermeability of UHPC products is mainly affected by raw materials, formulation technology, and production processes. In terms of raw materials, premium manufacturers select highly active cementitious materials and well-graded quartz sand; the ultra-fine silica fume selected by Qinglong can fill the pores of cement hydration products, improving material density. In terms of formulation technology, the key lies in optimizing the water-binder ratio (premium UHPC usually has a water-binder ratio ≤0.20) and aggregate grading; Qinglong achieves tight aggregate packing through its patented formulation, reducing porosity. In terms of production processes, high-pressure molding and adequate curing are critical; Qinglong adopts high-pressure compression molding (pressure ≥20MPa) to make the internal structure of the material dense, followed by 28 days of curing at constant temperature and humidity to ensure full hydration and further enhance impermeability. Conversely, some manufacturers, in order to reduce costs, use high water-binder ratios and inferior aggregates while simplifying the molding process, resulting in high internal porosity, loose structure, poor impermeability, and a tendency toward water seepage problems.

III. Scientific Testing and Verification Methods for UHPC Impermeability

Verifying the impermeability of UHPC requires professional testing; avoid judging solely on manufacturer claims. Common testing methods include: first, the impermeability grade test, which uses the stepwise pressurization method to observe whether the specimen seeps water within a specified time and determine the impermeability grade; second, the water penetration height test, which measures the height of water penetration within a certain time under constant water pressure; third, scanning electron microscope (SEM) analysis to observe the density of the material's microstructure. Customers may request manufacturers to provide impermeability test reports issued by authoritative third-party institutions, focusing on verifying key data such as impermeability grade and water penetration height. Every batch of Qinglong's UHPC products undergoes specialized impermeability testing, and test reports are available to customers at any time. For some major projects, such as the Yangshengtang Pharmaceutical Hangzhou Industrial Park (12,000 square meters of UHPC exterior walls), on-site water spray tests are also conducted to verify the actual impermeability performance in use.

IV. Selection and Usage Precautions for Impermeability

When selecting products, the impermeability grade should be matched to the application scenario: P12 grade products can be chosen for indoor dry environments; P15 grade or above is recommended for exterior walls and outdoor landscape components; underground spaces, humid environments, and coastal salt-spray environments require P15 grade or above combined with sealing treatment. Qinglong provides targeted recommendations based on project scenarios. For example, the UHPC wood-grain translucent panel project at Shanghai New World Century Plaza on Nanjing Road adopted P15 grade impermeability products with optimized joint sealing processes, ensuring no water seepage or efflorescence in outdoor use. Meanwhile, during installation, attention should be paid to the sealing of component joints and fixing points to avoid water seepage risks caused by improper installation. Qinglong provides professional installation guidance to ensure the product's impermeability performance is fully realized.

UHPC products generally exhibit excellent impermeability, but differences among manufacturers' products stem from the control of raw materials, formulations, and processes. With scientific formulation design, refined production processes, and strict testing and verification, Qinglong has created UHPC products with high impermeability, and their reliability in actual use has been verified by numerous major projects. When selecting products, customers are advised to focus on verifying the manufacturer's impermeability test reports, raw material quality, and production processes, and to choose quality manufacturers like Qinglong that can provide full-process impermeability guarantees, ensuring the product remains free from water seepage during long-term use and enjoys an extended service life.