Properties Of Self-consolidating Concrete Research Articles

Recent developments in evaluating pumping behavior of flowable and self-consolidating concretes

In this paper, recent developments in evaluating pumping behavior of flowable and self-consolidating concrete (SCC) are discussed. First, a brief overview of the underlying physics of pumping of concrete is given to introduce the concepts of friction, flow, hydrodynamic and hydrostatic pressure and to present the concept of the lubrication layer. Various methods to assess the lubrication layer properties are then discussed, including tribology and different visualization techniques for the velocity profile. Using tribology on the one hand, or by combining the rheological properties of the concrete and its constituent mortar and knowing the thickness of the lubrication layer on the other hand, it is shown that pressure losses during pumping of concrete can be successfully predicted. An overview is also provided to discuss the influence of flow rate, pipe diameter and critical SCC properties influencing the pressure during pumping.

An experimental research on self-consolidating concrete using tungsten Mine Tailings

This study examined the possibility of utilizing Tungsten Mine Tailings (TMT) as cement substitute for manufacturing Self-consolidating Concrete (SCC). Rheological properties of mortar mixed with TMT was evaluated using mortar viscometer and evaluation of SCC in the fresh state was examined by applying the standard presented by Japanese Society of Civil Engineering (JSCE). Its feature at hardening state was examined through compressive strength, splitting tensile strength, modulus of elasticity, carbonation depth and drying shrinkage test. As a result of examination, viscosity and yield stress decreased as the mixing ratio of TMT increased. Properties of SCC mixed with TMT while it is fresh state satisfied the standard within the mixing ratio of TMT at 20%. As for the mechanical properties of SCC, as the mixing ratio of TMT increased, the compressive strength decreased, carbonation depth and drying shrinkage rate increased. The relationship between the compression strength and the splitting tensile strength was found to be similar to the expression presented by CEB-FIP, and the relationship between the compression strength and the elastic moduli was found to be similar to the expression suggested by ACI 318-08 and CEB-FIP.

Effect of curing condition on shrinkage reducing property of self-consolidating concrete with different expansive admixtures

In accelerated bridge construction, self-consolidating concrete (SCC) shows great potential of application to fill the gap between the deck soffit and precast concrete girders with heavy reinforcement especially in precast construction . An experimental program was undertaken to evaluate the performance of SCC incorporating different expansive admixtures for filling distance between precast bridge deck panels and girders. The study aimed to investigate shrinkage reducing properties as well as wokability of proposed SCC mixture under different curing conditions (water, air-dry and sealed cure). A combination of tests including slump flow, J-ring, V-funnel flow time, L-box and static bleeding were also conducted to measure the workability as well as mechanical properties of developed SCC.

Properties of SCC prepared using natural pozzolana and industrial wastes as mineral fillers

The high unit cost of self-consolidating concrete (SCC) resulting from the use of conventional filler materials, such as fly ash or silica fume, has been identified as the main hindrance to its widespread use particularly at places where these materials are not available locally. To achieve economy in the production of SCC, it is highly desirable to explore possibility of using alternative materials as mineral fillers through the evaluation of technical and economic benefits of SCC made with these materials. This paper presents the results of a study conducted to evaluate the performance of ternary SCC mixtures prepared using some industrial wastes as mineral fillers which include limestone powder, cement kiln dust, bag house dust, pulverized steel slag and metakaolin, each in conjunction with natural pozzolana. The mechanical properties and durability characteristics of the SCC mixtures satisfying the requirements of self-compactability at optimally selected dosages of chemical admixtures were evaluated. Except the SCC mixture incorporating bag house dust, the early and later-age strengths of the other SCC mixtures were found to be very high. Further, the good corrosion resistance exhibited by the developed SCC mixtures showed that the high performance SCC mixtures can be prepared utilizing these industrial wastes as mineral fillers.

