Cementitious Capillary Crystalline Waterproofing Research Articles

Effect of nanocomposite cementitious capillary crystalline waterproofing material on self-healing properties of cementitious composites

There are limited studies about the effect of nanocomposite cementitious capillary crystalline waterproofing material (CCCW) on the self-healing properties of cementitious materials in different environments. Compressive strength recovery ratio(CSRR) test, electrochemical impedance spectroscopy (EIS) test, and macroscopic cracks healing observation test were adopted to study the self-healing properties of pure mortar specimens, mortar specimens mixed with CCCW, and nanocomposite CCCW respectively under three kinds of curing conditions. The self-healing mechanism of nanocomposite CCCW was analyzed using thermogravimetric analysis and differential scanning calorimetry (TG-DSC), mercury intrusion porosimetry (MIP), and scanning electronic microscope and energy dispersive spectroscopy (SEM-EDS) techniques. It was found that the curing condition significantly influenced self-healing performance, with touching water curing condition having the highest impact, followed by soaking water curing condition and natural curing condition. Nanocomposite CCCW promoted the healing performance of damaged specimens and significantly increased the CSRR. Under touching water curing condition, the CSRRs of the mortar groups with 3% nano-SiO2, 3% nano-CaCO3, and 2% nano-MgO were 26.1%, 11.5%, and 8.6%, respectively, higher than the CSRR of the single-doped CCCW group. After 28 days of touching water curing, change in charge transfer resistance before and after specimen healing (∆Rct) of the groups with 3% dosage of nano-SiO2, 3% dosage of nano-CaCO3, and 2% dosage of nano-MgO were 5.2, 1.8, and 2.7 times, respectively, higher than that of the single-doped CCCW mortar group. Throughout the healing process, the addition of the three nanocomposite CCCWs accelerated the hydration reaction to generate C-S-H gel, CaCO3, Aft, etc., improved the internal pore structure, reduced the size of the most probable pore diameter (MPPD) of the mortar specimens, and ultimately promoted the self-healing properties of the cementitious materials.

Study on impermeability of reinforced concrete wall with horizontal construction joints

The reinforced concrete (RC) water retaining tank walls with horizontal construction joints are prone to experiencing seepage under high hydrostatic pressure, which can affect the structural integrity and functionality. To evaluate the impermeability of construction joints with different improvement measures, the permeability test of concrete with and without horizontal construction joints was conducted. The test results show that the addition of Polypropylene fibers (PP fiber) and Cementitious Capillary Crystalline Waterproofing materials (CCCW) can improve the self-waterproofing ability of concrete. The impermeability at the construction joint is much lower than that of single-casting concrete. Moreover, applying CCCW to the water-facing surface of the construction joint can significantly enhance its impermeability. Then, two 1:2 scaled RC tank wall specimens were manufactured, with one wall of conventional concrete and the other wall of modified concrete. The impermeability tests of the typical single-casting and double-layer casting parts of the two wall specimens were carried out respectively. The experimental results show the RC tank wall with construction joint is prone to generate initial defects and seepage, making it difficult to achieve the design watertight requirements. The use of modified concrete materials and surface treatment in the relevant part can effectively improve the impermeability performance of the construction joint. Finally, the BP neural network was used to establish a prediction model between the impermeability of concrete and its material parameters and construction technology.

Investigation on the mechanism of self-healing effect of cementitious capillary crystalline waterproofing material on concrete and enhancement of its resistance to chloride erosion

To enhance the compactness of concrete in coastal areas and impede the ingress of chloride solutions into the structures, Cementitious capillary crystalline waterproofing material (CCCW) was internal incorporated into concrete. This study employed one-dimensional chloride immersion diffusion tests and wet-dry cycle tests to emulate the deterioration of concrete under natural conditions due to chloride ions. The optimal dosage of CCCW was determined by conducting chemical titration to measure the chloride ion concentration at various depths within the specimens. Subsequently, the influence of incorporating CCCW on the compressive strength of concrete under chloride conditions was assessed. Finally, employing experimental methods such as MIP, SEM and EDS, the pores within cementitious materials and the formation of internal crystals was examined at a microscopic level. Research indicates that in chloride salt environments, the penetration of salt solutions can trigger the formation of spider silk biomimetic shape crystalline structures within the internal pores of CCCW. thereby enhancing the compactness of concrete to achieve a self-healing effect while preventing the intrusion of chloride salt solutions.

