Normal Cement Concrete Research Articles

Strength, Durability and Permeability Studies on Cement Concrete with and without Nano-Silica

The application of nanomaterials in cement/concrete has resulted in the development of smart materials which are durable, sustainable and high performance oriented apart from being eco-friendly. Several types of nanomaterials are being used by researchers all over the world to improve the properties of cementitious system, amongst them silica nanoparticles (SNPs) have been credited with high pozzolanic reactivity and pore filling effects. It is also very well known that permeability is the major factor for deteriorations of concrete structures in the long term thus affecting its durability. A thorough study was performed on cement mortar composites and standard grade concrete with the additions of colloidal silica nanoparticles(SNPs) in various dosages starting from 0.5%,0.75%,1.0%,1.25% and 1.5% by weight of cement(b.w.c.) to understand the impact from micro-structure improvement to macro-level property enhancement. The results show that in presence of colloidal SNPs (Indian branded) having 35-40% active nano content with 5-40nm particle size the strength increase at 28 days is 32% increasing to 59% at 90 days. An influence on durability is also observed with strength increasing from 4% to 8% with the addition of more SNPs from 0.75% to 1.0% b.w.c. The microstructural investigations reveal that silica nanoparticles refines the pore structure due to accelerated hydrated mechanisms leading to the creation of more hydration products and thus to a more denser microstructure. A M-40 grade standard concrete was prepared as per IS:10262 with the addition of optimized SNPs as found for cement mortar composites strength results at 28 days maximum strength keeping the water-cement(w/c) ratio fixed at 0.4. Tests were conducted on concrete to find out the compressive strength and permeability of concrete. The compressive strength of concrete containing nano materials were found to be 24% more than that of normal cement concrete (NCC) of M-40 grade. The permeability values were found to be decreased by 57% with the addition of nano silica particles to concrete.

A feasibility study on Engineered cementitious Composites mixed with coarse aggregate

Coarse aggregate (CA) is one of the major components in normal cement concrete. However, CA is excluded from the mixture of Engineered Cementitious Composites (ECC), due to its negative effects on material’s tensile behavior. This brings some issues to ECC, such as high shrinkage, high production cost, and insufficient greenness. In an attempt to improve ECC without losing its advantages in tensile properties, the authors challenged to develop ECC with a high volume fraction of CA. In the present study, the authors experimentally studied the influences of CA content and water to binder (w/b) ratio on mechanical properties, shrinkage, and material sustainability. The test results indicated that ECCs mixed with moderate CA not only maintain strong strain-hardening and multiple-cracking characteristics, but also have similar tensile stress and tensile strain capacity, as compared with the conventional ECC. The maximum value of strain capacity of CA-ECC reached 7.9 % at 0.21w/b, and the average tensile strain of all mixtures exceeded 2 %. Moreover, CA was experimentally verified capable to reduce shrinkage, carbon footprint, energy consumption and producing cost simultaneously. The carbon footprint, energy consumption and cost of CA30-ECC18 were reduced by 33.1 %, 24.4 % and 36.1 %, compared to conventional ECC. The present study preliminarily verified the feasibility of producing ECC with coarse aggregate.

Analysis of Adding GGBS and Fly Ash in Self Compacting Geo - Polymer Concrete for Structures

In the olden days, some eco-friendly and easily accessible materials such as mud, lime, and egg mixer were used in the building constructions. However, these materials are not sufficient to construct huge and more buildings. For this, the researchers preferred the cement as the main binding material used in the concrete mixture. The cement manufacturing companies are releasing more CO₂ during cement production, which leads to the environmental pollution in the earth. To overcome the problem of the ecological system, this work proposed the Self Compacting Geo- Polymer Concrete – SCGPC, which is not a normal cement concrete. The SCGPC is used to fill cavities easily and rapidly without any compaction. The industrial wastes like fly ash, GGBS - Ground Granulated Blast - furnace Slag, metakaolin kaolinite, clay, iron ore, silica fume and limestone can be used as the substitute materials for cement. This work mainly concentrates on the effects of two specific mechanical properties such as split tensile and compressive strength of SCGPC by adding fly ash and GGBS. These factors were evaluated with the Alkaline Activator Solution (AAS) to fly ash and GGBS ratio, the ratio of Na₂SiO₃ solution to the NaOH solution, the dosage of superplasticizer, rest period and temperature degree. The proposed SCGPC (8M, 10M and 12M) has analyzed both split tensile and compressive strength in three sets (7, 28 and 56 days). At last, the analyzed results were compared with conventional concrete. Based on the comparison, while the increase of curing temperature, both mechanical properties of SCGPC have reduced.

