High Strength Self-compacting Concrete Research Articles

Permeation, corrosion, and drying shrinkage assessment of self-compacting high strength concrete comprising waste marble slurry and fly ash, with silica fume

Production of self-compacting high-strength concrete (SCHSC) needs a colossal quantity of cement, which is perilous for the environment and economy. Researchers are intended to lower down the dependency on this cement and seeking for alternate green materials. The incorporation of industrial by-products together with mineral admixtures has been found suitable to minimize aforesaid problems. This investigation is, therefore, aimed to study the durability performance of SCHSC by comprising silica fume and fly ash (mineral admixture), and waste marble slurry (WMS) as an alternative to cement. The durability of such SCHSC mixes was evaluated by performing water permeability, chloride penetration, carbonation, corrosion, and drying shrinkage tests. X-Ray Diffraction (XRD) analysis was carried out for the microstructural formation of SCHSC mixes. The results revealed that the incorporation of mineral admixture and WMS improved the durability performance of the mixes. The durability parameters confirm the optimal performance of the SCHSC made with 10% of WMS and 15% of fly ash, with 5% of silica fume.

Rheological behavior of low shrinkage very high strength self-compacting concrete

High performance self-compacting concretes have high potential to develop shrinkage, and possible solutions for this comportment should not compromise the workability of the mixtures. This work investigated rheological behavior over time of high performance self-compacting concretes (HPSCCs) containing an expansive admixture (EXA) and a shrinkage-reducing admixture (SRA). Cement pastes formulated from these HPSCCs were produced. The flow behavior of the HPSCCs and pastes were evaluated by rheometry and workability tests for up to 90 min. Isothermal calorimetry was utilized to measure the effect of EXA and SRA on cement hydration. The results showed that cement pastes containing SRA required less superplasticizer than pastes containing EXA and reference mixture, for the same workability. The flow behavior of cement pastes was similar at 90 min, independent of the rheological model adopted (Herschel-Bulkley or Bingham). The dynamic yield stress values of pastes containing some shrinkage mitigator agent ranged from 143 to 233 Pa at 90 min. The mixtures containing EXA showed an accelerated hydration, while incorporation of SRA in the pastes resulted in a retarded hydration of Portland cement compared to the reference mixture. After 90 min, by the slump flow diameter, all concretes could still be considered as self-compacting. The highest flow loss (−19.1%) was observed for concrete containing 15% EXA and the lowest (−0.1%) for the concretes containing 0.5% and 1.0% of SRA. After 90 min, the dynamic yield stress values of HPSCCs ranged from 19.5 to 40.7 Pa. Overall, shrinkage mitigator agents can be used in HPSCCs without compromising the workability of the mixtures.

The potency of metakaolin as addition material in high strength self-compacting concrete to increase Modulus of Rupture (MOR) in rigid pavement application

This study focused on the modulus of rupture (MOR) for high strength self-compacting concrete (SCC) using varied metakaolin (MK) composition. The MOR significantly contributes to the resilience and mechanical performance of the rigid pavement, and is enhanced by modifying the regular concrete material. In addition, the MK is known to be potentially economical and occurs abundantly as natural resources. Plain concrete beams with dimensions 400 x 100 x 100 mm3, were tested in the laboratory in an effort to measure the MOR from varied MK composition for each specimen or modified concrete type. The result showed the MOR increase is exclusively as a result of additional metakaolin. Also, the newly modified material was proven to offer more advantages when applied as rigid pavement material. Furthermore, the analytical laboratory result showed the optimum MK dosage was estimated at 20% of the binder weight. This subsequently enhances the MOR by 17.28% compared to non-MK concrete.

Performance Evaluation of Durability and Flexural behaviour of Self Compacting Concrete blended with Alccofine

Due to its superior performance over traditional concrete mixes, Self Compacting concrete (SCC) has increased in popularity in the construction industry in recent years. The major downside of using self-compacting concrete is that there is no universal design mix norm. The aim of this research is to determine the best mix proportioning and strength and durability parameters for M40 Alccofine based high strength self-compacted concrete. It often provides an exclusive application for self-compacting concrete since it can flow into any section of a heavily reinforced region without creating any vibration. Consequently, if using self-compacting concrete in beam-column joints does not adversely affect the frame’s seismic efficiency, it could be used rather than traditional concrete. During earthquake excitation, the beam-column joints of reinforced concrete building frames play a very important role. As those are the highly congested areas of reinforced concrete framed buildings, effective concrete placement and compaction in these regions is extremely difficult. This study involves determining the impact of Alccofine with replacement levels from 10 to 50 percentages with cement is substituted for M40 grades with Viscosity Modifying Agent, with both the purpose of increasing compressive strength, lowering gas emissions, and making concrete more cost efficient. In specific, increasing the CaO volume of the Alccofine 1203 increases the binding capacity and compressive strength.

