Influence of Coupled Chemo-Mechanical Process on Corrosion Characteristics in Reinforcing Bars

We studied the corrosion characteristics of reinforcing bars in concrete under different corrosion conditions. The area-box （AB） value was used to classify the shape of pitting corrosion morphology in meso-scale, and fractographs of reinforcing bars with different corrosion morphology were discussed in micro- and macro-scales. The results show that the existence of the tensile stress affects the corrosion characteristics of reinforcing bars. The pitting morphology and fractograph of reinforcing bars exhibit a statistical fractal feature. The linear regression model fits the relationship between fractal dimensions of corrosion morphology and fractal dimension of fractograph fairly well. Using fractal dimension as the characterization parameter can not only reflect the characteristics of pitting corrosion morphology in reinforcing bars, but also reveal the fracture feature of corroded reinforcing bars.

A Study on the Bond Strength between High Performance Concrete and Reinforcing Bar

As a preliminary study for the erection of floating structures using high performance concrete, this paper examines the bond characteristics between concrete and the reinforcing bar. Since the floating structure is constructed in aquatic environment, corrosion of the reinforcing steel is likely to develop more prematurely than in onshore structure in case of concrete cracking. A solution to this corrosion problem could use FRP rebar instead of steel reinforcement. To that goal, an experimental study is conducted on the concrete-FRP bond strength to verify if such FRP rebar develops performance comparable to the conventional steel rebar. A series of tests are performed considering the bond length of ordinary steel rebar and G-FRP rebar as test variable with respect to the strength of concrete, and the results are presented.

Comparative Studies of Steel, Bamboo and Rattan as Reinforcing Bars in Concrete: Tensile and Flexural Characteristics

This study comparatively evaluated the flexural performance and deformation characteristics of concrete elements reinforced with bamboo (Bambusa vulgaris), rattan (Calamuc deerratus) and the twisted steel rebars. The yield strength (YS), ultimate tensile strength (UTS) and the elongation of 50 specimens of the three materials were determined using a universal testing machine. Three beams of concrete strength 20 N/mm2 at age 28 days were separately reinforced with bamboo, rattan and steel bars of same percentage, while the stirrups were essentially mild steel bars. The beams were subjected to centre-point flexural loading according to BS 1881 to evaluate the flexural behaviour. The YS of bamboo and rattan bars were 13% and 45% of that of steel respectively, while their UTS were 16% and 62% of that of steel in the same order. The elongation of bamboo, rattan and steel were 7.42%, 10% and 14.7% respectively. The natural rebars were less than the 12% minimum requirement of BS 4449. The load-deflection plots of bamboo and steel RC beams were quadratic, while rattan RC beams had curvilinear trend. The stiffness of bamboo RC beams (BB) and rattan RC beams (RB) were 32% and 13.5% of the stiffness of steel RC beams (SB). The post-first crack residual flexural strength was 41% for BB and SB, while RB was 25%. Moreover, the moment capacities of BB and RB corresponded to 51% and 21% respectively of the capacity of steel RC beams. The remarkable gap between the flexural capacities of the natural rebars and that of steel can be traced not only to the tensile strength but also the weak bonding at the bar-concrete interface. It can be concluded that the bamboo bars are suitable rebars for non-load bearing and lightweight RC flexural structures, while more pre-strengthening treatment is required more importantly for rattan for improved interfacial bonding and load-carrying capacity.

Experimental Study on the Degradation of Bonding Behavior between Reinforcing Bars and Concrete after Corrosion and Fatigue Damage

In marine environments,the durability of reinforced concrete structures such as bridges,which suffer from the coupled effects of corrosion and fatigue damage,is significantly reduced.Fatigue loading can result in severe dete-rioration of the bonds between reinforcing steel bars and the surrounding concrete,particularly when reinforcing bars are corroded.Uniaxial tension testing was conducted under static loading and fatigue loading conditions to investigate the bonding characteristics between corroded reinforcing bars and concrete.An electrolyte corrosion technique was used to accelerate steel corrosion.The results show that the bond strength was reduced under fati-gue loading,although the concrete did not crack.Therefore,fatigue loading has negative effects on the bond strength between corroded steel bars and concrete.The effects of corrosion cracking on bond strength become more pronounced after corrosion cracking appears along the main reinforcing bars.When the average width of cracking along main reinforcing bars exceeds 3 mm,the bonding properties deteriorate rapidly based on the effects of corrosion cracking,whereas fatigue loading exhibits no additional effects on bond strength.

