Strength Of Grouting Material Research Articles

Study on macro performance and micro-analysis of high strength grouting material

Wind turbine duct put forward higher requirements for the performance of grouting materials. In order to obtain more economical high strength grouting materials (HSG), three kinds of low price main components, cement, quartz sand (QS) and fly ash microspheres (MS) were utilized and developed. Macro performance and micro-analysis of the HSG were conducted. The macro performance tests revealed that the mix proportion of HSG is determined as, cement: QS: MS: superplasticizer: swelling agent = 80:10:10:0.3:0.12, water binder ratio is determined as 0.26. Compressive and flexural strength of the HSG exceeding 120 MPa and 20 MPa respectively. The HSG also showed good fluidity and homogeneity. The micro-analysis showed that a complete and continuous micro-structure was formed and interface transition zone could not be observed. XRD and TG-DSC results meant that the amount of AFt increased. On the contrary, the amount of Ca(OH)2 decreased. pore diameter of the HSG was mostly 10 nm. The addition of swelling agent and MS did not changed the types of hydration products of HSG, but the pore structure was optimized. Due to the cheap components, HSG contributed higher profits with the lower price, and which perform good economic benefits and market competitiveness.

Design of Anti-blocking and Anti-seepage shield grouting materials and their performance enhancement mechanism analysis

To solve the current problems of long-distance pumping blockage and poor stability of shield grouting material in the construction of subway tunnels, we studied the effects of thickener and water reducing type, dosage, and water-to-binder (W/B) ratio on the workability and mechanical properties of shield grouting materials with high-volume crushed sand and ultrafine powder. The mechanism of thickeners' effects on improving mortar properties was analyzed using the cryo-scanning electron microscopy (Cryo-SEM). The results show that proper compatibility of components and proportion optimization make it possible to prepare high-performance shield grouting materials with excellent anti-blocking and anti-seepage properties. These materials exhibit high fluidity, low pressure bleeding rate, homogeneous distribution of components, and meet the engineering requirements regarding setting time and strength of grouting material. A comparison of the performance of three types of thickening agents reveals that although hydroxypropyl methylcellulose (HPMC) improves the pressure bleeding rate of mortar significantly compared to seaweed gum, it leads to a significant delay in the setting time and a decrease in mortar strength. Welan gum (WG) has a minor impact on grouting materials' setting time and strength, and its water retention performance is similar to that of HPMC. However, WG is expensive and causes significant fluidity loss of slurry over time. On the other hand, seaweed gum demonstrates comprehensive advantages in enhancing various aspects of shield grouting materials, exhibiting good anti-blocking and anti-seepage effects. For its calcium-induced gelation property, seaweed gum forms an orderly screen structure of an “egg-box” shape in the pore liquid, then fills the pores between the screens through the film effect of the gel. Finally, the gels form a “screen-printing-like” overall effect, so that seaweed gum has the three-dimensional space network effect as WG and the film forming effect as that of HPMC, which can significantly improve the stability of the grouting material. Therefore, seaweed gum has almost no adverse impact on the strength of shield grouting material but has a relatively lower price.

Synergistic effect of polycarboxylate superplasticizer and silica fume on early properties of early high strength grouting material for semi-flexible pavement

Nowadays, the application of early high strength grouting material (EHSG) is in line with the development trend of semi-flexible pavement. In this paper, the synergistic effects of polycarboxylate superplasticizer (PCE) and silica fume (SF) on the properties of EHSG were studied. The results suggest that the flow time of slurry with high fluidity has a linear relationship with its dynamic yield stress. The mechanism of PCE and SF on rheological properties was analyzed via water film thickness (WFT), zeta potential, PCE adsorption, and SEM. It can be found that the crucial role of SF on slurry is to improve the adsorption of PCE on binders. The model describing the synergistic effect of SF and PCE on the particle aggregation of EHSG is proposed. SF addition weakens the interlocking effect and reduces the friction but may form the interparticle bridging effect between cement grains. PCE can not only inhibit the aggregation of cement grains but also mitigate the bridging effect of SF.

Experimental research and finite element analysis on the seismic behavior of CFRP-strengthened severely seismic-damaged RC columns

This study describes a new strengthening technique that involves the combination of CFRP jackets, CFRP sheets and high- strength grouting material. Three different strengthening alternatives were employed to strengthen three severely damaged RC columns. Based on the experimental results, the failure mode, hysteresis curve, skeleton curve, ductility, energy dissipation ability, stiffness degradation and strength degradation of both the original and strengthened test specimens were compared and discussed. All three strengthened test specimens exhibited similar damaging processes, yielding of longitudinal reinforcement, cracks on CFRP jackets, rupture of CFRP sheets and collapse of high-strength grouting material were successively observed in the loading procedure. The results showed that the three strengthened seismic damaged concrete columns all presented a bending failure mode and met the “strong shear, weak bending” design attributes. Compared with the original columns, the ductility and energy dissipation capacity of the three strengthened test specimens were significantly improved, while the capacity and stiffness were not fully restored. Strengthened test specimen Z3-R, which was strengthened by the combination of CFRP jackets, CFRP sheets and high-strength grouting material, showed the best seismic performance among all three strengthened test specimens. A finite element model based on OpenSees was developed and validated by a comparison with experimental results. The effects of the axial compression ratio and thickness of CFRP sheets were also discussed through parametric studies.

