Cement-based Slurry Research Articles

Penetration mechanism of grouting by using the cement-based slurry with time-dependent viscosity

Penetration mechanism of grouting by using the cement-based slurry with time-dependent viscosity

Slurry Infiltrated Fiber Concrete Properties: A Review

“Slurry infiltrated fibrous concrete” refers to a contemporary, high performing fiber-reinforced concrete and infiltrated with a specially designed fiber bed, cement-based slurry. The material has excellent mechanical properties along with high durability and ductility. The SIFCON Laboratory’s research revealed SIFCON to be a unique building material with improved abilities to absorb energy and resist impact, as well as greater ductility and strength. With all these qualities, SIFCON can repair and fortify both reinforced and unreinforced concrete structures. Ductility is currently one of concrete’s most critical characteristics. The issue of brittleness with concrete has been solved by utilizing a high volume of fibers instead of coarse aggregate, which provides stress-resistant properties and increases the ductility of the structural component. However, due to the placement and mixing challenges because of the high volume of fibers’ interlocking action, there is a necessity to design unique production techniques. Since SIFCON compounds are a novel trend in the fields of areas of civil engineering that have a catalytic effect, it is necessary to highlight the few studies that included it so this review paper discusses and presents the behavior of SIFCON under various external loads. The focus is on the effects of the SIFCON mortar type—which substitutes silica fume and/or fly ash for cement—and fiber type—which uses hooked end fiber and micro steel fiber— are the main topic of discussion. The mechanical characteristics and optimal percentages are also reviewed. All previous studies are noted and summaries are made in comprehensive tables, which display the studied parameters and SIFCON mortar mix ratios. In addition to indicating research gaps, for example, future work in this field needs to focus on developing a detailed analytical model that requires the ability to calculate these factors. A better understanding of the SIFCON’s features can serve as a theoretical foundation for future research projects and engineering applications for creating concrete materials for the construction industry.

Diffusion mechanism of cement-based slurry in frozen and thawed fractured rock mass in alpine region

The problem of slope stability after freeze-thaw damage in cold regions has become increasingly prominent. To explore the grouting diffusion mechanisms of different grouting materials in frozen and thawed rock masses, a true triaxial stress-state frozen and thawed rock mass fracture grouting experiment was conducted. Computed tomography (CT) and scanning electron microscopy (SEM) were performed on the grouted specimens to obtain the grouting diffusion patterns and three-dimensional reconstruction of the grout veins in different frozen and thawed rock masses under fracture grouting. The results show that Portland cement slurry with low viscosity has better diffusion performance in unfrozen rock mass and rock mass after 10 freeze-thaw cycles. In the case of cement slurry containing graphene oxide and microsilica powder additives, the reinforced area exceeded that of ordinary cement after 10 freeze-thaw cycles, with the reinforced area reaching its maximum after 25 cycles. The “slurry-rock” interface primarily forms three modes: contact, embedding, and covering. Graphene oxide and microsilica effectively fill the larger pores in the cement particles, with microsilica being particularly effective in promoting cement hydration and reducing microdefects in the transition zone between the slurry and rock interfaces.

Graphene oxide coated fly ash for reinforcing dynamic tensile behaviours of cementitious composites

By virtue of its low cost, high workability, wide availability and suitability for large-volume fabrication, cement-based grouting is the most applied material in underground projects. However, due to the weak tensile strength and high-frequency impact dynamic load disturbance in underground engineering, cement-based grouting is vulnerable to tensile damage, seriously influencing the stability and safety of underground projects. Hence, in this work, the graphene oxide (GO) coated fly ash was adopted to reinforce the dynamic tensile behaviour of the cement-based matrixes to fabricate high-performance, cost-effective and environmentally friendly cementitious composites. The test results show that the GO-coated fly ash could significantly enhance the dynamic tensile performance of the cementitious composites. With only 0.08 wt% GO mixing, the dynamic tensile properties can be strengthened by 19.5–88.5%. After GO nanosheets accelerate the cement hydration process and improve the chemical composition of hydration products, GO nanosheets exhibit macroscopic nucleation and "crack-bridging" effects on the cement matrixes, and the cracks propagation of the hardened specimens would be suppressed under dynamic loading, thus enhancing the tensile resistance of the specimen. The fractal dimension calculation results prove that the GO-coated fly ash-modified cementitious composites have higher integrity after tensile impact, about 2.8–11.9% higher than plain cement-based slurry. Finally, the theoretical analysis reveals that GO nanosheets can enhance the tensile behaviours of the cement matrix by optimizing the dynamic load coefficient. Nevertheless, with the crack propagation, the reinforcing efficiency of GO would be gradually weakened. The findings of this study can promote an understanding of the enhancing mechanisms of GO on the dynamic tensile behaviour of cementitious composites and inspire the potential application of GO-coated fly ash to reduce cement usage in grouting engineering.

