Concrete Surface Treatment Research Articles

Preparation and characterization of Lithium-stabilized Colloidal Silica as a silicate densifier for concrete surface treatment

Enhancing the durability of concrete by safeguarding it against cracking and environmental deterioration is paramount. While silicate-based densifiers have been instrumental in shielding concrete surfaces from wear and environmental factors, the surging popularity of lithium silicate solutions faces a significant impediment due to the high cost of lithium, mainly attributed to its predominant use in manufacturing lithium batteries. To address this substantial challenge, an intriguing approach involves blending lithium silicate with colloidal silica, potentially offering a cost-effective and efficient solution for concrete surface treatment. This study delves into the feasibility of utilizing lithium-stabilized colloidal silica as a silicate densifier, focusing on their preparation, characterization, and efficacy in lab-scale applications. The results demonstrate that lithium-stabilized colloidal silica can heighten surface hardness while concurrently reducing porosity. However, it is worth noting that this approach presents particular challenges, particularly regarding preparation and water resistance, when compared to surfaces treated solely with lithium silicate. Addressing these hurdles holds promise for optimizing and enhancing lithium-stabilized colloidal silica and advancing the concrete surface treatment field in future research endeavours.

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.

An Experimental Investigation on Mechanical Properties of Bacterial Concrete Using Bacillus Subtilis

Abstract: This Concrete is susceptible to micro crack formation and has pores which are highly undesirable because they provide an open pathway for the ingress of water and other deleterious substances. The use of concrete surface treatments with water proofing materials to prevent the access of aggressive substances is a common way of contributing to concrete durability. However, the most common surface treatments use organic polymers (epoxy, acrylics and polyurethanes) all of which have some degree of toxicity. Bio inspired materials can lead to a more sustainable construction industry, especially when providing new low toxic solutions. Hence, there is an urgent need to pay more attention for improving the properties of concrete with respect to strength and durability, especially in aggressive environments. One effective remedy for closure of cracks is the Bacterial Concrete (BC) which will continuously deposit calcite in concrete. This, phenomenon is called as Microbiologically Induced Calcite Precipitation (MICP). The urease enzyme enables the deposition of calcium carbonate (CaCO3) with the help of bacteria. The bacterial remediation technique surpasses other techniques as it is bio-based, eco-friendly and durable. Bacteria need to offer resistance to withstand high pH of concrete and mechanical stresses during mixing. In these present investigations bacterial sample name Bacillus Subtilis (BS) is considered in concentrations of 104 , 105 and 106 cells/ml of mixing of water. investigations are carried out on strength-related properties such as compressive strength, splitting tensile strength and flexural strength to assess the quality of concrete. The optimum dosage of cell concentration of bacteria is found to be 105 cells/ml for BS based on compressive strength results. M25 grade concrete is designed and used for embedding Bacillus subtilis bacteria.

Multiscale analysis of shrinkage-induced performance degradation of shear wall and application to structural analysis

Shrinkage-induced cracks reduce the stiffness of concrete structures. Shear walls are more sensitive to drying shrinkage than other members because of their fully restricted condition and large surface areas exposed to air. This study examines how concrete structural performance is affected by shrinkage due to moisture loss via hydration or dissipation by applying multiscale integrated finite element analysis. First, a cyclic shear loading test on shear wall specimens subjected to drying in a previous study was reproduced. Based on the reproduction analysis model, parametric analysis was conducted, focusing on the member scale, mix proportion, and surface treatment of concrete. Shrinkage-induced cracks reduced member stiffness, and the effects of the member scale on drying speed were shown. The dominance of autogenous shrinkage in the case of high-strength concrete was also observed. The sealing of the concrete surface effectively prevented moisture dissipation, but moisture supply from ambient air was also blocked when the humidity inside the concrete was low. Thus, a proper surface protection method should be selected considering water consumption via hydration. Finally, the use of equivalent material properties for considering initial damage due to shrinkage was proposed as a simple way to account for drying effects in structural analyses.

