Concrete Substrate Research Articles

Application of neuro-fuzzy estimation in prediction of shear bond strength between concrete layers through the efficient laser roughness analyzer

To ensure the monolithic behavior of reinforced concrete composite parts, the bond strength at the interface between concrete layers cast at various ages must be high. Reinforced concrete composite members include precast beams with cast-in-place slabs, bridge decks strengthened by adding a new concrete layer, and repair and strengthening of existing concrete structural members by adding a new concrete layer. in this study, the shear bond strength (SBS) of reinforcing steel on Portland cement and a hybrid cement including slag and Portland cement activated with sodium carbonate is investigated. The pull-out test was used to determine SBS; also a subsequent test data is evaluated using ANFIS, as well as surface classification utilizing a laser roughness analyzer designed particularly to assess the roughness of the concrete substrate. As a result, this research tried to create an in situ non-destructive approach for assessment of concrete surfaces and its influence on shear bond strength measurement of the concrete layers. All test data is analyzed using an adaptive neural fuzzy inference system (ANFIS) to classify the different input variables for determining the shear bond strength between concrete layers using the mean and maximum surface roughness (SR) height parameters Ra and Rt in X and Y direction. ANFIS was used to optimize the process based on five processing parameters. Skillful prediction could play a pivotal role in the optimal conditions during laser cutting process. Based on results, laser speed is the most influential on the Ra in X and Y direction (RMSE: 0.3255, RMSE: 0.6869, respectively). The most influential parameter on the Rt in X direction is laser power (RMSE: 1.5611), while the most influential parameter on the Rt in Y direction is laser speed (RMSE: 2.0781), resulting that the roughness of the substrate surface highly affects the shear bond strength of concrete interfaces.

Structural flexural strengthening through material bonded to the concrete substrate

This article proposes an alternative method for the structural design of reinforced concrete elements strengthened in bending by metallic plates or fiber-reinforced polymer (FRP) bonded to the concrete substrate. It is proposed a new calculation procedure for the strengthening using thin adhered material bonded to the element surface that dispenses the iterative process generally used in the design. The proposed routine is validated by comparison with other methods. A practical example is also presented, applying the procedure to an element of a building where a load change was foreseen. As result, it was verified that the proposed procedure provides values similar to the trial-and-error method used in the FRP strengthening design. Results are also coherent with other methods available in the literature for metallic plates. Therefore, since this routine obtains similar values without using an iterative method, its applicability in the design becomes advantageous.

Performance of bond strength between ultra-high-performance concrete and concrete substrates (concrete screed and self-compacted concrete): An experimental study

Ultra-high-performance concrete (UHPC) is one of the contemporary overlay materials for repairing and retrofitting of reinforced concrete (RC) members. It possesses excellent compressive and tensile strength, as well as long durability. Nevertheless, the bonding performance between the overlay interface (UHPC) and the substrate concrete must be adequate under various loading, curing, and exposure circumstances. Therefore, this research examined, experimentally, the interfacial bonding behavior of UHPC overlay and two distinct substrates, namely concrete screed (CS) and self-compacted concrete (SCC). Four parameters impacting bond strength behavior, including three different substrate surface preparations, curing conditions, exposure environments, and testing techniques, were used to fulfill the goal of this study. The tests findings revealed that the substrate surface preparation and the exposure conditions had significant effects on the bond behavior of both UHPC-SC and UHPC-SCC while curing conditions seemed not to have any significant effects. The highest bond strength was obtained for specimens having sandblasted substrate preparation technique regardless of the bond test method. However, specimens tested under the bi-surface shear strength technique exhibited high bonding strength with the drill holes substrate preparation technique due to the presence of drilled holes that were being filled with UHPC. The splitting tensile test is a reliable test technique to examine the impact of repeated cyclic exposure samples. As a result of this, a substantial reduction in bond strength of nearly 32%, 55%, and 26% of the UHPC-SCC and 31.84%, 51.5%, and 41.42% for UHPC-SC interfaces for as-cast (AC), drilling hole (DH), and sandblasting (SB) substrate surface preparations, respectively, were obtained. ANOVA was carried out and found to be aligned with the experimental findings.