Rheological properties of cement-based slurry and evaluation of rheological model: Influence of particle size and shape

With the continuous development of mineral admixtures and additives, the influence of various factors on the rheological properties of cement-based slurry remains unclear. In this study, the effects of particle size, particle shape, shear rate, and time on the rheological properties were analyzed. The rheological curves were determined using an RST-SST rheometer and fitted with the Bingham model, Modified Bingham model and Herschel-Bulkley model, respectively. The rheological parameters were evaluated. The results showed that the effect of particle size on the rheological properties is much greater than that of the particle shape. The small particle size is evidently affected by the shear rate, and the rheological parameters increase with time. The three rheological models can well describe the samples containing microfine cement (MC), fly ash (FA) and calcium carbonate whisker (CaCO3 whisker). The sample containing nano-silica (nano-SiO2) requires special analysis. The yield stress predicted by the Bingham model is the highest, whereas that predicted by the Herschel–Bulkley model is the lowest. The plastic viscosity predicted by the Bingham model is lower than that predicted by the modified Bingham model. The rheological index (n) of the Herschel–Bulkley model can effectively characterize the degree of shear thinning. The three rheological models demonstrate their characteristics and advantages, and an appropriate rheological model should be selected to evaluate the rheological parameters according to the requirements. The research aims to provide theoretical support for the analysis of rheological properties and the selection of rheological models.

Hydro-Mechanical Coupling of Cement-Based Slurry Grouting in Saturated Geomaterials

A mathematical model is proposed to simulate the fully hydro-mechanical coupling of two-phase cement-based slurry migration in saturated deformable geomaterials from microscopic to macroscopic scale. The mass conservation equations and the momentum balance equations for cement-based slurry and geomaterials are derived based on the thermodynamically constrained averaging theory (TCAT). The Galerkin discretization of the governing equations of hydro-mechanical coupling are developed by the isogeometric analysis (IGA) integrated with the Bézier extraction operator, and the numerical calculation is implemented with the generalized backward Euler method. The presented modeling is verified by comparison of the numerical calculation with the experimental tests, and the pore fluid pressure of the stratum and the slurry concentration of cement-based slurry migration in saturated deformable geomaterials are discussed. The modeling presented provides an effective alternative method to simulate cement-based slurry migration and explore isothermal multiphase coupled problems.

Experimental Study on Performance of Modified Cement-Based Building Materials under High-Water-Pressure Surrounding Rock Environment

Traditional cement-based grouting materials have good reinforcement and anti-seepage effects on the surrounding rock under normal conditions, but the grouting effect is not ideal due to problems such as a long setting time, a low stone ratio, and poor crack resistance under high water pressure and in a dynamic water environment. In this study, we aimed to improve the physical properties, chemical properties, and microstructure of a cement-based slurry by forming a hydrogel through its chemical crosslinking with polyvinyl alcohol and boric acid as modifiers for the purpose of improving the permeability resistance of the surrounding rock grouting under high-water-pressure conditions, which can expand the function of traditional building materials. The grouting effect of the modified cementitious material on the surrounding rock was analyzed through indoor tests, the SEM testing of the performance of the modified slurry, the numerical calculation of the seepage field, and the application of the modified slurry in combination with the actual project to verify the water-plugging effect. The research findings demonstrate that (1) the additives boric acid and PVA can significantly speed up the slurry gel time, and the gel time can be controlled within 2–20 min to meet the specification requirements. (2) At a velocity of moving water > 1 m/s, the retention of the solidified modified slurry stone body reaches more than 80%. According to the SEM analysis, the structure of the solidified modified slurry stone body is dense and has good impermeability. (3) According to the numerical calculation analysis, the modified slurry can effectively change the seepage field of the surrounding rock and improve its seepage resistance. The water pressure outside the lining is reduced by 47%, 31%, and 22%, respectively, compared with no slurry, the pure cement slurry, and cement–water-glass grouting, and the indoor test and numerical simulation conclusions are consistent.

