Laboratory Studies on Stone Mastic Asphalt with varying fillers

. Stone Mastic Asphalt (SMA) is based on the concept of designing a coarse aggregate skeleton in order to attain stone -on -stone contact is obtained, which provides a highly rut resistant bituminous course for heavy traffic loads. It is a homogeneous mixture of selected gap graded aggregate, filler and bitumen in such proportion as to yield a plastic and void less mix. The main objective of this study is to evaluate the effect of different fillers (stone dust, bagasse ash and palm oil fuel ash) on the SMA mixes in terms of Marshall Stability values. A comprehensive laboratory tests were conducted on aggregates, Bitumen (VG-30) and fillers. The prepared SMA specimens with varying combination of filers such as 10% of stone dust, 5% of stone dust and 5% of Bagasse ash, 5% of stone dust and 5% of palm oil fuel as along with 0.3% of mineral additive (waste plastic) were subjected to marshall stability tests and results indicates that use of partial replacement of bagasse ash for stone dust as a filler material gives more stability values and less voids when compared to absolute stone dust (10%).


Introduction
Stone mastic asphalt (SMA) was developed in Germany in the mid 1960s and it has been used successfully by many countries in the world as a highly rut resistant bituminous course, both for intermediate and wearing courses, for heavy traffic roads. The specifications for SMA for Indian condition was developed in the year 2007. SMA samples are prepared by varying the binder content for different fillers in Marshall Method. These specimens are analysed for the density, voids, stability and flow. The optimum bitumen content for the mix with VG -30 is determined. The laboratory performances of the SMA mixes are checked for repeated load tests.
Here in this project we are trying to use certain percent of industrial waste (Bagasse ash and POFA) as a filler material in the total mix to check its performance with the conventional filler. Hence trying to use the industrial waste material for enhancing the properties of SMA. Rosli Hainin et.al, were reviewed on stone mastic asphalt that addressed these major elements through interviews with a number of respondents and through an investigation of previous researches used SMA. The first aim of this study is to provide an updated systematic review of the evaluation of stone mastic asphalt in construction. The second aim is to develop knowledge readers and researchers for advantages and disadvantages of stone mastic asphalt to help focus future research in this area. Ashish Talati et.al, were observed that rutting is a major distress in flexible pavements and several studies were carried out across globe to quantify mechanisms of rutting and to reduce the effective rut depth along the wheel path. The United Kingdom is currently resurfacing most of its heavy traffic roadway with a SMAtype surface to provide a cost-effective surface treatment. Gazia Khurshid Khan et.al, in their paper made an attempt to improve the quality, various material or chemical are used to improve the quality or to improve the property of raw material. The study is about to improve the properties of bitumen. In this paper various applications and properties of SMA mixes are studied. Also, the studies done by various authors are reviewed in this study. Raghuram Bhardradri Kadali et.al, were stated that there is a significant influence of the type of filler, binder and stabilizer on the drain down of asphalt. Cellulose fibres has been used to reduce the drain down of asphalt from mixes. This investigation considers the use of various low cost stabilizer and also high viscosity binders as drain down retarders. The performance of the mix is evaluated in terms of stability and resistance to rutting. It is observed that the use of low cost fibres as stabilizer additive improved the performance of SMA mixes when compared to the control mix. The mixes with cement and fly-ash fillers resulted in less drain down; this clearly shows the importance of fillers in SMA mixes. Dr. A Ramesh et.al.in their work have carried works on the behavior of the SMA layer in addition with the fibers. The fibers used in the study were cellulose and polyester fibers, the optimum fiber was found out to be 0.4% when performed through the drain down test. Polyester fibers showed good drain down characteristics and provided good homogeneous mixture when compared to the normal conventional mix. The results showed that there is increase in Marshall Properties as well as in the tensile strength ration of the mix. Gummadi Chiranjeevi, states that Stone Matrix Asphalt depends upon gradation aggregates, gradation improves performance of material and bonding capacity of mix. Based on its performance history "split matrix asphalt" began to be used as a surface layer for roadway carrying heavy track traffic throughout Germany and other European country. Today it is the pavement surface of choice where long-term performance and durability is needed. We have studied the effect of gradation on the fatigue life of asphalt mixtures using the SHRP-M009 four-point bending fatigue test.

1.
To determine optimum binder content for 10% of stone dust as a filler. 2. To determine optimum binder content for 5% of stone dust and 5% of POFA as a filler.
3. To determine optimum binder content for 5% of stone dust and 5% of Bagasse. 4. To compare the maximum stability values for varying mineral fillers and 0.3 % of stabilizer additive.

Aggregates:
The coarse aggregate shall consist of crushed rock retained on 2.36 mm sieve. It shall be clean, hard, durable of cubical shape and free from dust and soft organic and other deleterious substances. ▪ Size of aggregates: 20mm down, 10mm down, 6mm down. ▪ Location: Kallehol, Belagavi (19km from college)

Bitumen:
The bitumen for SMA shall be viscosity grade VG-30 complying with Indian standard Specification for paving bitumen IS: 73 (2013).

Mineral fillers:
Mineral filler is that portion passing the 0.075 mm sieve were used.

Fibres:
The standards developed in India and abroad specify the dosage rate of cellulose fibres as minimum 0.3% by weight of total mix. A length of 8mm plastic fibre is used to stabilise the SMA.

Aggregates:
Basic tests on conventional aggregates were carried out and the results are as presented in table 1.

Bitumen:
The bitumen used is VG-30. The different tests were conducted and the results are presented in table 2.

Fillers:
The different tests were conducted and the results are presented in table 3.

Adopted gradation:
The mix gradation adopted in the design is given below in table 4.

Marshall stability test:
The Marshall stability and flow test provides the performance prediction measure for the Marshall mix design method. The stability portion of the test measures the maximum load supported by the test specimen at a loading rate of 50.8 mm/minute. The specimens were prepared in the college laboratory in the standard temperatures and the results were tabulated below.    Air voids (%) 6.96    The study was concluded that among all the above observations the optimum binder content for the addition of 5% stone dust with 5% of Bagasse ash as a filler material will give the maximum stability with minimum binder content and flow value, so we can conclude that it is best suited for wearing course.