Increasing the crack resistance of high-strength self-compacting concrete

The object of research is high-strength self-compacting concrete, which does not require additional vibration during laying. One of the most problematic issues of high-strength self-compacting concretes is increased cracking, associated with large shrinkage deformations of such concretes and their fragile destruction.
 A decrease in shrinkage deformations of concrete was established when part of the cement was replaced to mineral additives. This effect is explained by a decrease of the cement content and, accordingly, a decrease of the chemical component of the autogenous shrinkage of concrete, and an increase of the adsorptive binding of capillary moisture by mineral additives, with reduces the physical drying shrinkage of concrete. In this case, the type and dispersion of the used mineral additive can affect to the shrinkage deformations of concrete. A significant decrease in shrinkage deformations when using metakaolin is explained by an increase the amount of ettringite as a result of the reaction of active metakaolin Al2O3 with two-water gypsum of cement. It was found that the replacement of cement to 10 % of mineral additives leads to a decrease in the value of the critical stress intensity factor (SIF), which is compensated by a decrease of the fragility of concrete fracture (an increase of the area of microplastic deformations). At the same time, the type of mineral additive used does not affect to the value of the critical stress intensity factor, but significantly affects to the fragility of fracture of concrete samples. The introduction of 10 % mineral additives (to replace cement) had a positive effect on the retention of flow of self-compacting concrete mixes; the best results according to this criterion were observed when using silica fume, fly ash and limestone. All mineral modifiers, except for silica fume, led to a decrease of the compressive strength of high-strength concretes on all terms of hardening. In the case of the tensile strength of concrete at bending and splitting, with the introduction of silica fume, metakaolin and fly ash, a positive effect was observed compared to the base composition without additives.
 Comprehensive accounting of the results obtained will allow a reasonable approach to the design of high-strength self-compacting concretes with increased crack resistance.

Assessment of High Performance Self-Consolidating Concrete through an Experimental and Analytical Multi-Parameter Approach.

High-performance self-consolidating concrete is one of the most promising developments in the construction industry. Nowadays, concrete designers and ready-mix companies are seeking optimum concrete in terms of environmental impact, cost, mechanical performance, as well as fresh-state properties. This can be achieved by considering the mentioned parameters simultaneously; typically, by integrating conventional concrete systems with different types of high-performance waste mineral admixtures (i.e., micro-silica and fly ash) and ultra-high range plasticizers. In this study, fresh-state properties (slump, flow, restricted flow), hardened-state properties (density, water absorption by immersion, compressive strength, splitting tensile strength, flexural strength, stress-strain relationship, modulus of elasticity, oven heating test, fire-resistance, and freeze-thaw cycles), and cost of high-performance self-consolidating concrete (HPSCC) prepared with waste mineral admixtures, were examined and compared with three different reference mixes, including normal strength-vibrated concrete (NSVC), high-strength self-compacted concrete (HSSCC), and high-performance highly-viscous concrete (HPVC). Then, a multi parameter analytical approach was considered to identify the optimum concrete mix in terms of cost, workability, strength, and durability.

Impact Performance of Steel Fiber-Reinforced Self-Compacting Concrete against Repeated Drop Weight Impact

The self-compacting concrete (SCC) was invented to overcome the compaction problems in deep sections, owing to its perfect workability characteristics. Steel fibers when used with SCC would affect the required fluidity characteristics but improve its impact resistance. In this research, an experimental work was conducted to evaluate the impact response of micro-steel fiber-reinforced SCC, under flexural impact. A 5.47 kg free-falling mass was dropped repeatedly from 100 mm height on the top center of 270 mm-length beam specimens. Eight mixtures with two design grades of 30 and 50 MPa were prepared to distinguish the normal and high-strength SCCs. The distinguishing variable for each design grade was the fiber content, where four volumetric contents of 0%, 0.5%, 0.75%, and 1.0% were used. The test results showed that the impact resistance and ductility were significantly improved due to the incorporation of micro-steel fibers. The percentage improvements were noticeably higher at failure stage than at cracking stage. For the 30 MPa mixtures, the maximum percentage improvements at cracking and failure stages were 543% and 836%, respectively. Weibull’s linear correlations with R2 values of 0.84 to 0.97 were obtained at the failure stage, which meant that the impact failure number followed the Wiebull distribution.