Assessment of Deviation in Quality of Steel Reinforcing Bars Used in Some Building Sites in Cameroon

The present work evaluated the deviations in the quality of steel reinforcing bars in terms of markings, diameter, yield strength and ductility in order to facilitate the drawing up of a yield strength value for the Cameroon National Annex to Eurocode 2. The methodology of the work started with the collection of steel samples from various active building project sites in four different towns viz: Bamenda, Douala, Maroua and Yaoundé and testing their tensile strength and elongation using a Universal Testing Machine and also carrying out the bending test. Results show that bars without marked manufacturer’s name fell all the tests. Other results show that 52% of all the steel had yield stresses below 400 Mpa and the highest deviation in the yield strengths was 22.50%. The study recommends that properly marked grade 500 steel bars should be adopted in the Cameroon national annex to Eurocode 2.

The Clinical Observation of 80 Patients with Diseases of Lumbar Vertebrae Treated by Reinforcing and Reducing Methods of Mani

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Analysis model for damage of reinforced bars in RC beams under contact explosion

The load-bearing capacity of reinforced concrete(RC) beams primarily relies on internal reinforced bars.However, limited research has been conducted on the dynamic response of these bars. To address this gap, this study has established an analytical model using dimensional analysis for calculating the deformation of reinforced bars within RC beams subjected to contact explosion. Comparison with experimental data reveals that the model has a relative error of 5.22%, effectively reflecting the deformation of reinforced bars. Additionally, based on this model, the study found that while concrete does influence the deformation of reinforced bars, this influence can be disregarded in comparison to the material properties of the bars themselves. The findings of this study have implications for calculating the residual load-bearing capacity of damaged RC beams, evaluating the extent of damage to RC beams after blast loading, and providing guidance for the blast-resistant design of RC structures.

Elliptical encirclement control capable of reinforcing performances for UAVs around a dynamic target

Most researches associated with target encircling control are focused on moving along a circular orbit under an ideal environment free from external disturbances.However,elliptical encirclement with a time-varying observation radius,may permit a more flexible and high-efficacy enclosing solution,whilst the non-orthogonal property between axial and tangential speed components,non-ignorable environmental perturbations,and strict assignment requirements empower elliptical encircling control to be more challenging,and the relevant investigations are still open.Following this line,an appointed-time elliptical encircling control rule capable of reinforcing circumnavigation performances is developed to enable Unmanned Aerial Vehicles(UAVs)to move along a specified elliptical path within a predetermined reaching time.The remarkable merits of the designed strategy are that the relative distance controlling error can be guaranteed to evolve within specified regions with a designer-specified convergence behavior.Meanwhile,wind perturbations can be online counteracted based on an unknown system dynamics estimator(USDE)with only one regulating parameter and high computational efficiency.Lyapunov tool demonstrates that all involved error variables are ultimately limited,and simulations are implemented to confirm the usability of the suggested control algorithm.

Experimental Study of the Anti-Corrosion Performance of Montmorillonite K-10 on Rebar in HCl Environment: Application in Mortar for the Rehabilitation of Reinforced Concrete Degraded by Corrosion

This work first investigates the corrosion-inhibiting behavior of montmorillonite K-10 on reinforcing steel. The corrosion-inhibiting power of the clay (Montmorillonite) is determined in a medium HCl (C = 1N) using free corrosion potential monitoring, Tafel potentiodynamic polarization curves and electrochemical impedance spectroscopy. The results of this study showed a satisfactory corrosion-inhibiting efficiency of around 72.665% for the optimum content of 1%. This is due to the presence of a stable oxide layer that protects the metal against corrosion. To validate the concept of montmorillonite as a corrosion inhibitor in repair mortar, we now turn to the influence of montmorillonite on the mechanical properties of mortars in the hardened state. In this part, montmorillonite K-10 is added to the mortar by partial substitution of the cement by 5% and 10% of the cement mass. The aim of this study is to ensure that the addition of this clay to the mortar composition will not have a negative effect on its compressive and flexural strengths. The results of the compression and flexural tests showed that the presence of montmorillonite in the mortar improved flexural and compressive strengths for the different compositions studied.