New insight into the equivalent concrete mortar approach for self-consolidating concrete

The concrete equivalent mortar (CEM) approach consists in replacing the coarse aggregates (CA) of concrete by a mass of sand to provide an equivalent specific surface area at mortar scale. Such approach can be used to reduce time and cost needed to design self-consolidating concrete (SCC). The approach is extended with less success to evaluate rheological properties of SCC using those of the corresponding CEM. The limitation of the approach is mainly due to the fact that the surface area of aggregates is the only used criterion. The objective of this investigation is to evaluate the applicability of the original CEM approach and establish correlations between rheological properties of CEM and SCC. Various SCC mixtures were proportioned with different CAs and binder contents varying from 27 to 36% and 300 to 500 kg/m3, respectively. The obtained test results show that the excess paste theory is a key factor in studying relationship between CEM and SCC. Good correlations between flow properties of CEM and SCC are obtained when the excess paste thickness and CA content are taken into account.

Future research needs in self-consolidating concrete

The development of self-consolidating concrete (SCC) had revolutionized construction by its ability to achieve full compaction without mechanical vibration and consistency of quality. Use of SCC results in significant reduction in construction time, cost, and noise. With the growing utilization of SCC, the necessity for research to understand and manipulate the fresh and hardened properties of SCC also increases. The paper presents future research needs of SCC in the areas of rheology, construction, and sustainability. Aside from yield stress and viscosity, which are key properties for flowability and stability, the mechanisms behind thixotropy need to be understood. To be able to obtain a better grasp of the mechanisms driving the rheology of cement-based systems, the system needs to be studied at multiple scales. Three research areas in construction using SCC are discussed; pumping, cast-in-place of bridge components, and rock-filled concrete. Finally, the research need for further sustainability is emphasize.

Ground copper slag as a supplementary cementing material and its influence on the fresh properties of self-consolidating concrete

This paper reports on an experimental programme to investigate the effect of using ground copper slag (GCS) as a replacement of cement on the fresh properties of self-consolidating concrete (SCC). Totally, seven self-compacting ground copper slag concrete (SCGCSC) mixtures were made with a fixed water–powder ratio of 0.51 in which a portion of the cement was replaced by GCS in weight ratios of 0%, 5%, 10%, 15%, 20%, 25% and 30%. The fresh properties were investigated by slump-flow, visual stability index, V-funnel, J-ring, L-box, air content, screen stability and setting time tests. The SCGCSCs were designed to give a constant slump flow of 680 ± 30 mm which was achieved by using the super-plasticiser at varying amounts. This allowed us to have a reasonable comparison of the obtained results. Totally, it has been concluded that using GCS significantly increased the workability of SCC mixtures. As the GCS increased, the slump flow is also increased at a constant amount of water and super-plasticiser, but t...

Properties of self-consolidating concrete containing high-volume supplementary cementitious materials and nano-limestone

In the present paper, conventional self-consolidating concrete (SCC) incorporating 40% Class F fly ash (FA) replacement for cement, and semi-flowable self-consolidating concrete (SFSCC) incorporating 40% FA and 15% metakaolin (MK) replacement for cement, with or without 1% nano-limestone (nanoLS) addition, were studied. Properties of the fresh concrete mixtures, such as air content, slump flow, and J-ring flow were tested. Properties of the hardened concretes, such as compressive strength, rapid chloride permeability, freezing–thawing resistance, and free drying shrinkage were examined. The results indicated that SCC mixture with 40% FA replacement displayed good workability and adequate compressive strength (33 MPa) at 28 days. In addition to enhancing strength (especially at early ages) and durability, MK also improved shape-holding ability of SFSCC. Addition of nanoLS further increased concrete strength and freezing–thawing resistance and reduced concrete permeability.