Graphene oxide as Nano material in high strength self-compacting concrete

The Particles with dimensions less than 100 nm are considered as Nano materials. These Nano materials have the ability to modify elements at Nano scale. By modifying cement at Nano scale, we can improve the micro structure of cement. One such Nano material is Graphene Oxide (GO). GO is incorporated in high strength self-compacting concrete (HSSCC) to improve the performance characteristics. HSSCC is the new age material in the fast growing construction industry. There are various methods to produce HSSCC, one finest method among them is by improving the microstructure of cement using Graphene oxide. It is an advanced Nano material which achieved significant levels in various fields. This paper investigates the rheological and mechanical properties of GO incorporated high strength self-compacting concrete. The percentage increase of Compressive strength, tensile strength and flexural strength was observed to be 17%, 40% and 28% respectively. GO is added to cement at contents 0, 0.02, 0.04, 0.06, 0.08 and 0.1% by weight of powder to determine the achieve High strength self-compacting concrete. Rheological and mechanical properties of HSSCC are determined at 7, 28, 56 and 90 days of curing.

Shear Behavior of High Strength Self-Compacting Concrete with Lower Transverse Reinforcement Index

ABSTRACT Self-Compacting Concrete (SCC) generally has lesser coarse aggregate contents and also the maximum size of aggregates is limited as compared to Normal Vibrating Concrete (NVC) for the same class of strength. This results in reduced aggregate interlock in Self-Compacting concrete as against NVC, which affects the shear strength of slender beams and thus, SCC might have lower shear strength. In this article, an experimental programme which includes six slender beams of High-Strength Self Compacting Concrete (HSSCC) with compressive strength more of than 90 MPa and with different stirrup spacing is presented. Experimental test results of shear strength of HSSCC beams are compared with high strength NVC beams for different stirrups spacing. The results showed the ultimate shear stress of HSSCC beams is lower than NVC beams and increase in transverse reinforcement index, ρw fy, in HSSCC beams decreases this difference. The results are also compared with different code provisions. Not much work has been done on beams with lower transverse reinforcement index (ρw fy) and in the present work, ρw fy ranges between 0.276 to 0.80.

Structural Behavior of Hollow-core One Way Slabs of High Strength Self-compacting Concrete

Reinforced concrete hollow-core slab (HCS) is a new type of lightweight slabs in which the longitudinal voids provide the ability to reduce the concrete amount. Reducing the concrete amount causes a reduction of the dead loads which consequently leads to cost-saving, fast construction, and getting long-span. The experimental program includes constructing and testing slab species with dimensions 1700×435×125mm to investigate the effect of eliminating concrete ratio by changing the size of the longitudinal void and the number of longitudinal voids on the performance of HCS. The experimental results showed that elimination of the concrete with percentages 10.83, 17.20 and 24.37% from the hollow-core high strength slabs using three longitudinal voids of diameters 50, 63, and 75mm, respectively, resulted in saving the ultimate strength by 90.06, 87.84 and 85.07%, and increasing the ultimate deflection by 5.48, 10.80 and 17.44%. While, elimination of the concrete with percentages 16.25, 24.37 and 32.50% from the hollow-core high strength slabs using two, three, and four longitudinal voids of 75mm diameter resulted in saving the ultimate strength with percentages 89.29, 85.07 and 80.61%, and increasing the ultimate deflection with percentages 7.57, 17.44 and 22.81% respectively when compared with the reference solid slab.

