M. Sc. Thesis Proposal
Impact of Different Curing Period on Mechanical Properties of Admixture Concrete
Submitted by : Shoaib Khan
Registration No. : 2017(F)-MS-AEI-14
Date of Registration: Sep 11, 2017
Part Time/Full Time: Full Time
Supervisor : Dr. Sajjad Mubin
Cell # : 0322-8880029
DEPARTMENT OF ARCHITECTURAL ENGINEERING
University of Engineering and Technology, Lahore
Impact of Different Curing Period on Mechanical Properties of Admixture Concrete
Concrete is known as the most widely used construction material in the world due to its versatility, easily availability, satisfactory compressive strength and durability. Concrete is a complex composite material over a wide range of length scales from nanometer to meter and is used in a variety of applications such as high-rise buildings, bridges, highways, dams and others, So therefore the demand of concrete in the world is increasing from day to day. The total concrete production in 2012 and 2017 reached approximately 14 and 16 billion tons respectively. The production of concrete is increasing dramatically in developing countries. It is predicted that in future by 2025, the concrete demand could increase approximately till 17 billion tons per year. This may reach 18 billion tons per year by 2050. So, in order to use it in effective way we must have idea that how its strength can be improved by different techniques.
Admixtures are used to improve characteristics of concrete. As concrete can be used for various purposes. Admixtures are may be in liquid or powder form which are added in small quantities in concrete. Concrete admixture have significant impact on fresh as well on hardened concrete properties by acting chemically or physically, Whereas dosage is usually defined on the bases of cement content. If the quantities of admixture is less than or equal to 5% by weight of cement then it will be permitted dosage. If the admixture quantity is less than o.2% by weight of cement then it will be low dosage and it is allowed practically when they can dissolve in parts of the mixing water.
Concrete admixture are used to improve the behavior of concrete under a variety of conditions and generally admixtures are of two types. Chemical admixtures which results in reduction of the cost of construction, modify the properties of harden concrete, Ensure quality of concrete during mixing, transporting, placing, curing and overcome certain emergencies during concrete operations. Chemical admixtures are used to improve the quality of concrete during different phases of concreting. Chemical admixtures fall into: Superplastizer, water reducer, air entrains, set retarders, set accelerators, and different especially admixture like corrosion inhibitors, shrinkage control, alkali-silica reactivity inhibitors and coloring. Mineral admixtures are more economical, reduce permeability, increase strength and influence many other concrete properties. Pozzolans are cementitious admixture which affect the nature of hardened concrete and it includes natural pozzolans, fly ash and silica fume etc.
Compressive strength is the maximum compressive stress that when gradually load is applied, and a given solid material can sustain without crushing or fracture. Compressive strength is calculated by dividing the maximum Compressive load to the original cross-sectional area of a specimen in a compression test. The compressive strength of concrete is the most common performance measurement. Compressive strength is very important factor in designing buildings and other structures through Engineer point of view. Concrete compressive strength requirement can vary from 2500 Psi for a residential structure concrete to 4000 Psi and higher in commercial structure Concrete. Higher strength up to 10000 Psi are specified for certain application.
The Tensile strength of concrete is basic and important property which greatly affect extend and size of cracking in structure. As we know concrete is weak in tension due to its brittle nature hence it is not expected to resist the direct tension, So concrete develops cracks when tensile force exceeds its tensile strength.
Curing plays an important role on strength development of concrete as well as curing increase durability of concrete. Curing takes place immediately after concrete placing and finishing and involves maintenance of desired moisture and temperature condition for extended period of time. In the proposed Research the impact of different curing period on compressive and tensile strength of admixture concrete will be evaluated. Admixture used in proposed research will be Sika and Conplast for reducing Shrinkage and Air entraining respectively.
In the past decades, many attempts are conducted to investigate mechanical properties of admixture concrete but few researchers’ works on studying the impact of different curing period on mechanical properties of admixture concrete. The researchers who did related work includes work of Heba A. Mohamed(2011), Ahmed Shaban Abdel-Hay(2017), Parameshwar Hiremath and Subhash C Yaragal (2017), and others.
Heba A. Mohamed (2011) determined Compressive strength of self-compacting concrete containing fly ash and silica fume under different curing condition. He investigated the compressive strength of three types of mixes, the first consisted of different percentages of fly ash (FA), the second uses different percentages of silica fume (SF), and the third uses a mixture of FA and SF. After each mix preparation, nine cylinder specimens are cast and cured. Three specimens are cured in water for 28 days, three specimens are cured in water for 7 days, and three specimens are left in air for 28 days. The slump and V-funnel test are carried out on the fresh SCC and concrete compressive strength values are determined. The results show that SCC with 15% of SF gives higher values of compressive strength than those with 30% of FA and water cured specimens for 28 days give the highest values of compressive strength.