Investigation of the behaviour of adhesively bonded joints between timber and self-compacting concrete

Composite constructions made of wood and concrete are being researched as revolutionary structural components that offer many benefits. The connection in timber-concrete-composite (TCC) is typically made via mechanical means. This study describes the TCC bonded by adhesives, particularly the mechanical behaviour of the joints between timber (GL24h) and self-compacting concrete (SCC) set by the dry or wet bonding process. For this purpose, double push-out shear tests on TCC joints bonded by epoxy resin of adhesives were performed. The role of several variables was considered for both fabrication processes. These parameters were: variation of moisture content (m.c.) of timber, adhesive type, adhesive thickness, sand addition, concrete surface treatment, and scale of bonding length. The results showed that glueing seems to be a feasible alternative instead of mechanical means for producing dry and wet TCC joints. Under dry conditions of timber elements, the shear strength can be considered highly satisfactory, with a mean value range of 6–8 MPa. The failure mode is primarily affected by concrete and timber failure. However, the findings of this study confirm the hypothesis that increasing the moisture content of timber before the gluing process significantly reduces the shear strength of adhesively bonded TCC joints by approximately 30% in certain instances. These results contribute to understanding the challenges and limitations of the bonding system, providing valuable insights for optimizing the design and manufacturing of timber-concrete composites.

Preparation and evaluation of TA/APTES-HDTMS hydrophobic nanocomposite coating for enhancing corrosion resistance of concrete

Coating anticorrosive technology has been widely used in marine concrete structures, but there are some problems such as poor adhesion, lack of durability or environmental pollution. Tannic acid (TA) -aminopropyl triethoxysilane (APTES) coating has good adhesion, corrosion resistance and secondary reactivity, and has been widely used in biomedicine etc. fields. However, the feasibility of applying TA-APTES to concrete surface treatment remains to be studied. In this study, hydrophobic nanocomposite coating TA/APTES- hexadecyltrimethoxysilane (HDTMS) was prepared by coupling HDTMS with TA-APTES, and applied to concrete surface treatment. By water contact angle measurement (WCA), Coulomb charge experiment and scanning electron microscopy test, the effects of TA-APTES mixture content, mass ratio of TA to APTES and HDTMS concentration on the hydrophobic property and ionic permeability of coated concrete were investigated. The results indicated that TA/APTES-HDTMS coating prepared with 4.0 mg/mL TA-APTES mixture content, 2:1 mass ratio of TA to APTES and 7.0 % HDTMS solution concentration showed optimal improvement efficiency. In this case, the chloride transport properties and sulfate resistance of coated concrete were studied by chloride and sulfate natural diffusion tests, respectively. The results indicated that compared with uncoated concrete, coated concrete showed better and stable resistance to chloride ion and sulfate. In addition, the chloride transport models of both coated and uncoated concrete were established based on Fick’s Second Law. It was found that the chloride diffusion coefficient of coated concrete was similar to that of uncoated concrete, but the surface chloride content was significantly lower. Meanwhile, the lifetime of TA/APTES-HDTMS coating was evaluated based on the change of surface chloride content and compared with other research literature. Furthermore, by WCA and Coulomb charge experiment, it was concluded that the anti-abrasion property and acid-alkaline resistance of coated concrete were significantly improved. Finally, the cost-benefit analysis of TA/APTES-HDTMS coating and existing commercial coatings also illustrated the advantages of TA/APTES-HDTMS coating.

Durability of concrete incorporating recycled coarse aggregates: carbonation and service life prediction under chloride-induced corrosion

The use of recycled aggregates (RA) is growing due to the environmental problems associated with extracting natural aggregates (NA) and the disposal of construction and demolition waste (CDW). However, the service-life prediction of recycled coarse aggregate concretes remains incipient. Thus, this study aimed to evaluate the effects of different replacement contents of NA by RA (25, 50, and 75 wt%) on physical (water absorption, porosity, and bulk density), mechanical properties (compressive strength and modulus of elasticity), microstructure (evaluated by X-ray microtomography), accelerated carbonation, and chloride penetration of concrete. A service life prediction analysis of RA concretes was conducted based on the chloride profile obtained and considering the application of different concrete surface treatments. The RA contents evaluated increased the carbonation and chloride diffusion coefficients by 75.7% and 43.0%, respectively, compared to the reference concrete. Nevertheless, reductions of approximately 50% on the critical chloride concentration depth of RA concretes are estimated considering the application of acrylic-based surface treatment. Therefore, applying surface treatments is promising to increase RA concretes' durability and service life, contributing to its wide use and dissemination feasibility.