Effect of discarded steel fibers on impact resistance, flexural toughness and fracture energy of high-strength self-compacting concrete exposed to elevated temperatures

This paper presents a systematic experimental investigation to explore the effect of incorporating discarded hybrid steel fibers (DSF) on the rheological, mechanical, and hardened properties of high strength self-compacting concrete (HSCC). This study also covers the effect of elevated temperatures (300 °C, 500 °C, and 700 °C) in the furnace with a heating time of 2 h on residual mechanical and hardened properties of produced concrete.The results revealed that adding DSF to the HSCC slightly reduced its filling ability and passing ability, while increasing its resistance to segregation. Although residual strength was decreased by exposure to elevated temperatures over 300 °C, residual mechanical properties of fiber-reinforced high strength self-compacting concrete (FRHSCC) was significantly higher than HSCC. There was a significant increase in the impact resistance, fracture energy, and toughness index of FRHSCC compared to HSCC, where the increase was about 130%, 500%, and 1300%, respectively. After exposure to 700 °C, it was found that concrete becomes more brittle, loses its strength, density, and changes color alongside the appearance of fine cracks on its surface at 500 °C. The results also indicated that elevated temperatures had a greater influence on impact resistance, toughness, and fracture energy compared to compressive strength. DSF almost doubled the impact resistance and tensile strength of HSCC, and the highest effect was on the toughness and fracture energy at both ambient and elevated temperatures. The ultra-pulse velocity test has also been shown to be a suitable technique to infer loss of strength and deterioration of fire-exposed concrete structures. Finally, this study confirms that DSF can be successfully used as a steel fiber in producing FRHSCC to be structurally used as well as improving residual hardened properties and resistance to heating effects.

Untreated rice husk ash incorporated high strength self-compacting concrete: Properties and environmental impact assessments

The suitability of untreated rice husk ash (URHA) as a supplementary to the ordinary Portland cement (OPC) and fine aggregates (FA) in high strength self-compacting concrete (SCC) was investigated in terms of mechanical properties as well as environmental impact assessments (EIA). In total, nine SCC mixes were prepared and investigated with various levels of URHA replacements to OPC and FA. Initially, the fresh and hardened properties of URHA incorporated SCC were determined. Further, EIAs were carried out considering eighteen different environmental impact indices for the optimum URHA incorporated SCC mixes to determine the most appropriate mix in terms of mechanical properties along with their environmental impacts. The experimental results reveal, URHA in the range of 10–15% can be used without compromising the fresh and hardened properties of SCC. The results of the EIAs are presented and discussed in terms of compressive strength to environmental indices ratios to normalise the comparison. The EIAs disclose that even through some of the mixes provide better performance in terms of certain environmental impact categories; especially CO2 emission, water pollution (fresh and marine) and ecotoxicity, their strength to environmental impact ratios are relatively low. Thus, it is recommended to select the optimum mix design of URHA incorporated high strength SCC in terms of mechanical properties and as well as EIA.

Resonance fatigue testing on high-strength self-compacting concrete

Concrete structures are increasingly affected by fatigue damage, while new slender building structures with greater mechanical requirements make it necessary to deepen knowledge of their behaviour under fatigue loading. In this research, high-strength plain concrete was studied under two different frequencies of cyclic compressive stress. Wöhler curves were obtained in two different ways, on the one hand, applying a uniform frequency of 10 Hz and, on the other hand, applying the specimen resonance frequency. The results show two different types of behaviour. A reduction in fatigue life was observed in those concretes tested at very high frequency. When loads were applied at resonance frequency, they did not seem to modify the breaking mechanisms of the concrete subjected to fatigue.

Strengthening and Repair of Self Compacting Concrete Beams( Dept.C )

While there is abundant research information on ordinary concrete beams strengthening or repairing with FRP, relatively little data on the behavior of self-consolidating concrete (SCC) is available. Carbon Fiber Reinforced Polymers laminates (CFRP) was investigated for strengthening and repairing SCC and high strength self compacting concrete (HSSCC) beams subjected to one midpoint load in in order to compared to beams made of normal concrete (NC) and normal high strength self compacting concrete (NHSSCC) at the same conditions respectively. To demonstrate the concept, this paper presents results of a laboratory investigation of 24 beams (150x200x1600 mm) on the behavior of self compacting concrete strengthening and repairing with one layer of CFRP laminate and subjected to one midpoint load, including the effect of using 8 different mixes to study the effect of mix proportions on rapped CFRP beams behavior. Test results showed that the addition of CFRP laminate to the tension surface of the beams demonstrated significantly improvement in stiffness and ultimate load capacity of beams. The response of control and strengthened beams were compared and evaluated by experimental and theoretical calculations. It was observed that ductility indexes of SCC and HSSCC beams were more efficient than NC and NHSC respectively. Load carrying capacity of control, strengthening and repairing self compacting concrete beams was closed to traditional concrete beams (about 90-95%). The paper also highlighted the crack pattern of all cases of beams which indicated more distribution and smaller crack amplitude for strengthened beams with respected to the control beams.