Properties of self-consolidating concrete with recycled clay-brick-powder replacing cementitious material

Clay brick is becoming a major demolition waste and causing environmental contamination in China. Recycling of wasted clay brick could conserve natural resources and preserve land from waste filling. In this research, recycled clay-brick-powder (CBP) was used to partially replace Portland cement (PC) and fly ash (FA) in self-consolidating concrete (SCC) mix. The effects of dosage of CBP on the workability, strength, and shrinkage of SCC were investigated. Test results show that partially replacing cementitious material with CBP can reduce the workability of SCC. Compared with the reference concrete, specimens with CBP had higher 28-day and 56-day strength. The specimens containing 1% CBP had the highest compressive strength. Meanwhile, the replacement of CBP to PC and FA could also reduce the shrinkage of the SCC due to the internal curing effect. Based on scanning electron microscope investigation, specimen with CBP had less pores than the specimen without CBP and improved the microstructure of concrete. Hence, CBP had positive effects on the mechanical and physical properties of SCC.

Influence of mixture composition on the properties of SCC incorporating metakaolin

This paper studies and evaluates the properties of self-consolidating concrete (SCC) containing different percentages of metakaolin (MK) by varying the mixture components and mixture proportions. In total, 32 mixtures with varied percentages of MK and mixture compositions are investigated for the effects on compressive strength, flowability, passing ability and high-range water-reducer admixture (HRWRA) demand. The percentage of MK, coarse-to-fine aggregate (C/F) ratio, coarse aggregate size, binder content and percentage of air entrained in the mixture are varied to study the influence of these variables on the fresh properties of SCC containing MK. SCC mixtures containing silica fume and SCC containing slag are also tested for comparison. The results show that increasing the percentage of MK up to 20% in SCC increases the compressive strength, viscosity, passing ability and HRWRA demand, but decreases the flowability of the mixture. In addition, the flowability of SCC mixtures improves with larger aggregate size, higher binder content and higher percentage of entrained air. The passing ability of SCC mixtures also improves with lower C/F ratio, larger aggregate size, higher binder content and the inclusion of entrained air in the mixture. The results also indicate that increasing the binder content or increasing the percentage of the entrained air has the most significant effect on improving the fresh properties of SCC mixtures.

Rheological properties of self consolidating concrete with various mineral admixtures

This paper reports an experimental study into the rheological behaviour of self consolidating concrete (SCC). The investigation aimed at quantifying the impact of the varying amounts of mineral admixtures on the rheology of SCC containing natural sand. Apart from the ordinary Portland cement (OPC), the cementitious materials such as fly ash (FA), ground granulated blast furnace slag (GGBS) and micro-silica (MS) in conjunction with the mineral admixtures were used in different percentages keeping the mix paste volume and flow of concrete constant at higher atmospheric tempterature (30ᵒ to 40ᵒC). The rheological properties of SCC were investigated using an ICAR rheometer with a four-blade vane. The rheological properties of self-consolidating concrete (SCC) containing different mineral admixtures (MA) were investigated using an ICAR rheometer. The mineral admixtures were fly ash (FA), ground granulated blast furnace slag (GGBS), and micro silica (MS). The results obtained using traditional workability results are compared with those obtained using ICAR rheometer. The instrument ICAR (International Center for Aggregate Research) rheometer employed in the present study for evaluating the rhelogical behaviour of the SCC is found to detect systematic changes in workability, cementitious materials, successfully. It can be concluded that the rheology and the slump flow tests can be concurrently used for predicting the flow behaviours of SCC made with different cementitious materials.

Utilization of high volumes of unprocessed lignite-coal fly ash and rice husk ash in self-consolidating concrete

Abstract This paper describes a study undertaken to explore the use of a high volume of lignite coal fly ash (FA) as a replacement for Type I Portland cement (OPC) and a high volume of rice husk ash (RHA) as a replacement for fine aggregate in the production of self-consolidating concrete (SCC). OPC was partially replaced with 0%, 20%, 40%, and 60% FA by volume, and fine aggregate was replaced with 0%, 25%, 50%, 75%, and 100% RHA by volume. Mixtures were designed based on a slump flow diameter of 70 ± 2.5 cm. The workability properties ( i.e. slump flow, T 50 cm slump flow time, V-funnel flow time, and J-ring flow) and hardened properties ( i.e. compressive strength and ultrasonic pulse velocity) of SCC were determined, and a blocking assessment was performed. Increasing the FA or RHA content beyond a certain level reduced the compressive strength and increased the water requirement of the SCC mixture. However, up to 60% FA could be used to produce SCC with a compressive strength of 40–50 MPa. In addition, RHA could comprise up to 25% of the SCC, which is an acceptable value of compressive strength according to the Building Code Requirements. Moreover, partial replacement of OPC by FA and fine aggregate by RHA can result in substantial cost savings and alleviate environmental problems.