Comparative Study on the Effects of Steel Slag Aggregate over Blended Cement Concrete

Abstract: Concrete is the most versatile construction material because it can bedesigned to withstand the harshest environments while taking on the most inspirational forms. Engineers are continually pushing the limits to improve its performance with the help of innovative chemical admixtures and alternative construction materials (ACM). Nowadays, most concrete mixture contains alternative construction materials which form part of the cementitious component. These materials are majority byproducts from other processes. The main benefits of ACM (alternative construction materials) are their ability to replace certain amount of cement or aggregates and still able to display major properties similarto concrete, thus reducing the cost of using traditional materials. The fast growthin industrialization has resulted in tons and tons of byproduct or waste materials, which can be used as ACMs (alternative construction materials) such as marble powder, silica fume, ground granulated blast furnace slag, steel slag etc. The useof these byproducts not only helps to utilize these waste materials but also enhances the properties of concrete in fresh and hydrated states. Most concrete produced today includes one or more ACM (alternative construction materials). For this reason, their properties are frequently compared to each other by mix designers seeking to optimize concrete mixtures. To design high strength concrete good quality aggregates is also required. Steel slag is an industrial byproduct obtained from the steel manufacturing industry. This can be used as aggregate in concrete. It has been usually used as aggregate in hot mix asphalt surface applications, but in the present work it has been used in conventional concrete mixture and performance is compared with normal aggregate concrete. Replacing all or some portion of natural aggregates with steel slag would lead to considerable environmental benefits. Steel slagaggregate generally exhibit a propensity to expand hence steel slag aggregates are generally not used in concrete making. However, use of blended cement concrete is reported to reduce the expansion of the concrete. In the present work a series of tests were carried out to make comparative studies of various mechanical properties of concrete mixes prepared by using normal cement concrete, marble powder and cement blend concrete (1:1 proportion ) with or without use of steel slag. The ingredients are mixed in 1: 1.5: 3 proportions. The properties studied are 7 days, 14 days and 28 days compressive strengths, workability and surface hardness. Keywords: Cement, Concrete, Steel Slag, Aggregates, Blended Cement,Marble Powder.

Ultraductile waterborne epoxy-concrete composite repair material: Epoxy-fiber synergistic effect on flexural and tensile performance

With the extension of service time, infrastructure is in growing urgency for repair and reinforcement due to its deterioration in safety and durability over the years. Normal cement concrete has shortcomings, e.g., high brittleness and low flexural-tensile strength, that fail to meet the requirements of construction repair. In this paper, a novel waterborne epoxy-concrete composite repair material (WECM) was prepared by using self-synthesized water-based epoxy resin based on the molecular structure-activity relationship. The mechanisms of waterborne epoxy (WEP) and WEP-fiber synergy on the improvement of concrete performance were clarified. The results show that the defects of high brittleness and poor ductility of concrete are significantly improved by WEP and that the ductility of WECM is increased by 300%–600% compared with the control concrete. The fiber and WEP in the WECM exhibited a synergistic effect on the tensile strength, ductility, and crack resistance of concrete in which the fiber coating layer mixed with WEP and embedded cement particles (inlay) provided fiber protection as well as an interfacial bonding enhancement. The P/C of 0.2 is the turning point of the flexural and tensile strength of the WECM, which is related to the continuous phase formation of the WEP-interpenetrating polymer network (WEP-IPN).

