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Compressive strength is a crucial factor in designing masonry walls to withstand various loading conditions, and it is equally significant for the designing of dry-stack masonry walls. Dry-stack masonry uses interlocking blocks, that enable a faster walling construction than the conventional mortared masonry. Widespread use of this walling system is limited due to lack of detailed design provisions in standards, as opposed to conventional mortared masonry. In this study, the compressive strength properties of un-grouted and grouted dry-stack concrete block masonry were experimentally evaluated. In total, 80 dry-stack concrete block masonry wallettes were built and tested with five different types of dry-stack blocks and three different grouts strength (20 MPa, 32 MPa and 40 MPa). The failure patterns, stress-strain curves and compressive strength characteristics obtained through the testing campaign are reported in this paper. The grouted dry-stack concrete block masonry wallettes demonstrated higher compressive capacities (ranging from 11 % to 152 %) than the corresponding un-grouted concrete block masonry wallettes, the increment was dependent on the grout and block types. The experimental data collected in this campaign was then used to assess the available formulae and tabulated values to predict the compressive strength of dry-stack concrete block masonry wallettes. The predictabilities of these formulae and tabulated values are presented and discussed. [Display omitted] • Compression behaviour of grouted dry-stack concrete block masonry was studied. • 80 dry-stack concrete block masonry wallettes have been tested. • The presence of grout had a significant impact on the axial compression capacities. • Compressive strength prediction models were verified, and best models are specified. [ABSTRACT FROM AUTHOR]

Ultrasonic guided wave (UGW) technique has been widely utilized in damage detection of pre-stressed steel strands. However, most of the current UGW-based methods only focus on bare strands, whereas in real projects the strands are usually pre-buried inside the structure and encapsulated by media such as concrete or grout. In this study, the effects of various grouting and tensioning factors on the propagation of UGW in grouted steel strand, as well as the effectiveness of UGW energy leakage ratio (α EL)-based pre-stress evaluation for grouted steel strand, were investigated. Firstly, the theoretical model of UGW propagating in the grouted steel strand was developed. Secondly, a finite element model of grouted strand was established to investigate the dispersion characteristic of UGW as well as the energy distribution and attenuation behavior of UGW in the grout. Thirdly, pre-stressed concrete (PSC) specimens with different grouting diameters, grouting lengths, and tension forces were designed to investigate the effects of grouting thickness, grouting length, and tension force on the group velocity, energy distribution and α EL of UGW. Finally, the α EL -based approach was validated in pre-stress evaluation for grouted steel strand, and the evaluation accuracy was compared with that for bare steel strand. Results show that compared with the helical wire excitation scenario, the UGW signals propagating in steel strands are significantly less affected by variations in grouting thickness and grouting length under core wire excitation scenario. In the grout, the UGW energy tends to decrease exponentially with the increase of the radial propagation distance, and the helical wire excitation scenario leads to more UGW energy leaking into the grout compared with core wire excitation. It is recommended to excite UGW signal in the core wire instead of the helical wire in α EL -based pre-stress evaluation approach for grouted steel strand, in such scenario, the evaluation error is only 4.93 %. • Variations of UGW with various grouting conditions were investigated. • Energy distribution and attenuation of UGW in grout were investigated. • 3. Exciting UGW in core wire instead of helical wire is recommended. [ABSTRACT FROM AUTHOR]

This study investigated the influence of fluorogypsum and KH 2 PO 4 on the mechanical properties and hydration mechanisms of aluminate cement based grouting materials. Physical properties including setting time, pH value and the compressive strength of aluminate cement based grouting materials with different mix design were investigated. The influencing factors and hydration mechanisms were quantified and discussed through XRD, TG, SEM and NMR. The water-cement ratio was fixed at 0.40, and the fluorogypsum content accounted for 10 wt% of the cement mass. With increasing KH 2 PO 4 content, the setting time initially decreased and then prolonged, while the compressive strength at 3d and 28d first increased and then decreased. Among these variations, a content of 0.2 wt% KH 2 PO 4 exhibited the optimal performance with initial and final setting times of 264 min and 308 min, respectively. The compressive strengths at 3 days and 28 days were recorded as 26.4 MPa and 60.5 MPa, respectively, exhibiting an increase of 76% and a remarkable enhancement of 228.80% compared to that of pure aluminate cement. The addition of fluorogypsum facilitated the formation of AFt, while KH 2 PO 4 regulated the slurry's pH, concurrently enhancing AFt production, and the morphology of AFt transformed from acicular to a more slender fiber shape, which exhibited improved interlacing and overlapped properties, thereby promoting strength development. The hydration process was analyzed in conjunction with low-field nuclear magnetic resonator analysis. The findings revealed that the samples containing 10 wt% fluorogypsum and 0.2 wt% KH 2 PO 4 in aluminate cement exhibited the highest levels of chemically bound water at both 3d and 28d, followed by samples with 10 wt% fluorogypsum in aluminate cement, while those composed solely of aluminate cement displayed the lowest content. The T 2 spectra data were also fitted to a function, revealing a positive correlation between pore evolution and the hydration rate of the samples. • Fluorogypsum and KH 2 PO 4 can shorten the setting time and increase the compressive strength of calcium aluminate cement. • Fluorogypsum contributed to AFt formation; KH 2 PO 4 further increased AFt and modified its morphology. • KH 2 PO 4 changed the morphology of AFt to elongated fibers and optimized the pore structure. • Hydration of aluminate cement can be significantly enhanced by combined addition of fluoropgypsum and KH 2 PO 4. • Fluoropgypsum alone could still cause a substantial promotion effect on the hydration rate of aluminate cement. [ABSTRACT FROM AUTHOR]

Highlights • Review on application of polyurethane grout for improving the properties of weak soils. • The paper also covered the chemistry of polyurethane components and its applications. • The methods of grouting and grouting materials were also explored. • Improving polyurethane by incorporating fillers and other additives are also covered. Abstract The recent need to develop infrastructure, driven by global population growth is forcing societies to construct on any soil type available within their vicinity including weak soils. However, due to the poor physical and engineering properties of weak soils, they are not suitable for construction purposes. Given many ground improvement techniques that are presently employed to improve the properties of weak soils and to reduce the potential damages caused by them, this paper addresses this issue by conducting a literature review and collecting information on the application of polyurethane chemical grout for improving the properties of weak soils. While, many researchers have investigated the application of polyurethane, its application and the methods of improving the properties of weak soils, including detailed information on the application of polyurethane on weak soils for improving its properties is limited. Accordingly, this paper has examined the chemistry of each component of polyurethane and its application and explored the methods of grouting, grouting materials, the advantages and disadvantages as well as the applications of grout both in the field and in the laboratory. The review also discussed the possible means of improving polyurethane by incorporating reinforcing fillers, surfactant, catalyst and other additives. The review concluded that improved polyurethane has the potential to improve weak soil types for infrastructure development. [ABSTRACT FROM AUTHOR]