Experimental study on the durability of BFRP bars embedded in concrete

This paper presents an experimental study on the alkali-resistant properties of basalt fiber reinforced polymers （BFRP） bars under a typical concrete environment. BFRP bars were embedded in concrete and exposed to different aggressive environments, including tap water, saline solution and ambient temperature environments, to study the effects of the type of solution and relative humidity （RH） on the durability of BFRP. Meanwhile, BFRP bars were directly immersed in an alkaline solution for comparison. The acceleration factor describing the relationship between the alkaline solution immersion and the moisture-saturated concrete was also obtained. Aging was accelerated with a temperature of 60 ℃. The results show that the chloridion in the saline solution does not have any harmful effects on the degradation of the concrete-encased BFRP bars. Contact with an alkaline （high pH） concrete pore-water solution is the primary reason for the degradation of the BFRP bars. The degradation rate of concrete-encased BFRP bars is accelerated when a high temperature and a high humidity are present simultaneously. The degradation rate of the BFRP bars is relatively quick at the initial stage and slows down with exposure time. Results show that the degradation of 2.18 years in moisture-saturated concrete at 60 ℃corresponds to that of one year when directly immersed in an alkaline solution （other conditions remaining the same） for the BFRP bars analyzed.

Experimental study on concrete columns hybrid reinforced by steel and FRP bars under seismic loading

In order to study the dynamic behavior of hybrid reinforced concrete columns, shaking table tests of three concrete columns with equal initial stiffness were conducted.The longitudinal reinforcements include an ordinary steel bar,a steel-fiber reinforced polymer（FRP） composite bar（SFCB）, and hybrid reinforcement（steel bar and FRP bar, CH）. Test results show that the peak ground acceleration（PGA） responses of different columns are similar to each other. For an ordinary reinforced concrete（RC） column, the plastic strain of the steel bar develops rapidly after the PGA of the input ground motion reaches 100 cm / s^2, and the corresponding residual strain develops dramatically. For a SFCB column, even after the peak strain reaches 0. 015, the residual strain is below 5 × 10^- 4. For the hybrid column C-H,the residual strain of the FRP bar is similar to that of the SFCB column. In general, concrete columns with hybrid steel and FRP bar reinforcement can achieve smaller residual deformation, and the SFCB reinforced columns can be constructed in extreme environments, such as offshore bridges, due to good anti-corrosion performance.

Seismic strengthening of reinforced concrete columns damaged by rebar corrosion using combined CFRP and steel jacket

In order to study the effectiveness of combined carbon fiber-reinforced polymer （CFRP） sheets and steel jacket in strengthening the seismic performance of corrosion-damaged reinforced concrete （RC） columns, twelve reinforced concrete columns are tested under combined lateral cyclic displacement excursions and constant axial load. The variables studied in this program include effects of corrosion degree of the rebars, level of axial load, the amount of CFRP sheets and steel jacket. The results indicate that the combined CFRP and steel jacket retrofitting technique is effective in improving load-carrying, ductility and energy absorption capacity of the columns. Compared with the corrosion-damaged RC column, the lateral load and the ductility factor of many strengthened columns increase more than 90% and 100%, respectively. The formulae for the calculation of the yielding load, the maximum lateral load and the displacement ductility factor of the strengthened columns under combined constant axial load and cyclically increasing lateral loading are developed. The test results are also compared with the results obtained from the proposed formulae. A good agreement between calculated values and experimental results is observed.

基于Reinforcing Steel本构的高强钢筋混凝土柱纤维模型研究

为了研究HTRB630E级高强钢筋的基本力学参数和疲劳性能,本文进行了应变等幅低周疲劳性能试验,并将试验结果与HRB400级钢筋的结果进行了对比分析。首先,基于应变等幅低周疲劳试验数据点,对OpenSees程序中Reinforcing Steel材料本构的疲劳参数C f、C d和α进行拟合,然后采用拟合的Reinforcing Steel材料本构疲劳三参数,基于OpenSees软件对钢筋混凝土柱有限元纤维模型进行数值模拟,最后将数值结果与试验柱结果对比分析。结果表明:拟合的疲劳三参数对有限元纤维模型有优化效果,为配置HTRB630E级高强钢筋混凝土结构数值纤维模型提供参考。

Simulation Study on Reinforcing Overburden to Prevent and Cure the Rupture of Shaft Lining

For preventing and curing the rupture disaster of shaft lining effectively, according to the additional force theory of shaft lining fracture, more than forty tests were carried out on the large scale test rig on the basis of simulating theory. The influence of the position of aquifer, the reinforcing scope of aquifer, reinforcing distance and the strength of grouting cemented mixture on the value and variation law of the axial additional force on shaft lining is studied. The relationships between the reinforcing parameters and the axial additional force on shaft lining are obtained, which provides the theoretic foundation and construction design parameters for the method of reinforcing strata by grouting to prevent and cure tbe rupture disaster of shart lining.