Performance of Soy Methyl Ester-Polystyrene as a Concrete Protectant: A State-of-the-Art Review

Freeze–thaw cycles, application of deicing salts, and rebar corrosion are becoming main sources of concrete deterioration in bridge decks and pavements. During the past few decades, concrete surface treatments have begun to receive wide acceptance because of their effectiveness in sealing the concrete. Surface treatments achieve this by limiting fluid ingress, thereby reducing damage associated with freeze–thaw cycles, deicing salt application, and rebar corrosion. Soy methyl ester-polystyrene blends (SME-PS) have been shown to be an innovative, promising method of topical sealing. SME-PS, which is a derivative of soybean oil and expanded polystyrene, has been continuously studied since 2008. In this context, a comprehensive literature review compared the performance of SME-PS with that of traditional concrete sealers, including organic, inorganic, hybrid, and biotic sealers. These sealers were reviewed for performance in reducing water absorption and chloride penetration and improving freeze–thaw durability of concrete. The reviewed papers indicate that SME-PS possesses superior performance as a concrete protectant for reducing water absorption, chloride penetration, and freeze–thaw damage. To further enhance the feasibility of SME-PS, future studies may include investigating the physical and chemical protecting mechanisms of SME-PS, understanding the factors that affect the penetration behavior of SME-PS in concrete, and evaluating the short and long-term effectiveness of SME-PS in concrete.

Experimental Evaluation of Bond Strength between Setting Retarder Added Concrete and Normal Concrete

The large size concrete structures are continuously placed with time delay due to practical reasons. The bond strength between old concrete and new concrete is related with a performance of concrete structures. In order to investigate bond strength of slant shear specimens, the specimens (100 × 100 × 300 mm) were fabricated and tested. Two fractions of setting retarder (0% and 1%), surface roughness (none, brushed, and chipping), and curing hours (8, 16, 24, and 72 hours) were considered as variables. Failure modes, compressive strength, and displacement were measured to evaluate the bond strength of specimens. As a result, chipping treatment, which is commonly applied to increase the bond strength between old and new concrete, did not show significant increase of bond strength. The addition of retarder shows that the increased bond strength compared with the chipping treatment. The addition of the retarder in concrete shows sufficient bond strength after the previous placing of 16 hours. Furthermore, the retarder-added specimens with additional brushing treatment of concrete surfaces showed increase of bond strength more than the specimens without brushing. From the test results, it is confirmed that the addition of the retarder can be a new method to increase the bond strength of the concrete surface in continuous placement of concrete.

Effects of Surface Treatment Conditions on the Bonding Strength and Electromagnetic Pulse Shielding of Concrete Using the 85Zn-15Al Arc Thermal Metal Spraying Method.

The surface treatment of concrete enhances the bonding of its metal coatings. Therefore, in the present study, on the concrete surface, prior to the deposit of an 85Zn-15Al coating via an arc thermal spraying process, different surface treatments were considered for the effective electromagnetic pulse (EMP) shielding properties of the concrete. However, the direct coating on a concrete surface possesses lower bond adhesion, therefore it is of the utmost importance to treat the concrete surface prior to the deposition of the metal coating. Moreover, to obtain better bond adhesion and fill the defects of the coating, the concrete surface is treated by applying a surface hardener (SH), as well as a surface roughening agent (SRA) and a sealing agent (SA), respectively. The metal spraying efficiency, adhesion performance, and bonding strength under different concrete surface treatment conditions were evaluated. The EMP shielding effect was evaluated under the optimal surface treatment condition. The proposed method for EMP shielding exhibited over 60% of spraying efficiency on the treated surface and a bonding strength of up to 3.9 MPa for the SH-SRA-SA (combining surface roughening and pores/defects filling agents) specimen compared to the control one, i.e., 0.8 MPa. The EMP shielding values of the surface-treated concrete with surface hardener, surface roughening agent, and sealing agent, i.e., SH-SRA-SA specimens, exhibited 96.6 dB at 1000 MHz. This was about 12 times higher than without coated concrete.

