U-box Tests Research Articles

Fresh and Hardened Properties of SCC Incorporating Rice Husk Ash and Sugarcane Bagasse Ash

Self-compacting concrete represents a unique type of concrete that achieves self-compression through its mass, eliminating the need for external vibrations. The mechanical characteristics of self-compacting concrete can be enhanced by incorporating agricultural waste materials as partial substitutes for cement. In this experimental study, a graded M30 concrete mix was employed to produce self-compacting concrete by replacing cement with 6, 8, 10, 12, and 14% of sugarcane bagasse ash and rice husk ash. To assess the concrete's properties, both in its fresh and hardened states, several tests were conducted. Fresh properties were evaluated using l-box, slump flow, and U-box tests. The results indicated that sugarcane bagasse ash outperformed rice husk ash in enhancing the fresh properties of concrete up to a certain level of replacement. Hardened properties, including split tensile strength, compressive strength, and flexural strength, were tested at both 7-day and 28-day intervals. These tests revealed that rice husk ash exhibited superior performance in enhancing the hardened properties compared to sugarcane bagasse ash. In conclusion, this study underscores the suitability of both sugarcane bagasse ash and rice husk ash as viable options for partial cement replacement in self-compacting concrete, with each material exhibiting strengths in improving certain aspects of fresh and hardened concrete properties.

An Investigation on Eco Friendly Self-Compacting Concrete Using Spent Catalyst and Development of Structural Elements

The theme of this initiative is "Waste to Wealth." Construction materials, particularly concrete, need to have better qualities, including strength, rigidity, durability, and ductility, because Oman's construction industry is expanding. Self-compacting concrete (SCC) has more benefits than regular concrete, including better workability. The major focus of this study is the C30-grade SCC for the control mix, spent catalyst (zeolite catalyst)-based SCC, and the development of the RC beam's flexural behavior employing control and spent catalyst-based SCC. The preliminary study and the main study are the two study outcomes included in this project. Preliminary research involves creating four mixtures with various dosages of 3%, 6%, 9%, and 12% in order to optimize spent catalyst in C30 grade concrete. All of the cubes undergo a 28-day curing test. The cubes' compressive strength is tested in order to establish the ideal dosage, which is 9%. Develop a C30 grade control modified design mix in accordance with SCC and optimize chemical admixtures such as superplasticizer (SP) at different dosages, like 2, 2.5, 3, and 3.5%, using various trials and tests (slump flow, L-box, J-ring, V-funnel, and U-box tests), as well as the optimized dosage of spent catalyst (SC). The main study includes six singly reinforced RC beams with dimensions of 750 (L)×100 (B)×150 mm (D) that were cast and tested in the laboratory. After a 28-day curing period, two specimens were placed under a two-point loading setup, with the remaining two samples receiving the optimum dosages of spent catalyst and superplasticizer. All of the beams were tested using a Universal Testing Machine (UTM) with a 1000 kN capability. From the preliminary study, partial substitution of cement in control concrete of grade C30 using spent catalyst (SC), it was found that the 9% optimum dosage produces greater compressive strength compared to other doses, which are almost 10% rises at 28 days of curing period. Based on a different test, it was discovered that the optimum dose of 3% SP gave closer agreement and satisfied the need for SCC as per the BS standard. The load-carrying capability of the SCC beams is almost 21.7% higher than that of the control beams. Comparing the SCC beams to the control beams, their deflection was reduced by about 26% at the same load level, and their ductility rose by almost 33%. Comparatively to the control beam, the stiffness of 21.6% of SCC also rises. According to test results, the SCC beam performs better in every way when superplasticizer and spent catalyst are used at the recommended dosage. Doi: 10.28991/CEJ-2023-09-05-08 Full Text: PDF

Simulation of U-box test for fresh self-compacting concrete based on lattice Boltzmann method