Evaluation of the bonding and fatigue properties of an innovative rapid repair structure for concrete pavement

Deterioration and damage of pavements require rapid and durable full-depth repair. This study proposes an innovative rapid repair structure for the incorporation of precast slabs, graded gravel bases, and grouting technology in concrete pavements. Two representative grouting materials and two types of graded gravel bases with different particle size compositions were selected to construct four types of rapid repair structures. Static stepwise loading, fatigue loading, and lateral loading tests were conducted to evaluate both the effectiveness and feasibility of the rapid repair structures by measuring deformation, strain, and pressure as well as by examining the failure modes of the repair structures. The results indicated that the high strength grouting material contributes to the mechanical properties and bonding performance of the repair structure. Moreover, a well-compacted base is critical for the deformation uniformity of the repair structures and a graded gravel base with large particle size provides firm support, which is conducive to the infiltration of grouting material. The rapid repair structure proposed in this work not only reduces the time and cost required to re-open traffic, but also meets the requirements of a semi-permanent repair of concrete pavement. However, a full-scale investigation needs to be conducted to assess the mechanical properties for rapid repair structure.

Investigation into the freeze–thaw durability of semi-flexible pavement mixtures

Semi-flexible pavement (SFP) is made of a composite material that consists of porous asphalt concrete (PA) filled with highly flowable grouting material. At present, most researches on SFP focuses on the materials design and pavement performance characterisation, and very limit effort has been made on evaluating its freeze–thaw durability, which limits the application of SFP in cold regions. The present paper was to fill this gap. In the study, two SFP mixes made with a given PA but two different grouting materials (early-strength (ES) and high-strength (HS) grouting materials) were evaluated. ASTM C666 freeze–thaw durability tests were performed not only on the SFP mixes but also on each of SFP component (PA, ES and HS grouting materials), where relative dynamic modulus and mass loss of the tested samples were measured. In addition, indirect tensile strength of the samples was also tested, and the stiffness and strain–stress behaviour of the samples were evaluated. The results indicate that the order of the freeze–thaw resistance of the individual components was the PA matrix < ES grouting material (4.9 MPa at 3 h and 25.4 MPa at 28 days) ≪ HS grouting material (82.4 MPa at 28 days). The relative dynamic elastic modulus and strain–stress behaviours of SFP-ES samples were very similarly to those of PA, indicating the loss of integrity of the composite during freeze–thaw cycling. Differently, relative dynamic elastic modulus and strain–stress behaviours of SFP-HS samples were close to those of HS grouting material, indicating that enhanced freeze–thaw resistance of a SFP mix can be achieved by incorporating a high strength grouting material into a PA matrix.

Experimental Study on the Stress-Temperature Curve of the Super High Early Strength Grouting Material at Elevated Temperature

Based on 75 cube specimens(100mm×100mm×100mm) of the super high early strength grouting material at elevated temperature,this paper describes the design of the high temperature test,compressive test and some relevant phenomena in testing,analyzes strength of the super high early strength grouting material at elevated temperature,and obtains the stress-temperature curves of the super high early strength grouting material at elevated temperature.By analyzing the staged characteristics of the curves,the regularity of the strength of the super high early strength grouting material at elevated temperature is discussed and some fitting mathematical formulas are suggested.

Research on Sand Gradation to Ultra Strength Grouting Material Properties

The gradation of coarse sand, medium sand and fine sand on fluidity initial, final setting time, flexural strength, compressive strength, and other properties and structure, of ultra early strength grouting material, was explored. The quartz sand gradation of cement sand ratio 1.0 was systematically studied. The results showed that, the coarse sand, medium sand and fine sand mixed according to the reasonable distribution, when glue sand ratio was 1.0-1.5, ultra-early-strength grouting material, with final setting time for 50-60(min), the initial fluidity greater than 320(mm), 0.5h fluidity greater than 280(mm), 2h compressive strength of 35.6(MPa), 1d flexural strength greater than 13(MPa), 28d compressive strength over 93(MPa), achieved the free vibration.

Several Common Retarders on Performance of Ultra-Early-Strength Grouting Material

To explore retarders on performance of ultra-early strength grouting material, Retarder, which are commonly used in the market after a preliminary screening, are further tested and analyzed for initial fluidity, setting time and mechanical strength properties of super early strength grouting material. The results show that: When borax content is 0.4%, the initial fluidity, final setting time, workability, mechanical strength are the best.

Research on the Compound early Strength Agent to the Performance of Super High early Strength Grouting Material

The effect of sodium sulfate, triethanolamine and early strength agent A on the early strength reinforcement material final setting time, flexural strength and compressive strength and structure were investigated. The results show that the composite of sodium sulfate, triethanolamine and early strength agent according to a reasonable proportion, the dosage of 0.35% -0.40% (in cementitious material quality), the final setting time of early strength material for 50 to 60 min, Initial fluidity over 320mm, 0.5h flow degree greater than 280mm, 1d bending greater than 12MPa and 28d compressive strength greater than 80MPa, meet the requirements.

Mechanical Properties of Modified Polypropylene Coarse Fiber-Reinforced, High-Strength, Lightweight Concrete

In this study, the effect of micro-expansion high strength grouting material (EGM) and Modified polypropylene coarse fiber (M-PP fiber) on the mechanical properties of lightweight concrete are investigated. The influence of EGM and M-PP fiber on compressive strength , flexural strength and drying shrinkage of concrete are researched, and flexural fracture toughness are calculated. Test results show that the effect of EGM and M-PP fiber volume fraction (Vf) on flexural strength and fracture toughness is extremely prominent, compressive strength is only slightly enhanced, and the rate of shrinkage is obviously decreased. It is observed that the shape of the descending branch of load-deflection and the ascending branch of shrinkage-age tends towards gently with the increase of Vf. And M-PP fiber reinforced lightweight aggregate concrete is more economical.