Study on the freezing resistance and repair technology of prestressed high-strength concrete pipe piles

This article takes a prestressed high-strength concrete tube pile (PHC tube pile) in Tianjin Port as the research object, considers the influence of the type of admixture, forming process, and maintenance method in the process of concrete fabrication, and carries out a rapid freeze-thaw test of PHC tube pile concrete. The changes in the mass loss rate, relative compressive strength, and relative dynamic modulus of elasticity with the number of freeze-thaw cycles, as well as the influence characteristics and mechanism of the admixture type, forming process, and curing method, were obtained. Based on this study, the repair and reinforcement of the base concrete were carried out using ultrahigh toughness cementitious composites and cementitious permeable crystalline composites, and a rapid freeze-thaw test was conducted on the repaired concrete specimens to verify the repair and reinforcement effects of the two materials. The study showed that the mass loss rate, relative strength, and relative dynamic elastic modulus can better characterize the freezing resistance of PHC piles, and it is safer to use the relative dynamic elastic modulus as the evaluation index of the freezing resistance of PHC pile concrete than the mass loss rate. The concrete admixture, forming process, and maintenance method have significant effects on the freezing resistance of the PHC pipe pile mix. The splitting damage surface of both ultrahigh-toughness cementitious composites (UHTTC) and cementitious capillary crystalline waterproofing (CCCW) repaired concrete is a reinforced surface, and both repair materials can improve the freezing resistance of PHC pipe piles through the crack arresting effect and reduction in initial porosity.

Combined effect of rice husk ash and cementitious capillary crystalline waterproofing materials on the performance of mortar

The cement industry is known to leave an enormous environmental footprint. Rice husk ash (RHA), due to its high silicon content, is commonly used as a supplementary cementitious material. However, excessive use of RHA may adversely affect the performance of mortar. Cementitious capillary crystalline waterproofing (CCCW) materials can produce crystals to fill cracks and pores in mortar through the permeation and crystallization of its internal active chemical substances. Therefore, the potential for the combined use of RHA and CCCW is investigated. The results of experiments demonstrate that the mechanical properties and impermeability of the specimens are further improved by the synergistic effect of the two materials. Compared to the control group, the compressive strength and flexural strength peak values of the specimens increased by 22.83 % and 25 %, respectively. The addition of CCCW mitigated the detrimental impact of RHA on the impermeability of the specimens. The microscopic tests indicated that the pozzolanic reaction and filling effect of RHA reduced the porosity of the specimens, enhancing their compactness. Additionally, the permeation and crystallization action of CCCW further contributed to this densification. In the joint utilization of both materials, the incorporation of CCCW serves to counteract the adverse effects of excessive RHA on the self-healing capacity of cracks within the specimens. Concurrently, the high specific surface area properties of RHA facilitate the permeation and crystallization processes of CCCW.

Preparation of cementitious osmotic crystalline waterproof material and its waterproofing mechanism analysis

Cementitious Capillary Crystalline Waterproofing materials (hereinafter: CCCW) with the advantages of good waterproof effect, green and low cost, it is widely used in the field of building waterproofing. Researchers and scholars have studied the proportioning of such materials. However, the experimental methods used in these studies are not perfect enough, therefore, this study uses a seven-factor, two-level orthogonal test method to conduct experiments and to study the waterproofing effect of CCCW coated on the substrate at different ages, and to discuss the existing waterproofing mechanism in conjunction with it. The results show that the group's homemade waterproofing agent has a good waterproofing effect, and the compressive strength is significantly increased at different ages, which suggests that CCCW can promote the hydration of cement and produce more penetrating crystals, thus blocking the capillary pores and microcracks, and making the matrix dense and waterproof.