• The 3-D model of the U-box test is successfully established based on H-B model and LBM with an average error of 7%. • The yield stress is the key rheological parameter that determines the passing performance of fresh SCC. • The increase of rheological parameters all reduce the flow ability of fresh SCC. • The rheological features made a greater impact on the average surface pressure of the steel bars at the start of U-box test. • The speed of pulling up the partition gate only had an influence on the early period of U-box test. In this research, the numerical model of fresh self-compacting concrete (SCC) U-box test was established by combining lattice Boltzmann method (LBM) and Herschel-Bulkley (H–B) model. The flow behavior of fresh SCC in U-box was studied and its rheological mechanism was analyzed. The test results showed that the simulation model established based on U-box test had high simulation accuracy, and the average error was about 7 %. The effects of rheological parameters (power-law index n , consistency index k and yield stress σ 0 ) on the U-box test were explored. The numerical results demonstrated that σ 0 was the crucial rheological parameter that determined the passing ability of fresh SCC, and its increase resulted in weaker passing ability . n and k had less effect on the passing ability. At the early stage of U-box test ( t < 1.0 s), the increase of n , k and σ 0 all reduced the velocity of flow and the pressure exerted on the fresh SCC, with n bringing the most significant effect. The peak velocity and pressure of shear-thinning ( n = 0.6) SCC could reach 0.74 m/s and 4200 Pa at t = 0.1 s. The peak velocity of shear-thickening ( n = 1.4) SCC was less than half of the former, and a larger negative pressure appeared, up to about −1600 Pa. The speed of pulling up the partition gate ( u g ) only had an effect, which gradually diminished with the increase of u g , on the initial phase of U-box test ( t < 5.0 s). The cross-sectional area corresponding to the obstacles that could be passed by the SCC was the main factor affecting the early velocity and pressure of the concrete.

Utilization of crushed recycled glass and metakaolin for development of self-compacting concrete

• Crushed recycled glass and metakaolin were used for developing self-compacting concrete. • Crushed recycled glass has capability to improve the flow-ability of SCC. • The use of metakaolin offers improved strength properties at all glass replacement levels. • A relation between compressive strength, glass replacement and metakaolin content was developed. • Microstructural investigation of SCC was done through SEM, EDS and XRD analysis. Hypothetically, all the glass is recyclable, despite of which, only a small fraction of it is recovered globally. Furthermore, decomposition rate of waste glass is lowest when compared to conventional waste such as paper, rubber and plastic. So a gainful utilisation of waste glass in production of self-compacting concrete (SCC) would be fascinating. To this goal, a greener SCC incorporating crushed recycled glass (CRG) has been developed in this study. Alongside, the influence of metakaolin (MK) on fresh, strength and microstructural properties of CRG incorporated SCC was studied. To achieve this purpose, a total of 24 different SCC mixtures were prepared in which MK was used as a cement substitute; cement was partially replaced with 0%, 4%, 8%, and 12% MK and CRG was used to replace fine aggregate at the level of 0, 10, 20, 30, 40 and 50 % by volume. Slump flow, V-funnel, l -box and U-box test relates to passing and flowing ability of SCC, were improved as the CRG content increased in the mix. However, mechanical properties were decreased with increase in CRG content. Incorporating MK in CRG incorporated SCC mixtures improved the strength properties corresponding to all the glass replacement levels. The results showed that a greener SCC can be made using crushed recycled glass as sand replacement material and metakaolin as cement substitute.

