Department of Civil Engineering
Poojya Doddappa Appa college of Engineering, Kalaburagi – 585102, Karnataka, India
Abstract:- This paper presents the ductile characteristics of hybrid Ferro cement slab incorporating polypropylene fibres and GFRP sheet. A total of 9 slab have been tested under two point flexural loading. The size of the slab is 1000 mm(length) x1000 mm(width) x 60 mm(thickness). The parameters studied in this investigation includes the number of weld mesh layers, polypropylene fibres i.e (0.3%) and GFRP sheet. from the studies, it is observed that the load carrying capacity and deformation. The stiffness of the specimens with zero layer weld mesh is lower than that of the specimens with two layers and three layers bundled. Further, there is reduction in number of cracks with increase in fibre content.
Keyword:- Ferrocement Slabs, GFRP Wrapping, Fibre Reinforcement, Ductility Factors, Crack Pattern
I. Introduction
The development of new technology in the material science is progressing rapidly. In recent two or three decades, a lot research was carried out throughout globe for how to improve the performance of concrete in terms of strength and durability qualities. consequently concrete has no longer remained as a construction material. A new material consisting of wire meshes and cement mortar called ferrocement. it is one of the construction materials which may be able to fill the need for building light structures. ferrocement composite consist of cement-sand mortar and single or multi-layers of steel wire mesh to produce elements of small thickness having high durability, and when properly shaped it has high strength and rigidity. These thin elements can be shaped to produce structural members such as folded plates, flanged beams, wall pane,. etc for use in the construction of cheap structures. Ferro cement elements are generally more ductile when compared to conventional reinforced concrete elements but post peak portion of load- deflection curve in bending test of Ferro cement elements reveals that failure occur either due to mortar failure in compression or due to failure of extreme layers of mesh. From the above discussions, it can be noted that, research work out on the ductile behavior of hybrid ferrocement slab with fibre. The present Investigation is aimed at to investigate the ductile behavior of hybrid ferrocement slabs with and without Considering the effect of fibres. Compared with the conventional reinforced concrete, ferrocement is reinforced in two directions; therefore, it has homogenous-isotropic properties in two directions. Benefiting from its usual high reinforcement ratio, ferrocement generally has a high tensile strength and a high modulus of rupture. In addition, since the specific surface of reinforcement in ferrocement is one to two orders of magnitude higher than that of reinforced concrete, larger bond forces develop with the matrix resulting in average crack spacing and width more than one order of magnitude smaller than in conventional reinforced concrete (Shah and Naaman 1997, Guerra et al 1978). Other appealing features of ferrocement include ease of prefabrication and low cost in maintenance and repair. Based on the abovementioned advantages, the typical applications of ferrocement are water tanks, boats, housing wall panel, roof, formwork and sunscreen (Nimityongskul et al 1980 and Kadir 1997).. Ferrocement over the years have gained respect in terms of its superior performance and versatility. Ferrocement is a form of reinforced concrete using closely spaced multiple layers of mesh and/or small diameter rods completely infiltrated with, or encapsulated in, mortar. In 1940 Pier Luigi Nervy, an Italian engineer, architect and contractor, used ferrocement first for the construction of aircraft hangars, boats and buildings and a variety of other structures. It is a very durable, cheap and versatile material.
II. Experimental investigation
The experimental investigation consists of testing of nine hybrid ferrocement slabs. the Variables Considered In The Study(I) Numbers Of Welded Square Mesh Reinforcement.(ii) Percentage of polypropylene fibres in mortar.(iii) Number of GFRP layer wrapping. The details of experimental studies including characterization are presented below.
A. Materials Used
The materials that are used in this experiment are cement, steel fiber, fine aggregate, super plasticizer and water.
1) Cement:
OPC 53 grade cement from a single batch has been used throughout the course of the project work, properties of cement are shown in table 2.
2) Fine aggregates:
Only fine aggregate is used in Ferrocement the aggregate consists of well graded fine aggregate (sand) that passes a 4.75 mm sieve. and since salt-free source is recommended, sand should preferably be selected from river-beds and be free from organic or other deleterious matter. Good amount of consistency and compactibility is achieved by using a well- graded, rounded, natural sand having a maximum top size about one-third of the small opening in the reinforcing mesh to ensure proper penetration. The moisture content of the aggregate should be considered in the calculation of required water.
3)
Super plasticizer:
Super plasticizer used in the present investigation is
FOSROC CONPLAST SP430. and the details of super plasticizer is given in table.1.
4)
Polypropylene Fiber:
Having specific gravity 0.90 -0.91 gm/cm3 because of its low
specific gravity ,polypropylene yields the greatest volume of fibre for a given
weight. This yield means that the polypropylene fibre provides good and bulk
cover, while being lighter in weight. Polypropylene is lightest of all fibres
and is lighter than water. It is 34% lighter than polyester and 20% lighter
than nylon.
5)
Water:
Potable water was used in the present investigation
for both casting and curing. the
water used for
mixing cement mortar
should be fresh, cleanand fit for construction
purposes; the water of pH equal or greater than 7 and free from organic
matter—silt, oil, sugar, chloride and acidic material.
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