Highlights • The w/b of cement-sodium silicate grouts is 1.1–2.5, which is higher than previous studies. • The sodium silicate solution is adopted 4.4–7.5 wt% as an accelerator. • The setting time, sulphate resistance, permeability and shrinkage are investigated. • A workable and durable mixture is obtained in marine environments. Abstract This study aims to investigate the durability and microstructure of cement-sodium silicate grouts with high water to binder ratios (w/b) of 1.1–2.5 upon exposure to sea water. Grout specimens were prepared by mixing ordinary Portland cement paste and 4.4–7.5 wt% sodium silicate (water glass solution), which was adopted as an accelerator to prevent dilution and displacement during injection for geological strengthening and water control. The setting time, sulphate attack resistance, permeability and autogenous shrinkage of the grouts were assessed and compared. The microstructures were investigated in terms of the morphology and structure of the pores and cracks. The results reveal that satisfactory properties and durability, such as a setting time of 60–120 s, a flexural strength reduction of −3–6% after sulphate attack by sea water, a permeability of 1.2–1.6 MPa and an autogenous shrinkage of −0.298–1.22 milli, were obtained in cement-sodium silicate grouts with a w/b of 1.1–1.6 and dosages of sodium silicate of 4.4–5.7 wt%. However, hardened grouts suffered serious deterioration due to sulphate attack in 3 wt% sodium sulphate solutions and fatal drying shrinkage when exposed to air with a relative humidity of 60% at 20 °C. The cement-sodium silicate grout with the recommended composition is feasible and durable in marine environments, but special care must be taken when this grout is applied in environments with a high sulphate concentration or wetting-drying cycles. [ABSTRACT FROM AUTHOR]

Highlights • The segment-grout structure with defects was simulated experimentally. • STFT and WT were carried out to analyze the signals. • Energies of wavelet packet were calculated. Abstract In shield tunneling construction, grout of precast concrete segments is widely applied to various geological conditions. However, the connection performance between the grout and segments after the grout cannot be determined by destructive means, such as coring. The impact-echo method is used extensively in nondestructive testing of civil engineering structures. Nevertheless, there are inadequate researches on determining defects in segment-grout structure. In this paper, the segment-grout structure was simulated experimentally and artificial defects were introduced in the grout. The Short-time Fourier Transform (STFT) and Wavelet Transform (WT) of signals obtained by the impact-echo method were carried out to analyze the time-frequency domain features of the impact-echo signals with and without defects in the grout. On this basis, defects in the grout layer were determined. Finally, energies of wavelet packet were calculated and characteristic relative energy indexes of wavelet packet at different positions were detained. It’s found that the values at positions without defects are relatively low. It’s demonstrated that the signal analysis of impact-echo method has to combine time-frequency domain information and energy distribution for detection of defects in the grout layer. Wavelet transform and energy analysis methods are effective means to detect defects in the grout layer. [ABSTRACT FROM AUTHOR]

Highlights • Enhanced durability performance in improved grout with silica fume. • Quantitative corrosion evaluation with impressed current method. • Considerations of various tendon corrosion in one tendon-grout system. • Investigation of bleeding and crack effect on corrosion. • Evaluation of corrosion in tendon with small cover depth of grout. Abstract Pre-stressed Concrete (PSC) has various engineering advantages like reduction of dead load, enhancement of shear strength, and reducing crack, however tendon corrosion in grout caused by deficient grout and intrusion of chlorides causes a tendon break and the related structural problems. It is important to understand the corrosion pattern varying with grout properties and placement conditions. In the work, TG (Tendon-Grout) systems are prepared considering grout quality, bleeding, tendon location, and crack width. In order to evaluate corrosion pattern in TG systems in a short period, ICM (Impressed Current Method) is adopted for corrosion acceleration for 2 and 4 days of duration. For two types of grout (conventional one and improved grout with reduced water to cement ratio and silica fume), corrosion current and its amounts are evaluated for various conditions. In the TG system with crack, corrosion greatly increases with extension of test duration for both types of grout since crack width on grout is a main channel for ion intrusion. In spite of crack effect, improved grout has better resistance to corrosion considering crack and bleeding condition. When TG system has eccentricity of tendon with small cover depth, no significant differences between conventional and improved grout are measured since cover depth is too small to protect chlorides from outside. Various effects like bleeding, crack, tendon location, and grout quality are discussed in the work. The improved properties in IG like porosity, strength, absorption ratio, and expansion rate are also investigated. [ABSTRACT FROM AUTHOR]

This paper aims to evaluate the influence of concrete blocks and grout’s properties on the masonry’s compressive strength and stiffness. Prisms were produced with blocks and grouts with different strength levels, and mortars with strength of 70% of the blocks’ net area strength. It was possible to understand the effects of using low strength and high strength blocks, check the effectiveness of using grout or increasing its strength, and develop response surfaces, contour graphs, and empirical equations. Predictions about the masonry failure mechanisms are proposed for different block and grout combinations. It helps the designer to associate strength and failure mechanisms, prevent or mitigate their undesirable consequences, and eliminate brittle rupture modes. Results complement the existing database and can be used to properly select blocks and grout for masonry structures. [ABSTRACT FROM AUTHOR]

The evolution of technical and environmental requirements fosters the development of geopolymer based grouts for soil reinforcement. Geopolymer based materials actually have several advantages but the improvement of their rheological performances remains a challenging task, as the raw materials, especially sodium silicate and metakaolin, do not have favorable properties and the main chemical admixtures used to optimize cement-based materials have not been found compatible. As mix-design takes into account the performances in both fresh and hardened states, a comprehensive study is necessary to develop geopolymer grouts based on metakaolin-fly ash-stabilizer mixtures. Fly ash allowed reducing the viscosity and increasing the setting time and the stabilizer provided the fresh mixes with better homogeneity and stability. At constant liquid to solid ratio, the packing density of the powders actually increases with fly ash proportion. Fly ash affected the mechanical properties, especially at replacement rates of 40% and higher, due to combined effects of reduced reactivity and higher packing density of the powders. This could be shown by a new methodology combining the monitoring the elastic properties with isothermal calorimetry for understanding the early-age behavior and the distinction between the geopolymerization stages. The addition of xanthan gum had a beneficial effect on the stability of grouts, by acting on the activation solution without having any significant effect on the geopolymerization reaction. [ABSTRACT FROM AUTHOR]

In grouted post-tensioned (PT) systems, cementitious grouts are supposed to completely fill the interstitial spaces between the strands and act as the ‘last line defence system’ against corrosion. However, use of poor quality grout materials and grouting practices result in voided grout systems, ultimately leading to premature failure of tendons in many bridges around the world. To ensure an intact system, the grout must have excellent fresh properties, in particular the flow properties. Such high-performance grouts are not available in many developing countries, where grouting for post-tensioned structures is still a nascent technology. In this research, a two-stage test program was carried out to evaluate the fresh and hardened properties of seven commercial grouts, which includes three Pre-Packaged Grout mixes (PPG); three Site-Batched Grout mixes (SBG) and one standard Ordinary Portland Cement grout mix (PCG). Further, one PPG mix and SBG mix were chosen and their properties were evaluated for three levels of mixing speed and two ambient temperature conditions. Fresh properties such as wet density, efflux time and its retention, standard bleed, wick-induced bleed and pressure bleed, as well as set/hardened properties such as setting time, compressive strength and volume change were evaluated. Three batches of grout were tested for each grout material, to ensure reliability of results. The influence of binder fineness on the performance of grouts was also evaluated. The study serves as a strong evidence in substantiating that the most commonly used grout materials for PT system in developing countries, fail to meet the standard requirements and even the manufacturer’s own specifications. It is also found that the performance of the grout is influenced by mixing speed, ambient temperature, and fineness. The study emphasises that the evaluation of the grout behaviour under simulated field conditions is essential to ensure void free and durable PT systems. [ABSTRACT FROM AUTHOR]

Recent laboratory experiments have demonstrated the superior performance (high stiffness, load-carrying capacity and ductility) of bolt shear connectors embedded in the pockets of cementitious grout compared to conventional fasteners (e.g. screws) for developing composite action between steel beams and timber slabs. Accordingly, this paper investigates the structural behaviour of steel-timber composite (STC) joints with bolt connectors embedded in grout pockets (BCGP) using 3-D continuum-based finite element (FE) models. Following validation of the FE models against available push-out test data, they are used to conduct a parametric study that elucidates the influences of the compressive strength of the grout, the yield strength and size of the bolt shear connectors, the size of the grout pockets and the thickness of the steel profile flange on the load-slip behaviour, service stiffness, peak load-carrying capacity and failure modes of STC joints with BCGP. Simple formulae for the stiffness and load-carrying capacity of the STC joints with BCGP are derived from linear regression of the results of the parametric study. [ABSTRACT FROM AUTHOR]