Explicit reinforcement models for fully-grouted rebar rock bolts

This paper investigates the explicit use of rock reinforcement in a discontinuous stress analysis model.A series of numerical experiments was undertaken to evaluate the performance of local and global reinforcement models implemented in universal distinct element code(UDEC).This was made possible by calibrating the reinforcement models to the laboratory behavior of a fully-grouted rebar bolt tested under pure pull and pure shear loading conditions.The model calibration focuses on matching different loading stages of the force-displacement curve including the initial elastic response,the hardening behavior and the bolt rupture.The paper concludes with a discussion on the suitability of the different reinforcement models in UDEC including their advantages and limitations.Finally,it addresses the choice of input parameters required for a realistic simulation of fully-grouted rebar bolts.

Immediate effects of scalp acupuncture with twirling reinforcing manipulation on hemiplegia following acute ischemic stroke: a hidden association study

Data mining has the potential to provide information for improving clinical acupuncture strategies by uncovering hidden rules between acupuncture manipulation and therapeutic effects in a data set. In this study, we performed acupuncture on 30 patients with hemiplegia due to acute ischemic stroke. All participants were pre-screened to ensure that they exhibited immediate responses to acupuncture. We used a twirling reinforcing acupuncture manipulation at the specific lines between the bilateral Baihui（GV20） and Taiyang（EX-HN5）. We collected neurologic deficit score, simplified Fugl-Meyer assessment score, muscle strength of the proximal and distal hemiplegic limbs, ratio of the maximal H-reflex to the maximal M-wave（Hmax/Mmax）, muscle tension at baseline and immediately after treatment, and the syndromes of traditional Chinese medicine at baseline. We then conducted data mining using an association algorithm and an artificial neural network backpropagation algorithm. We found that the twirling reinforcing manipulation had no obvious therapeutic difference in traditional Chinese medicine syndromes of ＂Deficiency and Excess＂. The change in the muscle strength of the upper distal and lower proximal limbs was one of the main factors affecting the immediate change in Fugl-Meyer scores. Additionally, we found a positive correlation between the muscle tension change of the upper limb and Hmax/Mmax immediate change, and both positive and negative correlations existed between the muscle tension change of the lower limb and immediate Hmax/Mmax change. Additionally, when the difference value of muscle tension for the upper and lower limbs was 〉 0 or 〈 0, the difference value of Hmax/Mmax was correspondingly positive or negative, indicating the scalp acupuncture has a bidirectional effect on muscle tension in hemiplegic limbs. Therefore, acupuncture with twirling reinforcing manipulation has distinct effects on acute ischemic stroke patients with different symptoms or stages of disease. Improved muscle tension in the upper and lower limbs, reflected by the variation in the Hmax/Mmax ratio, is crucial for recovery of motor function from hemiplegia.

Can trans-anal reinforcing sutures after double stapling in lower anterior resection reduce the need for a temporary diverting ostomy?

AIM:To evaluate trans-anal reinforcing sutures in low anterior resection using the double-stapled anastomosis technique for primary rectal cancers performed at a single institution.METHODS:The data of patients who received transanal reinforcing sutures were compared with those of patients who did not receive them after low anterior resection.Patients who underwent laparoscopic low anterior resection and the double-stapled anastomosis technique for primary rectal cancer between January2008 and December 2011 were included in this study.Patients with no anastomosis,a hand-sewn anastomosis,high anterior resection,or preoperative chemoradiation were excluded.The primary outcomes measured were the incidence of postoperative anastomotic complications and placement of a diverting ileostomy.RESULTS:Among 110 patients,the rate of placement of a diverting ileostomy was significantly lower in the suture group(SG)compared with the non-suture control group(CG)[SG,n=6(12.8%);CG,n=19(30.2%),P=0.031].No significant difference was observed in the rate of anastomotic leakage[SG,n=3(6.4%);CG,n=5(7.9%)].CONCLUSION:Trans-anal reinforcing sutures may reduce the need for diverting ileostomy.A randomized prospective study with a larger population should be performed in the future to demonstrate the efficacy of trans-anal reinforcing sutures.

