Normal Portland Cement Concrete Research Articles

Durability of SFCB reinforced low-alkalinity seawater sea sand concrete beams in marine environment

Seawater sea-sand concrete (SWSSC) provides an alternative to normal concrete, while Steel-FRP Composite Bars (SFCB) offer corrosion resistance in offshore and marine structures. Despite their benefits, the long-term performance of SFCB-reinforced SWSSC structures remains under-explored. This study evaluated the durability of such beams, particularly focusing on the effects of using Portland cement versus low-alkalinity calcium sulphoaluminate (CSA) cement. The investigation involved tensile and pull-out tests conducted on SFCB, and flexural tests conducted on the beam components after accelerated marine environmental exposure over periods ranging from one to six months. Results highlighted that SFCB embedded in low-alkalinity CSA cement exhibited improved retention of tensile strength, elastic modulus, and bonding strength by 32.0 %, 39.1 %, and 56.7 % respectively, compared to that embedded in normal Portland cement concrete. Microstructural analyses showed much less hydrolysis of the resin matrix and shallower corrosion of the basalt FRP (BFRP) cover on the SFCB. Furthermore, flexural tests demonstrated superior cooperative performance between low-alkalinity CSA concrete with SFCB in beam components, showing only marginal degradation in crack density, crack strength, and yielding points. The ultimate failure load of beams made with CSA concrete was 1.89 times higher than those made with normal SWSSC after 6 months of exposure. These results underscore the potential of low-alkalinity concrete in improving the long-term durability and structural performance of SFCB-reinforced marine concrete infrastructures.

CHARACTERIZATION OF WASTE BUILDING DERIVED MATERIALS AS AN ALTERNATIVE MATERIAL FOR REPLACING SOIL IN CIVIL ENGINEERING

Generation of Construction and Demolition Wastes and their disposal is a critical issue at present. The amount of waste generated during demolition activities is much greater than the waste generated during construction activities. Our country generates an estimated 150 million tons of C&D waste every year. But India recycles just one per cent of its construction and demolition (C&D) waste. So, on the contrary of just leaving the landfills, we are utilizing this building waste as an alternative of soil by replacing the soil via varying the composition. The primary component of Building Derived Materials (BDM) is predominantly composed of concrete and bricks. In our Project, we have used Light weight concrete, Crushed Tiles, Crushed Normal Portland cement concrete and Crushed Bricks. We have done various Engineering properties tests on the combined form of soil and Building Derived Materials. Based on the results obtained, a comparison of various Building Derived Materials specimens is done and presented in tabular formand can be applied in various Geotechnical applications. The reuse of construction demolition materials like concrete,bricks, etc., is an attempt to reduce the cost of using new materials and reduces the consumption of natural resources.Since there are no existing ASTM standards for the practical use of such materials, the outcomes of this study can also be used to formulate standard code of practice to use BDM for ground improvement purposes.

Very high volume fly ash concrete utilising microash and hydrated lime, with silica fume

The incorporation of a high volume of fly ash (FA) (up to 80%) in concrete without compromising mechanical and durability properties is potentially very advantageous to the concrete industry in terms of economic, social and environmental benefits. The compressive strength, carbonation, chloride ion penetration, water absorption and permeability of two high-volume FA mix designs incorporating 80% class F ultrafine FA (known as microash) and hydrated lime, with and without the addition of silica fume (SF) were investigated in this study. The specimens were cured for a maximum of 90 days to optimise completion of the hydration reaction. The concrete containing with 80% microash exhibited compressive strength in excess of 40 MPa at 28 days and over 70 MPa at 90 days. The material also displayed excellent durability properties compared with normal Portland cement concrete and other high-volume FA concretes. The addition of SF (10%) further improved the strength and durability properties of the material.