Development of cementitious capillary crystalline waterproofing agents and durability study of concrete in the presence of chloride with sulfate in aqueous environment

In this study, the chemical composition of cementitious capillary crystalline waterproofing agents (CCCW) was developed by using the water penetration resistance test method. Response to impermeability by first permeability and self-healing properties by second permeability, five effective single components were obtained: Ethylene diamine tetraacetic acid (EDTA), l-aspartic acid, sodium sulfate, sodium silicate and nano-silica. With the help of chloride ion diffusion coefficient measurement and sulfate attack resistance test, it investigates the effect of five components on the durability of the concrete matrix. According to the differential thermogravimetric analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis methods, the waterproof mechanism of each component acting in the matrix was proposed. Finally, also combined with the results of macroscopic performance and microscopic analysis designed orthogonal experiments, the results show that the optimal blending of five waterproofing agent components up to 300% increase in substrate impermeability. The optimal amount of each component is 0.5% EDTA, 2% l-aspartic acid, 3% sodium sulfate, 2% sodium silicate, and 2% nano-silica.

Research and Development of Self-Waterproofing Concrete for Tunnel Lining Structure and Its Impermeability and Crack Resistance Characteristics.

This research paper systematically investigates the combined influence of fly ash, cementitious capillary crystalline waterproofing (CCCW) materials, and polypropylene fibers on the mechanical properties and impermeability of concrete through comprehensive orthogonal tests. Microscopic morphological changes in the concrete induced by different composite materials are examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) testing. The objective is to facilitate a beneficial synergetic interaction among these materials to develop highly permeable, crack-resistant concrete. Key findings of this study are: (1) The study unveils the impact of the concentration of three additive materials on the concrete's compressive strength, tensile strength, and penetration height, thereby outlining their significant influence on the mechanical properties and impermeability of the concrete; (2) An integrated scoring method determined the optimal composite dosage of three materials: 15% fly ash, 2% CCCW, and polypropylene fibers at 1.5 kg/m3. This combination increased the concrete's compressive strength by 12.5%, tensile strength by 48.4%, and decreased the average permeability height by 63.6%; (3) The collective introduction of these three materials notably augments the hydration reaction of the cement, resulting in denser concrete microstructure, enhanced bonding between fibers and matrix, and improved concrete strength and durability.

Study on improvement of waterproofing performance of CCCW with silicone waterproof material and waterbased capillary inorganic waterproofer

The silicone waterproof material and waterbased capillary inorganic waterproofer possess the advantages of rapid film formation and significant hydrophobic effect. In this study, the material composition and mixing ratio of the silicone waterproofing material and waterbased capillary inorganic waterproofing were investigated by multiple performance tests. The results indicated that a white coating was formed on the surface when the mixing ratio of isobutyl-triethoxy-silane and isooctyl-triethoxy-silane was more than 69 %. When the content of sodium and potassium methyl silicate exceeded 0.5 %, respectively, there was an upward trend of contact angle while the reduction in water absorption gradually decreased. Meanwhile, the contact angle and water absorption height of silicone waterproof material were tested. The results showed that the coating performance and hydrophobicity were the best when the mixing ratio of isobutyl-triethoxy-silane, isooctyl-triethoxy-silane, sodium methyl silicate, and potassium methyl silicate was 1.5:0.2:1:0.5. When the matrix mortar specimen was made of Cementitious Capillary Crystalline Waterproofing Materials (CCCW), the lowest water absorption height and water absorption of the experimental group consisted of sodium silicate, sodium tetraborate, sodium phosphate, and sodium hydroxyethyl cellulose were 316.7 % and 39%, respectively. The lowest water absorption height and water absorption of the experimental group consisted of sodium silicate, sodium tetraborate, nano-silica, and sodium hydroxyethyl cellulose were 215.4 % and 28 %, respectively. The results showed that CCCW combined with the experimental group consisted of sodium silicate, sodium tetraborate, sodium phosphate, and sodium hydroxyethyl cellulose had better waterproofing effect.