• Porous titanium slag used to modify grout for high radiation attenuation. • LAC improved by 12.8% and 9.8% at 3 days and 2 years, respectively. • LAC and HVL improved with titanium slag content and curing age. • Possible for low-density high-strength radiation shielding cementitious materials. The utilization of industrial waste materials for civil engineering structures has received massive attention in recent decades. In this work, the feasibility of using titanium slag to enhance the radiation attenuation properties of cementitious grout at the ages of 3 days and 2 years was studied. Titanium slag (TS) was incorporated as cement grout replacement at 0%, 10% 20% and 30%. Hardened blocks in dimension of 146 × 146 × 30 m m were fabricated. The porosity of titanium slag was characterized while the phases in the raw materials as well as the fabricated grout were identified. The influence of the titanium slag addition on the grout hydration kinetics, density, compressive strength and porosity of hardened grouts was evaluated. The results show a decrease in density with the increase of titanium slag content as well as a decrease in compressive strength at curing ages of 3, 7 and 28 days. The slag also refined the microstructure, leading to a reduction in average pore diameter. Furthermore, the hardened blocks were subject to gamma-ray sources such as 137Cs (0.662 MeV) and 60Co (1.173 and 1.332 MeV) and the Linear Attenuation Coefficient (LAC) and Half Value Layer (HVL) were evaluated. The results show that increasing curing age improves the shielding performance of the composite. At 30% replacement, the LAC improvement of the samples exposed to Co sources (1.173 and 1.332 MeV) at 3 days was 11.7% and 12.8% respectively while at 2 years, 9.9% and 9.8% improvement was obtained. Reduced HVL is obtained for an increase in replacement percentage and increased curing age. Therefore, this gives an indication of the possibility of developing low-density radiation shielding cement-based materials. [ABSTRACT FROM AUTHOR]

• With microcalorimetry (MC) it was possible to measure thermal events in heterogeneous grout. • The melting and crystallisation in phase change materials was successfully obtained by MC. • Large samples (10 g) could be tested accurately in non-isothermal MC. • Non-isothermal MC were able to properly capture the features of cyclic-temperature tests. • MC is proposed as a standard test for specific/latent heat in heterogeneous (cementitious) systems. • The calibration carried out using standard reference material shows that MC results are only < 2% erroneous. Microencapsulated phase-change-materials (PCMs) incorporated in cementitious grout can be used as a source of energy in an underground thermal energy storage system. Differential scanning calorimetry (DSC) is a widely used technique to measure the latent heat or specific heat of PCM-embedded cementitious materials. However, using milligram sample sizes (as required by DSC) of a cementitious material fails to represent the actual scale of cementitious components. This is the reason why, in the present paper, non-isothermal heat conduction microcalorimetry (MC) was evaluated as a tool for determining the thermal properties of PCM-embedded grout as well as pure PCM (three PCMs were used). An MC experimental protocol (using both single and 5–6 temperature cycles) was developed and used to measure latent heat and melting and crystallization temperatures, which were in good agreement with those reported for pure PCMs by the producers. In addition, the specific heats of the PCM-containing grout also agreed with measurements using the hot disk technique. Overall, the results show that the MC technique can be used as a potential standard method in determining thermal processes in complex systems, such as in PCM-embedded cementitious systems, where a large sample size is needed to represent the material. [ABSTRACT FROM AUTHOR]

Durability and useful life of the structural concrete are related to the environmental conditions and degrading factors present in the environment. One of most concerning aggressive agents in the civil construction industry is carbon dioxide that penetrates into the pores of the concrete reacting with the interstitial hydrates reducing its pH, promoting depassivation of the steel armours inside the concrete, thus enabling to start the corrosion process. This paper produced grout proof-bodies, concretes with high fluidity used to fill the blocks in structural masonry, with different resistance to compression: 15 MPa, 20 MPa, 25 MPa. The specimens were submitted to a carbonation front in an accelerated chamber under controlled humidity, temperature and carbon dioxide. A numerical model was used aiming to estimate the forecast of the useful life by making a comparison of the values forecasted by the Brazilian and international performance rules. It was observed that the 15 MPa grout has a useful life forecast lower than that recommended by the standard, around 60% lower, while the 20 MPa and 25 MPa grout presented a satisfactory useful life. Hence, it was certified the importance of controlling the grout resistance and coverage in structural masonry works as a form to assure the desired durability to the structure. [ABSTRACT FROM AUTHOR]

This paper represent the results of an experimental study handled with developed grouting materials for fully-cement-grouted ribbed rockbolts. These experimental studies cover the effects of some mineral admixtures (silica fume, blast furnace slag, fly ash etc.) on the bond characteristics between grout and rockbolts. The effect of mineral admixtures on the grout strength of fully-grouted rockbolts and block punch index (BPI) and compressive strength (CS) of the grout on the load bearing capacity (LBC) were investigated. Totally 150 rockbolt pull-out tests were performed using ten different grouts in order to investigate and improve the LBC of grouted rockbolts for five different curing times (1, 3, 7, 28 and 90 days). All grout types were prepared same ratios, and silica sand was used as fine aggregate. Grout mixtures that 15% of mineral admixtures replaced with cement by weight were prepared. The results showed that grouts produced with silica fume (SF) and metakaolin (MK) in all mixtures were yielded the highest CS and bond strength at all ages. The all strength tests of fly ash (FA) grout exhibited low values till 28 days of curing time in accordance with reference grout, but a sharp increase was observed after this period. Grouts with perlite (PRL) and blast furnace slag (BFS) showed the similar strength values according to reference grout. In conclusion, mineral admixtures can be used for high-strength and low cost grout in tunneling applications. In addition, the use of waste materials can contribute to the resolution of environmental problems. [ABSTRACT FROM AUTHOR]

The paper presents the assessment of a metakaolin-slag-sodium-silicate GeoPolymer (GP) grout as a matrix for bonding four bidirectional meshes made of basalt, glass, carbon fibres and two unidirectional ultra-high tensile strength steel fabrics to soft mud and strong extruded clay bricks for strengthening purposes. A detailed chemical/physical characterization of the geopolymer is given, evidencing the completion of the geopolymerization reaction and the good stability of the geopolymer to leaching, freeze-thaw cycles and high temperature treatments as well as its adequate mechanical properties. Pull-off tests proved the excellent adhesion strength of the geopolymer grout, also embedding meshes and fabric, to both types of clay bricks. [ABSTRACT FROM AUTHOR]

During cold weather precast wall construction, in-situ heating of the grout used in grouted dowel connections is usually conducted for short periods of time. Hence, early-age exposure to subfreezing conditions may affect the quality of the grout and subsequently the bond strength of the connection, which can compromise structural integrity. In this study, grout specimens typical of that used in precast wall construction were initially cured at ambient conditions for one day and then placed inside a walk-in environmental chamber at subfreezing temperatures. The hardened grout properties and bond strength of the connection were examined and compared to that of specimens cured at ambient temperature. The compressive strength of the grout was monitored at temperatures of 1°, −10° and −20 °C. The effect of subfreezing exposure on the mechanical properties, hydration process and pore size distribution of the grout were examined. It was found that early-age subfreezing curing temperatures reduced the compressive strength of the grout, leading to increased dowel embedment length to achieve bar fracture. The bond strength of the connection remained proportional to the square root of compressive strength, even subsequent to early-age exposure to subfreezing temperature. [ABSTRACT FROM AUTHOR]