Experimental research on mechanical behavior and strengthening technologies of joints in hollow-core slab bridge

The joint is the connection part of a hollow-core slab bridge. Thus, it is necessary to study the joint systematically. In this paper, 15 beams with the joint were designed to study the mechanical behavior and the load transfer mechanism of the joints under flexure load, shear load, and flexure-shear load, and the corresponding failure mode was observed. The effects of pavement layer thickness, concrete surface treatment, joint concrete strength, and joint form on the mechanical properties of joints were studied. And the strengthening effects of CFRP strengthening technology and locally prestressed tendons strengthening technology were studied. The test results showed that the failure mode of all specimens was cracking at the interface between the joint and the beam segment. Cracks started from the bottom of the specimen and extended upward with the increase of load. The mechanical behavior of joints could be improved by increasing the pavement layer thickness, interface roughness, joint width, and the number of tensile rebars. However, the concrete strength of the joint had little effect on the mechanical behavior. CFRP could effectively delay crack development and improve mechanical behavior. The specimen with a locally prestressed tendon performed better structural integrity than the control specimen. Furthermore, according to the results obtained from the AASHTO and experiments, a factor with the aim to correct the calculated values of the bearing capacity in the code was proposed.

Abrasion resistance enhancement of concrete using surface treatment methods

Abrasion is a phenomenon in which the reduction of volume and mass of the material surface is caused by friction, scratching and percussion, thus, it is promising to modify the surface characteristics for abrasion resistance enhancement. In this study, polyurea waterproof adhesive (PUA), polyurethane waterproof coating (PUR), iron sheet (IS), and rubber (RB) are applied for surface treatments to improve the abrasion resistance of concrete, and their effects on the mechanical strength, nano-scratch, drop-weight impact and resistance to debris flow abrasion are investigated. The results show that all surface treatment methods improve the flexural strength of concrete, while PUA, PUR and IS surface treatments reduce the compressive strength due to the size effect of concrete. The high-hardness surface treatments (PUA and IS) significantly reduce the abrasion rate due to their excellent resistance to impact and scratches, exhibiting a low roughness after abrasion. Abrasion rate of concretes PUA and IS at 48 h are 0.04 g/h and 0.03 g/h, respectively, which decrease by 75% and 81%, compared to the untreated concrete. The aggregates cutting, micro-cracks, scratches and indentation formation are abrasion failure mechanisms of surface-treated concrete caused by debris flow. PUA and IS surface treatment methods with a suitable thickness are recommended to enhance the resistance to debris flow abrasion of concrete protective structures.

Study on preparation and strengthening mechanism of new surface treatment agent of concrete at multi-scale

Concrete is susceptible to external erosion during service, the life of which was thus shortened due to the deterioration from the surface to the inside. In this study, the concrete surface treatment agent at multi-scale was innovatively proposed, which compounded of nano-silica sol–gel, micron-scale lithium silicate and sodium silicate. The physical properties and mechanical properties were investigated. Moreover, the mechanism of the new surface treatment agent was revealed in terms of pore structure and hydration products by XRD, TG, NMR, iMicro, and SEM. The results show that the Mohs hardness, flexural strength, and hydration degree are increased (by 260%, 78.7%, 12.1%), and porosity is reduced by 22% after the surface treatment. The mechanism is that pores can be repaired by particles of multi-scale. In addition, pretreatment of Ca2+ can further promote the pozzolanic reaction. The extra of EDTA-2Na can promote not only the pozzolanic reaction but also secondary hydration reaction.