Properties of self-consolidating concrete containing nano-CaCO3

This paper studied the effect of nano-CaCO3 on workability, strength development, and pore structures of cement paste and self-consolidating concrete. The effects of dosage and size of nano-CaCO3 were considered. For the workability, slump flow (total spread and T50 time), L-box, and V-funnel tests were conducted. The compressive strength was tested at 1, 7, and 28 days for concrete and 1 and 7 days for cement paste. The pore structure, including pore size distribution and volume, was measured using nitrogen adsorption method. The results show that the addition of nano-CaCO3 reduced the setting times. Concrete with a low content of nano-CaCO3 (≤2.5%) had satisfactory workability. No segregation was observed for all concrete specimens. The addition of nano-CaCO3 increased the compressive strength of the concrete and paste. The compressive strength decreased as the particle size increased. The addition of nano-CaCO3 reduced the average pore diameter. XRD test showed no new hydration products.

Capillary tension theory for prediction of early autogenous shrinkage of self-consolidating concrete

Based on the capillary tension theory and microstructure pore of concrete, a prediction method of early autogenous shrinkage of self-consolidating concrete (SCC) was established. Self-consolidating concrete (SCC) specimens with different strength grades were prepared. The physical and mechanical properties (autogenous shrinkage, Poisson’s ratio, modulus of elasticity and compressive strength) of SCC with different strength grades were tested at the age of 3, 7, and 28days. The 3, 7 and 28days pore distribution of capillary pores of SCC with different strength grades were also tested. Negative pressure of capillary and autogenous shrinkage were determined by means of capillary tension theory. Finally, based on the calculation results, a prediction method of early autogenous shrinkage of SCC was established. The results show that predicted values derived from this model matched very well with measured values.

Effect of Rubber Aggregates on the Thermophysical Properties of Self-Consolidating Concrete

In this work, our choice fell on the exploitation of rubber aggregates from used tires. In this context, an experimental study was conducted to provide more data on the effect of rubber aggregates on the thermophysical properties of self-consolidating concrete (SCC). To this end , four sets of rectangular specimens were prepared by varying the proportion of the rubber aggregates with percentages of 0%, 10%, 20% and 30% of the volume of gravel .Tests on hardened self-consolidating concrete rubber SCCR included measuring the thermal conductivity and the thermal diffusivity by the method of the boxes at steady and determining the specific heat . The results showed that the thermal conductivity and thermal diffusivity were decreased according to the increase of the percentage of rubber aggregates. This decrease was significantly improved thermal performance of the SCCR.

Effects of particle packing density on the stability and rheology of self-consolidating concrete containing mineral admixtures

This paper presents an experimental study on the influence of packing density of solid particles on the stability and rheology of self-consolidating concrete (SCC). Also it is tried to address a new method for determination the packing density of SCC mixtures. Seven powder-types of SCC mixtures with different packing density were made with inclusion of silica fume, metakaolin or low activity-granulated blast furnace slag as a substitution of Portland cement. Results demonstrated that there is an optimal packing density about 0.804 and a little lower than maximum packing density of 0.807 with minimum static segregation and final plastic settlement. Moreover in the optimum packing density of particles, the calculated velocity and rheological properties of SCC are improved. The results emphasized that the effects of mineral admixtures are completely different in the static and dynamic segregation. Mineral admixtures reduced static segregation (SCC at rest in vertical state) but increase dynamic segregation (SCC at flowing in horizontal state). This finding shows that the cementitious binder content must be sufficient in flowing state to restraint from dynamic segregation.