Experimental Study on Influence of Methylcellulose on Tensile and Flexural Strength of Normal Strength Ordinary Portland Cement Concrete

Current study explores the possibility of improvement in various categories of concrete’s strengths (including tensile strength, flexural strength etc.) by using methylcellulose as an additive. The effect of methylcellulose on concrete’s compressive strength has also been investigated experimentally. Concrete samples were casted with several methylcellulose to binder ratios varying from 0.002 to 0.01 by weight of cement. Several tests were performed on concrete specimens including concrete cylinder and cube compression tests, split cylinder tests and modulus of rupture tests. Results showed that addition of methylcellulose increased the tensile strength of concrete. Addition of 0.2% of methylcellulose increased the tensile strength of concrete by 16%. This increase in tensile strength reached up to 73% of the control sample on addition of 1% methylcellulose. It was observed that the effect of methylcellulose on compressive strength of concrete depends upon the type of samples being tested (cube or cylinder). The compressive strength of concrete cylinders showed a plateau behavior with peak at 0.4% methylcellulose content with an increase of 18.7%. Effect of methylcellulose on concrete cylinder strength becomes insignificant beyond 0.6%. It was observed that addition of methylcellulose reduces the modulus of rupture values. The reduction in MOR was only 3% at 0.2% methylcellulose content but it grew to 30% at 1% methylcellulose content. The research presents an effective way of increasing tensile strength of concrete but without significant effect on concrete’s compressive strength and modulus of rupture values. These findings can be used to determine optimum content of methylcellulose to achieve desired performance from concrete depending upon the intended use.

Study of mechanical properties of fly ash-based geopolymer concrete

The world is facing the challenges of climate changes due to the increase in CO2 emissions. Cement production is one of the biggest contributors to CO2 emissions due to combustion processes that require high temperatures. The new development in building construction showed that fly ash based Geopolymer concrete can be as structure materials to reduce or even eliminate ordinary Portland cement concrete. This paper presented the research results of fly ash based geopolymer concrete mechanical properties, like the compressive strength, flexural strength, and Elastic Modulus. The data were collected from the test results of geopolymer concrete specimens made from 2 sources of Fly Ash with varying concentration of sodium hydroxide solution from 4 M up to 12 M. The range of achieved compressive strength was from normal to high strength concrete. The correlation between the compressive strength and flexural strength and the Elastic Modulus of geopolymer concrete will be the highlight of this paper. The mathematical formulation of compressive strength and its flexural strength and Elastic modulus will be determined and compared with normal Portland Cement Concrete.

Characterization of optimum fluidized bed combustion ash-based geopolymer concrete

The fluidized bed combustion (FBC) ash was evaluated for value-added use in the production of geopolymer concrete where alkali aluminosilicate hydrates are the primary binder constituents. The FBC was supplemented with other raw materials in order to achieve chemical balance, and they were milled with CO2 and air to evaluate the benefit from CO2 uptake. An experimental study on the properties of the optimum FBC ash-based hydraulic cement and the concrete fabricated from it was conducted. Also, the corresponding properties of Portland cement concrete were also investigated as the reference group. For the FBC ash-based cement, tests were performed to measure the CO2 uptake and heat of hydration; for FBC ash-based hydraulic cement concrete, measurements were made on the compressive strength of hardened material, residual compressive strength after immersion in boiling water and sulfates resistance. The results of this study suggest that, the FBC ash-based geopolymer with the mechanicochemical aviation can provide desired mechanical attributes, sulfates resistance when compared with normal Portland cement concrete.

Experimental Investigations on Building Derived Materials in Chemically Aggressive Environment as a Partial Replacement of Soil in Geotechnical Applications

Construction and associated demolition processes produce huge amount of solid waste, generally termed as construction and demolition waste (CDW). Management and proper disposal of these wastes is an area of prime concern for modern civil engineers. About 90% of all CDW is composed of building derived materials (BDM) obtained from concrete, bricks, and tiles from structural and non-structural elements of a building. The present study emphasizes on the use of virgin BDM, which conserves natural aggregate, reduces the impact on landfills, saves energy, and thus can provide significant cost benefit. Five types of BDM—crushed lightweight concrete (T1), crushed marble tiles (T2), crushed high strength concrete (T3), crushed normal portland cement concrete (T4), and crushed bricks (T5)—are characterised to assess their compatibility when used in conjunction with local soil. The soil, BDM and soil–BDM mixes are characterized from physical, mechanical, mineralogical, microstructural, and chemical aspects. These tests are then repeated for the aforementioned soil-BDM mixes after immersion in acids. Aggregate impact value (AIV) results on the five types of BDM indicate that T1 and T5 are poorly resistant to impact loads. However, T2, T3, and T4 show relatively better resistance to impact loads and satisfy the requirements for sub-base material standards. Shear strength studies show that the average optimum replacement of soil by BDM is in the range of 17–23% by mass. In order to test the compatibility of BDM in soils containing aggressive chemicals, the properties mentioned above are re-evaluated after exposing the BDM to aggressive chemical environments. The results indicate that the internal angle of friction (ϕ) of virgin BDM is found to vary significantly due to acid attack. The results of AIV after exposing the BDM to acids show that BDM are highly susceptible to chemically aggressive environment. The performance of all types BDM are affected by the presence of acids and appropriate measures must be adopted while using BDM in such chemically aggressive environment. These standards can be used as guidelines in the present study in the absence of specific standards for BDM applications.

