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The ACI Universidad Catolica San Pablo (UCSP) Student Chapter in Arequipa, Peru, organized a technical talk with CHEMA, a Peruvian company with over 50 years of experience in the construction industry, specializing in additives, adhesives, and waterproofing solutions that enhance quality and durability. The company shared valuable insights on innovative construction materials and techniques with ACI members and students, strengthening the link between academia and industry.

This study introduces a constant water pressure seepage rate detection method to assess the impermeability recovery of cracked concrete using crystalline waterproofing agents. The method focuses on quantifying crack repair effectiveness. Tests involve 100mm cubic C35 concrete specimens with induced micro-cracks under uniaxial compression. Three groups are studied: C-0 (reference), S-1.3 (internally-mixed), and P-1.3 (sprayed). Specimens are repaired and submerged in water at 25°C. Seepage rate tests are conducted at 7d, 14d, 28d, and 56d post-crack formation. Seepage rates decrease over time with repair age, notably declining from 7 - 28 days and stabilizing from 28 - 56 days. Application methods significantly affect impermeability recovery, with C - 0 > P - 1.3 > S - 1.3 consistently in seepage rates. By 56 days, rates are approximately 0.8mm/h for S - 1.3, 4.2mm/h for P - 1.3, and 9.8mm/h for C - 0, indicating better long-term stability and anti-seepage effects for the internal mixing method over spraying. The study demonstrates the seepage rate method’s ability to quantitatively track crack leakage evolution and differentiate the repair effects of crystalline waterproofing agents.

This paper analyses the status quo of exterior wall waterproofing technology of prefabricated building, introduces the application of waterproofing coil laying, sealant waterproofing, grouting method, exterior wall waterproofing coating, waterproof concrete and the integration technology of heat preservation and drainage, and analyses their advantages and disadvantages. In the future, the research and application of new materials should be strengthened, and the effects of different waterproof technologies should be quantitatively compared through experiments to further improve the waterproof performance of prefabricated building external walls.

Water-based elastomeric waterproofing membranes based on styrene-acrylic (S/A) copolymers have emerged as an important class of materials for modern construction due to their combination of flexibility, adhesion, environmental compatibility, and long-term durability. These membranes form seamless protective layers capable of accommodating substrate movement while preventing water ingress across a wide range of building structures. Recent advances in polymer chemistry and emulsion technology have significantly improved the performance of S/A systems, particularly in terms of crack-bridging capability, weather resistance, and UV stability. In addition, optimized formulations incorporating functional fillers, rheology modifiers, and hybrid polymer architectures enable improved mechanical performance and impermeability. This review provides a comprehensive overview of S/A elastomeric waterproofing membranes, covering polymer chemistry, formulation strategies, physico-mechanical properties, durability mechanisms, and real-world construction applications. The review also compares S/A systems with alternative waterproofing technologies such as polyurethane (PU), cementitious coatings, and bituminous membranes. Finally, emerging developments in advanced polymer architectures, nano-reinforced coatings, and sustainable formulations are discussed, highlighting future research directions for high-performance waterproofing systems.

Seepage poses a significant challenge in construction, undermining structural durability and stability. Dry-mix mortar, valued for its consistent quality and improved durability over traditional mortar, still require enhanced waterproofing capabilities. Polymer additives, which form a strong bonding membrane during curing, present a viable approach to improving mortar’s water resistance. This study determines the optimal polymer additive content, assesses their effects on physical and mechanical properties of fresh and harden mortar, and compares the waterproofing performance of additive-enhanced mortar with that of conventional mortar. The results establish a scientific basis for incorporating polymer additives into mortar production, promoting enhanced quality and sustainability in construction projects.

An evaluation method for assessing the difference in the relative humidity (RH) control performance of waterproofing material is proposed. For a demonstration of this evaluation method, two waterproofing materials (urethane coating and cementitious waterproofing material) installed with different methods (positive and negative side of concrete structure respectively) are exposed to temperature conditions representing three seasonal conditions: Summer (40 °C), spring/autumn (20 °C) and winter (4 °C). Condensation level changes on the inner side of the waterproofing material installed specimen is measured, and for derive criteria for comparison, three parameters based on the average RH, intercept RH (derived from a linear regression analysis of RH measurement), and maximum relative humidity are derived for each different waterproofing material installed specimen. Based on quality specification for underground concrete structures, the demonstration evaluation establishes provisional standard criteria of below 70% RH, and all three parameters are evaluated to determine whether the tested waterproofing material/method complies to the performance requirement. Additional analysis through linear regression and cumulative probability density graphs are derived to evaluate the RH consistency and range parameters. The evaluation regime demonstrates a quantitative RH analysis method and apparatus, and a newly designed evaluation criteria is used to compare the RH control performance of positive-side installed urethane waterproofing materials and negative-side installed cementitious waterproofing material.