Creep Strain Behaviour of Triple-Blended Steel Fiber Self-Compacting Concrete

The objective of the research article is to present the experimental results on the creep strain behaviour of steel fiber Self-Compacting Concrete (SFSCC). In respect of binder content, aggregate size, fine-to-coarse aggregate ratio, water-to-cement ratio, and chemical admixtures, Self-Compacting Concrete (SCC) differentiates from conventional cement concrete. Steel fibers are also inserted into SCC at a predetermined percentage to reinforce it. Steel fibers have been shown to contribute to improved strength characteristics, a dense mass of concrete with little or no voids, reduced pores in concrete, a higher Young’s modulus, and fewer deflections and strains in concrete. Hence, an investigation was conducted on the creep variation of SFSCC over a longer duration. The test approach follows ASTM C512’s standard test method for concrete creep in compression. The test specimens (SFSCC) are standard cylinders that have been cast and cured for 28 days before being tested. Three SFSCC cylinders with 0.80% steel fiber were tested at the same time. The load is applied to just the cylinders in the loading frame and kept constant, producing constant stress. The strains that occur only due to creep, excluding the initial elastic strain, are digitally recorded. As a logarithmic function, the creep strain-time connection was established. The conclusions are observed based on the findings of the experiments and compared with normal cement concrete (NCC).

Geopolymer concrete: Sustainable green concrete for reduced greenhouse gas emission – A review

Concrete is one of the important components of construction, which constitute cement as the major component. Due to this increased use of concrete, there has been an increase in greenhouse gas evolution, mainly cardon dioxide, which occurs in the process of hydration. In order to reduce the greenhouse gas evolution, geopolymer has been introduced which is an alumino-silicate based binding material comprising of fly ash, which is an industrial waste material, and alkaline liquids, which reacts with the fly ash to form geopolymer. This paper reviews the different techniques or material proportions adopted by different researchers for design mix of geopolymer concrete to obtain the maximum compressive strength. The strength and durability properties, carbon footprint and cost analysis of geopolymer concrete have been studied and analyzed against normal cement concrete. The study shows that inclusion pozzolanic materials in the geopolymer concrete mix increases the compressive strength substantially. Silica fume when used in geopolymer concrete along with sodium hydroxide serves as alkali activator, thus, reducing the overall carbon footprint and giving an added advantage over normal cement concrete. Also, the use of industrial waste materials over conventional cement in concrete reduces the overall cost of geopolymer concrete.

Development of pavement quality concrete with SCM’s, fibers and graphite

Concrete is widely used for the construction of pavements all over the world. Nevertheless, normal cement concrete has certain shortcomings, which are low flexural strength, and high thermal conductivity. So, to overcome these draw backs admixtures like fly ash, silica fume etc. are used. Further, fibers also significantly participate in reducing the thermal conductivity and improving the flexural strength of concrete. Increasing coarse aggregate content also, decreases the thermal conductivity of concrete, but it reduces the flexural strength. The aim of this study is optimize the aggregate content and make sequential inclusion of mineral admixtures as well as fibers and graphite to enhance the mechanical, Durability and thermal conductivity properties of pavement quality concrete. This studies show that a permissible amount of 55% coarse aggregates could be used along with 10% of silica fume (SF) and 20 % of fly ash (FA) in the presence of 1.5% of steel fibers and 10% of graphite to yield better result in comparison to conventional concrete.

The Influence of Different Natural Fibers on the Mechanical Properties of Geopolymer

Geopolymers can effectively deal with construction waste disposal problems, achieving resource recycling and higher strength than normal cement concrete. However, natural defects make geopolymer concrete difficult to apply in actual construction. This paper aims to make up for the natural defects of geopolymers while maintaining environmentally friendly materials. The low-calcium fly ash and blast furnace refining slag powder are used as raw materials, sodium silicate and sodium hydroxide are used as alkali activators, and chopped natural fibers are added as reinforcing materials to prepare natural fiber reinforced low-calcium fly ash and blast furnace refining slag base. Polymeric composites were used to investigate the effects of different natural fibers on the workability, compressive strength, tensile strength, water absorption, shrinkage and microstructure of geopolymer composites.

High Density Concrete Using Different Aggregates With Addition of Geo Polymers and Rice Husk Ash

S Cement Concrete is one of the most important material used in construction, as it provides good ductility and can be moulded into any shape. Normal cement concrete holds a very short tensile strength, limited ductility and little resistance to cracking. It has been initiated that various types of fibers added in exact percentage to concrete expands the mechanical properties, durability and serviceability of the structure. The main aim of the study is to study the strength of M20 grade of concrete by adding rice husk ash and barite comparing with conventional concrete. The admixtures are added from replacing cement with fly ash and GGBS at 25%, 50% & 75% to the volume of cementious material. The mechanical properties namely compressive strength, split tensile strength were carried for concrete specimen at different age level and the basic test was conducted for cement, coarse aggregate and fine aggregate.