Facile preparation of robust superhydrophobic coating on concrete surface through “all-covalent” strategy

PurposeThe purpose of this study is to prepare a robust superhydrophobic coating on concrete substrate with remarkable chemical and mechanical durability through “all-covalent” strategy.Design/methodology/approachAmino-modified silica nano/micro-particles were prepared through two synthetic steps. “All-covalent” strategy was introduced to prepare a robust superhydrophobic coating on concrete surface via a “all-in-one” dispersion and a simple spraying method. The successful construction of the products was confirmed by Fourier transform infrared spectroscopy, water contact angles (WCA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The concrete protective properties were verified by solution immersion test, pull-off test and rapid chloride migration coefficient test. The mechanical durability was tested by falling sand impact.FindingsHierarchical structures combined with the low-surface-energy segments lead to typically superhydrophobic coating with a WCA of 156° and a sliding angle of 1.3°. The superhydrophobic coating prepared through “all-covalent” strategy not only improves chemical and mechanical durability but also achieves higher corrosion and wear resistance than the comparison sample prepared by physically blending strategy. More importantly, the robust superhydrophobic coating showed excellent adhesion and protective performance of concrete engineerings.Practical implicationsThis new “all-covalent” superhydrophobic coating could be applied as a concrete protective layer with properties of self-cleaning, anti-graffiti, etc.Originality/valueIntroduction of both silica nanoparticles and silica microparticles to prepare a robust superhydrophobic coating on concrete surface through “all-covalent” strategy has not been systematically studied previously.

Large-scale (Phase III) evaluation of broflanilide 50WP (VECTRON\u2122 T500) for indoor residual spraying for malaria vector control in Northeast Tanzania: study protocol for a two-arm, non-inferiority, cluster-randomised community trial

BackgroundIndoor residual spraying (IRS) is a major method of malaria vector control across sub-Saharan Africa. Effective control is being undermined by the rapid spread of insecticide resistance. There is major investment in development of new insecticides for IRS that possess novel modes of action, long residual activity, low mammalian toxicity and minimal cross-resistance. VECTRON™ T500, a new IRS product containing the active ingredient broflanilide as a 50% wettable powder (WP), has been shown to be efficacious against pyrethroid susceptible and resistant vector species on mud and concrete substrates in experimental hut (Phase II) trials.MethodsA two-arm non-inferiority cluster randomized controlled trial (Phase III) will be undertaken in Muheza District, Tanga Region, Tanzania. VECTRON™ T500 will be compared to the IRS product Fludora® Fusion (clothianidin 50% WP + deltamethrin 6.25% WP). The predominant malaria vectors in the study area are pyrethroid-resistant Anopheles gambiae s.s., An. arabiensis and An. funestus s.s. Sixteen village clusters will be pair-matched on baseline vector densities and allocated to reference and intervention arms. Consenting households in the intervention arm will be sprayed with VECTRON™ T500 and those in the reference arm will be sprayed with Fludora® Fusion. Each month, CDC light traps will collect mosquitoes to estimate changes in vector density, indoor biting, sporozoite and entomological inoculation rates (EIR). Susceptibility to IRS active ingredients will be assessed using World Health Organisation (WHO) bottle bioassays. Target site and metabolic resistance mechanisms will be characterised among Anopheles field populations from both trial arms. Residual efficacy of both IRS products will be monitored for 12 months post intervention. Questionnaire and focus group discussions will explore factors that influence adherence, adverse effects and benefits of IRS.DiscussionThis protocol describes a large-scale non-inferiority evaluation of a novel IRS product to reduce the density and EIR of pyrethroid-resistant Anopheles vectors. If VECTRON™ T500 proves non-inferior to Fludora® Fusion, it will be considered as an additional vector control product for malaria prevention and insecticide resistance management.Trial registration: ClinicalTrials.gov, NCT05150808, registered on 26 November 2021. Retrospectively registered.