In order to explore the waterproofing mechanism of F-type socket joint in rectangular pipe jacking tunnel, full-scale tests and finite element numerical calculations were conducted to analyze the sealing performance and failure modes of rubber rings with different heights under different water pressures, revealing the distribution law of contact stress and leakage mechanism of rubber rings. The results show that low-height rubber rings experience leakage at a water pressure of 0.2–0.3 MPa, while the waterproofing ability of medium and high height rubber rings is significantly improved, withstanding 0.7 MPa and 1.0 MPa water pressure, respectively. The 28 mm rubber ring still has no leakage at a 1.6 MPa water pressure. At 0.4 MPa water pressure, the height of the rubber ring increases from 22 mm to 24 mm, the proportion of effective contact stress increases from 35.7% to 78.6%. The waterproofing performance of tunnel joints is jointly determined by the rubber ring height and the proportion of effective contact stress. No leakage occurs at the pipe gallery joint when the proportion of effective stress exceeds 70%. This research provides a theoretical basis for the size selection of waterproofing rubber rings for the rectangular pipe jacking tunnel.

In addition to mechanical compliance, achieving the full potential of on-skin electronics needs the introduction of other features. For example, substantial progress has been achieved in creating biodegradable, self-healing, or breathable, on-skin electronics. However, the research of making on-skin electronics with passive-cooling capabilities, which can reduce energy consumption and improve user comfort, is still rare. Herein, we report the development of multifunctional on-skin electronics, which can passively cool human bodies without needing any energy consumption. This property is inherited from multiscale porous polystyrene-blockpoly(ethylene-ran-butylene)-block-polystyrene (SEBS) supporting substrates. The multiscale pores of SEBS substrates, with characteristic sizes ranging from around 0.2 to 7 μm, can effectively backscatter sunlight to minimize heat absorption but are too small to reflect human-body midinfrared radiation to retain heat dissipation, thereby delivering around 6 °C cooling effects under a solar intensity of 840 W·m−2. Other desired properties, rooted in multiscale porous SEBS substrates, include high breathability and outstanding waterproofing. The proof-of-concept bioelectronic devices include electrophysiological sensors, temperature sensors, hydration sensors, pressure sensors, and electrical stimulators, which are made via spray printing of silver nanowires on multiscale porous SEBS substrates. The devices show comparable electrical performances with conventional, rigid, nonporous ones. Also, their applications in cuffless blood pressure measurement, interactive virtual reality, and human–machine interface are demonstrated. Notably, the enabled on-skin devices are dissolvable in several organic solvents and can be recycled to reduce electronic waste and manufacturing cost. Such on-skin electronics can serve as the basis for future multifunctional smart textiles with passive-cooling functionalities.

Dislocation of segments in shield tunnels significantly contributes to joint leakage, making it crucial to identify the critical dislocation amount of segment linings. To explore the waterproofing mechanism of sealing gaskets under water pressure, a structural coupling finite element analysis model was created. This model simulates water intrusion dynamics at segment joints, analyzing contact stress distribution and waterproof performance across various dislocation amounts. The comparison of finite element calculations with experimental data shows a positive correlation, although simulation results are slightly lower than experimental findings. The analysis demonstrates that lower effective contact stress due to dislocation increases leakage risk. In small deformation ranges, opposite segment constraints can enhance gasket contact, reducing leakage risks. However, exceeding critical dislocation leads to leakage. Findings indicate that as dislocation increases, the effective contact stress between the gasket and groove first decreases, then increases. A dislocation of 9 mm and an opening of 8 mm yield the lowest effective contact stress proportion and worst waterproof performance, marking a critical point for sealing water pressure changes. This study provides a scientific basis for determining critical dislocation amounts, optimizing joint sealing performance, and reducing leakage in shield tunnels.

Polymer modified bituminous thick coatings are increasingly used in the construction industry to protect underground parts of buildings from groundwater. When assessing their durability, one vital issue related to their functional properties is the influence of water absorption on the waterproofness of the applied solution as a result of the action of groundwater with different pH values. As part of the research, the water absorption of the products in question was assessed using the method of total immersion in water with pH of 4.0, 7.0 and 7.5 as well as comparatively, as a result of one-way exposure to demineralized water under successively increasing pressure up to 0.5 MPa. The moisture susceptibility of the coatings was assessed both concerning the local surface damage and the continuous waterproofing coating. It was established that the coatings show the highest water absorption when the water pH is 4.0, which simulates the groundwater aggressiveness on construction products. It was proven that moisture absorbed by the coatings is retained within this layer and is not transferred to the substrate on which the coatings are laid. It was also found that water in contact with the tested coatings changes its reaction to alkaline, which can result in contamination of groundwater in the area of waterproofing coating. A modification of the method of assessing the water absorption of polymer modified bituminous thick coatings was proposed, taking into account their use in conditions of use.