Performance of GGBFS and silica fume on self compacting geopolymer concrete using partial replacements of R-Sand

Experimental analysis has been carried out to determine the mechanical behaviour of self-compacting geopolymer concrete beams using silica fume and GGBFS under two point loading condition. In this study, evaluate the effect of M sand on self-compacting geopolymer concrete. First phase, fly ash is replaced with 10 % of silica fume (Mix S1-S5) and second phase, the fly ash is replaced by 30 % of GGBFS (Mix G6-G10). The 12 M molarity of sodium hydroxide is used. Alkaline liquid to binder by mass is 0.33 and sodium hydroxide to sodium silicate solution is 1.25 is maintained for all the mix. Fine aggregate (River sand) is replaced with manufacturing sand (M sand) is varies from 0 % to 100 % with an increment of 25 %. Super plasticizer Glenium B233 is added to enhance the properties of concrete. Researcher implement EFNARC guidelines for Self compacting concrete. Age of curing of concrete is for 48 h of heat curing later on ambient curing by 28 days. Fresh properties of concrete mix were measured by slump flow test, T50cm slump flow, V-funnel test, L-box test and U-box test and harden properties are measured by compressive strength, split tensile strength and flexural strength. Mechanical properties of geopolymer concrete such as compressive, split and flexural strength of S5 is 37.56 MPa, 4.5 MPa and 4.58 MPa which is higher than S1 to S2. Compressive strength of G10 is 12.08 %, 10.23 %, 7.26 %, 2.52 % higher than the G6, G7, G8 and G9 respectively. Researcher tested totally 10 numbers of beams with 10 different mixes under flexural loading condition. Three LVDT were mounted, two under loading point and one at middle, to measure the deflection. Load vs deflection of beam is carefully measured. Ultimate load of S5 and G10 is 24 kN and 21 kN, respectively. Experimental load carrying capacity beam is compared with numerical analysis. Nonlinear finite element software ANSYS carried out the numerical analysis and based on the basic properties from experimental investigation, is used to measure the numerical behaviour. Variation of ultimate load of experimental obtains vs numerical analysis is not less than 0.88. Finally, it concluded that the numerical values are good agreement with experimental results.

Application of Artificial Intelligence to Evaluate the Fresh Properties of Self-Consolidating Concrete.

This paper numerically investigates the required superplasticizer (SP) demand for self-consolidating concrete (SCC) as a valuable information source to obtain a durable SCC. In this regard, an adaptive neuro-fuzzy inference system (ANFIS) is integrated with three metaheuristic algorithms to evaluate a dataset from non-destructive tests. Hence, five different non-destructive testing methods, including J-ring test, V-funnel test, U-box test, 3 min slump value and 50 min slump (T50) value were performed. Then, three metaheuristic algorithms, namely particle swarm optimization (PSO), ant colony optimization (ACO) and differential evolution optimization (DEO), were considered to predict the SP demand of SCC mixtures. To compare the optimization algorithms, ANFIS parameters were kept constant (clusters = 10, train samples = 70% and test samples = 30%). The metaheuristic parameters were adjusted, and each algorithm was tuned to attain the best performance. In general, it was found that the ANFIS method is a good base to be combined with other optimization algorithms. The results indicated that hybrid algorithms (ANFIS-PSO, ANFIS-DEO and ANFIS-ACO) can be used as reliable prediction methods and considered as an alternative for experimental techniques. In order to perform a reliable analogy of the developed algorithms, three evaluation criteria were employed, including root mean square error (RMSE), Pearson correlation coefficient (r) and determination regression coefficient (R2). As a result, the ANFIS-PSO algorithm represented the most accurate prediction of SP demand with RMSE = 0.0633, r = 0.9387 and R2 = 0.9871 in the testing phase.

Effect of using dimensional stone waste sourced from Lorestan Province on the performance of high-strength self-compacting concrete