Properties and Durability of Cement Mortar Using Calcium Stearate and Natural Pozzolan for Concrete Surface Treatment.

Applying a concrete surface treatment method (epoxy or primer) can prevent water from penetrating concrete through surface pores. However, if the concrete surface is damaged, the subsequent reconstruction can be expensive and time-consuming. Concrete that is resistant to internal and external water has been extensively developed and used to supplement the surface treatment method. Herein, we prepared specimens by mixing cement mortar with fatty-acid-salt-based calcium stearate attached to two natural pozzolanic materials—diatomite and yellow clay. The physical tests measured (1) the air content, (2) flow test, (3) compressive strength, and (4) activity Factor. Durability experiments were performed on (1) the contact angle, (2) chloride ion diffusion coefficient, and (3) water absorption test. The results revealed that the compressive strength of concrete decreased as the calcium stearate content increased. Furthermore, it was confirmed that the contact angle of the test piece using the pozzolanic substance and calcium stearate was twice as high. It was confirmed that the sand test specimen had the highest water absorption rate, and the DT3% had the lowest. (Sand%: 11.8 > OPC: 6.5 > DT3%: 2.4), the chloride diffusion coefficient also showed similar results. (Sand%: 12.5 > OPC: 8.4 > DT1%: 8.8)Due to its unique insolubility, calcium stearate retards hydrate formation when mixed alone and negates compressive strength loss when combined with pozzolanic mixtures rich in SiO2 and Al2O3. Furthermore, the ideal method for producing water-resistant cement mortar is to evenly disperse calcium stearate in the porous powder of cement mortar.

A Study on Impact of Different Surface Treatment Agents on the Durability of Airport Pavement Concrete

Concrete surface treatment is one of effective methods to increase the durability of concrete. This study chose tetraethyl orthosilicate (TEOS), lithium silicate (Li2SiO3), SiO2 nanoparticles (nano-SiO2) as surface treatment agents, tested their resistance to water penetration, chloride ion penetration, frost, sulfate erosion and abrasion of concrete specimens with different strengths, compared and evaluated the impacts to the durability of concrete by using three surface treatment agents, researched the impact of concrete strength on the surface treatment effects, and analyzed the mechanism of these surface treatment agents in connection with microscopic tests. It was found that all three agents can improve the durability of concrete, of which, the treatment effect from using tetraethyl orthosilicate (TEOS) was the best; however, along with the improvement of concrete strength, its other effects were gradually reinforced except for some small improvement effect in resistance to frost, which means it is an ideal concrete surface treatment agent; for lithium silicate (Li2SiO3), the improvement effect of resistance to frost was the best with little impact on the strength of the concrete, however, the other performance improvement effects were a little bit worse than that of tetraethyl orthosilicate (TEOS), which means it is more suitable for airport pavement with a higher concrete resistance to frost; For SiO2 nanoparticles (Nano-SiO2), the surface treatment effect was extreme limited, not recommended to be solely used for airport pavement with its requirement of high resistance to frost. Upon scanning electron microscope (SEM), X-ray diffraction (XRD), fourier transform infrared radiation (FTIR) and thermo gravimetric analyzer (TGA) tests, the surfaced concrete specimens did not produce any new substances, and the effect of the surface treatment agents was mainly to improve the concrete performance by physical filling, or by filling the cavities with the hydrated calcium silicate gel produced in the chemical reaction. These results may direct the selection of surface treatment agents in airport engineering.

STUDY ON REINFORCEMENT OF FABRICATED HOLLOW SLAB BRIDGE BY POLYURETHANE-CEMENT COMPOSITE (PUC)

In this paper, a new polyurethane-cement composite (PUC) material is used to reinforce a 25-year hollow slab bridge. PUC material is composed of polyurethane and cement, which has good mechanical properties. After pouring PUC material at the bottom of the hollow slabs, the traffic can be restored in a short time. Ultimate bearing capacity was discussed based on the concrete structures. The failure mode of the reinforced beam depends on the PUC material. The strengthening process includes surface treatment of concrete, formwork erection and polyurethane cement pouring. In order to verify the effectiveness of PUC reinforced bridges, load tests were carried out before and after reinforcement. The test results showed that PUC could remove the bridge load and increase the stiffness of the hollow slabs.

