رئوس مطالب
- چکیده
- کلیدواژه ها
- مقدمه
- تجربیات
- مخلوط کردن و نمونه‌برداری
- آزمون خمشی
- ابزار
- روش‌های آزمایش برای مطالعات مداوم
- نتایج و بحث
- خواص مکانیکی مقاومت
- قدرت کششی تقسیم‌شده
- مدول گسیختگی
- عملکرد انعطاف‌پذیر
- مطالعات میکرو ساختار
- الیاف زبر و سخت
- الیاف خردشده
- خواص پایداری
- انجماد
- نتیجه گیری
Abstract
Investigations to overcome the brittle response and limiting post-yield energy absorption of concrete led to the development of fibre reinforced concrete using discrete fibres within the concrete mass. Out of the commonly used fibres, easily available low cost natural fibres are renewable source materials. Though these fibres are ecologically advantageous, they have some limitations such as lower durability and lesser strength. But recent research provides several treatment processes to enhance the durability of natural fibres. In this paper, the durability of natural fibres such as coconut coir and sugarcane bagasse has been reported by conducting an experimental investigation. This investigation includes two parts. The first part focuses on the determination of mechanical strength properties such as compressive, tensile, modulus of rupture and flexural properties of natural fibre reinforced concrete specimens once every 3 months for a period for 2 years under alternate wetting and drying conditions. Gain or loss in strength of composite concrete at 9 intervals were computed and are reported here. The second part covers the microstructural properties of fresh natural fibres in as received condition and natural fibres reacted with concrete under accelerated curing conditions for two years. SEM and EDAC test results are discussed.
Keywords: concrete composite - mechanical strength - Natural fibres - SEM analysisConclusions
From this extensive experimental study, it is well known that natural fibres enhance all the strength and flexural performance of concrete. The effect of curing ages on mechanical properties such as compressive strength, split tensile strength, modulus of rupture and flexural performance and microstructural properties have been ascertained and discussed. The following conclusions are drawn from this investigation:
(I) At all the curing ages, both the natural fibres such as coir and sugarcane fibres enhance all the three mechanical strength properties such as compressive strength, split tensile strength, modulus of rupture and flexural performance.
(II) Though the natural fibres enhance the strength properties at earlier curing ages, the rate of increments are lower than conventional concrete specimen at later curing ages.
(III) The flexural performance of the natural fibre reinforced concrete beam specimens do not yield much difference at the three curing ages such as 28 days, 1 year and 2 years. They possess a little bit difference at the yielding stage only.
(IV) SEM and EDS analyses confirmed that the boundary of fibre–matrix transition zone have excellent adhesion. The impregnation of calcium content on the fibre walls showed better strength enhancement.
(V) Both the natural fibre reinforced concretes were less susceptible against sulphate attack in terms of mass loss and compressive strength deterioration. Since the difference observed was large, application of natural fibre reinforced concrete would be limited in marine areas.
(VI) Although effect of freezing and thawing on natural fibre reinforced concrete was higher than conventional concrete, the difference in mass loss and relative modulus of elasticity between fibre reinforced and conventional concrete was acceptable.