Studying the Influence of Silica Fume on Bond Strength of the PCM-Concrete Interface under Shear Stress Condition.

The polymer cement mortar (PCM) overlay method is a promising solution for strengthening deteriorated concrete structures in which the occurrence of premature debonding at the interfaces prevents the strengthened structures from achieving full serviceability. The purpose of this study is to improve the concrete–PCM interfacial bond to prevent premature debonding. There are two main focuses of this study: (i) investigation of the effectiveness of adding 5% silica fume to PCM in forming a chemical connection between concrete and PCM, based on a direct single-surface shear test using two roughness levels of concrete (smooth and rough) and microstructure analysis and (ii) performance evaluation of the bond between substrate concrete and a PCM overlay with/without silica fume at early ages and with different moisture conditions at the interface, based on a bi-surface shear test using rough substrate concrete surface. The inclusion of 5% silica fume with PCM caused an improvement in the interfacial strength (approximately 113% relative to the normal PCM in cases of without primer), with a smooth concrete substrate surface where mechanical bonding had less influence. In addition, lower Ca/Si values in the interface of modified 5% silica PCM specimens compared to the normal PCM specimens quantified by energy-dispersive X-ray spectroscopy (EDS) indicate the formation of a chemical connection at the concrete–PCM interface by transforming harmful Ca(OH)2 into more C-S-H which strongly improves the bonding strength. As a repair layer mortar, the positive influence of silica fume in modified 5% silica PCM specimens was also found at early ages and with different moisture conditions at the interface compared to the normal PCM. In conclusion, the addition of silica fume to the PCM caused chemical connection at the concrete–PCM interface and improved the interfacial performance.

The bond properties between ultra-high-performance concrete and normal strength concrete substrate: Bond macro-performance and overlay transition zone microstructure

This study investigates the bond performance between ultra-high-performance concrete (UHPC) and normal strength concrete (NSC) substrate. A hoop constraint method is designed to assess the shrinkage effect of repair materials on bond macro-performance. The bond strength and permeability of the same specimen are determined using the hoop constraint method. Additionally, the properties of repair materials, such as drying shrinkage, thermal gravity analysis, and mercury intrusion porosimetry, were investigated. The overlay transition zone (OTZ) microstructure is analysed to reveal the bonding mechanism. The results indicate that the hoop constraint method effectively reflects the ability of UHPC to overcome the significant autogenous shrinkage effect and achieve good bond macro-performance. Moreover, the UHPC-combined substrate exhibits better bond strength than that of the NSC because the repair interface of the UHPC is more compact than that of the NSC. Furthermore, the OTZ width of the UHPC-combined substrate is narrower than that of the NSC, and in the OTZ, the modulus of the UHPC is higher than that of the NSC.

Numerical Simulation on Cement Hydration and Microstructure Development in Repair-Substrate Interface

One of the key parameters for the performance of concrete repairs is the quality of the interface between the repair material and concrete substrate, which is determined by cement hydration and microstructure development. The moisture exchange between the repair material and concrete substrate plays an important role in the cement hydration and porosity of cementitious repair materials. To better understand the influence of moisture exchange on the hydration of cementitious repair materials, this paper presents a numerical simulation of cement hydration and microstructure development of repair materials, considering moisture exchange. The simulation results reveal that the moisture exchange between the repair material and concrete substrate results in a water content change in two parts. Before the repair material setting, the water absorption of an unsaturated concrete substrate causes a reduction in the w/c ratio in the repair material, decreasing the hydration rate of the repair material. After the repair material setting, the water migrates from the concrete substrate to the repair material to provide additional water to accelerate the hydration of unhydrated cement in the repair material.