Impact of Concrete Mix Ingredients and Surface Treatments on Epoxy Overlay Performance

Epoxy overlays are applied on bridge decks after curing concrete in patches and repairs for 28 days. A tensile bond pull-off strength of at least 250 pounds per square inch (psi) is expected from a properly applied overlay. Even though the overlay performance at room temperature is mostly satisfactory, the performance at elevated temperatures is not convincing. The degradation of mechanical and adhesion properties of epoxy, shear stress at the concrete/overlay interface caused by thermal incompatibility, and the interface moisture vapor pressure are the commonly cited parameters for poor bond strength at elevated temperatures. A combined effect of these parameters results in the most unfavorable failure mode (which is bond failure at the concrete/overlay interface) at a strength lower than the specified limit of 250 psi. The moisture migration through concrete depends on many factors including moisture content along the depth of concrete, pore microstructure, exposure condition, and drying period. This study investigated the impact of concrete mix ingredients and surface treatments on the thin epoxy overlay bond strength. The results show that the use of concrete mixes with slag and penetrating sealant pretreatment improves the bond strength.

Surface rehabilitation of Portland cement concrete (PCC) pavements using single or double surface dressings with soft bitumen, conventional or modified emulsions

Surface dressings are a sustainable maintenance alternative for pavements with surface distresses, due to the low amount of resources involved. This paper aims to analyze the viability of using twelve different surface dressing solutions, including three binders (conventional and modified emulsions, and a soft 160/220 bitumen) and a covering with diluted emulsion, for surface treatment of Portland cement concrete (PCC) pavements. Several test methods were used to evaluate the macrotexture, skid resistance, adhesion, and resistance to wearing on a large scale prototype. In general, single surface dressings increased further the macrotexture of the concrete pavement surface. The skid resistance of single and double surface dressings was similar. The best surface dressing in the pull-off test was that with the 160/220 bitumen. The conventional and modified emulsions presented similar mechanical adhesion in the Vialit plate test. Concerning the prototype wearing test, the best result was obtained for the double surface dressing with bitumen covered with diluted emulsion. Based on this work’s results, the surface dressings are a potential surface rehabilitation alternative for concrete pavements.

Influence of different surface treatment on water penetration resistance of concrete

Concrete is easily affected by all kinds of erosive substances during its use. Surface treatment is a simple method to improve the surface compactness and water permeability resistance of concrete. In this paper, silicate infiltration agent, nano-SiO2 and ethyl silicate are selected as concrete surface treatment material. The results of water permeability test showed that all the three treatments can effectively improve the water resistance. Silicate infiltration agent and nano-SiO2 were the most effective, which greatly reduced the penetration depth of water from 66 mm to 34mm and 32 mm, while ethyl silicate was reduced to 50 mm. Through the water permeability test curve, we can see that the water entered the concrete under a certain pressure, and the result showed the shape of high, middle and low edge.

Surface treatment of concrete by retarder: Investigation of pattern change and preliminary application

As a novel surface treatment technology, graphic concrete features its meticulous pattern and an excellent visual expression. In this paper, the effect of concentration of retarder, curing age, water-cement ratio (w/c) and sand-cement ratio (s/c) on area change percentage (ACP) of the transferred patterns was investigated. The results show that with the increase of concentration of retarder, the ACP increased sharply from negative to positive, while the ACP decreased from positive to negative with a rise of curing age of concrete. It presents strength gradient in the concrete for the synergistic effect of retarder diffusion and strength development of concrete matrix which lead to the various pattern change of graphic concrete. The practical graphic concrete with size of 270 mm × 330 mm was prepared with 20% retarder, 0.3 w/c, 2.0 s/c and cured at 20 ± 1 °C for 20 h, which shown an extremely high similarity between transferred patterns and designed patterns.