Fresh Behavior and Hardened Properties of Self-Compacting Concrete Containing Coal Ash and Fly Ash as Partial Replacement of Cement

Due to the higher price of cement compared to other concrete ingredients, the problems associated with greenhouse gases emissions during its production and its high popularity have arisen concerns in its substitution with other supplementary cementitious materials (SCMs). In this regard, the current experimental program was established to investigate the fresh and hardened performance of self-compacting concrete (SCC) made with coal ash (CA) and fly ash (FA) as fractional substitution of cement. In this paper an attempt was made to use the remaining CA from the barbecue process of the restaurants from Fallujah city, Iraq. A total number of 7 concrete mixes were prepared with unchanged (w/b) ratio of 0.37 and total cementitious content of 450 kg/m3. Reference mix was produced by using 100% cement without FA or CA. Then, other mixtures were batched with 10%, 20% and 30% (by weight) replacement of cement by FA and CA, respectively. The results illustrated that, in contrast to the FA, the CA has negative influences on the fresh properties of SCC but the results still meet the criteria for the fresh behavior of SCC. On the other hand, the inclusion of CA was significantly improved the strength and water absorption of SCC. Sustainable high strength SCC can be produced due to the addition of CA.

KAJIAN KARBONASI PADA BETON MUTU TINGGI MEMADAT MANDIRI DENGAN VARIASI KOMPOSISI METAKAOLIN

<p class="Abstract"><em>The construction industry is an important thing to support the development of a country. In concrete construction, quality, strength, and durability of concrete are the main requirements of all. In urban tropical countries, carbonation is one of the essential factors that affect the durability of concrete, and it may cause corrosion of reinforced steel in concrete. Therefore, high strength self-compacting concrete may be expected as the solution, improved by pozzolanic additions, metakaolin with substitution dosage at 10%; 12,5%; 15%; 17,5%; and 20%. This study purposed to determine the effect of metakaolin and its optimum dosage to improve high strength self-compacting concrete quality on its carbonation rates. This study was done by using experimental methods. It needs a plain cylindrical concrete with 75 mm diameter and 150 mm height, and testing by SNI 03-6468-2000, EFNARC 2002, and SEM-PUPR 25-2015. The carbonation test is done using accelerated laboratory carbonation </em><em>in Structures and Materials Laboratory, Faculty of Engineering, Universitas Sebelas Maret </em><em>by soaking the specimens in a 4% carbonate solution for 15 days, 37 days, and 51 days, proceeded by splitting using CTM, and spray it using a 1% phenolphthalein indicator to determine its carbonation depth. Based on the results, metakaolin might improve concrete quality by reducing its carbonation rates by 15% substitution dosage of cement content, with a nominal atmospheric carbonation coefficient 3,71 mm/year<sup>½</sup>, reduced 44,41% from HSSCC without metakaolin substitution. Metakaolin addition might reduce fresh concrete's workability and fulfill self-compacting concrete requirements specified by EFNARC 2002.</em></p>

Microstructural analyses of the addition of PP fibres on the fracture properties of high-strength self-compacting concrete by X-ray computed tomography

This paper analyses the influence of the presence of polypropylene fibres in the microstructure of a high-strength self-compacting concrete by X-ray computed tomography and its consequences on the mechanical and fracture properties. The addition of PP fibres alters the pore structure of the concrete matrix, and this affects the macroscopic response (i.e., mechanical and fracture behaviour). A microstructural analysis of an unreinforced concrete, used as reference mix, and two polypropylene fibre-reinforced mixes with two fibre length (6 and 24 mm) were experimentally carried out. Complementary, a comprehensive experimental study of the mechanical and fracture properties of each concrete were performed. Finally, it was established a correlation between the microscopic response (pore morphology and pore distribution) and the macroscopic behaviour of high-strength self-compacting concrete.