Influences of Efficient Spraying of Cement-Based Slurries on Recycled Coarse Aggregate.

The inferior property is usually one of the major problems of recycled coarse aggregate (RCA), and the utilization of the RCA is limited. Strengthening the RCA is being widely explored. Immersing the RCA in the cement-based slurry is an effective approach. However, lots of slurry and time are required, and it is difficult to integrate the immersing method into the production line of the RCA. In this paper, a circular spraying method was proposed to treat the RCA using cement-based slurry. The immersing method was also conducted to verify the feasibility of the spraying method. The crushing value (CV), 24 h water absorption (WA), apparent density (AD) and dynamic water absorption (DWA) were tested, and the micro-morphology was also observed to explore the strengthening mechanism. Results showed that the CV and the WA decreased by up to 30.0% and 14.3% when the spraying method was used. The AD was slightly influenced by the cement-based slurry regardless of the treatment method. Considering the CV, WA and AD, the comprehensive grade of the RCA could be enhanced from III to II by using the spraying method. It was worth noting that the effects of the spraying method and the immersing method were basically equivalent. When the spraying method was adopted, only about 1 min and a small amount of slurry (about 5% of the RCA mass) were required to treat the RCA.

Effects of Low-Cost Repair Techniques on Restoration of Mechanical Properties of Fire-Damaged Concrete

Researchers have conducted numerous investigations on various repair techniques to restore the mechanical properties of fire-damaged concrete. However, most of the techniques are either expensive or require high technical skills. As a continuous work, this study involved an experimental investigation of the effects of various low-cost repair techniques to restore the mechanical properties of fire-damaged concrete. Sixty cylindrical concrete samples were subjected to heat ranging from 400°C to 800°C in a propane gas furnace. The samples were categorized into six groups, including the following: undamaged, fire-damaged, and fire-damaged and repaired using water curing; fire-damaged and repaired using cement-based slurry injection; re-curing fire-damaged and repaired with steel wire mesh along with epoxy resin wrapping; and fire-damaged and repaired using epoxy injection. The samples were tested for non-destructive and destructive tests, including ultrasonic pulse velocity, rebound hammer, and compressive strength. The results showed that the use of cement-based slurry injection along with the water-curing repair technique could regain almost 90% of its ultimate strength and secant stiffness, making it the most effective low-cost repair technique for fire-damaged concrete exposed up to 700°C.

Using MgO activated slag and calcium bentonite slurry to produce a novel vertical barrier material: Performances and mechanisms

Slag-cement–bentonite (SCB) slurry has been widely used for the construction of vertical cutoff walls to restrain the movement of groundwater at contaminated sites. However, the conventional cement-based slurry needs a long time to evolve satisfactory performance along with a relatively high environmental load. This paper proposes an innovative material for the self-hardening slurry system, consisting of reactive MgO, slag, bentonite and lots of water. The properties of fresh slurry, unconfined compressive strength (UCS) and permeability of the MgO activated slag and bentonite (MASB) slurry are investigated in comparison with SCB slurry. The results indicate that compared with SCB slurry, MASB slurry with appropriate proportions has comparative fresh properties, but possesses higher UCS and much lower hydraulic conductivity (close to 1.0 × 10−10 m/s) at a later age. A massive formation of expansive hydration products (hydrotalcite phases) could satisfactorily fill in the voids of matrix, leading to a dense microstructure which is responsible for the excellent mechanical and penetrative performance of MASB slurry. The overall findings from this study well demonstrate that the developed MASB slurry holds great potential as a novel, eco-friendly and cost-effective material in the construction of vertical cutoff walls.