Producing enormous quantities and continuous stockpiling of granite industrial by-product enforced researchers to utilize this waste in a sustainable state in concrete to diminish its adverse impacts on the ecosystem. This study aims to experimentally investigate the possibilities of reusing granite waste sourced from Lorestan Province in fiber-reinforced self-compacting cementitious composite using hooked-end steel fibers. The L-box and U-box tests were performed to assess the fresh properties of mixes, whereas compressive strength, flexural strength, ductility, flexural toughness, and tensile strength tests were conducted for measuring the hardened properties of self-compacting concrete mixes. Results of the fresh properties tests for all of the steel fiber reinforced-recycled aggregate mixtures were found within the satisfactory limit of standard. In other words, the incorporation of granite waste in self-compacting concrete augmented the hardened properties. It should be noted that the effects of simultaneous use of granite waste and steel fiber in improving the tensile strength, flexural performance, ductility, and bending toughness of the specimens are higher than the compressive strength. In specimens without steel fiber, brittle failure occurred immediately after the formation of the first crack. With the increasing percentage of steel fibers in the samples, the ductility increased, and the ductile failure occurred in samples.

Effect of polymineral systems and disperse reinforcement on self-compacting fibre concrete

In this study, composite binders were prepared as novel, eco-friendly polymineral binders by using rice husks to produce active silica-containing additive, based on which self-compacting fibre concretes (SCFCs) with high impact strength and impermeability characteristics were created. Two types of fibre were used as disperse reinforcement – namely, steel brass-plated fibre and basalt fibre. Ten different mixes of SCFC were investigated. The rheological characteristics of concrete mixes were determined by a series of tests including slump flow, V-funnel, L-box, U-box and segregation resistance tests. In addition, the impact endurance was determined using standard techniques, such as the impact of hammer blows on both panels and cylinders, and this confirmed the creation of dynamically durable composites with high workability. In addition, the microstructural, morphological and thermal properties of such concrete at 28 days of curing were determined. The results indicated that the incorporation of a composite binder in SCFCs significantly improved the mechanical properties and microstructure of the cement matrix by clogging the capillary pores of the cement paste and reducing the growth of portlandite crystals, thereby increasing the compressive strength of fibre concretes by about 31%, the impact endurance by up to six times, and the crack resistance by up to nine times.

Effects of halloysite nanotube, nano-silica and micro-silica on rheology, hardened properties and fracture energy of SCLC

In this paper, the effects of different replacement levels of halloysite nanotube (HNT), colloidal nano-silica (CS), micro-silica (MS), and the combination of them on the fresh and hardened properties of self-compacting lightweight concrete (SCLC) are studied. Four factors including water to binder ratio (w/b) with two levels of 0.35 and 0.45, CS with three replacement levels of 1, 3 and 5%, MS with the replacement level of 10% and HNT with three replacement levels of 1, 2 and 3% were chosen. The fresh properties of SCLCs were observed in terms of slump flow diameter and time, J-ring diameter, Vfunnel time and U-box tests. The hardened properties were determined through mechanical properties including compressive strength, tensile strength, modulus of elasticity and flexural strength. The non-destructive tests including electrical resistivity and water absorption were executed too. Moreover, the effects of MS, CS and HNT contents on the fracture energy of SCLC samples were studied. The results displayed that the mentioned properties for the SCLC specimens containingMS, CS and HNT improved, but the superior performance was obtained in binary mixes, which were created by adding both MS and CS simultaneously. The optimal conditions for having the best results were obtained when the amounts of MS and CS were 10% and 3%, respectively.

An art of Research on concrete-Ternary blended

In this research, we experiment a ternary blended concrete, which is a concrete with silica fumes, GGBS, and Fly ash. By using sika viscocrete we achieved self compacting also, so it is a ternary blended self compacting geo polymer concrete. Three mixes were chosen namely M1, M2 and M3. The alkaline activator with different molarities were tried to get the optimum strength. The strength factors such as compressive strength and split tensile strength were carried out; similarly the fresh concrete properties such as slump test, flow table test, V-funnel test, U-Box Test & L Box test were carried out. The strength properties are did 7 days and 28 days. This research is mainly focused on fresh concrete properties of ternary blended self compacting geo polymer concrete.