Influence of added water and fly ash content on the characteristics, properties and early-age cracking sensitivity of alkali-activated slag/fly ash concrete cured at ambient temperature

For an appropriate air void system, good mechanical properties and low porosity/microcracking in alkali-activated binder systems, appropriate slag/fly ash proportioning, water and admixture contents are needed. Air entraining admixture dosages of up to 10 times the recommended dosage were necessary to obtain minimal air void properties similar to what is needed for normal portland cement concretes subjected to freezing conditions. Increasing added water resulted in increasing absorption and decreasing crack counts in concrete. Increasing fly ash contents resulted in increasing absorption and decreasing early-age crack counts. Increasing both added water and fly ash content resulted in less autogenous shrinkage.

Study on concrete with rice husk ash

Rice husk ash (RHA) possesses high pozzolanic activities and very suitable as partial replacement of cement in concrete. This paper presents a comparative study on use of RHA as partial replacement of cement in concrete specimens. Review of the researches on physical, mechanical and structural properties of concrete containing RHA as partial replacement of ordinary Portland cement was included in this paper. Simultaneously, concrete specimens were tested with different percentages of RHA as replacement of cement content and with different w/c ratio. Compressive strength, flexural strength, tensile strength and slump test were carried out to evaluate the appropriateness of using RHA in concrete. The replacement of cement by RHA in structural concrete represents a good alternative in as economical as strength consideration of concrete, even without any kind of processing and found environmental benefits related to the disposal of waste. Review of researches shows that RHA-used concrete can resist chloride penetration more than normal ordinary Portland cement concrete.

Potentials of Momordica angustisepala fiber in enhancing strengths of normal portland cement concrete

Presence of cracks in concrete affect the integrity. It reduces the life expectancy of concrete structures and is often responsible for collapse of structures, especially in the developing nations....

The influence of bending crack on rebar corrosion in fly ash concrete subjected to different exposure conditions under static loading

In the present study an effort was made to clarify the performance of pre-cracked fly ash concrete against corrosion under different exposure conditions. A total of twenty specimens from two different concrete mixes were tested against three different exposure conditions for 106 days. It was observed that the crack filling ability of concrete is more sensitive to crack width than fly ash replacement and exposure conditions. Under submerged conditions the fly ash concrete showed greater pitting corrosion, while under wet and dry cycle conditions, the corrosion damage was found to be less penetrating as compared to normal Portland cement concrete.

Strength development characteristics of concrete produced with blended cement using ground granulated blast furnace slag (GGBS) under various curing conditions

To reduce the embodied carbon dioxide of structural concrete, Portland cement (PC) in concrete can be partially replaced with ground granulated blast furnace slag (GGBS). In this research effect of partial replacement of cement with GGBS on strength development of concrete and cured under summer and winter curing environments is established. Three levels of cement substitution i.e., 30%, 40% and 50% have been selected. Early-age strength of GGBS concrete is lower than the normal PC concrete which limits its use in the fast-track construction and post-tensioned beams which are subjected to high early loads. The strength gain under winter curing condition was observed as slower. By keeping the water cement ratio low as 0.35, concrete containing GGBS up to 50% can achieve high early-age strength. GGBS concrete gains more strength than the PC concrete after the age of 28 day till 56 day. The mechanical properties of blended concrete for various levels of cement replacement have been observed as higher than control concrete mix having no GGBS.