Effect of Cementitious Capillary Crystalline Waterproofing Materials on the Mechanical and Impermeability Properties of Engineered Cementitious Composites with Microscopic Analysis

Building structures are prone to cracking, leakage, and corrosion under complex loads and harsh marine environments, which seriously affect their durability performance. To design cementitious composites with excellent mechanical and impermeability properties, Engineered Cementitious Composites (ECCs) doped with ultrahigh molecular weight polyethylene short-cut fibers (PE-ECCs) were used as the reference group. Different types (XYPEX-type from Canada, SY1000-type from China) and doses (0%, 0.5%, 1.0%, 1.5%, 2.0%) of Cementitious Capillary Crystalline Waterproofing materials (CCCWs) were incorporated. The effect of CCCWs on the mechanical and impermeability properties of PE-ECCs, and the microscopic changes, were investigated to determine the best type of CCCW to use and the best amount of doping. The results showed that with increasing the CCCW dosage, the effects of both CCCWs on the mechanical and impermeability properties of PE-ECC increased and then decreased, and that the best mechanical and impermeability properties of PE-ECC were achieved when the CCCW dosing was 1.0%. The mechanical properties of the PE-ECC were more obviously improved by XYPEX-type CCCW, with a compressive strength of 53.8 MPa, flexural strength of 11.8 MPa, an ultimate tensile stress of 5.56 MPa, and an ultimate tensile strain of 7.53 MPa, which were 37.95%, 53.25%, 14.17%, and 21.65% higher than those of the reference group, respectively. The effects of the two CCCWs on impermeability were comparable. CCCW-PE-ECC(X1.0%) and CCCW-PE-ECC(S1.0%) showed the smallest permeation heights, 2.6 mm and 2.8 mm, respectively. The chloride ion diffusion coefficients of CCCW-PE-ECC(X1.0%) and CCCW-PE-ECC(S1.0%) exhibited the smallest values, 0.15 × 10-12 m2/s and 0.10 × 10-12 m2/s, respectively. Micromorphological tests showed that the particle size of the XYPEX-type CCCW was finer, and the intensity of the diffraction peaks of C-S-H and CaCO3 of PE-ECC increased after doping with two suitable doping amounts of CCCW. The pore structure was improved, the surface of the matrix was smoother, and the degree of erosion of hydration products on the fiber surface was reduced after chloride ion penetration. XYPEX-type CCCW demonstrated a more obvious improvement in the PE-ECC pore structure.

Preparation and performance investigation of a high efficiency cement permeation type waterproofing materials

The active chemicals play the primary waterproof role in Cementitious Capillary Crystalline Waterproofing Materials (CCCW). Based on the combined mechanism of precipitation reaction and complexation precipitation reaction, precipitation component, complexing agent, calcium ion compensator, surfactant, and defoaming agents were determined as the composition of the active chemicals in this study. Based on the multiple performance tests, the material components and the content of active chemicals were investigated with the single and orthogonal factors. The results showed that with the increase of sodium silicate content, the flexural and compressive strengths of the specimens at 28 d increased, and the water absorption of the specimens gradually decreased. When the sodium silicate content was 2 wt%, the flexural and compressive strengths of the specimens at 28 d increased by 55% and 16%, respectively, and the water absorption of the specimens decreased by 27%. When the content of the complexing agent was constant, the setting time of the specimen gradually prolonged with the increase of the proportion of the hydroxyl and carboxyl groups in the molecular structure. Meanwhile, the flexural and compressive strengths of the specimen decreased gradually with the increase of the content of the complexing agent. With the increase of calcium formate content, the strength of the specimens tended to increase first and then decrease. When the ratio between calcium formate and calcium hydroxide was 10:90, the compressive strength of the specimens cured for 28 d increased by 42%. Based on the analysis of the mechanical properties, water absorption, and expansion of the specimen under orthogonal factors, the mixing ratio of the active chemicals was: precipitation component 2 wt%, complexing agent 1 wt%, calcium ion compensator 3 wt%, surfactant 1.5 wt%, and defoaming agents 0.7 wt%. The impermeability pressure ratios of specimens with and without CCCW coating reached to 275% and 200% at 28 d, respectively. The water resistance of the specimens increased with the increase of curing age, and the water absorption of the specimen was reduced by 56% at 28 d.