Numerical calculation and multi-factor analysis of slurry diffusion in an inclined geological fracture

Slurry grouting plays an important role in water plugging for hydrogeological engineering and there are multiple factors that restrict the slurry flow. This study investigates the restriction mechanisms, based on a single inclined rough fracture, employing a space stepwise method (SSM) using multi-direction sectors (MDS) for calculating the diffusion of variable-viscosity slurry under constant flow. The specifically developed numerical algorithm is validated by experimental results. The spatio-temporal effects of major factors on the flow, and the rock hydraulic properties, were analyzed for cement-based slurry. The results show that the slurry flow calculated by MDS-SSM exhibits strong fitting with experimental results. The diffusion pattern no longer exhibits a circular plane, but rather a double semi-elliptical distribution. The fracture direction angle, especially for the upward vertical flow, must be considered in the case of a larger dip angle. The main controlling factor of the pressure field is the higher slurry viscosity in regions far from the injection hole, and the influence of dip angle is significantly greater closer to the hole. Roughness has an influence on the fracture hydraulic properties, and the required grouting pressure increases with an increase in roughness. The fracture aperture, viscosity coefficient, and diffusion radius are three key factors with strong sensitivity affecting the forecasting accuracy of grouting parameters. The role of the fracture dip angle can be neglected only in narrow fractures and long-distance diffusion with higher-viscosity slurry or larger pressure. The key threshold value can be obtained with a fitting formula under given conditions.

BEHAVIOURAL STUDIES ON TRIPLE BLENDED FOAM CONCRETE

In recent days construction industry focuses on other than conventional concrete in infrastructural purposes like building etc., due to excess usage of cement, sand and other aggregates which leads depreciation of natural resources and effects on the environment. By utilization of lightweight bricks and foam concrete which reduces not only its self-weight but also improve resistance against heat and sound insulation and architectural features. The density of foam concrete varies from 300 to 1800kg/m3. Foam concrete composes of cement, water, fly ash and foaming agent without coarse aggregate. The function of foam is to create air bubbles in the cement-based slurry. The density of foam concrete depends on the quantity of foam added. The foam creates several pores with this effect; it has low thermal conductivity. As density of foam concrete is low at same time strength also low when compared to conventional concrete, so an attempt made to improve mechanical properties of foam concrete by adding admixtures like Silica fume and GGBS in different percentages. In these experimental studies, the workability and compressive strengths are mentioned

Strengthening of concrete by using hybrid SIFCON sections

Slurry infiltrated fibrous concrete [SIFCON] is a recent form of superior performance fiber reinforced concrete made by penetrating steel fiber bed, with an exceptionally designed cement-based slurry. Researches have demonstrated that SIFCON is an imaginative building material, having both extensive ductility and high strength. In the current investigation, the use of SIFCON has been investigated as a strengthening layer for conventional concrete section. The effects of the SIFCON layer position: bottom, top & bottom, and jacket, thickness: 15 mm, 25 mm, and 35 mm, and steel fiber volume fraction: 6.0%, 7.5%, and 9.0% on ultimate flexural load, toughness, and ductility of hybrid prisms were reported. The results showed that the increase in the thickness of the SIFCON layer and the steel fiber volume fraction improve load-bearing capacity, toughness, and ductility of the composite sections. The ultimate flexural load was improved by up to 1148%. Ductility factors were increasing up to 2.54. On the other hand, toughness enhanced greatly in the case of the top and bottom hybrid sections. It was 33 times higher than of control prisms.

Enhanced Mechanical and Microstructural Properties of Portland Cement Composites Modified with Submicron Metakaolin

This work aims to study the influence of submicron metakaolin (SMK) on the mechanical strength, pore structure, and microstructural properties of hardened cement‐based slurry (HCS). Portland cement was replaced by SMK at a proportion of 1, 3, 5, and 7 wt%. The compressive strength and flexural strength of the HCS samples were tested at a curing period of 3, 7, 14, and 28 days, and the pore structure of the specimens was analyzed by mercury intrusion porosimetry (MIP) at a curing period of 3 and 28 days. The microstructure characteristics of the hardened samples were investigated by scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDS). Thermogravimetric analysis (TGA) was also employed to analyze the change in the chemical composition of the HCS. The results showed that the SMK could accelerate the hydration rate of the cement and could improve the mechanical properties of the HCS; the compressive strength and flexural strength of the HCS samples were remarkably enhanced, compared to those of the plain cement, by 67 and 46%, respectively, at a curing period of 3 days and by 33 and 35%, respectively, at a curing period of 28 days. The SMK had a significant impact on the internal pore structure of the hardened samples, and the number of pores with a diameter of larger than 3000 nm significantly decreased. Because the hydration products filled the pores, the microstructure of the HCS was further refined and densified with the addition of SMK. Submicron metakaolin has a simple process and high activity, which can significantly improve the performance of the cement slurry. Therefore, submicron metakaolin has the potential for practical engineering applications.