Fresh and mechanical performance and freeze-thaw durability of steel fiber-reinforced rubber self-compacting concrete (SRSCC)

The self-compacting concrete (SCC) with the replacement of recycled rubber aggregates is limited for the field application due to high-performance requirements. The steel fiber was introduced to the rubberized SCC (RSCC) to enhance its performance and promote its application. The fresh and mechanical properties and durability performance of steel fiber-reinforced rubber self-compacting concrete (SRSCC) were evaluated. The SRSCC samples were prepared with replaced rubber aggregate based on fine aggregate volume percentages of 10%, 15%, and 25% and a consistent steel fiber ratio of 0.2%. The plain SCC and rubberized SCC samples were also produced for comparison. The fresh performance was evaluated with slump flow, J-ring flow, V-funnel, and U-box tests. The results showed that both filling and passing ability could be affected by the added steel fiber and rubber aggregate. However, the SRSCC could still meet most of the recommended criteria for passing and filling abilities when the rubber content is lower than 25%. Regarding the hardened properties, the compressive strength was reduced in rubber SCC samples with increased rubber contents by comparing with the control SCC samples. Nevertheless, SRSCC samples with 10% rubbers have higher splitting tensile strength than RSCC and plain SCC. Also, the SRSCC specimens showed excellent freeze-thaw resistance after 600 F-T cycles. The relative dynamic modulus of elasticity slightly increased without any dimensional expansion in SRSCC samples. In summary, the proposed SRSCC can meet required flowability, filling and passing abilities along with good mechanical and freeze-thaw performance. This study will provide lab test data for the applications of recycling waste tire aggregates in steel fiber-reinforced SCC.

Literature review of influence of M-Sand on the flexural properties of M-20 grade glass fiber reinforced self compacting concrete

Abstract Self-compacting concrete (SCC) is a fresh concrete that can drift under its very own load to totally fill the structure work and self-solidifies with no mechanical vibration. In this undertaking, the examinations were done on the M20 grade SCC, with various proportions of polypropylene fiber. The measure of the polypropylene fiber is 5 mm. L-Box, U-Box, V-Funnel and J-Ring tests were performed to decide the properties of the new polypropylene fiber fortified cement created utilizing river sand and manufacture sand. Additionally the properties of solidified cement was examined through the flexural quality test. Along these lines this investigation causes us to comprehend the impact of M sand on the attributes of crisp and solidified M20 grade polypropylene fiber fortified cement.

Mechanical and durability properties of self-compacting concrete with marble fine aggregate

Abstract Self-compacting concrete (SCC) enhances qualities and working conditions due to the elimination of compaction during construction. The usage of river sand in concrete affects natural resources and groundwater. This the paper deals the different testing methods to test high-flow ability, resistance against segregation, and passing ability of self- compacting concrete for M60 grade of concrete with a partial replacement of marble waste as a fine aggregate. Slump flow, V-funnel, L-box and U-box tests were carried out to examine the performance of fresh state SCC. In hardened state, the tests were conducted and cured at different periods to find compressive strength, tensile strength and flexure strength test with the replacement of marble fine aggregate percentage of 0%, 25%, 50% and 100% in SCC for 14, 28 and 56 curing days. The chemical admixture super plasticizer master Glenium sky 8233 and the viscosity modifying agent are used. The specimens are cast with 0.28 water-powder ratio. And also durability of SCC is tested by RCPT, WPT, chemical attack tests like acid and sulphate attack are conducted at the age of 28 and 56 days in SCC specimens. The results are compared with the conventional SCC and found satisfied up to 25% of partial replacement of fine aggregate as a marble aggregate for 28 and 56 curing days.