Influence of Cementitious Capillary Crystalline Waterproofing Material on Mechanical Properties and Resistance to Chloride Ion Penetration of Engineered Cementitious Composites

Influence of Cementitious Capillary Crystalline Waterproofing Material on Mechanical Properties and Resistance to Chloride Ion Penetration of Engineered Cementitious Composites

Effect of cementitious capillary crystalline waterproofing coating on the gas permeability of mortar

AbstractThis study presents an experimental investigation in the effect of cementitious capillary crystalline waterproofing (CCCW) coating on the gas permeability of mortar and the mechanism how the gas permeability is affected. The gas permeability coefficient of mortar coated with or without CCCW material was measured through modified Cembureau method. The pore structure, micromorphology and hydration products of cement paste with or without CCCW coating were analyzed by the means of mercury intrusion porosimetry (MIP), scanning electron microscopy‐energy disperse spectroscopy (SEM‐EDS), X‐ray diffraction (XRD) and thermogravimetry‐differential scanning calorimetry (TG‐DSC). The results showed that under the effect of CCCW coating, the gas permeability of mortar got decreased and the pore structure changed towards smaller pore sizes. SEM‐EDS results exhibited that there was a large amount of ettringite filling in the pores in the paste with CCCW coating. XRD and TG‐DSC analysis indicated that there was more calcium carbonate formed in the paste with CCCW coating than blank paste. The formation of ettringite in pores and increased calcium carbonate production refines the pore size distribution and densifies the cement matrix, which induces the decrease in gas permeability of mortar coated with CCCW material.

Influence of Cementitious Capillary Crystalline Waterproofing Material on the Water Impermeability and Microstructure of Concrete

The main objective of this study is to investigate the effect of cementitious capillary crystalline waterproofing (CCCW) material on the water impermeability and microstructure of concrete. The water impermeability of concrete covered with or without CCCW material was tested according to the Chinese standard GB 18445-2012. The results indicate that concretes coated with CCCW material showed much higher water impermeability than blank ones, and the ratio of water impermeability pressure between them reached 275. The samples obtained in various depths of hardened cement paste specimens with or without CCCW coating were analyzed through scanning electron microscopy (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC), to study the differences in microstructure and hydration products. The results present that after a 28-day standard curing, there were lots of ettringite crystals and CaCO3 formed in the paste in 1 cm from the coating, but the action depth of the CCCW coating could not reach 3 cm. The ettringite and CaCO3 is precipitated in the pore structure of cement matrix and filling the voids, which leads to the significant enhancement in water impermeability.

Activated chemicals of cementitious capillary crystalline waterproofing materials and their self-healing behaviour

Activated chemicals play a key role in the waterproof performance of cementitious capillary crystalline waterproofing materials (CCCW). We proposed sodium carbonate, sodium silicate, sodium aluminate, tetrasodium EDTA and glycine as activated chemicals of CCCW. The proportion of activated chemicals of CCCW was optimized by two key parameters evaluation of the second permeability ratio and pre-pressure self-healing rate for their self-healing ability of CCCW. Results show that sodium silicate has the most significant impact on the self-healing ability of CCCW. In the self-healing progress of CCCW, the consumption of Ca(OH)2 (CH) and the production of Calcium Silicate Hydrate (CSH) gel, calcium carbonate and ettringite were observed through XRD and SEM analysis. The white crystals with an average diameter of 0.2 mm are produced on both sides of cracks, and consequently the cracks were healed by the accumulation of crystals. The self-healing mechanism of CCCW was proposed based on the self-healing experimental results.