Shear Strengthening of RC Beams with FRP Composites: Database of FE Simulations and Analysis of Studied Parameters

The use of externally bonded fiber-reinforced polymer (EB-FRP) composites for shear strengthening of reinforced concrete (RC) beams presents many challenges given the complex phenomena that come into play. Premature bond failure, the behavior of the interface layer between FRP composites and the concrete substrate, the complex and brittle nature of shear cracks, and the adverse interaction between internal steel stirrups and EB-FRP are some of these phenomena. Compared to experimental investigations, the finite element (FE) technique provides an accurate, cost-effective, and less time-consuming tool, enabling practicing engineers to perform efficient, accurate nonlinear and dynamic analysis as well as parametric studies on RC beams strengthened with EB-FRP. Since 1996, many numerical studies have been carried out on the response of RC beams strengthened using FRP. However, only a few have been related to RC beams strengthened in shear using EB-FRP composites. In addition, the analytical models that have been reported so far have failed to address and encompass all the factors affecting the contribution of EB-FRP to shear resistance because they have mostly been based on experimental studies with limited scopes. The aim of this paper is to build an extensive database of all the studies using finite element analysis (FEA) carried out on RC beams strengthened in shear with EB-FRP composites and to evaluate their strengths and weaknesses through various studied parameters.

Sensorimotor Underpinnings of Mathematical Imagination: Qualitative Analysis.

Many mathematicians have a rich internal world of mental imagery. Using elementary mathematical skills, this study probes the mathematical imagination's sensorimotor foundations. Mental imagery is perturbed using body position: having the head and vestibular system in different positions with respect to gravity. No two mathematicians described the same imagery. Eight out of 11 habitually visualize, one uses sensorimotor imagery, and two do not habitually used mental imagery. Imagery was both intentional and partly autonomous. For example, coordinate planes rotated, drifted, wobbled, or slid down from vertical to horizontal. Parabolae slid into place or, on one side, a parabola arm reached upward in gravity. The sensorimotor foundation of imagery was evidenced in several ways. The imagery was placed with respect to the body. Further, the imagery had a variety of relationships to the body, such as the body being the coordinate system or the coordinate system being placed in front of the eyes for easy viewing by the mind's eye. The mind's eye, mind's arm, and awareness almost always obeyed the geometry of the real eye and arm. The imagery and body behaved as a dyad, so that the imagery moved or placed itself for the convenience of the mind's eye or arm, which in turn moved to follow the imagery. With eyes closed, participants created a peripersonal imagery space, along with the peripersonal space of the unseen environment. Although mathematics is fundamentally abstract, imagery was sometimes concrete or used a concrete substrate or was placed to avoid being inside concrete objects, such as furniture. Mathematicians varied in the numbers of components of mental imagery and the ways they interacted. The autonomy of the imagery was sometimes of mathematical interest, suggesting that the interaction of imagery habits and autonomy can be a source of mathematical creativity.

Interfacial shear behavior between UHPFRC layers and normal concrete substrate for shear-strengthened squat RC shear walls under cyclic loading

This paper presents an experimental and numerical investigation on the significant effect of the bond properties between Ultra-high performance fiber reinforced concrete (UHPFRC) layers and normal strength concrete (NSC) on the performance of strengthened composite squat shear walls through shear cyclic tests. Moreover, governing equation was derived to predict the shear strength capacity of UHPFRC strengthened walls considering tensile strength of UHPFRC, thickness of UHPFRC layers, surface roughness degree, ratio of steel shear connectors and its yield strength, concrete strength and thickness of original RC wall, and the axial normal force. A series of numerical analyses had been carried out, so proving the capabilities of the proposed formulation. The results indicated that the concrete substrate surface roughness, use of shear connectors, and UHPFRC layers thickness significantly affect the shear bond behaviour between UHPFRC layers and concrete. Installation of shear connectors at UHPFRC-concrete interfaces could significantly improve the post-peak shear behaviour as well as altered the failure mode from brittle due to debonding to ductile. The layer's thickness had a high influence on the shear behavior of specimens with properly roughened surfaces.