Ahmed Shaban Abdel-Hay (2017) use the idea of using recycled concrete aggregate in new concrete production. The paper presents the results of an experimental study to evaluate the effects of recycled concrete aggregate (RCA) percentages under different curing condition. The percentages of recycled coarse aggregate to dolomite were (0:100%, 25:75%, 50:50%, 100:0%) respectively. Compressive and splitting strength were studied in research whereas the concrete specimens were exposed to three different curing conditions, moist, open-air, and painted Specimens. The results showed that curing using paint material was the most efficient method of curing at all ages and percentages of recycling except at 100% recycling, where the maximum value of both compressive and tensile strengths was obtained using water curing.
Parameshwar Hiremath and Subhash C Yaragal (2017) determined the effect of different curing regimes on the strength of reactive powder concrete whereas Reactive Powder Concrete (RPC) is a form of Ultra High Performance Concrete (UHPC). Results have shown considerable enhancement in compressive strength when RPC specimen were subjected to hot air curing of different duration, whereas specimen cured under hot air curing and steam curing shown better performance compared to normal curing and air curing.
Fathollah Sajedi and Hashim Abdul Razak (2011) studied the crucial effect of curing techniques and curing duration on strength and other mechanical properties of mortar. Proper curing can protect against moisture loss from fresh mixes. The objective of this experimental work is to examine the compressive strength of ordinary Portland cement mortars (OMs) under various curing regimes and cement fineness. The results showed that the highest and lowest compressive strengths are attributed to the specimens of OPC mortar water cured using grounded OPC for duration of 6 h and OPC mortar air cured under room temperature with oven heated after demoulding of the specimens at 60 “C for duration of 20 h, respectively. The maximum levels obtained of compressive strengths at 7, 28, and 90 days are 57.5, 70.3, and 76.0 MPa, respectively.
Shuling Gao, Zhe Wang, Wenchang Wang and Huafang Qiu (2018) evaluate the effect of shrinkage-reducing admixture and expansive agent on mechanical properties. This paper designs eighteen groups mix proportions based on Taguchi Methods. The influences of admixture on the compressive strength, tensile properties and drying shrinkage are researched. The results indicate that the shrinkage strain of cementitious composite material increases with the raising of water-binder ratio, and decreases with the increasing of sand-binder ratio, fly ash content, expansive agent, and shrinkage-reducing agent. The compressive and tensile strength of Specimen will greatly reduce with increasing of shrinkage-reducing agent, rather the compressive strength of specimen will enhance with the increase of expansive agent; But the expansive agent will lower the tensile strength and ultimate tensile strain.
Nikoo Haghighatnejad, S. Yasin Mousavi, S. Jalal Khaleghi, Alireza Tabarsa, Saman Yousefi (2016) presents the properties of concrete by replacing natural sand with recycled PVC (RPVC) aggregates under different curing condition. Six different curing regimes were applied including continuous water curing, continuous open air curing, continuous laboratory curing and in the remaining three regimes, concrete specimens were exposed to initial water curing periods of 3, 7 and 14 days. The effects of each curing techniques on the compressive strength, splitting tensile strength, elastic modulus, initial and final absorption were determined. Results showed that irrespective of the curing condition, RPVC incorporation generally reduces the mechanical properties of concrete measured in terms of compressive strength, splitting tensile strength and modulus of elasticity. In general Continuous water curing is the most suitable curing condition for concrete; however, initial water curing for 14 and 7 days decrease the strength of RPVC concrete only up to 7.3% and 9.8%, respectively.
Paulo Cachim, Ana Luísa Velosa and Fernando Rocha (2010) evaluate the effect of pozzolanic addition lime concrete over time of 7, 28, 90 and 360 days. In order to evaluate the pozzolanic effect, compressive strength were performed and analysed by relative strength-time plots and by the application of different indexes. The main conclusion of research that pozzolanic addition providing an increase in mechanical strength. Testing of samples should be performed at 28 days when Portlandite consumption is complete.
In this study, Impact of different curing on admixture concrete will be evaluated by using experimental approach. Curing plays an important role on strength development, So it is very necessary to study the curing impact with various period, in order to study true behavior of samples. We can develop a comparison in strength properties of uncured, moderate cured and longtime cured. In this research, after experimentation, Compression and tensile strength of samples will be evaluated at different curing period. This will help the fore-runner to understand a comparison in strength of admixture concrete with different period.
• Study of curing impact on compression strength of cubes and cylinder samples.
• Study of curing impact on tensile strength of beam prism.
• Comparison in strength of samples with different periods of curing.
After the literature review, the investigation will move toward the experimental study of admixture concrete. Following methodology will be worked out to achieve the objective of this study.
• For Compressive strength, different samples of cubes and cylinders of admixture concrete will be casted.
• For tensile strength, samples of beam prism of admixture concrete will be casted.
• After casting, proper curing of compression samples will be done for period of 0,7, and 14 days.