Impact resistance of concrete with nano materials

Nano science and technology is a new field of emergence in materials science and engineering, which forms the basis for evolution of novel technological materials. Nano materials in concrete improve the mechanical properties of concrete. An attempt has been made to determine the impact strength of concrete in which cement is replaced with nano materials and to compare the impact strength of concrete with nano materials with that of the Normal Cement Concrete (NCC). M20, M30, M40 and M50 grades of concrete were designed as per IS 10262-2009. For each grade of concrete, 10%, 20%, 30%, 40% and 50% of cement was replaced with Nano Cement (NC), Nano Fly Ash (NFA), Nano Silica (NS) and Nano Silica Fume (NSF). The behaviour under impact was studied as per drop weight impact method. The results indicated that the concrete with nano materials exhibited better performance against impact loading when compared with NCC.

Comparison of Mechanical Properties of Normal and Fibre Reinforced Concrete (Grade M15)

Concrete is weak in tension, hence some measures must be adopted to overcome this deficiency as well as to enhance physical and other mechanical properties but in more convenient and economical method. Through many research from the past, it has been observed that addition of different types of fibres has been more effective for this purpose. This report presents the work undertaken to study the effect of steel and hay fibre on normal cement concrete of M-15 Grade on the basis of its mechanical properties which include compressive and tensile strength test and slump test as well. Although hay fibres are abundantly available in Nepal, no research have been popularly conducted here regarding the use of hay fibres in concrete and the changes brought by it on concrete’s mechanical properties. Experiments were conducted on concrete cubes and cylinders of standard sizes with addition of various percentages of steel and hay fibres i.e. 0.5%, 1% and 1.5% by weight of cement and results were compared with those of normal cement concrete of M-15 Grade. For each percentage of steel and hay fibre added in concrete, six cubes and six cylinders were tested for their respective mechanical properties at curing periods of 14 and 28 days. The results obtained show us that the optimum content of fibre to be added to M-15 grade of concrete is 0.5% steel fibre for compression and 0.5% hay fibre content for tension by weight of cement. Also, addition of steel and hay fibres enhanced the binding properties, micro cracking control and imparted ductility.
 In addition to this, two residential buildings were modeled in SAP software, one with normal concrete and other with concrete containing 0.5% steel fibre. Difference in reinforcement requirements in each building was computed from SAP analysis and it was found that 489.736 Kg of reinforcement could be substituted by 158.036 kg of steel fibres and decrease in materials cost of building with 0.5% steel fibre reinforced concrete was found to be Rs. 32,100.

Effect of Fly Ash and Fibres on Strength and Permeability Characteristics of Pervious Concrete

Conventional normal cement concrete is generally used as construction material of buildings. The impervious nature of concrete contributes to the increased water runoff into drainage system, over-burdening the infrastructure and causing excessive flooding in built-up areas. Pervious concrete has become significantly popular during recent decades, because of its potential contribution in solving environmental issues. Pervious concrete is a type of concrete with significantly high water permeability compared to conventional concrete. It has been mainly developed for draining water from surface to underground, so that storm water runoff is reduced. Due to high water permeability then normal concrete, pervious concrete has very low compressive strength. The characteristic of high permeability of pervious concrete contributes to its advantage in storm water management. However, the mechanical property such as low compressive strength limits the application of pervious concrete to the roads having light volume traffic. It is observed form previous studies that the strength of pervious concrete can be enhanced by substituting some of the cement with other materials, such as fly ash and fibres. The objective of present study was to make pervious concrete mix with high strength and pore properties by partial replacement of cement with fly ash and using steel and glass fibres. For this purpose cubes beams were casted with and without replacement of cement with flyash and addition of steel and glass fiber by total weight of concrete mix. Test such as compressive strength, flexural strength, total porosity and Infiltration rate were performed. It was observed addition of fly ash decreased the compressive as well as flexural strength of the pervious concrete. Further, incorporation of 1% steel fibres by weight of concrete mix was found adequate in achieving high strength and permeability, when compared to control mix concrete