In recent years, the deep mixing technique that utilizes cement-based grout mixtures has become a popular approach, particularly for the enhancement of soft soils. Despite the advantages of deep mixing technique in numerous construction applications, the effort given for this technique still needs to be extended using new material as additive. Thus, this study investigates the use of cement-based grout combined with glass powder to enhance the clay soil via deep mixing technique. An experimental program has been conducted including grout mixtures at different replacements of glass powder (0%, 3%, 6% and 9% by dry weight of binder) mixed with clay having different water contents (36%, 31% and 21%). The Vicat, unconfined compressive strength (UCS) and ultrasonic pulse velocity (UPV) tests have been carried for analysing performances of mixtures. The results indicate that the setting times of the mixture pastes increase, while the bulk densities of the soilcrete samples do not significantly change with the replacement of glass powder. Moreover, due to the use of glass powder, both the UCS and UPV increase alongside decreasing water content as well as increasing curing time. Test results imply that, owing to the replacement of glass powder, all UCS values of the soilcrete samples are applicable for the purpose of deep mixing. However, the replacement of glass powder by 3% produces a more favorable UCS response. Strong correlations exist for the UCS versus elastic modulus (R ⩾ 0.84) as well as for the UCS versus UPV (R ⩾ 0.82), which practically could be useful for the strength predictions of soil-cement columns. Consequently, the use of cement-based grout with the glass powder replacement could provide a new insight into the deep mixing technique for the treatment of clay. Moreover, the employment of glass powder as a waste material could also benefit the environment and construction costs. [ABSTRACT FROM AUTHOR]

• The behavior of the grouted samples up to the yield point (YP) and beyond the YP is different. • The stress–strain curves is separated into two parts, pre- YP and post- YP. • The derived PNN models can effectively predict the stress (q) of the grouted samples. • Up to the YP , the CP is the most important parameter on the injected sand strength. • Beyond the YP , the effect of Z , W/CM and CP on the injected sand strength is almost the same. The process of cement production is costly and one of the main factors in carbon dioxide emission. Hence, part of it should be replaced with eco-friendly pozzolanic materials like zeolite. As the determination of shear behavior of injected sands is time-consuming and laborious, in the present research the polynomial neural network (PNN) model was used to predict stress (q)-strain ( ε ) behavior of zeolite-cement injected sand. For this purpose, a number of consolidated undrained (CU) triaxial tests was performed on sand samples injected with zeolite-cement grout. Due to the difference in the shear behavior of the injected sand before and after the yield point (YP), the stress–strain curves were divided into two parts (up to the YP and beyond the YP), and the curves of each part were predicted with separate relationships. The results revealed that the PNN -based equations can accurately estimate the q - ε curves of sand samples injected with zeolite-cement grout, such that the mean absolute percent error (MAPE) for testing data sets to estimate pre- and post- YP q was 7.79 and 5.38%, respectively. Sensitivity analysis indicated that up to the YP , the confining pressure (CP) was the most important parameter affecting the injected sand strength. The importance of water to cementitious materials ratio (W/CM) and cement replacement with zeolite content (Z) on the pre- YP q predicted by the PNN model was close to each other and less than the CP. Beyond the YP , the effect of W/CM , CP and Z was almost the same. [ABSTRACT FROM AUTHOR]

• Compression behaviour of RMM with changing block types, steel bars and panel heights is presented through experiments and analytical investigation. • Steel bars did not yield and did not contribute significantly to the compression capacity of RMM panels. • Grout played major role in the compression capacity improvement and bonding of mortarless blocks. • Analytical equations for compression capacity prediction and stress–strain behaviour of RMM are proposed. Mortarless masonry can facilitate faster construction of walls over conventional mortared masonry due to the absence of a mortar laying process and availability of interlocking features on the blocks. The structural performance of mortarless masonry can be improved by grouting and providing reinforcement in hollow cores of the interlocking blocks. In this study, axial compression behaviour of the reinforced mortarless masonry (RMM) panels was investigated. The influence of mortarless block types (single and double webbed), grouting and vertical reinforcement ratios were examined to comprehend the axial compression and displacement characteristics of RMM assemblies. In total, 44 RMM panels were constructed and tested under concentric axial compression. Failure patterns, load–displacement responses and compression capacities of the RMM panels were assessed and presented in this paper. The experimental results revealed that grouting significantly improved the axial capacities of RMM panels by bonding the interlocking blocks and reducing the initial settlement in the mortarless block interfaces. The single webbed blocks had higher compressive strength as compared to double webbed blocks, however in RMM panels, early cracking and spalling of face-shells of single webbed blocks resulted in lower compression capacities and stress ratios as compared to double webbed RMM assemblies. Prediction of compression capacities of the tested RMM panels using the current design provisions of Australian Masonry Standards (AS 3700) were found conservative with a safety ratios of 1.1 (for single webbed RMM panels) and 1.4 (for double webbed RMM panels). Subsequently, an analytical stress–strain model was proposed for the RMM under axial compression by calibrating the experimental data obtained through this study. [ABSTRACT FROM AUTHOR]

Grout is widely used in bonded post-tensioned bridge construction as an anti-corrosive material for protecting the steel strands. Several occurrences of tendon failures in U.S. bridges, however, have led to an interest in unbonded tendons where a flexible filler, such as wax, grease, or gel, is injected into the tendon duct instead of cement grout. In general, the consistency of these flexible fillers in ambient temperature falls within the realm of semi-solids and, thus, they are not readily injectable without preheating. A major concern with flexible filler injection is, therefore, maintaining an adequately elevated filler temperature to keep the material’s viscosity sufficiently low for complete filling of the duct and to avoid a blockage that might result in a burst pipe or duct. This paper presents a simplified heat transfer model that computes the decrease in temperature of the moving filler front during injection as it cools while interacting with the surrounding strands and duct. The proposed model has been validated by multiple mockup experiments conducted with different filler materials and injection rates. A comprehensive parametric study has been conducted to determine the sensitivity of the filler front temperature to several practical factors, such as effective strand surface area, tendon length, injection rate, ambient temperature, injection temperature, and number of strands in a tendon system. The required minimum injection pressure for different flow velocities and tendon lengths has also been determined. The experimental results confirm the model’s applicability to a wide range of tendon lengths and strand patterns, and its usefulness in determining tendon constructability. [ABSTRACT FROM AUTHOR]

Fresh and hardened properties of steel fiber-reinforced grout (SFRG) containing ground granulated blast-furnace slag (GGBS) were investigated for applications to prestressed concrete substructures of offshore wind turbines. The addition of short smooth steel fibers (6 mm in length, 0.2 mm in diameter) generally decreased the flow, bleeding, and time of setting of SFRG, whereas the addition of GGBS for the replacement of 40% of the cement by weight ratio clearly increased its flow and the time of setting. The effect of adding GGBS on bleeding was different according to the type of cement. Despite these outcomes, it was observed that the addition of GGBS notably enhanced the chloride penetration resistance of SFRGs, while the addition of steel fibers significantly increased their flexural strength. [ABSTRACT FROM AUTHOR]

Oil sands drill cuttings waste represents one of the most difficult challenges for the oil sands mining sector. Reducing the amount oil sands drill cutting waste sent to landfill offers one of the best solutions for waste management. The present work offers an innovative solution for the recycle and reuse of treated oil sands drill cuttings waste (TOSW) in grout manufacture. In this study, the physical, chemical and mineralogical characteristics of the treated oil sands drill cuttings waste were investigated. Fresh and hardened properties for grouts incorporating the treated solid drill cuttings waste were evaluated. The results show that incorporating up to 20% of the treated solid drill cuttings waste as a partially replacement of cement will not adversely affect the properties of the grout. Leaching tests evidenced the reduction in the release of heavy metals from the tested mixtures compared to that of the raw waste indicating successful stabilization/solidification of such waste in the grout. [ABSTRACT FROM AUTHOR]