Guidelines for mix proportioning of fly ash/GGBS based alkali activated concretes

The effects of paste volume, water content and precursor blend on consistency, setting time and compressive strength of alkali activated concrete (AAC) produced with fly ash (FA) and ground granulated blast furnace slag (GGBS) have been investigated with the aim of developing a suitable mix design procedure. Paste volumes in the range 30–33% were found not to influence the compressive strength but did influence the consistency of the mixes. The water-to-solid ratio was found to influence compressive strength and setting time. Increasing GGBS content in the binder blend resulted in an increase of the compressive strength, but higher GGBS content caused also early setting which may be undesirable. A mix design procedure has been developed and has been used to determine the constituent mix proportions for three classes of concretes, i.e. (a) a ready-mix concrete with nominal strength 35MPa, (b) a typical structural concrete with nominal strength 50MPa, and (c) a high strength concrete for precast applications with nominal strength 70MPa. Cost analysis was carried out to compare the AAC with Portland cement concretes with similar properties. Normal strength Portland cement concrete (PC), as typically used in ready mix industry has been shown to be less expensive than AAC. However, alkali activated concrete can be competitively priced for high strength concretes. An empirical step-by-step procedure is presented for selecting trial mix proportions for concretes with a range of consistency values, setting times and cube compressive strengths.

The effect of silica fume on durability of alkali activated slag concrete

The effect of substitution the slag with silica fume on compressive strength and permeability of alkali activated slag concrete has been examined and analyzed in this study. The use of alkali activated slag concrete is one of the strategies for production of environmentally friendly concrete which is produced through activation of adhesion feature of blast furnace slag in an alkaline solution. Alkali activated slag concrete with a proper mixture shows superior mechanical properties and durability compared to traditional normal Portland cement concrete. For cases in which AAS concrete with higher performance and durability is needed, AAS concrete with silica fume can be considered as a possible alternative. Since the permeability plays an effective role in concrete durability, this research was carried out to examine the effect of using silica fume on permeability of alkali activated slag concrete by substitution of three levels of silica fume including 5wt%, 10wt% and 15wt% of slag. The effects of two types of curing conditions including water curing and curing under plastic cover were also examined. Short-term and final water absorption, penetration of chloride ion and depth of penetration of water were measured to examine the permeability. The effect of these factors on compressive strength was examined and the relation between compressive strength and passing electrical charges and depth of water penetration was also evaluated. To contrast the use of silica fume on internal characteristics of concrete, samples were observed by scanning electron microscopy (SEM). The results showed that the application of silica fume could increase compressive strength and reduce the permeability of alkali activated slag concrete and water curing was the most appropriate type of curing.

Flexural Behavior of Steel Fiber-Reinforced Rubberized Concrete

AbstractThis research focused on the study of the flexural load-deflection behavior of steel fiber reinforced rubberized concrete (SFRRC) up to the first-crack load. Specifically, this study used an experimental method to examine simultaneous flexural load-deflection response measurements on normal portland cement concrete (PCC), rubberized concrete (RC), steel fiber reinforced concrete (SFRC), SFRRC, and others. Other basic tests were utilized to characterize fresh mix and constituent material properties. Regression models were developed to predict the following: (1) first-net deflection; (2) net deflection at any applied load; and (3) first-crack load at different mix combinations of crumb rubber and steel fiber. Results from this investigation showed that the incorporation of crumb rubber imparts its elastic property to concrete; however, the additional gain in elasticity from the increased strength due to the incorporation of steel fiber as a second constituent played a more dominate role in improving...

Flexural Behavior of Flat-End Steel-Fiber-Reinforced Concrete

AbstractThis research focused on modeling the first-crack load as a function of steel-fiber fraction to optimize the steel-fiber fraction through load-deflection response and flexural behavior of steel-fiber-reinforced concrete (SFRC). Specifically, this study involved an experimental method to examine simultaneous flexural load-deflection response measurements on normal portland cement concrete and steel-fiber-reinforced concrete. Other basic tests were addressed to characterize fresh mix and constituent material properties. Regression models were developed to predict the following: (1) first-net deflection; (2) net deflection at any applied load; and (3) first-crack load at different mix combinations of steel fiber. Results from this investigation showed that in the flexural load-deflection response tests, SFRC beams experienced an increase in first-crack net deflection. In addition, Inclusion of steel fiber at 0.64% by volume of concrete did not cause a significant change in the first-crack strength.

