Review on the Application of Supplementary Cementitious Materials in Self-Compacting Concrete

Effects of different supplementary cementitious materials on durability and mechanical properties of cement composite - Comprehensive review

Ordinary Portland cement is the highest produced cement type in the world, however its production is high energy consumption means expensive, huge natural resource consumptive, and creating high environmental pollution. Hence many researchers studied to reduce the effect of ordinary Portland cement by substituting artificial and natural supplementary cementitious materials (SCMs) commonly in a concrete/mortar mixture. However, the comprehensive effect of different SCMs on various properties of cement composite materials are not well known. So the present study sought to review the effect of different natural and artificial SCMs on the durability and mechanical properties of cement composites, especially due to their doses, types, chemical composition, and physical properties. Hence the review shows that many SCMs used by literatures from different places satisfy ASTM replacement standard based on their chemical compositions. Also, the review indicated as adding 5-20% of different SCMs positively affect mechanical properties, durability, and microstructures of the cement composite materials, specifically as most researchers found isolately adding of 15% SCMs such as bentonite, kaolin, and biomass, 20% addition of volcanic ash and 10% employment of fly ash, silica fume, and zeolite to the cement composites achieves the most optimum compressive and split tensile strength. These observations reveal that most natural pozzolana can more replace cement to give optimum strength, hence can more reduce energy consumption, production cost, and environmental pollution comes due to cement production. Furthermore, most researchers found employing different SCMs generally improves durability, however there is a limited study on the effect of silica fume on water absorption and acidic attack resistance of cementitious materials. Therefore, it is recommended that future research should also focus more to know the effect of silica fume on the durability of cement composites.

Prediction of the Rheological Properties of Fresh Cementitious Suspensions Considering Microstructural Parameters

Supplementary cementitious materials (SCMs) are commonly used to partially replace cements. Although it is necessary to investigate the rheological properties of the individual supplementary cementitious materials (SCMs) for understanding complex rheological behaviors of the blended mixes, the study on the investigation of rheological properties of various SCMs such as fly ash, blast-furnace slag, and silica fume, according to various solid volume fractions and prediction models is fairly limited. This study investigated the rheological properties of non-blended cementitious suspensions with Portland cement (PC), fly ash (FA), blast-furnace slag (BS), and silica fume (SF) materials in the experiments and predicted using YODEL (Yield stress mODEL) and Krieger-Dougherty's (K-D's) equation. Experiments were designed with various solid volume fractions (ϕ) from 0.28 to 0.44, and the rheological properties of all cementitious suspensions were noted to increase with increasing ϕ, showing an improved flowability at low ϕ. YODEL, derived from the first principles considering particle-size distributions, interparticle forces and microstructural parameters predicted the yield stress. The YODEL predictions were consistent with the experiments with a positive correlation coefficient of above 0.96. K-D's equation with the maximum particle fractions and intrinsic viscosity as key parameters predicted the plastic viscosity. The K-D's equation predictions match up with the experiments with a positive correlation coefficient of above 0.94. Both models showed more quantitative predictions without any fitting parameters and could be applied to any multimodal powder suspensions.

Properties of Self-Compacting Concrete Using Multi-Component Blend Binders for CO2 Reduction

This paper aims to reduce the quantity of cement used by up to 80% by utilizing industrial by-products. By reducing the amount of cement used, there is an effect of reducing CO2 emissions during cement manufacturing. To reduce the amount of cement used, ground granulated blast-furnace slag (GGBF), fly-ash (FA), and calcium carbonate (CC) were used as substitute materials for cement. CC is a by-product, discharged by collecting CO2 emitted from a coal-fired power plant and reacting with additives. The specific surface area and the average particle size of CC used are 12,239 cm2/g and 5.9 μm (D50), respectively. The viscosity of pastes that contained GGFF and FA decreased by up to 51 and 49% respectively compared to the use of only cement (OPC) paste. However, paste using with CC increased up to 23% in relation to plain. As a result of measuring slump flow, segregation resistance ability, and filling ability to evaluate construction performance, slump flow was reduced by up to 3% (G40F10C30) in relation to plain concrete. Segregation resistance ability of fresh concrete using, GGBF (15, 30, and 45%), FA (10, 20, and 30%), CC (10, 20, and 30%), the time it takes for the slump flow to reach 500 mm, time it takes to through the V-funnel showed a decreasing tendency as the usage of FA increased. However, CC increased with increasing mixing ratio. This trend is, the viscosity increase when CC was mixed in terms of rheology. Filling ability of fresh concrete using GGBF (15, 30, and 45%), FA (10, 20, and 30%) and CC (10, 20, and 30%), the criteria were met, and the average increase was 16% and the maximum was 20% in relation to plain concrete. In the case of compressive strength, the compressive strength at 1 day was found to be an average of 5 MPa when 80% of the cementitious was substituted. At 3 days, at least 8 MPa was measured. The compressive strength at 28 days showed a tendency to decrease as the mixing rate of CC increased, but was measured to be at least 34 MPa. The relationship between compressive strength and splitting tensile strength or elastic modulus at 28 days satisfies the standard range.