• Commercially available pre-packages grouts tend to form a highly porous layer of grout, that can lead to corrosion of strands. • Prototype scale tendon-grouting tests were conducted assess the resistance against bleeding. • Ability of the fresh grout to retain its properties against variations in the ambient temperature and water content was studied. • A set of stringent and comprehensive specifications were developed for applications in PT systems. • Newly developed grout satisfies all the performance specifications while site batched grouts do not. Grouted, post-tensioned (PT) concrete structures are protected from tendon corrosion by filling the interstitial spaces with cementitious grouts. To achieve complete grouting, the cementitious grout must be sufficiently flowable and bleed resistant. Nowadays, many commercial pre-packaged grouts are available. However, simulated bleed measurements with prototype-scale tendon grouting tests have shown that pre-packaged grouts tend to form a highly porous layer of grout, which poses a severe threat to corrosion protection. This study focuses on evaluating the performance of a novel pre-blended grout produced on an industrial scale using the fluidity and fluidity retention tests, standard, wick-induced, pressure-induced, and inclined tube bleed tests. Also, the ability of the fresh grout to retain its properties against slight variations in the ambient temperature and water content was studied. The performance of the pre-blended grout on a real scale was evaluated and compared with a widely used site-batched grout composition using prototype tendon grouting tests. In addition, a set of stringent and comprehensive specifications were developed for applications in PT systems. It was also observed that the pre-blended grout considered in this study met all the proposed specifications, therefore, can be used for the corrosion protection of tendons in PT structures. [ABSTRACT FROM AUTHOR]

Conservation, repair and strengthening of historic masonry buildings should preserve their significance and ensure their structural stability. The condition of a given structure and the extent of damage determine the type of action needed. Grouting is a well-known remedial technique, which can be durable and mechanically efficient whilst preserving the historic value. Still, the selection of a grout for repair must be based on the physical and chemical properties of the existing materials. Parameters such as rheology, injectability and stability of the mix should be considered to ensure the effectiveness of grout injection. In addition, the bond strength of the grout to the existing material is the most relevant mechanical property. Several commercial lime based grouts are available but it is unclear what are the applicable standards and requirements. This paper evaluates the behavior of commercial grouts under laboratory conditions. First, the properties of the grouts as an independent product are assessed with the objective to perform a comparative analysis of their behavior subjected to different conditions (temperature and working time of grout after mixing). Then, the behavior of the grouts when used in combination with stones used in the construction of masonry buildings is addressed (granite, schist and limestone), again considering different conditions (dry, wet and saturated). It is shown that the performance of the commercial products is rather different and careful selection of injection materials in practical applications is recommended. [ABSTRACT FROM AUTHOR]

This study deals with the reuse of an industrial waste rich in CaCO 3 as a mineral addition and agent of stability in low-strength filling grout for soil reinforcement applications. The physical, chemical and mineralogical characteristics of these Carbonated Residual Brines (CRB) were determined and completed by a study of CRB behavior in cement-based materials and of the optimization of a composition of low-strength filling grouts rich in CRB filling. The results showed that it was possible to use CRB in low-strength filling grout, in replacement of bentonite and fine sand, with better performance – especially in terms of stability. [ABSTRACT FROM AUTHOR]

A large testing program was devised to determine the compressive strength of masonry grouts made with various combinations of class F fly ash and ground granulated blast furnace slag to replace high amounts of Portland cement. In a first phase, mixes were proportioned by volume and batched with 0, 20, 30, 40, 50, and 60 percent Portland cement replacement; specimens were cured in a dry and wet environment. The objective of the first phase was to determine the viability of and the methodology for the overall project. In the second phase, mixes were proportioned by weight, the more common practice in the United States, and batched with 0, 20, 30, 40, 45, 50, 55, 60 and 65 percent Portland cement replacement. Specimens in the second phase were cured in a wet environment only. In the first and second phases, Portland cement was replaced only by fly ash. In the third phase, mixes were proportioned also by weight and batched with 0, 50, 60, 65, 70, 75, 80, and 85 percent Portland cement replacement. In the third phase, Portland cement was replaced by combinations of fly ash and ground granulated blast furnace slag; however, the fly ash content was maintained constant at 25 percent. Specimens in the third phase were also cured in a wet environment only. Specimens were typically tested at 14, 28, 42, 56, and 90 days; in Phase I specimens were also tested at 7 days but not at 90 days. Three specimens were tested for each replacement rate, age, and curing conditions. Several mixes developed satisfactory strength, i.e., the mixes achieved the ASTM specified minimum compressive strength of 13.8 MPa at 28 days. The results show that mixes with up to 55 percent fly ash and 85 percent fly ash-ground granulated blast furnace slag substitutions reached the minimum compressive strength required at 28 days. Mixes with up to 60 and 65 percent fly ash achieved the minimum compressive strength of 13.8 MPa in 44 and 54 days, respectively. [ABSTRACT FROM AUTHOR]

Steel reinforced polymer (SRP) and steel reinforced grout (SRG) have emerged as promising and cost-effective technologies for the external strengthening of RC structures. Although the first studies date back to 2004, so far the literature related to the flexural strengthening of RC slabs/beams with steel tapes is rather limited. As a result, the application of such materials on a real structural member may be discouraged and, conversely, the use of carbon/glass FRP alternative systems may be preferred. The study presented in this paper contributes to filling this knowledge gap by presenting the results of 10 four-point bending tests performed on RC slabs strengthened with SRG/SRP systems. Test results have provided valuable information in terms of maximum forces, deformability and failure modes by varying number of layers and density of the steel tape. In particular, it has been shown that, disregarding the nature of the matrix (inorganic or polymeric), the presence of the external strengthening significantly increased the flexural strength of slabs, with percentage increases over the control (unstrengthened) member ranging from a minimum value of 27%, when using a single layer of low density tape, to a maximum of 106% in the case of SRP system with one layer of high density sheet. Preliminary analytical studies were also performed in order to investigate the possibility of extending to the SRP/SRG systems the applicability of formulations currently reported in some national and international guidelines for the flexural strengthening of RC members with FRP sheets. [ABSTRACT FROM AUTHOR]

This paper investigates the fluidity and rheological properties of the cement based grout mixed with rice husk ash (RHA). The experimental program consisted of fifteen different mixture having 5%, 10%, 20%, and 30% RHA content and three different water to binder ratios (w/b = 0.75%, 1.00%, and 1.25%). Workability properties (marsh cone flow time, plate cohesion, and mini slump diameter), plastic viscosity, apparent viscosity, and the yield stress of the mixtures were determined. Test results showed that increasing replacement level for the RHA amount increases marsh cone flow time, plate cohesion, plastic and apparent viscosity, and the yield stress, but also decreases mini slump diameter. Shear thickening and pseudo-plastic behavior was observed for high RHA content for w/b ratios greater than 1.00. [ABSTRACT FROM AUTHOR]

Highlights: [•] Two-stage concrete (TSC) technology and history are presented. [•] The materials specifications for TSC are outlined. [•] The engineering properties of TSC and its long-term performance are compiled. [•] Future research on TSC and need for further development are discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] The aggregate type influence on the mortar properties is higher than the freeze thaw cycles applied. [•] The use of aggregate on mortars prevented the damage caused by freeze–thaw cycles. [•] Damage caused on the neat cement probes did not alter its thermal conductivity. [•] Mortar water dosage and volumetric content indicated the probe core non-saturation. [Copyright &y& Elsevier]