Influence on flexural properties of glass powder in self compacting concrete

Abstract Self-compacting concrete is a high performance concrete that can flow under its own weight to completely fill the form work and self-consolidates without any mechanical vibration. This work summarizes the utilization of glass powder addition on the concrete as to relieve the provision, affordability, strength and contamination issues. In this paper the experimental study were done on the M20 grade of SCC specimens were casted, arranged with addition of four different proportions weight (0.3%, 0.6%, 0.9%, and 1.2%) of glasspowder with water cement ratio of 0.45. Prism-100*100*500 mm and cylinder-150*300 mm were prepared for testing after 28 days natural process in water served as the control. Slump cone, L-Box, U-Box, V-Funnel and J-Ring tests were performed to determine the properties of fresh concrete on both r-sand and m-sand. The fresh concrete tests are done for self-compacting concrete to know the flow and workability of the concrete. The properties of hardened concrete tests on both river sand and manufacturing sand can also experimented by conducting the flexural strength and split tensile strength test. The tests are conducted after 28 days age of curing. The tests results show the workability and characteristics of concrete.

Influence of m-sand on the flexural properties of m-20 grade glass fiber reinforced self compacting concrete

Abstract Self-Compacting concrete (SCC) is a high – execution solid that can stream under its very own load to totally fill the structure work and self-solidifies with no mechanical vibration. In this undertaking, the examinations were done on the M20 grade SCC, arranged utilizing four unique proportions (0.3, 0.6, 0.9 and 1.2%) of polypropylene fiber and a water concrete proportion of 0.47. The measure of the polypropylene fiber is 5 mm. L-Box, U-Box, V-Funnel and J-ring test were performed. Mortar for self-compacting concrete has been tested in a paste viscometer. This model has been used to express the concrete’s rheology in yield stress and plastic viscosity. By this method different types of filler have been investigated [1] , [2] , [3] . Testing has also been done on some types of viscosity agents. The evaluation of the concrete has been done with the so-called slump flow and the L-box. The investigation has given a method and criteria to achieve self compacting concrete. Using the model, different binder, filler and admixture can be evaluated in the process to achieve a mix composition for self-compacting concrete.

Proportioning Self Compacting Concrete in Hot Weather Utilizing Limestone Powder

Self-compacting concrete (SCC) is a special type of concrete able to flow and compact under its self-weight. The SCC requires high powder content (mainly of cement) up to 600kg/m3 to achieve its properties. This will be problematic if all cement content in the powder exceeded 400 kg/m3used in hot weather of Sudan. This paper investigates addition of Sudanese limestone powder (LSP) to reduce cement content. The LSP dosages between 20% and 28 % (by cement weight) are used in six mixes having maximum cement content 380kg/m3. Results show that five trial mixes achieved the self-compactibility tested by slump flow, sieve segregation, V-funnel and U-box tests. Compressive strength of these mixes show that the LSP increases strength with dosage. Therefore, further investigations of hardened concrete properties are recommended for the successful mixes to be applied in real projects in the Sudan. Also, it has been found that dry batching and forced-action pan mixers are the most suitable for producing SCC with high homogeneity compared to commercial tilted-drum mixers.

Numerical simulation of self-consolidating engineered cementitious composite flow with the V-funnel and U-box

A 3D numerical model is developed in this paper to simulate the flow of self-consolidating engineered cementitious composites (SC-ECC) through the V-funnel test and U-box test. The synthetic fibres utilized in SC-ECC are considered as flexible fibres and modelled as separated particles, virtually connected by a drag force between two adjacent fibre particles. The fibre particles and mortar particles possess similar continuum properties in the domain of SC-ECC. The constitutive equations of the flow of SC-ECC are solved using the mesh-free, weakly compressible smoothed particle hydrodynamics (WCSPH). The V-funnel model focuses on the flow rate characteristic and the correlation of the dispersion of synthetic fibres with the plastic viscosity of fresh mixtures. The U-box simulation is to confirm the self-consolidating capability and the passing ability of SC-ECC flow through reinforcing bars. The simulation results of the discharge time in the V-funnel model and the self-levelling index in the U-box model agree well with experimental results from the literature, which provide convincing evidence for the correctness and effectiveness of the developed model. The proposed model thus is capable of providing insight into the flow behaviour of SC-ECC in terms of filling, passing abilities and the dispersion/orientation of flexible synthetic fibres.