Cementitious coatings for improved corrosion resistance of steel reinforcement

The viability of cementitious capillary crystalline waterproofing materials for corrosion protection of steel reinforcing bars for civil engineering infrastructure was evaluated using the half-cell potential method according to ASTM C876. The coatings were characterized by a novel eka-molecular sieve type structure which is breathable yet highly impermeable to water and possesses self-healing characteristics. The test program monitored the corrosion activity of 102 reinforcing bar samples embedded in mortar and immersed in a 3.5% concentration sodium chloride solution for one year. For some samples, the coating was applied directly on the embedded reinforcing bar while for other samples the outside surface of the mortar was coated. Three different types and combinations of coatings were applied. It was found that, in general, the coatings significantly delayed the onset of corrosion compared to the uncoated control samples. Samples that underwent mortar surface coating demonstrated no signs of corrosion after one year of exposure to the chloride solution.

Polymer-Modified Cement Waterproofing Coating and Cementitious Capillary Crystalline Waterproofing Materials: Mechanism and Applications

As the Integrant Construction Material for Infrastructure Construction and Real Estate Industry, Building Waterproof Materials is a Key Part of the Construction Quality Guarantee. it Plays an Important Role in Saving Energy, Reducing Consumption and Environmental Protection. it Lays the Foundation for the Realization of the Cleaning Production and High Efficiency for Economical Production. Currently, the Direction of Waterproof Construction is from Multi-Layer to Single Layer, from Heat to Cold Construction. there are many Different Kinds of Waterproof Materials on Building Materials Market. when the Waterproof Materials Need to Be Used for the Project, we should Deal with Problems Case by Case in Order to Be Able to Select the Waterproof Coating Suitable for the Characteristics of the Project. Attention Need to Be Paid for the Differences of the Constituents, the Physical Mechanical Properties and Characteristics, and Construction Points and Matters during Construction Works Polymer-Modified Cement Waterproofing Coating and Cementitious Capillary Crystalline Waterproofing Materials are Reviewed in the Present Study. Waterproof Mechanism and Influence Factors of its Application Discussed. as a New Type of Waterproof Materials, its Unique Advantage and Price Decline, it has been Widely Used in Industrial and Civil Buildings, and the Remarkable Economic Benefits and Social Benefits has been Achieved in Past few Years.

Development length of steel reinforcement with corrosion protection cementitious coatings

The bond strength and development length of steel reinforcing bars coated with cementitious capillary crystalline waterproofing materials were evaluated using a modified pull-out test method. The coatings possess self-healing capabilities and are characterized by a novel eka-molecular sieve type structure to prevent moisture penetration. Following a study on corrosion protection, in which the coating showed a great promise, it was decided to investigate the effect of the coating on bond strength. A self-reacting inverted T-shaped beam was designed to simulate the stress conditions of flexural structural members. Six T-beams were fabricated, each of which contained eight rebar test samples. Tests were conducted at approximately seven days and at three months after casting to investigate curing effect on bond. Although the bond strength of the coated samples were reduced compared with the uncoated bars, theoretical development lengths obtained from current concrete design code equations were sufficient to reach the yield strength of the bars.

Research on Cementitious Capillary Crystalline Waterproofing Coating for Underground Concrete Works

Research on Cementitious Capillary Crystalline Waterproofing Coating for Underground Concrete Works

Research on Cementitious Capillary Crystalline Waterproofing Coating for Underground Concrete Works

Cementitious capillary crystalline waterproofing coating was developed, whose doping quantity of active substances was primarily determined by using orthogonal tests, the doping quantity of the active substances and the cement-sand ratio were optimized, and the formulation of the waterproofing coating was: 50.45% of silicate cement, 40% of quartz sand, 2.4% of assistants and 7.15% of active chemical substances. Test results showed that all the properties of the developed waterproofing coating conform to standard requirements, the bonding strength of wet substrate reached 1.8 MPa, and 28d seepage resistance reached 1.3 MPa.