Effect of the Cyclic Crack Opening-Closure during Epoxy-Curing Period of a CFRP Strengthening System Bonded on Concrete Substrate

This article investigates the potential detrimental effects of cyclic load during the installation of externally bonded (EB) carbon fiber-reinforced polymer (CFRP) on a damaged reinforced concrete (RC) structure. Four RC specimens were tested in three point bending to study the consequences of crack cyclic opening-closure during epoxy-curing period. A first RC specimen (without bonded CFRP) was loaded monotonically up to failure to serve as undamaged control sample. The three other specimens were pre-cracked before being subjected to a fatigue loading procedure to simulate service condition of a damaged RC structure. Two of the three pre-cracked specimens were strengthened by EB CFRP. One specimen was repaired before the fatigue test while the other one was repaired during the fatigue test. Finally, remaining capacities of all three pre-cracked specimens were measured through monotonic bending tests until failure. It was found that, although bonding of CFRP reinforcement during cyclic load can induce some interesting features with regard to serviceability, cyclic crack opening and closing alters the cure process of epoxy located below the initial crack and decreases the effectiveness of the strengthening at ultimate state. Extended experimental studies are then needed to assess reliable safety factor for the design of repairing operations in which the bridge has to be maintained in service during CFRP installation.

Effects of Sulfate and Sulfuric Acid on Efficiency of Geopolymers as Concrete Repair Materials.

Various geopolymer mortars (GPMs) as concrete repairing materials have become effective owing to their eco-friendly properties. Geopolymer binders designed from agricultural and industrial wastes display interesting and useful mechanical performance. Based on this fact, this research (experimental) focuses on the feasibility of achieving a new GPM with improved mechanical properties and enhanced durability performance against the aggressive sulfuric acid and sulfate attacks. This new ternary blend of GPMs can be achieved by combining waste ceramic tiles (WCT), fly ash (FA) and ground blast furnace slag (GBFS) with appropriate proportions. These GPMs were designed from a high volume of WCT, FA, and GBFS to repair the damaged concretes existing in the construction sectors. Flexural strength, slant shear bond strength, and compatibility of the obtained GPMs were compared with the base or normal concrete (NC) before and after exposure to the aggressive environments. Tests including flexural four-point loading and thermal expansion coefficient were performed. These GPMs were prepared using a low concentration of alkaline activator solution with increasing levels of GBFS and FA replaced by WCT. The results showed that substitution of GBFS and FA by WCT in the GPMs could enhance their bond strength, mechanical characteristics, and durability performance when exposed to aggressive environments. In addition, with the increase in WCT contents from 50 to 70%, the bond strength performance of the GPMs was considerably enhanced under sulfuric acid and sulfate attack. The achieved GPMs were shown to be highly compatible with the concrete substrate and excellent binders for various civil engineering construction applications. It is affirmed that the proposed GPMs can efficiently be used as high-performance materials to repair damaged concrete surfaces.

Assessment of Adhesion of Geopolymer and Varnished Coatings by the Pull-Off Method

This paper presents the results of testing the adhesion of geopolymer coatings and varnishes with ceramic additives to concrete and steel substrates. The measurement method used and described in this article was the pull-off method. The pull-off method test provides an easy way to evaluate the degree of adhesion of coatings to metal surfaces. The pull-off device provides values for the peel stress, which not only allows a quick determination of the adhesion of the coating to the substrate, but also makes it easier to compare the adhesion of several coatings to each other. However, this method requires appropriate preparation, so an attempt was made to determine its suitability for geopolymer layers. The results of testing the adhesion of a geopolymer layer to a geopolymer substrate and a concrete substrate are presented. As a result of this study, a higher adhesion strength of the geopolymer layer to the geopolymer substrate was found in comparison to geopolymer coatings applied on conventional concrete. Adhesion tests were also conducted for steel substrates to which both geopolymer and acrylic lacquer were applied.

