International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 06 | June -2017
p-ISSN: 2395-0072
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Rupture Probability of Type of coarse aggregate on fracture surface of concrete Dr Siva Murthy Reddy*, Dr G Rama Krishna*, B Ramakrishna** Department of Civil Engineering, Pondicherry Engineering College, Puducherry, India, *Professor in civil engineering Department, **Research scholar in Civil engineering Department ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - The various types of aggregates such as granite,
dolerite, Quartzite, dolomitic limestone, limestone and river gravel were used to produce the concrete with 28-day target compressive strength of 30, 50 and 70 Mpa. The compressive strength of concrete as well as aggregates was measured to study the effect of rupture probability of aggregate on fracture surface of concrete. Also, the petrographic studies were carried out to study the texture, type of minerals present and their relative proportions in various types of aggregates. The concrete of various grades produced with a same aggregate have shown rise in RPCA with strength. However, the above relationship has ceased to exist in the concretes of same grade, made of different types of aggregates. The carbonate aggregates namely Limestone and Dolomitic limestone have produced concrete with higher RPCA irrespective of strength of concrete. The mode of origin, texture and mineralogical composition of aggregates have significant impact on their pulse velocity and thereby the pulse velocity of concrete
focuses the effect of aggregate on RPCA of various grades of concrete made of granite, dolerite, quartzite, limestone, dolomitic limestone and river gravel.
Experimental Work Materials Grade 53 Portland cement conforming to I.S.8112-1989, with a 28-day compressive strength of 53 Mpa was used for the program. The silica fume with 93.6% silicon dioxide and a sulphonated naphthalene formaldehyde superplasticizer was used for high strength concrete. The fine aggregate was river sand having fineness modulus of 2.35. The coarse aggregates used for the present work includes granite, dolerite, Quartzite, limestone and dolomitic limestone from Kadapa district of Andhra Pradesh,India. The locally available siliceous river gravel was also used as coarse aggregate.
1. INTRODUCTION
Mix Proportion
Normally concrete when subjected higher loads fails in three different zones: Cement matrix, Aggregate cement interface (called as transition zone) and Aggregate rupture. In high strength concrete coarse aggregate rupture is relatively more than normal strength concrete. Hence, the study of aggregate on fracture of concrete gains more importance in mechanical behaviour of concrete. A parameter [1] representing the failure mode of the coarse aggregate, rupture probability of coarse aggregate (RPCA) is determined and the relationships [2] between RPCA, the water-binder ratio (W/ B) of concrete, and the size and type of coarse aggregate are analyzed.
In order to study the effect of aggregate on the pulse velocity of concrete, three mixes were designed to have 28day target compressive strength of 30, 50 and 70 Mpa. The concrete mixes were made with W/B ratio of 0.5, 0.35 and 0.3 with cement / binder content of 360, 480 and 550 respectively. The type of cement and fine aggregate were same for all mixes. Mixes were coded with letter D, G, Q, DL, LS and R.G. designates dolerite, granite, quartzite, dolomitic limestone, limestone and river gravel respectively. The number following the letter indicates the target strength of concrete at 28-day. The details of mix proportions are shown in table 1.
The RPCA of concrete is closely related to its physical and mechanical properties of coarse aggregates. The aggregate may exert profound influence on the strength and deformation characteristics of concrete (6,7). It has already been recognized that the aggregate mineral properties, texture ,and shape influence the strength and durability of concrete. The characteristics of aggregate- matrix interfacial zone which influences the properties of concrete. It depends on the type of aggregate used in concrete.( 8,9,10,11,12,13). The effect of aggregate is more significant on the characteristics of high strength concrete.(14,15) This paper
The maximum size of the aggregates for all mixes was 20 mm. The silica fume was used only in concrete with a target strength of 70 MPa. The superplasticizer was used for the mixes with water binder ratio of 0.3 and 0.35.
Š 2017, IRJET
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