Structural repair of shear-deficient reinforced concrete beams using SIFCON

This article reports on the structural behaviour of shear-deficient reinforced concrete beams repaired with Slurry Infiltrated Fibre Concrete (SIFCON), and proposes a simple analytical procedure for predicting the shear capacity of the repaired beams. SIFCON is made by pre-placing short, discontinuous steel fibres into the form, followed by infiltrating the fibres with cement-based slurry. A series of 14 shear-deficient reinforced concrete rectangular beams was tested under third-point loading to study the effectiveness of using externally applied SIFCON jackets as a method of increasing the beams' shear capacity. The parameters investigated included the shear span-to-effective depth ratio (a/d), amount of longitudinal reinforcement (ρ) and the thickness of the jacket (t). For the range of variables tested, the results indicate that all the beams failed in shear tests and those repaired with SIFCON displayed an excellent shear capacity. The use of SIFCON jackets as external shear reinforcement eliminated the brittle shear failure and increased the ultimate shear strength of the repaired beams from 25–55%. This indicates that SIFCON may be considered as a promising material for design–maintain–rehabilitate programme of concrete structures.

Compressive Properties of Slurry Infiltrated Fiber Concrete under Monotonic and Cyclic Loading

SIFCON (Slurry Infiltrated Fiber Concrete) is a type of high volume fiber reinforced concrete in which fibers are preplaced in the mold or on a substratum and infiltrated with cement-based slurry under vibration. The effect of fiber volume fraction on the compressive properties of SIFCON under monotonic loading is investigated in this paper. The compressive properties of SIFCON under cyclic loading are also studied and compared with that of SIFCON under monotonic loading.

Tensile Behavior of Slurry Infiltrated Mat Concrete (SIMCON)

This paper presents the tensile behavior of a new type of high-performance (steel) fiber reinforced concrete called slurry infiltrated mat concrete (SIMCON). SIMCON is made by first placing continuous steel fiber-mats into the form, followed by infiltration of the dense fiber network with a cement-based slurry. Due to the very high fiber aspect ratio, SIMCON displays a high increase in both strength and toughness. In addition, since fiber-mats are easier to handle than short discontinuous fibers, SIMCON has no major construction-related shortcomings. Thus, SIMCON is well suited for repair, retrofit, and new construction of earthquake resistant buildings, bridges, and other structures that require high strength and ductility. This paper presents experimentally obtained stress-strain properties of SIMCON in direct tension. After a month of curing, tensile strengths of up to 17 MPa and strains at ultimate stress ranging between 1 and 1.5 percent were reached with as little as a 5.29 percent fiber volume fraction SIMCON. This paper discusses the observed tensile behavior and proposes models for predicting the entire stress-strain relationship including the elastic modulus, ultimate stress, and strain at ultimate stress.

Bond-Slip Mechanisms of Steel Fibers in Concrete

A comprehensive experimental program on pullout and pullthorugh tests of steel fibers from a cement-based matrix is described. Emphasis is placed on the accurate measurements of the pullout load versus end-slip response. Parameters included 3 different type of fibers, three different mortar matrixes with low medium, and high strengths, one cement-based slurry matrix, and additives such as latex, fly ash, and microsilica. The medium from which the fiber was pulled out included a control mortar mix without fibers, mortar mixes with 1, 2, and 3 % fibers by volume, and a SIFCON matrix containing about 11 % fibers by volume. For smooth fibers, 5 different diameters and 3 different embedment lengths were investigated. Experimental pullout load versus slip curves are needed to derive typical bond shear stress versus slip curves considered to be a property of the interface.