Mechatronic complex based on sliding formwork for the construction of monolithic high-rise buildings and tower-type structures made of reinforced concrete

The article is devoted to the use of mechatronic sliding complexes for the construction of high-rise monolithic buildings and tower-type structures made of reinforced concrete. It is shown that high-rise monolithic towers of variable radius, characterized by the increased complexity of technological operations can be erected with high efficiency using automated sliding formwork, which makes it possible to achieve the highest possible pace of construction technology, while ensuring the high quality of work using self-compacting high-strength concrete. A mathematical description of the mechatronic complex as a completely observable multidimensional object with control limitations is given, which allows predicting deviations and deformations of the sliding formwork working platform design during the lifting process, evaluating the internal and external disturbances’ effect on the complex’s operation, and also modeling the interaction of the lifting and regulating mechanisms in violation of their synchronous operation. It is proposed to use the two-level systems to control the formwork lift and synchronize the movements between the actuators groups. The results of modeling the sliding formwork lifting process are presented.

Fresh and hardened properties of high strength self-compacting concrete using by-product ferronickel slag fine aggregate

Concrete nowadays is the most frequently used building material all over the world. This is causing a tremendous pressure on the supply of its constituents like natural sand which is traditionally used as the fine aggregate. Therefore, it is essential to search for alternative materials in order to meet the increasing demand of concrete and improve the sustainability of concrete industry. This study investigated the effect of using by-product ferronickel slag (FNS) as a partial replacement of natural sand in high strength self-compacting concrete (SCC). Utilization of by-product FNS will also lessen the risk of environmental pollution. Results show that concrete containing up to 40% FNS fine aggregate met all the recommended criteria of EFNARC for SCC without any segregation in the flow and J-ring tests, and no blockage in the L-box and V-funnel tests. The increase of FNS to 60% resulted in significant segregation and reduced flowability due to the larger size, angular shape and higher density of FNS as compared to sand. The 28-day uncompacted compressive strength of concrete with 40% FNS was 66 MPa, which was almost same as that for the vibrated concrete of same mixture, confirming the achievement of self-compaction property. Tensile strength could be conservatively predicted from compressive strength by using the ACI318 and AS3600 equations. The volume of permeable voids and water absorption of the SCC using up to 60% FNS were in the category of “Excellent” and “Low” as per the VicRoads specifications. Sorptivity values were far less than the recommended value of 27.11 × 10−3 mm/s0.5. The charge passed in the rapid chloride permeability test was less than 1000 Coulombs. Therefore, FNS content up to 40% was found as an environmentally friendly substitute of natural sand for the production of high strength SCC of good durability.

Rheological behavior and fresh properties of self-compacting high strength concrete containing recycled PP particles with fly ash and silica fume blended

Solid waste management can be regarded as one of the major environmental concerns across the globe. Annually, substantial quantities of plastics are produced. The utilization of this waste can result in a variety of huge problems such as health hazards, disposal, and environmental pollution. In this paper, the workability and rheological characteristics of self-compacting high strength concrete (SCHSC) made with recycled polypropylene plastic particles (RPPP) with fly ash (FA) and silica fume (SF) are investigated. The SCHSC was employed by replacing the medium-coarse aggregate (MCA) with five percentages of RPPP contents at 0%, 10%, 20%, 30%, and 40% by volume. The first group of mixtures contained 20% FA and 80% Portland cement (PC). On the other hand, the second group of the mixes made with 20% FA, 10% SF, and 70% PC. To investigate such workability-related properties as slump flow diameter (SFD), T50 slump flow time (SFT), V-funnel flow time (VFT), L-box height ratio (LHR), and L-box T200 and T400 flow times, 10 concrete mixtures were produced and tested. ICAR rheometer in the rheological testing of fresh SCHSCs was used to determine the rheological parameters. For all mixtures, the compressive strength was measured at 28 days. With respect to the experimental results of the current study, the Herschel-Bulkley and modified Bingham models can provide well defined rheological representations for SCHSC with RPPP. The mixtures containing a combination of FA, SF, and RPPP can have better fresh characteristics compared to those without SF. Moreover, all produced SCHSC mixtures can be at a satisfactory level with the limitations required for the fresh properties of SCC.