Self-cleaning durability assessment of TiO2/SiO2 photocatalysts coated concrete: Effect of indoor and outdoor conditions on the photocatalytic activity

A self-cleaning nanostructured TiO2 coating has demonstrated the capacity to mitigate undesired effects from air pollution. Not only it reduces the deterioration of building materials but may also prevent certain pollution-related human health problems. In this study, mesoporous TiO2/SiO2 photocatalysts were synthesized in order to produce self-cleaning and long-lasting coatings that meet the necessary requirements for outdoor applications. The synthesized products were sprayed on concrete substrates and their self-cleaning and air depolluting capabilities were evaluated. The former one as a function of methylene blue (MB) and soot degradation and the latter, according to nitrogen oxides reduction. The coatings proved to have high photocatalytic activity, and their efficiency was enhanced as TiO2 loadings were increased. Thus, after the first 60 min of their irradiation by UV–vis light, the photocatalysts ST1 and S4T had removed 79% and 95% of the MB, respectively. These coatings presented particulate surfaces that provided more surface area and porosity, which are key factors for a high photocatalytic activity. Moreover, the same samples after 104 h of irradiation exhibited 38% and 49% conversion of total NO, respectively. While E503, a commercially available photocatalyst, produced coating cracked surfaces and a total MB degradation of just 50% after 60 min of irradiation as well as 35% of NO conversion after 104 h of irradiation. The TiO2/SiO2 coatings’ photocatalytic efficacy remained practically invariable after four months of exposure to real-life conditions and three MB degradation cycles. After the outdoor durability tests, the coated surfaces exhibited a practically unchanged structure, which confirms their long-lasting efficiency.

1 Bond Performance and Mechanisms of Sulphoaluminate Cement-Based Uhpc for Reinforcing Old Concrete Substrate

1 Bond Performance and Mechanisms of Sulphoaluminate Cement-Based Uhpc for Reinforcing Old Concrete Substrate

Concrete substrate moisture requirements for durable concrete repairs – a field study

In concrete repair specifications, the required moisture condition of the substrate, which can play an important role for bond development, and, ultimately, on the long-term repair / overlay durability, is generally ill-defined and addressed without due consideration to the given substrate characteristics. The standard specification, if any, is to require saturated surface dry (SSD) condition of the substrate prior to application of cementitious repair materials, which is theoretically achieved after saturating the substrate and then letting the surface just start to dry out. This does provide an intuitive solution founded on rational considerations, but it has never really been precisely defined, measured, nor validated. The influence of substrate surface moisture on the bond between the existing concrete and the new repair material is an issue of significant importance. This paper revisits the question, in light of results from a project designed to develop guidelines for moisture conditioning of a concrete substrate prior to a cementitious repair, which was part of a larger effort to develop guidelines for surface preparation of concrete prior to repair. Over the course of the project, multiple series of test slabs were repaired after being subjected to different surface moisture conditioning and then tested for bond strength tests at different ages. The findings are discussed, together with those from previous studies, and recommendations are issued.

Evaluation on the effect of anchor embedment depth on the flexural capacity of concrete prisms