Highlights: [•] We studied the effect of temperature over superplasticized hydraulic lime grouts proportioned with silica fume. [•] A loss of workability occurs if the grout temperature increases beyond 20°C. [•] An environmental temperature of 20°C allowed a more complete hydration reaction. [•] Grouts performance could be improved if they were properly designed and a suitable processing temperature was ensured. [ABSTRACT FROM AUTHOR]

Highlights: [•] Development of a composition that is deemed consistent with the original render. [•] Development of lime based grouts for consolidation. [•] Rheological behaviour of analysis grouts. [•] The rheological behaviour was evaluated with a proper mortar rheometer. [•] Study of the hardened state properties of grouts. [ABSTRACT FROM AUTHOR]

Abstract: Strengthening foundations with micropiles is progressively being used, due to the major advantages that this technique presents. Nevertheless, the influence of some relevant parameters in the overall behavior of the retrofitted foundations has not yet been studied. Generally, micropiles are installed in holes drilled through the existing RC footing, which are then filled with grout. The efficiency of the load transfer mechanism depends on the bond strength of both the micropile–grout and the concrete–grout interfaces. This paper describes an experimental study performed to specifically study the influence of the following parameters on the bond strength between micropile–grout interface: hole diameter; embedment length of the micropile; and level of confinement of the grout mass. Thirty micropile–grout specimens were submitted to monotonic push-off tests, until failure. Bond strength was found to increase with a decrease of the hole diameter and with an increase of the confinement level. [Copyright &y& Elsevier]

Abstract: The feasibility of using steel fibres to improve the tensile strength and durability of cement–sand grout was investigated. Initial tests focused on achieving pumpable grout mixes and 13mm round steel fibres with a diameter of 0.16mm were found to be compatible with a conventional grout paddle mixer and piston pump. Subsequently, grouts with 0.5% and 1% fibre volume fraction were subjected to compressive and splitting tensile strength tests, coefficient of permeability tests and wet–dry cycles. The effect of partial cement replacement with silica fume and blast furnace slag was also investigated. It was found that steel fibres were beneficial for short- and long-term tensile strength. Coefficient of permeability was not adversely affected by addition of fibres. Resistance to microcracking and increase in permeability after wet–dry cycles was also improved by steel fibres. Partial replacement of cement with blast furnace slag resulted in enhanced mechanical properties, whereas the results for silica fume were mixed. [Copyright &y& Elsevier]

Abstract: The new concrete often incorporates several organic and mineral admixtures which interact with the various constituents of the cements and cause some problems of hardness and workability. In the present study, limestone cement (C1) and pozzolanic cement (C2) were used to make cement paste with two types of superplasticizer; SP1 based on polynaphthalene sulphonate (PNS); and SP2 based on resins melamines (PRM). Marsh cone test was adopted to check the combined effects of the following factors on the fluidity namely the type of cement, the type and the dosage of the superplasticizer, the type and the replacement rate of the mineral admixture and the water–cement ratio (W/C). The results of this work show that limestone cement presents a high fluidity with low loss after 1h relatively to the pozzolanic cement within the saturation proportioning. Superplasticizer SP1 constitutes an incompatibility case when it is mixed with cement containing high C3A or alkali content such as C2 cement. Also, limestone powder is found to be the best mineral admixture when it replaces a part of cement, where more fluidity is exhibited caused by the dilution effect. [Copyright &y& Elsevier]

• Using 3-D velocity contour plots to detect voids in grouted tendon ducts. • Dispersion curve obtained by a receiver and a small instrumented hammer. • Low velocity at wavelengths twice the duct's range indicates the existence of void. • Latticed grid test quickly detects probable voids without knowing ducts' location. • Grouting conditions can be detected using vertical grids directly above the ducts. • Provide wave velocity reduction for different grouting conditions and cover. 3-D velocity contour plots are constructed to detect voids in grouted tendon ducts by a stress-wave test method requiring a receiver and a small instrumented hammer. Each time-domain waveform due to hammer impact is processed using the short-time Fourier transform to obtain the spectrogram (frequency-time relationship), which is enhanced using the reassignment method. The reassigned spectrogram is used to obtain the dispersion curve (velocity-wavelength relationship). The results from all test points are assembled to develop wave-velocity contour plots at different wavelengths. A wall specimen containing ducts with five different grouted conditions was constructed. Two types of test grids were used, namely latticed grids covering the entire wall surface and vertical grids directly above the ducts. For the former method, 3D contour plots of a large area can be constructed with few testing lines. For the latter method, the wave velocity contour plots can distinguish different grouting conditions. Finally, the wave velocity reduction to be expected for different grouting conditions and cover depth is provided. [ABSTRACT FROM AUTHOR]

Following the experimental and structural investigation the design for reconstruction was proposed. The authors were requested to test new materials, stones, mortars, grouts for injection in order to choose and proposed the material to be used for the reconstruction of the pillar and for the repair of damaged elements. [Copyright &y& Elsevier]

[Display omitted] • Properties of CGN- and NHL-based pastes were investigated and compared. • The UCS of the CGN-based specimens improved significantly after aging for 90 days. • CGN-based pastes exhibited similar pore size distribution to the original plaster. • The strength mainly depended on the morphology of the hydrate and carbonate. In order to study the consolidation mechanism of traditional lime-based binders in the restoration of earthen plaster, the mechanical strength, hydration kinetics, and microstructure properties of calcined ginger nut (CGN)- and natural hydraulic lime (NHL)-based pastes were systematically investigated and compared. The results showed that CGN had good compatibility with clayish earth. Compared with the NHL-based pastes, the CGN-based pastes exhibited a higher late-stage compressive strength, lower heat release, denser microstructure and similar pore size distribution compared to the original plaster. [ABSTRACT FROM AUTHOR]

• A new polyurethane grouting material with high strength and deformation is developed. • The stress–strain process of mechanical test is analyzed in stages. • The microscopic mechanism of failure is revealed by SEM test. • The influence of size and strain rate on the properties of PUE was studied. Cement-based grouting materials have high compressive strengths, but they are brittle. The low strain burden limits their rehabilitation application in the high compressive strain engineering. A new cleaner polyurethane elastomer (PUE) grouting material with high hardening strain is proposed in this work to provide a better choice for the fundamental rehabilitation. The new grouting material is pollution-free and environmentally friendly, and it has very high strength in compression, tension, and shear tests. Moreover, compared with cement-based grouting materials, its ultimate strain is very high, e.g., greater than45% in compression and greater than 40% in tension. Furthermore, scanning electron microscopy (SEM) test is conducted to study the broken surface characterization and the fracture mechanisms for compression, tension, and torsional shear samples. The new PUE grouting material has a great potential application in rehabilitating a damaged structure of fundamental engineering. [ABSTRACT FROM AUTHOR]