Application of Statistical Analysis for Mixture Design of High-Strength Self-Consolidating Concrete Containing Metakaolin

A statistical design of experiments method was applied to optimize the mixture proportions of high-strength self-consolidating concrete (SCC) incorporating metakaolin (MK). The optimization involved varying three mixture factors (variables) at five different levels. These factors included total binder content, percentage of MK in the mixture, and water-to-binder ratio. The statistical analysis was exploited to determine the most significant factors affecting the properties of SCC and the optimum level of each variable. A total of 27 mixtures were tested at both the fresh and hardened states to obtain the best SCC mixture containing MK and to compare its results with SCC mixtures containing other supplementary cementing materials. The fresh properties tests included slump flow, V-funnel, L-box, J-ring, and air content tests. On the other hand, at 28 days, the compressive strength of SCC samples under two curing regimes was evaluated. The results showed that the optimized high-strength SCC mixture had a superior performance in the fresh and hardened states compared with the SCC mixtures containing silica fume, fly ash, or slag. The results of the numerical optimization for SCC mixture containing MK showed optimum levels of total binder content of 490 kg/m3, water-to-binder ratio of 0.39, and replacement of cement by MK of 19.9%. The results also showed that MK replacement proved to be the most significant factor affecting the 28-day compressive strength of all tested mixtures regardless of curing techniques.

Effect of paste amount on the properties of self-consolidating concrete containing fly ash and slag

The objective of this paper is to compare the performance of concrete containing fly ash and slag under different water-to-cementitious materials ratios and different cement paste content. The densified mixture design algorithm (DMDA) was applied in the concrete mix design. Concretes designed by DMDA with excellent flow-ability and without bleeding and segregation were obtained. The proper paste amount the better the workability and the less the workability loss. On the basis of sufficient paste amount condition, the study discovers that the less the cement paste amount as well as the denser the blended aggregate, the lower the early-age compressive strength will be, on the contrary, the higher the long-term compressive strength becomes. To design of good quality concrete, the amount of cement paste and water should be minimized as low as possible to obtain the high ultrasonic pulse velocity.

Mechanical and durability properties of self consolidating high performance concrete incorporating natural zeolite, silica fume and fly ash

Mineral admixtures are widely used as cement replacement materials in both high performance concrete (HPC) and self consolidating concrete (SCC). While the effect of mineral admixtures on rheological properties of SCC and mechanical behavior of HPC has been investigated by many researchers, further research is needed to optimize the effective dosage of these admixtures in self consolidating high performance concrete (SCHPC). Moreover, the effects of some mineral admixtures such as natural zeolite on properties of SCHPC has not been well established yet. This paper discusses the effect of natural zeolite, silica fume and fly ash on the properties of fresh and hardened concrete. Slump flow, superplasticizer demand, compressive strength, electrical resistivity, water absorption and chloride permeability were measured for all mixes. The test results indicate that incorporation of mineral admixtures generally improve mechanical and durability characteristics of the mixes. However, silica fume is slightly more effective than natural zeolite or fly ash in improving durability properties of SCHPCs, while natural zeolite is much more cost effective.

Mechanical properties of prestressed self-consolidating concrete

Since the mix design of self-consolidating concrete (SCC) differs from that of conventional concrete, mechanical properties of SCC may differ from those of vibrated concrete. An experimental program was performed to evaluate mechanical properties of SCC used for precast, prestressed applications. Sixteen SCC mixtures with a fixed slump flow of 680 ± 20 mm were prepared with different mixture parameters, including binder content and binder type, w/cm, dosage of viscosity-modifying admixture, and sand-to-total aggregate volume ratio. Two high-performance concrete mixtures that represent typically concrete used for precast, prestressed applications were investigated for the control mixtures. They were proportioned with 0.34 and 0.38 w/cm and had slump values of 150 mm. Mechanical properties of SCC were compared to code provisions to estimate compressive strength, elastic modulus, and flexural strength. The modified ACI 209-90 and CEB-FIP MC90 codes are found to provide good estimate for compressive strength prediction. The AASHTO 2007 model can provide good prediction of the elastic modulus and flexural strength of SCC.