Development of High-Tech Self-Compacting Concrete Mixtures Based on Nano-Modifiers of Various Types

Promising areas of concrete material science are maximum greening, reducing the carbon footprint, and, at the same time, solving the problems of increasing the cost of raw materials using industrial waste as modifiers for self-compacting concrete mixtures. This study aimed to review, investigate and test from the point of view of theory and practice the possibility of using various industrial types as a nano-modifier in self-compacting concrete with improved performance. The possibility of nano-modification of self-compacting concrete with a complex modifier based on industrial waste has been proved and substantiated theoretically and experimentally. The possibility of improving the technological properties of concrete mixtures using such nanomodifiers was confirmed. The recipe and technological parameters of the process were revealed and their influence on the characteristics of concrete mixes and concretes were expressed and determined. Experimental technological and mathematical dependencies between the characteristics of the technological process and raw materials and the characteristics of concrete mixtures and concretes were determined. The optimization of these parameters was carried out, a theoretical substantiation of the obtained results was proposed, and a quantitative picture was presented, expressed in the increment of the properties of self-compacting concrete mixtures using nano-modifiers from industrial waste concretes based on them. The mobility of the concrete mixture increased by 12%, and the fluidity of the mixture increased by 83%. In relation to the control composition, the concrete strength increased by 19%, and the water resistance of concrete increased by 22%. The ultimate strains decreased by 14%, and elastic modulus increased by 11%.

Residual Compressive Behavior of Self-Compacting Concrete after High Temperature Exposure-Influence of Binder Materials

This paper presents an experimental investigation of the compressive behavior of high-strength self-compacting concrete exposed to temperatures up to 600 °C. Ten different concrete compositions were tested, in which part of the cement (by weight) was replaced by three different mineral additives (5–15% metakaolin, 20–40% fly ash and 5–15% limestone). The stress–strain curves, compressive strength, modulus of elasticity and strain at peak stress were evaluated from uniaxial compression tests. Scanning electron microscope micrographs were also taken to evaluate the damage caused by the high temperatures. A sharp decrease in mechanical properties and an increase in peak strain were observed already after 200 °C for all mixes tested. The different mineral additives used in this study affected the variations of residual compressive strength by 24% and peak strain by 38%, while the variations of residual modulus elasticity were 14%. Comparing the obtained results with the recommendations for compressive strength given in regulatory code EN 1992-1-2 for high strength concrete, it can be concluded that the strength loss observed in EN 1992-1-2 at temperatures up to 400 °C is too conservative. The Popovics model for the relationship between stress and strain provided a good approximation for the experimentally determined stress–strain curves at different temperatures.

Rheological and Durability Properties of Self-Compacting Concrete Produced Using Marble Dust and Blast Furnace Slag

Self-compacting concrete (SCC) is a special, highly fluid type of concrete that is produced using chemical additives. It is easier to pour and reduces defects arising from workability. Waste marble dust is generated during the production of marble using different methods, or during the cutting of marble in processing plants; however, the uncontrolled disposal of waste marble dust in nature is associated with some environmental problems. Cement and concrete technology is a field with potential for the utilization of these large amounts of waste. The present study explores the use of marble dust (MD) (an industrial waste generated in abundance around the province of Bilecik) and granulated blast furnace slag (GBFS) (another industrial waste product) in the production of SCC. In this study, MD and GBFS are used as fine materials in SCC mixtures, and the rheological and workability properties and other hardened concrete properties of the produced SCC specimens are tested. Additional tests are conducted to identify the durability of the specimens to sulfate attack, as well as their freeze–thaw and abrasion resistance, followed by microstructure tests to identify the effects of MD and GBFS on bond structure. The late-age performances of MD and GBFS were then examined based on the results of the durability tests. The presented results revealed improvements in the fresh and hardened properties of SCC produced using MD and GBFS.

Effect of Fineness and Heat Treatment on the Pozzolanic Activity of Natural Volcanic Ash for Its Utilization as Supplementary Cementitious Materials

The aim of this study was to investigate the influence of fineness and heat-treatment on the pozzolanic and engineering properties of volcanic ash. To this end, two different fineness levels of volcanic ash, ultra-fine (VAF) and fine (VA), without and after heat treatment at different temperatures (VA550, VA650, and VA750), were partially substituted for cement. In addition to the control (100% cement), five binary mortar mixes, each containing 20% of the different types of volcanic ash (VAF and VA; heat-treated and not), were prepared. First, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), particle size analysis, and modified Chappelle tests were used to characterize the material. All mortar mixes were then tested for compressive strength development, water absorption, and apparent porosity. Finally, the microstructure of each of the mixes was evaluated by performing XRD, thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) analyses on paste samples at 91 days post-formation. The XRD and Chappelle reactivity results revealed increased pozzolanic reactivity with increasing volcanic ash fineness. In contrast, heat treatment adversely affected the pozzolanic reactivity of the volcanic ash due to the formation of crystalline phases at high temperatures. The mortars containing VAF20 (VAF, no heat, at 20%) showed slightly improved compressive strength (69.6 MPa) than the control (68.1 MPa) and all other binary mixes (66.7, 63.5, 64.2, and 63.9 MPa for VA20, VA20-550, VA20-650, and VA20-750, respectively) at 91 days. The mortar containing VAF20 demonstrated the lowest level of water absorption (9.3%) and apparent porosity (19.1%) of all mixes, including the control. The XRD results for the paste samples show that both VA and VAF showed the least intensity of portlandite phase, as compared to the control and other binary mixes. TGA results also show that binary mixes of VA and VAF have a reduced amount of portlandite, resulting in the densification of the mixes’ microstructures. With the addition of VAF, there is a significant shift in the FTIR band from 980 to 992 cm−1, which causes the formation of additional C–S–H gels that lead to the densification of the paste matrix. These results demonstrate that VAF exhibits high pozzolanic reactivity, making it suitable for use as a natural pozzolan that can partially substitute cement in the production of strong, durable, and environmentally friendly concrete.