• Design rules pertaining to RM walls under compression are appraised. • Reliability of RM walls under compression outlined in standards were assessed. • Provisions in all the standards conservatively predict the axial capacities of RM walls. • Provisions in AS 3700 (2018) are effective in predicting the axial capacities of RM. The provisions pertaining to design of reinforced masonry (RM) walls under axial compression in the Australian masonry standard AS 3700 (2018 version) have been revised based on the recent findings that the lateral restraining ties do not significantly affect the performance under axial compression. The other design codes such as Canadian (CSA S304.1-14), American (MJSC) and previous version of Australian (AS 3700-2011) standards consider the RM walls as unreinforced masonry (URM) under axial compression, if they are not restrained with lateral ties in both directions. However, it is widely believed that these provisions are stringent and over-conservative, as proven by the experimental studies that the compression bars in RM are effectively restrained by the surrounding well compacted grout. Hitherto, no systematic studies have been carried out to determine the applicability of these provisions to the reliability of the compression design approaches of RM walls. Therefore, in this research an attempt has been made to evaluate the accuracy and reliability of the design provisions outlined in the selected design standards (AS 3700, CSA S304.1-14 and MSJC). The experimental database generated in the authors' previous study was used to verify the reliability of the design provisions. The reliabilities of the design expressions were verified using the first-order reliability method (FORM). The reliability analyses revealed that the provisions specified in the standards are quite conservative as they have exceeded the target reliability index of 3.6 for the analysed RM walls. The current provisions of AS 3700 (2018 version) have shown to predict the axial capacities of the walls better than other standards, while satisfying the target reliability limit. Thus, it can be stated that revisions made in AS 3700 (2018 version) are effective and economical for designing the RM walls as they have eased the requirement of lateral restrainers and account for a realistic contribution of grout and compression steel strengths in determining the axial capacity. [ABSTRACT FROM AUTHOR]

• Fully grouted rock bolts are a desired support method in tunnel engineering. • Pull out test is performed to measure load carrying capacity of the rock bolt. • Grouting method directly affects bolt's load carrying capacity and displacement. • PG rock bolts show better performance compared to SN rock bolts. • Failure of rock bolts happens due to debonding or grout failure. The actual study presents a thorough investigation on the bearing capacity and failure causes of fully grouted rockbolts. For this purpose, 144 real scale in-situ rockbolt pull-out tests were conducted on Fan River hydropower plant's power tunnels in Rreshen region, Albania. The pull-out tests were performed on full grouted rockbolts of two types: SN-Stor Norfors and PG-Post Grouted, two different bolt diameters: 22 and 25 mm, three bolt lengths: 3, 4 and 6 m and three inclination groups such as: horizontal, 0–30° and 30–90°. The results showed that, the SN bolts have lower bearing capacity and smaller displacement compared to PG bolts. On the other hand, the rockbolts' bond strength and displacement decrease as the installation angle to the horizontal increases. This is due to the difficulties faced in filling the drilled hole with grout as the inclination opposes the gravitational direction. In their entirety the results indicate that grouting quality is a crucial factor on the bearing capacity of fully grouted rockbolts and the system failure is mainly related to the shear failure along the bolt–grout or grout–rock interfaces. [ABSTRACT FROM AUTHOR]

• Design and construction of open-graded asphalt (OGA) mixtures were investigated. • Fundamental engineering properties for design of OGA mixtures were presented. • The amount of air void affected the mechanical properties of OGA mixtures. • Marshal Design method were used for preparing OGA mixtures. This study presents a procedure for design and preparing the open-graded asphalt (OGA) mixture used in the semi-flexible pavement (SFP) according to the principle engineering characteristics and performance. In this study, different aggregate gradations, cellulose and synthetic fibers, modified and neat asphalt binders, and air void contents were used to prepare the OGA mixtures. Furthermore, several experimental tests, including the Cantabro, Semi-circular bending (SCB), binder drainage, indirect tensile strength (ITS), wheel tracking, and permeability tests were conducted to assess the engineering properties of the OGA mixtures. According to the results of the mechanical tests (i.e., Cantabro, moisture sensitivity, semi-circular bending, and rutting), the increase of air void content in OGA mixtures causes a reduction in the failure resistance. However, considering the rutting and ITS test results, the performance of SFP (OGA mixture filled with grout) increases as the initial air void content of the OGA mixtures increases, which is because of the higher infiltration of grout inside of OGA mixture and higher internal integrity. The results of the mechanical performance tests on OGA mixtures indicate that the low and high ranges of the air void content to acquire most possible mechanical performance are 25% and 30–35%, respectively. [ABSTRACT FROM AUTHOR]

• The bond property between high strength grout and steel bar was investigated. • Improving grout compressive strength cannot improve the bond strength. • Simplified formulas were presented for the characteristic bond-slip values. • A constitutive model was proposed to predict the bond-slip curve. • FEA models were established to evaluate the constitutive model. Engineers use high-strength grout to connect precast concrete members for its low shrinkage and good fluidity. This paper designed 87 central pull-out specimens using the control variable method to investigate the influence of factors on the rebar-grout bond property such as compressive strength, steel grade, bar diameter, transverse stirrups, and bond length. The test result showed that improving grout compressive strength (85.8 MPa–122.7 MPa) cannot improve the bond strength, which was different from the previous conclusions of concrete pull-out tests. Simplified formulas were presented for calculating the characteristic values of bond strength, residual strength, peak slip, and relative slip of load-holding platform based on parameter analysis. Then, a constitutive model was proposed to predict the full-range bond stress-slip curve of high-strength grout and steel bar specimens from bearing to failure. Finally, FEA models were established to evaluate the applicability and accuracy of the constitutive model. [ABSTRACT FROM AUTHOR]

• Expandable foam grout (EFG) is a material to repair underground cavities. • EFG specimens with five admixture-cement ratios (AD/Cs) are used for strength test. • Strength and stiffness of the specimens are evaluated at each curing time. • Regression models for EFG properties are established from curing time and AD/C. Underground cavities induced by damaged slurry walls or soil erosion in urban areas require suitable repair materials and methods. The objective of this study is to evaluate the strength and stiffness of expandable foam grout (EFG) as a repair material. EFG consists of water, ordinary Portland cement, and admixtures. EFG was prepared at a fixed water-cement ratio of 100% and different admixturecement ratios (AD/Cs), ranging from 0 to 8%. The unit weights of EFGs with different AD/Cs at the slurry and expanded states are measured, and the air contents for both states and the theoretical expansion ratio (ER) are subsequently estimated. Stressstrain curves are obtained using unconfined compressive strength tests to evaluate the unconfined compressive strength and modulus of elasticity. The experimental results show that the air content in the slurry state gradually increases with the AD/C, while the air content in the expanded state and the ER rapidly increased and then converges. The strength and modulus of elasticity increased with curing time, whereas they decreased with increasing AD/C. Based on logarithmic and exponential regression models, the relationships between the strength/modulus, curing time, and AD/C are established with high values of the coefficients of determination. Thus, the relationships proposed in this study can be effectively used to predict the strength and modulus of EFG with respect to curing time and AD/C. [ABSTRACT FROM AUTHOR]

• The impact response of functionally-graded two-stage fibrous concrete (FGTFC) is analyzed. • Steel fibre is most effective in improving impact resistance of FGTFC than macro polypropylene fibre. • The flexural toughness and impact strength are increased significantly with increased beam size. • Three-layered FGTFC beams exhibited excellent impact resistance due to the many interface layers. This research focuses on developing functionally-graded two-stage fibrous concrete (FGTFC) comprising steel and polypropylene fibres to enhance impact resistance and alleviate the damage. The FGTFC was developed based on the bionic-inspired impact resistance of turtle shells. This research examines the flexural and impact performance of FGTFC beams of three sizes. Three different beams were prepared of size 250 × 50 × 50 mm, 400 × 100 × 100 mm and 550 × 150 × 150 mm with a 2.4% average dosage of steel and polypropylene fibres. Additionally, steel and polypropylene used in this study are the new types of fibres which are not used by researchers and not found in the literature. Totally twelve mixtures were prepared; one was Two-Stage Concrete (TSC) and considered a reference specimen. Two-Stage Fibrous Concrete (TSFC) was another two with fully reinforced single layer cross-sectional beams, with their fibres constituents being dispersed evenly. The remaining were two and three-layered FGTFC beams with evenly dispersed fibre constituents. Uneven dispersion in the current research meant that the fibre dosage was more in the peripheral layers and less in the inner layers, despite the fibre dosage being used remains the same in all beams. The fabricated FGTFC beams were synchronously cast using cement grout and tested against the three-point bending and falling mass impact. All beams were tested through the falling mass impact as per the guidelines of ACI Committee 544. Compressive strength, first crack and peak stress, flexural toughness, initial crack impact number, failure impact number, impact ductility index, and failure patterns were examined. Findings indicated that the peak load, flexural toughness and impact strength increased significantly with increased beam size. Additionally, steel fibre significantly contributed to increasing flexural toughness and impact strength than the polypropylene fibre. Thus, the proposed three-layer FGTFC beams had greater efficacy and exceptional fiber usage in the peripheral layers, despite the exact fibre dosage in all TSFC beams. [ABSTRACT FROM AUTHOR]