• Different period of cured samples will be tested for compression on 2,14 and 28 days separately.
• Beam prism will be cured for 7 days and tensile test will be carried out on 28 day of casting.
• Comparison of compressive and tensile strength of samples will be shown in tabular and graphical forms.
• Impact of curing will help to understand the comparison of strengths of admixture concrete cured at different period.
• Experimental study of smples will enable the researchers to understand the effect of curing period on admixture concrete.
• Further properties can be computed by fore runner in the light of this research.
Considering the scope of this research, minimum 6 months will be required for its completion. A tentative break up of time is given below
• Literature review 12 Weeks
• Casting of Specimens 4 Weeks
• Testing of Specimens 6 Weeks
• Analysis of test results 5 Weeks
• Thesis Write up and Seminar Preparation 5 Weeks
Table-1 Research duration
For this extensive testing, procurement of materials and testing will cost approximately 60,000 PKR.
In order to achieve the research objectives, the following literature has been reviewed.
• Heba A. Mohamed, “Effect of fly ash and silica fume on compressive strength of self-compacting concrete under different curing conditions”, Ain Shams Engineering Journal, vol. 2 pp. 79–86 (2011).
• Ahmed Shaban Abdel-Hay “Properties of recycled concrete aggregate under different curing conditions”, HBRC Journal, vol. 13, pp. 271–276 (2017).
• Parameshwar Hiremath and Subhash C Yaragal “Investigation on Mechanical Properties of Reactive Powder Concrete under Different Curing Regimes”, Materials Today Proceedings, vol. 4, pp. 9758–9762 (2017).
• Fathollah Sajedi and Hashim Abdul Razak “Effects of curing regimes and cement fineness on the compressive strength of ordinary Portland cement mortars”, Construction and Building Materials, vol. 25, pp. 2036–2045 (2011).
• Shuling Gao, Zhe Wang, Wenchang Wang and Huafang Qiu “Effect of shrinkage-reducing admixture and expansive agent on mechanical properties and drying shrinkage of Engineered Cementitious Composite (ECC)”, Construction and Building Materials, vol.179, pp. 172–185 (2018).
• Nikoo Haghighatnejad, S. Yasin Mousavi, S. Jalal Khaleghi, Alireza Tabarsa, Saman Yousefi “Properties of recycled PVC aggregate concrete under different curing Conditions”, Construction and Building Materials, vol. 126, pp. 943–950 (2016).
• Paulo Cachim, Ana Luísa Velosa and Fernando Rocha “Effect of Portuguese metakaolin on hydraulic lime concrete using different curing conditions”, Construction and Building Materials, vol. 24, pp. 71–78 (2010).
• Qingxin Zhao, Xiaojun He, Jinrui Zhang, Jinyang Jiang ” Long-age wet curing effect on performance of carbonation resistance of fly ash concrete” , Construction and Building Materials, vol. 127, pp. 577–587 (2016).
• Cahit Bilim, Okan Karahan, Cengiz Duran Atis, Serhan Ilkentapar ” Influence of admixtures on the properties of alkali-activated slag mortars subjected to different curing conditions”, Materials and Design, vol. 44, pp. 540–547, (2013).
• Anna Kotwa “Effect of selected admixtures on the properties of ordinary concrete”, Procedia Engineering, vol. 108, pp. 504 – 509, (2015).
• Grzegorz Ludwik Golewski “Effect of curing time on the fracture toughness of fly ash concrete composites” Composite Structures, vol. 185, pp. 105–112, (2018).
• Qingxin Zhao, Xiaochen Liu, Jinyang Jiang ” Effect of curing temperature on creep behavior of fly ash concrete”, Construction and Building Materials, vol. 96, pp. 326–333, (2015).
• A. Ferhat Bingöl,Ilhan Tohumcu ” Effects of different curing regimes on the compressive strength properties of self-compacting concrete incorporating fly ash and silica fume”, Materials and Design, vol. 51, pp. 12–18, (2013).
Comments of supervisor
The M.Sc. thesis research proposal entitled “Impact of Different Curing Period on Mechanical Properties of Admixture Concrete” of Engr. Shoaib Khan has been discussed in the meeting of the Program Committee of Architectural Engineering Department held on ______________.
All proposed suggestions have been incorporated.
The proposal may kindly be placed in the meeting of the PGRC for further necessary action.
Dr. Sajjad Mubin Shoaib Khan
Department of Architectural Engineering 2017(F)-MS-AEI-14
Endst. No. AED_____________ Dated: ____________
The above proposal duly recommended by the Post-Graduate Research
Committee of the Architectural Engineering Department in its meeting held on ______________ is forwarded through Dean, Faculty of Civil
Engineering to the Director of Research for obtaining approval of the Vice Chancellor.
Department of Architectural Engineering Faculty of Civil Engineering
(Director of Research)