Effect of aggregate size on spalling of geopolymer and Portland cement concretes subjected to elevated temperatures

This paper presents a study on the effect of aggregate size on spalling of concrete in fire. Three concretes with completely different chemical compositions and strengths were investigated, namely, geopolymer concrete and high strength and normal strength Portland cement concretes. The effect of aggregate size was found to be the same regardless of the type of concrete. The concretes containing 10mm aggregates spalled while the ones with 14mm did not spall. Since this effect is the same in geopolymer and Portland cement concretes, it is independent of binders’ chemical compositions. This paper shows that the degree of spalling has a good correlation to the fracture process zone length, which increases with increasing aggregate size; this in turn reduces the flux of kinetic energy from pore pressure and thermal stress that is released into the fracture front and thereby improves the spalling resistance.

Recycled aggregate concrete produced with red granite dust as a partial cement replacement

Sustainable development involves reducing natural resource consumption by appropriate recycling. To reduce the amount of waste going to landfill, red granite dust arising from the rock-crushing process was assessed for suitability as a replacement for up to 30% by mass of the cement content of structural grade concretes made with recycled coarse aggregates. While the impact on worldwide cement demand will be minimal, the contribution to waste reduction may be valuable. Laboratory trials showed that this red granite dust rendered it suitable in terms of workability, stiffness and strength compared to normal aggregate and Portland cement concretes. The potential for thereby overcoming the problem of low early strength in some pulverised fuel ash concretes was demonstrated.

Hydro-mechanical behavior of a newly developed sulfur polymer concrete

This study has focused on evaluating the durability of the newly manufactured sulfur polymer concrete (SPC) from recycled waste materials such as sulfur (by-product from oil industry), fly ash (recovered from the gases of burning coal during the production of electricity) and desert sand from abundant sand dunes quarries. The first step in such manufacturing process is the sulfur modification using polymeric additives to control sulfur crystallization and to prevent macro-crystals growth. In a controlled temperature surroundings, modified sulfur was mixed with elemental sulfur, fly ash and desert sand to form the newly SPC. The durability of the SPC was evaluated in: de-ionized water, acidic solutions of 20, 40, 70, and 98 wt% H2SO4 solutions, and saline solutions of 0.5, 1, 2, 3, 4, and 5 wt% NaCl, at different temperatures for different periods of time. To compare the SPC results with known material, normal Portland cement concrete (PCC) mortars were also studied. The results indicated that the manufactured SPC material has high compressive strength, low hydraulic conductivity, and high resistance to permeation of water, and particularly resistant to corrosion in acid and salt environments.

Wet and dry cured compressive strength of concrete containing ground granulated blast-furnace slag

This paper reports a part of an ongoing laboratory investigation in which the compressive strength of ground granulated blast-furnace slag (GGBFS) concrete studied under dry and wet curing conditions. In the study, a total of 45 concretes, including control normal Portland cement (NPC) concrete and GGBFS concrete, were produced with three different water-cement ratios (0.3, 0.4, 0.5), three different cement dosages (350, 400, 450 kg/m 3) and four partial GGBFS replacement ratios (20%, 40%, 60%, 80%). A hyperplasticizer was used in concrete at various quantities to provide and keep a constant workability. Twelve cubic samples produced from fresh concrete were de-moulded after a day, then, six cubic samples were cured at 22±2 °C with 65% relative humidity (RH), and the remaining six cubic samples were cured at 22±2 °C with 100%RH until the samples were used for compressive strength measurement at 28 days and three months. Three cubic samples were used for each age and curing conditions. The comparison was made on the basis of compressive strength between GGBFS concrete and NPC concrete. GGBFS concretes were also compared within themselves. The comparisons showed that compressive strength of GGBFS concrete cured at 65%RH was influenced more than that of NPC concrete. It was found that the compressive strength of GGBFS concrete cured at 65%RH was, at average, 15% lower than that of GGBFS concrete cured at 100%RH. The increase in the water-cementitious materials ratios makes the concrete more sensitive to dry curing condition. The influence of dry curing conditions on GGBFS concrete was marked as the replacement ratio of GGBFS increased.