Effect of Lakhra Fly Ash as Partial Replacement of Cement in Traditional Concrete

This study was aimed to determine the effect of LFA (Lakhra Fly Ash) as partial replacement of cement in concrete. To conduct this study, a total of 72 standard concrete cylinders were cast with 1:2:4 proportions at 0.5 water-binder ratios. Cement was partially replaced by weight with LFA and the percentage replacements of FA (Fly Ash) were kept as 0, 5, 15, 25, 40 and 50%. In addition to that, workability of each mix was determined by Slump Cone test and Compaction Factor test. Out of 72 cylinders, 36 cylinders were tested to determine the compressive strength while the remaining 36 cylinders were tested to determine the tensile strength of concrete, at 7 days curing period, by using UTM (Universal Testing Machine). The results revealed that 25% replacement of binder with LFA, determined an increase in compressive strength of concrete up to 15% as compared to normal cement concrete. Moreover, the tensile strength of concrete also increased up to 16% for the same percentage replacement. Furthermore, it also increased the workability, cohesiveness and surface finishes of concrete. This finding can help to reduce the admixture dosage or the water content of the mix. On the contrary, the compressive strength as well as the tensile strength of concrete decreased in case of 40 and 50% replacements of the cement with FA.

Effects of Coconut Sawdust on Mechanical Properties and Porosity of Concrete Mixtures

The presence of coconut sawdust in North Sulawesi is very potential to be utilized as an alternative material for application in construction field. This paper aims to investigate experimentally the effect of coconut sawdust as an addition on concrete mixtures based on compressive strength, flexural strength and volume permeable voids tests. In this study, coconut sawdust with percentage of 2.5%, 5% and 7.5% by weight of cement was added into concrete mixture. The results show that concrete containing 5% of coconut sawdust exhibited highest compressive strength at 7 days with average value is 25.71 MPa while at 28 days the compressive strength is 30.50 MPa and there is no significant difference compared with 2.5% variation. When comparing the results of flexural strength test between 5% and normal cement concrete, the highest result is achieved by normal concrete reaching the value 6.78 MPa while for the concrete with 5% of coconut sawdust addition is only on 4.82 MPa. In terms of the volume of permeable voids, the results show that the porosity of concrete with coconut sawdust increased with the increase of percentage of coconut sawdust at 7 days but the values decreased as the age of curing increased.

EFFECTS OF METAKAOLIN ON COMPRESSIVE STRENGTH AND PERMEABILITY PROPERTIES OF PERVIOUS CEMENT CONCRETE

This paper presents the experimental results on the effect of metakaolin (MK) as a replacement of cement in pervious cement concrete based on compressive strength, void ratio and permeability test. Metakaolin was used to replace Portland Cement Composite (PCC) in pervious concrete by 10% (by wt.). The results show that pervious concrete sample containing 10% metakaolin with 1% superplasticizer exhibited 4 times higher compressive strength at 7 days when compared to normal cement concrete. In addition, the continuous voids of 10%MK concrete sample was found higher than PCC only, indicating the effectiveness of metakaolin in improving the interfacial bond of the binders due to micro-filler effect of metakaolin and the additional CSH gel formation. The continuous voids of pervious concrete with 10% MK is 17%, which is higher than the percentage of continuous voids in normal pervious concrete. This finding is also supported by the infiltration rate of concrete samples. Furthermore, the microstructure analysis through Backscattered Electron Imaging and X-Ray Diffraction reported denser matrix and CH reduction in polished paste samples due to 10%MK addition.

Effect of Nano Iron Oxide on Strength and Durability Characteristics of High Volume Fly Ash Concrete for Pavement Construction