Properties of self-compacting lightweight concrete reinforced with steel and polypropylene fibers

The aim of this study is to investigate the effect of incorporating steel (ST) and polypropylene (PP) fibers and silica fume on the rheological properties, mechanical properties and microstructure of self-compacting lightweight concrete (SCLC). ST fiber combined with PP fiber in four volume fractions (ST/PP = 0.5%/0, 0.5%/0.5%, 0.5%/0.75%, 0.5%/1.0%) is introduced in this study. The self-compacting characteristic of concrete is evaluated by means of slump flow, V-funnel, L-box and U-box tests. Compression, splitting tensile and flexural tests are performed to characterize the mechanical properties of SCLC. In addition, a microscopic study on the aggregates/paste and fibers/paste interfaces were conducted using Scanning Electron Microscopy (SEM). The results of the workability test show that all of the mixes can be defined as SCLC with good flowability, viscosity and passing ability. An improvement in the mechanical properties of SCLC is observed following the incorporation of silica fume and fibers. In particular, ST and PP fibers in hybrid form effectively enhance the mechanical behavior of SCLC, and result in a positive synergy. Moreover, good bond behavior at aggregates/paste and fibers/paste interfaces is observed.

Strength properties and microstructural analysis of self-compacting concrete incorporating waste foundry sand

Waste Foundry Sand (WFS) is a solid waste generated from the metal casting industry. Globally, casting production is about 105 million metric tons per year, about 0.60 ton of WFS is produced per 1 ton of cast steel production. Hence, the yearly production of WFS is approximately 62.64 million metric tons. Therefore, disposal of WFS generated from the casting industry poses serious environmental problems. On the other hand, continuous extraction of natural resources is depleting the environment at a rapid pace increasing the cost of production due to an insufficiency of natural resources.This paper presents the results of an experimental investigation on the influence of waste foundry sand (WFS) as a fine aggregate replacement on the fresh, strength and micro-structural properties of self-compacting concrete (SCC). Initially, control SCC was designed and then, fine aggregates were replaced with 5, 10, 15, 20, 25 and 30% of WFS by volume. The fresh state properties of SCC were evaluated using slump flow, T500, V-funnel-box, and U-box test. Strength and microstructural investigations were carried up to the age of 365 days. Tests results indicate all concrete mixes exhibited the properties of fresh state SCC. The 28-day compressive strength of control SCC was 58 MPa. There was 6.38–18.76% reduction in the strength of SCC with the use of 5–30% WFS at 28 days. Micro-structural results of XRD and SEM validate the experimental results. Hence, WFS could be suitably used in the manufacturing of SCC.

Effects of colloidal nano-silica on fresh and hardened properties of self-compacting lightweight concrete

The aim of this study is to investigate the effects of different levels of colloidal nano-silica (CS) on fresh and hardened properties of self-compacting lightweight concrete (SCLC). For this purpose, two concrete series including 16 concrete mixes with two water to binder (w/b) ratios of 0.35 and 0.45 were considered. The percentage of CS that replaced cement were 0%, 1%, 3% and 5%. Also, mixtures containing 0% and 10% MS were considered. The fresh properties of SCLCs were observed in terms of slump flow diameter and time, J-ring diameter, V-funnel time and U-box tests. The hardened properties were determined through mechanical properties (compressive strength, splitting tensile strength, flexural strength) and non-destructive tests (electrical resistivity and ultrasonic pulse velocity). The results of this work indicate almost all SCLCs satisfied the requirements of EFNARC. The results of hardened properties indicate that combined addition of MS and CS in SCLC was better than adding just one of them. The higher mechanical properties were obtained by ternary mixes containing 10% MS and 3% CS at both w/b ratios of 0.35 and 0.45. Moreover, the improvement of electrical resistivity and ultrasonic pulse velocity in ternary mixes were better than the binary and control mixes.