Synergistic action on hypnosia: Yinao capsules with pentobarbital sodium of threshold and sub-threshold dosages

BACKGROUND： Sedative and hypnotic drugs could cure insomnia in a dependent manner, and traditional Chinese medicine has some superiority in treating insomnia. OBJECTIVE： To observe the synergistic action of yinao capsules with pentobarbital sodium in threshold and sub-threshold dosages in hypnosia and sedation. DESIGN： A completely randomized grouping design and control experiment. SETTING： Pharmacological laboratory, College of Pharmacy, Henan College of Traditional Chinese Medicine. MATERIALS： Totally 200 grade II Kunming mice of 18 - 21 g, either male or female, were used. Yinao capsules, main ingredients of which were turtleback glue, thinleaf milkwort root, Chinese magnoliavine fruit, mythic fungus, tangshen, ginseng and grassleaf sweetflag rhizome, were offered by Chinese-American Huayi Pharmacy, Co.,Ltd. （ratified number： 040901）; Kangnaoshuai capsules, main ingredients of which were prepared rehmannia root, tuber fleeceflower root, ginseng, membranous milkvetch root, thinleaf milkwort root, Fushen, grassleaf sweetflag rhizome, spine date seed, lecithin, barbary wolfberry fruit, pueraria root, vitamin E, etc., were produced by Shijiazhuang Siyao, Co.,Ltd. （ratified number： 040964）; Pentobarbital sodium was produced by China Medicine （Group） Shanghai Chemical Reagent, Co,.Ltd. （Ratified number： 030816）. ZZ-6 mice spontaneous activity apparatus was produced by Chengdu Taimeng Science and Technology, Co.,Ltd. METHODS： The experiment was carried out in the Animal Experimental Center, Henan College of Traditional Chinese Medicine from October to December in 2005. （1） Influence of Yinao capsules on the spontaneous activity of mice： Fifty mice were randomly divided into five groups with 10 mice in each group： Mice in the large, middle and small dosages of Yinao capsules groups were intragastrically infused with Yinao capsules suspension （1.36, 0.68, 0.34 g/kg）; Those in the Kangnaoshuai capsules group were infused with Kangnaoshuai suspension （1.12 g/kg）; Those in the control group were given physiologic saline of the same volume. The mice were administrated once a day for 7 days continuously, and they were placed into the mice spontaneous activity apparatus after 60 minutes from the last administration, the times of spontaneous activities and the times of arising within 10 minutes were recorded after adaptation for 5 minutes. （2） Synergistic action in hypnosia by Finao capsules with pentobarbital sodium of threshold dosage： Seventy mice were randomly divided into 5 groups as above-mentioned with 14 mice in each group, and they were treated the same as above. They were intraperitoneally injected with 50 mg/kg pentobarbital sodium after 60 minutes from the last administration, then conditions of falling asleep were observed. The disappearance of righting reflex was taken as the index of falling asleep, the latency of falling asleep was the duration from intraperitoneal injection of pentobarbital sodium to fall asleep, the sleeping time was from falling asleep to the disappearance of righting reflex. （3） Synergistic action in hypnosia by Yinao capsules with pentobarbital sodium of sub-threshold dosage： Eighty mice were randomly divided into 5 groups as above-mentioned with 16 mice in each group, and they were treated the same as above. They were intraperitoneally injected with 27 mg/kg pentobarbital sodium after 60 minutes from the last administration. Mice whose righting reflex disappeared for at least 1 minute within 30 minutes were taken as falling asleep, the number of sleeping animals in each group was recorded, and the rate of falling asleep was calculated. MAIN OUTCOME MEASURES： Synergistic action of Yinao capsules with pentobarbital sodium of threshold and sub-threshold dosages in hypnosia and sedation. RESULTS： All the 200 mice were involved in the analysis of results. （1） Influence of Yinao capsules on the spontaneous activity of mice： The times of spontaneous activities within 10 minutes in the large and middle dosage of Yinao capsules groups and Kangnaoshuai capsules group [（138.0±37.0）, （156.8±28.3）, （133.3±46.1） times] were obviously fewer than those in the control group [（204.3±61.3） times, P 〈 0.05- 0.01]. The arising times within 10 minutes in the middle and small dosages of Yinao capsules groups and Kangnaoshuai capsules group [（30.7 ± 18.3）, （26.5± 11.2）, （24.2±11.6） times] were obviously fewer than those in the control [（71.7±38.6） times, P 〈 0.01 ]. （2） Synergistic action in hypnosia by Yinao capsules with pentobarbital sodium of threshold dosage： The sleeping latencies in the large and middle dosages of Yinao capsules groups and Kangnaoshuai capsules group [（4.49±1.84）, （4.83±1.72）, （3.85± 1.94） minutes] were obviously shorter than that in the control group [（6.73 ±2.75） minutes, P 〈 0.05 - 0.01 ]. The sleeping time in the large, middle and small dosages of Yinao capsules groups and Kangnaoshuai capsules group [（89.0± 38.42）, （67.21 ±24.07）, （66.28±18.94）, （84.36±29.81） minutes] were obviously longer than that in the control group [（45.78±20.78） minutes, P 〈 0.05- 0.01]. （3） Synergistic action in hypnosia by Yinao capsules with pentobarbital sodium of sub-threshold dosage： The rates of falling asleep in the large and middle dosages of Yinao capsules groups were higher than that in the control group [56% （9/1 6）, 38% （6/1 6）, 6% （6/16）, P 〈 0.01, 0.05], whereas Kangnaoshuai capsules and small dosage of Yinao capsules had no synergistic action with pentobarbital sodium of sub-threshold dosage （P 〉 0.05）. CONCLUSION： Yinao capsules have synergistic action with pentobarbital sodium in hypnosia. Yinao capsules possess obvious sedative and hypnotic effects in a dosage-dependent manner.