Cement is the principal component of cement concrete used for construction of rigid pavements and is produced by an energy intensive process. Large scale production and its subsequent utilization detrimentally contributes towards global warming. In order to cater for sustainable development, there is a need to utilize waste materials having cementitious properties as a partial substitute for cement. Fly ash is one of such waste which is being extensively used for the production of cement concrete. Concrete produced by utilizing fly ash more than fifty percent of cement is termed as high volume fly ash concrete (HVFAC). Although HVFAC facilitates utilization of large volume of fly ash, it however has the disadvantage of delayed gain in strength which limits its usage as pavement quality concrete (PQC). Contemporary literatures show the usage of various types of nanomaterials to overcome this disadvantage. The present study was carried out to investigate the influence of nano iron oxide on strength and durability properties of HVFAC. The HVFAC used in the study was prepared by replacement of fifty five percent ordinary Portland cement with F-type fly ash obtained from thermal power plant. Nano iron oxide was utilized in different percentages to improve the strength and durability characteristics of HVFAC. The strength properties of the concrete was evaluated by flexural, compressive and split tensile strength tests, whereas the durability characteristics were evaluated by density, permeability, sorptivity, ultrasonic pulse velocity and rapid chloride penetration tests. The tests were carried out at 28, 56 and 90 days age of concrete. The test result showed that HVFAC modified with 0.75% nano iron oxide by weight gave the optimal strength and durability results which were comparable with that of normal cement concrete used for construction of rigid pavements.

Behaviour and design of rubberised concrete filled steel tubes under combined loading conditions

Rubberised concrete has the benefit of utilising waste material, preventing resource extraction and improving concrete ductility, however at the cost of reduced strength and stiffness. This paper explored the option to effectively confine the rubberised concrete with steel tubes to obtain enhanced strength and ductility. The behaviour and performances of thirty rubberised concrete-filled single-skin steel tubes of various rubber content, steel section and load eccentricities was systematically investigated in this study. The results have shown that confined rubberised concrete and the restrained steel tube improved ductility of the composite section. The rubberised concrete was more effective in delaying the premature buckling failure of the steel tube compared to the more brittle normal cement concrete. The 15% rubber replacement ratio showed a good balance of strength and ductility and thus recommended for design of roadside barriers. The behaviour of the rubberised concrete filled steel tubes could be accurately predicted using existing design guidelines and safe designs can be produced. This study demonstrated the possibility of using rubberised concrete as a solution to problems that require high moment and deformation capacity, such as the roadside barriers and columns in buildings located in seismic active zones.

Air Pressure Test on Concrete with Nano-Cement

Nanotechnology is an emerging area of research that has received a lot of attention for its ability to make use of the unique properties of nano-sized materials. The grain size of the nano particles will be in the order of 10–9 m (1–100 nm). Due to the very small particle size and extremely large specific surface area, nano particles have same remarkable properties. The use of nano materials for making concrete is of recent origin. Addition of nano materials in concrete can lead to significant improvements in the strength and durability of concrete. For nuclear power plants, concrete with high compressive strength, high split tensile strength, low porosity and high density are required. An attempt has been made to increase the compressive and split tensile strength of concrete by replacing a portion of cement with nano cement. M20, M30, M40 and M50 grades of concrete were cast. For each of these mixes, 10%, 20%, 30%, 40% and 50% of cement was replaced with nano- cement. Nano-cement was made by grinding the commercially available 53 grade pozzolona cement in the ball grinding mill. A scanning electron microscope was used to determine the particle size of the nano-cement produced. A hollow cylinder of the concrete was made with concrete containing nano materials. The Air pressure test was carried at on hardened concrete and the results were compared with that of normal cement concrete. The safe internal pressure for M50 concrete with 50% replacement of cement with nano-cement was found to be 13.3 kg/cm2, which 31.6% higher than that of the normal M50 concrete.

Very ductile polymer concrete using carbon nanotubes

Polymer concrete (PC) is a type of concrete where a polymer is used to replace cement as the binder. PC is an impermeable and chemical resistant concrete with appreciable mechanical properties. However, for most structural engineers, PC advantages do not outweigh its higher cost when compared with normal cement concrete. We report on the production of very ductile PC (measured by tensile strain at failure) with appreciable tensile strength utilizing a hybrid mixture of pristine and carboxyl (COOH) functionalized multi-walled carbon nanotubes (MWCNTs) at 2.0 wt% of epoxy resin. Experimental investigations reveal that COOH functionalization maximizes PC ductility reaching unprecedented 5.5% failure strains and increasing toughness by 184%. Fourier transformation infrared spectroscopy and dynamic modulus analysis indicate an increase in crosslinking density of the epoxy matrix up to 84% due to the carbonyl band formation induced by the COOH functionalization of MWCNTs. The significant improvement in ductility and energy absorption provides a promising platform for creating very ductile PC with attractive properties.