Using fiber-reinforced polymer (FRP) composites to strengthen and retrofit existing reinforced concrete (RC) structures has gained wide acceptance owing to the superior properties of FRPs such as high strength-to-weight ratios and corrosion resistance. Externally bonded FRP (EB-FRP) laminates can be applied to enhance the flexural and shear capacities of RC beams and improve the ductility of RC columns. However, the premature debonding of FRP laminates from the concrete substrate is a major concern and usually results in a brittle member failure. To tackle this issue, many studies proved that adequate anchorage systems could improve the FRP-to-concrete bond, and therefore results in delaying the FRP debonding and further developing the tensile strength of the FRP laminates. One of the most commonly used anchorage systems is FRP spike anchors. Compared to other anchorage systems (for e.g., metallic anchors), FRP anchors have high compatibility with the FRP laminates. In addition, FRP spike anchors are noncorrosive and have high tensile strengths. Although several studies addressed FRP spike anchors in flexural and shear strengthening of RC beams and slabs, the literature still lacks comprehensive information on the effect of all anchor parameters on the performance of the strengthening system. As a result, the aim of this study is to investigate the effect of anchor embedment depth on the behavior, strength, and effectiveness on the FRP spike anchorage system. Six concrete prisms were cast and strengthened with carbon FRP (CFRP) laminates and spike anchors then tested in flexure under four-point bending tests. Test results showed that installing anchored CFRP laminates increased the capacity of the plain concrete prism by 80-120%. Anchoring the laminates at different embedment depths of 50mm, 75mm, 100mm, and 125mm enhanced the capacity of the unanchored prisms by 11%, 13%, 15%, and 33% respectively. Thus, it was concluded that increasing the anchor embedment depths increased the ultimate load carrying capacity of the prisms.

Morphology and characterization study on effective microorganism (EM) water based epoxy coatings

Water based polymeric epoxy coating is an important material in providing protection against extreme weather condition. Crack and fungus formation are natural phenomenon when coating surface is exposed to extreme weather and normally related to the durability of the coating. It is essentially a coating layer that shields the material from harmful conditions. In this research, Effective Microorganism (EM) was used as an additive in the coating formulation. The EM loading was added in 4 different ratios which are 0, 2, 4 and 6% and applied on concrete and asbestos substrate. The cured coating was characterized using Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), hardness, pH, chemical resistance, viscosity, pH and adhesion. From the TGA graph result, 2% EM loading is capable to remove the volatile matter and has delayed the degradation temperature up to almost 30 °C compared to control formulations. The hardness and viscosity are slightly affected by EM loading. Meanwhile for pH and adhesion on substrate is reduced with the increasing loading on EM additives. Water absorption test depicted that EM reduces the water uptake up to 4% loading but the chemical resistance depicted best result at only 2% loading. Lastly, for morphology study, exposure to natural weather after 12 months depicted serious surface failure with high addition of EM up to 4%. Overall, this study concludes that the use of EM at 2% loading has positive effects on the properties of coatings.

Ecological Protection Technology of Spraying Vegetation Concrete on Carbonaceous Rock Slope Experimental Research and Application

To solve the environmental protection issue of carbonaceous rock slope, the failure mechanism of carbonaceous rock slope and the protection mechanism of vegetation concrete are analyzed based on the engineering characteristics of carbonaceous rock and vegetation concrete. Therefore, the field test of vegetation concrete was carried out to obtain the optimal dosage of vegetation concrete greening additive. The application of environmental protection technology of vegetation concrete on carbonaceous rock slope is applied in slope engineering of Hebai highway, and the change law of soil fertility was analyzed to verify the effect of ecological protection. The results show that the protection mechanism of vegetation concrete slope protection technology is mainly categorized into two groups, namely, the surface sealing effect of vegetation concrete substrate in the early stage and the plant ecological protection effect in the later stage. The experiment results show that the optimum dosage of green additive for vegetation concrete is ranging from 30 kg/m3 to 40 kg/m3. According to the field application, within one year after the construction of vegetation concrete, the contents of available phosphorus, potassium, and organic matter increased by 70.2%, 24.9%, and 76.8%, respectively. Moreover, the content of alkali hydrolyzed nitrogen decreased by 44.8% and bulk density by 17.4%; the content of total phosphorus changed little. After 60 days of construction, the vegetation coverage rate of the slope can reach more than 95% and there is no obvious soil erosion phenomenon after three times of heavy rainfall.