• High-performance grout for the corrosion protection of post-tensioned (PT) tendons was developed. • Developed grout is made with two fly ashes to improve the packing density and fluidity. • Developed grout has excellent resistance against shrinkage and the formation of voids, bleedwater and softgrout. • A set of stringent performance specifications for PT grouts are developed. In order to provide corrosion protection of tendons in post-tensioned (PT) concrete systems, the congested interstitial spaces between the strands and duct are ideally to be filled with cementitious grouts. However, many currently used grouts do not have the desired fluidity and resistance to segregation – leading to formation of voids, frothy grout materials, and premature corrosion of strands. This paper presents a 3-phase study on the development of high-performance, pre-blended grouts. Several grouts were formulated with various proportions of ordinary portland cement (OPC), fly ash and chemical admixtures. The fluidity, bleed (i.e., standard, wick-induced, pressure-induced, and -inclined tube), softgrout, rheological, and shrinkage parameters of the formulated grouts were assessed; based on which a systematic selection of grouts was performed in three phases. Finally, a grout with 52 and 48% of OPC and fly ash, respectively (by volume) and optimal dosages of chemical admixtures was formulated and pre-blended in an industrial facility. This grout satisfies a set of performance specifications on fluidity, resistance against segregation (say, bleedwater and softgrout formations), and shrinkage. Therefore, the grout is capable of filling the ducts and providing long-term corrosion protection of PT strands. [ABSTRACT FROM AUTHOR]

• Properties of Ca(OH) 2 -GGBS and MgO-GGBS grouts were investigated. • Compared with MgO, Ca(OH) 2 was more effective on activating GGBS in short term. • Effect of activator/GGBS ratio on viscosity of grouts was limited when W/C ratio ≥ 1. • Bleeding and setting times of MgO-GGBS grouts were lower due to hydration of MgO. Hydrated lime (Ca(OH) 2)- and reactive magnesia (MgO)-activated ground granulated blast-furnace slag (GGBS) have shown advantages in geotechnical applications compared with Portland cement (PC). To apply these two novel binders in slurry form to field applications, the properties of their grouts need to be investigated, which is the objective of this study. The heat of hydration, bleeding, viscosity, and setting behavior of Ca(OH) 2 -GGBS and MgO-GGBS grouts were investigated and compared with PC and pure GGBS grouts in this study. All grouts indicated a decrease in bleeding and setting time, but an increase in viscosity with decreasing the water/cementitious material (W/C) ratio. Compared with the PC grout, the pure GGBS grout with the same W/C ratio demonstrated higher bleeding and setting time, and lower heat rate and viscosity. Bleeding and setting time decreased and peak heat rate and viscosity increased with an increase in the activator (Ca(OH) 2 or MgO)/GGBS ratio within GGBS-based grouts. The peak heat rate in Ca(OH) 2 -GGBS grouts was higher than that of pure GGBS or Ca(OH) 2 grout, indicating that Ca(OH) 2 was effective on activating hydration of GGBS. The peak heat rate in MgO-GGBS grouts was significantly lower than MgO grout and the heat rate was limited after 8 h. The bleeding and setting times of MgO-GGBS grouts were significantly lower than those of Ca(OH) 2 -GGBS grouts, which was primarily attributed to the hydration of MgO. [ABSTRACT FROM AUTHOR]

• Design of cement grouted bituminous mixes: Binder content, Compaction effort and water content in the grout. • Effect of aggregate gradation on design of grout in the mixture is analysed. • Variation of flowability of grout with respect to mixing time and water content is analysed. • X-ray Micro Computed Tomography test was used to analyse the air voids content and their interconnectivity in the mix. • Field Performance of CGBM sections is evaluated by Falling weight deflectometer and results compared with control section. Cement Grouted Bituminous Mix (CGBM) is a composite paving mix comprising of a high voids bituminous mix impregnated with a cementitious grout. This type of mix is suitable for wearing course. The high void mix is prepared by selecting a suitable aggregate gradation, binder content and compaction effort to result in sufficiently optimized air void content. Six different cement grouted bituminous mixes prepared with varying aggregate gradations, compaction effort and grout composition are evaluated in this study. To design an acceptable bituminous mixture skeleton for CGBM, the effects of aggregate gradation on resulting grouting in the mixture are analysed. Results showed that the extent of grouting in bituminous mixture skeleton is affected by its internal void interconnectivity, structure and size of pores rather than the initial void volume. A mix design approach is developed to prepare the bituminous mix skeleton for CGBM. The study also examines the issues related to the design of aggregate gradation and cementitious grout and evaluates the properties of cement grouted bituminous mixes. For laboratory samples, X-ray Micro Computed Tomography (XRμCT) test was used to analyse the air voids content and their interconnectivity. Test sections were laid in field and monitored for their performance. Field core samples extracted showed effective full depth grouting. Falling Weight Deflectometer test was also conducted to check the in-situ moduli of CGBM mix. [ABSTRACT FROM AUTHOR]

• The effect of adding glass-fibre to grout on the masonry strength was investigated. • Fully grouted half-scale concrete-masonry prisms were tested under compression. • Analysis of the stress-strain behaviour, ultimate capacity, and ductility was conducted. • Fibre-grout enhanced the crack propagation as well as the post-cracking performance. • Existing models for predicting the strength were validated against the test results. The overall compressive behaviour of grouted concrete hollow block prisms is dependent on the mechanical properties of both the masonry block and its grout. Grout is typically characterized by exhibiting greater longitudinal and lateral strains when compared to concrete blocks. Hence, a direct consequence is a composite-action incompatibility due to grout-to-block differential strain response under compressive loading. In order to enhance the overall composite behaviour, adding glass fibres to the grout mixture is considered in this study. The fibre-reinforced grout is expected to reduce grout longitudinal and lateral strains to be more consistent with the concrete block, which will result in better control of the cracking propagation and thus enhancing the overall ductility. This study investigates the effect of adding glass fibres to grout mix on the compressive strength and strain of the concrete masonry prisms. The presented experimental program involves testing of 36 fully grouted half-scale masonry prisms, with different glass fibre ratios (0%, 0.03%, 0.06%, and 0.10%). Twenty-four prisms were of one block thickness and two blocks in height, divided into two groups of normal and high strength blocks. The remaining twelve prisms were two blocks in thickness and five blocks in height with normal strength blocks. The prisms were tested concentrically up to failure. Results demonstrated that the addition of glass fibres to the grout enhanced the crack control as well as the post-cracking performance. The influence of adding glass fibres to the grout on increasing the masonry prisms' compressive strength was evident at high fibre percentage (i.e., 0.10%) by approximately 9.8%, 10.1 %, and 39% for the high strength two-block high specimens, normal strength two-block high specimens, and normal strength five-block high specimens, respectively. [ABSTRACT FROM AUTHOR]