Control mechanism and technique of floor heave with reinforcing solid coal side and floor corner in gob-side coal entry retaining

Floor heave is the most common convergence in gob-side entry retaining.The paper analyzes the form,process and characteristics of gob-side entry retaining with the comprehensive methods of theoretical analysis,numerical simulation and the field trial.Research results present that bending and folding floor heave is the main factor in the stage of the first panel mining;squeezing and fluidity floor heave plays a great role in the stable stage of gob-side entry retaining;the combination of the former two factors affects mainly the stage of the second mining ahead;abutment pressure is a fundamental contribution to the serious floor heave of gob-side entry retaining,and sides corners of solid coal body are key part in the case of floor heave controlling of gob-side entry retaining.Floor heave of gob-side entry retaining can be significantly controlled by reinforcing sides and corners of solid coal body,and influence rules on the floor heave of gob side entry retaining of sides supporting strength and the bottom bolt orientation in solid coal side are obtained.Research results have been successfully applied in gob-side entry retaining of G20-F23070 face haulage roadway in #2 coal mine of Pingmei Group,and the field observation shows that the proposed technique is an effective way in controlling the floor heave of gob-side entry retaining.

Fundamental principles of an effective reinforcing roof bolting strategy in horizontally layered roof strata and areas of potential improvement

It is arguable that the development of reinforcing roof bolting systems has largely stagnated in recent times, primarily due to the prevailing industry view that few, if any, further improvements can be made to what currently exists.However, this paper contends that reinforcing roof bolting systems can be further refined by considering both the specific manner by which horizontally bedded roof strata loses its natural self-supporting ability and the specific means by which reinforcing roof bolts act to promote or retain this natural self-supporting ability.The Australian coal industry has insisted on minimising bolt-hole diameter to maximise load transfer and on targeting full-encapsulation by any means necessary for many years.This has led to a significant, albeit unintended, consequence in terms of overall roof bolting effectiveness, namely increased resin pressures during bolt installation and the associated potential for opening bedding planes that may have, otherwise, remained closed during the bolt installation process.Given that the natural self-supporting ability of roof strata is strongly linked to whether bedding planes are open or closed, logically, minimising resin pressures should be a significant benefit.This paper focuses primarily on three key issues that relate directly to the function of the roof bolting system itself:(1) the importance of proper resin mixing in the context of maximising load transfer strength and stiffness,(2) the importance of minimising resin pressures developed during bolt installation, and(3) the importance of maximising the effectiveness of the available bolt pre-tension.All mine operators should be invested in improving the individual effectiveness of each installed roof bolt, even by relatively small incremental amounts, so this is an important topic for discussion within the mining community.