Case Study On Aggregates

“Roman concrete (opus caementicium), like modern concrete, is an artificial building material composed of an aggregate, a binding agent, and water. Aggregate is essentially a filler, such as gravel, chunks of stone and rubble, broken bricks, etc. Binding agent is a substance which is mixed with the aggregate wet (water added) and solidifies when it dries, or "sets." Many materials, even mud, can be a binding agent, and used to make, what we generally call, mortar. Historically lime or gypsum, mixed with rubble stones, have been used as binding agents in making a strong mortar” (Roman Concrete).

Seven distinct grades of bitumen emulsion are specified under Australian Standard AS1160 Bitumen emulsions for road construction and maintenance – each defined by their basic type and setting characteristics.

1 Brune, PF, AI Ingraffea, MD Jackson, and R Perucchio. 2012. The toughness of Imperial Roman concrete.

Soft rocks are very important geomaterials since they are heavily used in construction for example, buildings, road and dams but they sometimes seem to cause some problems due to their sedimentary properties like fast weathering and low strength. Weathering is a process in which rock break down or dissolve with the help of natural agents. Weathering and erosion are constantly changing the earth’s surface, so that has a big impact on construction and usage of soft rocks over time. Weathering can be either mechanical or chemical. Some regions in the world mainly possess weak sedimentary rocks and very low in other stronger rock like igneous or metamorphic. Because of the these weak characteristics, it might be tough to use soft rocks especially since some methods and systems are made mainly for hard rocks. These issues that we are dealing with lead to the need of the understanding of soft rocks, how they work and how to prevent them from breaking up and crumbling in order to maximize their usage.

The objective of this experiment is to obtain the grading curve for both fine and coarse aggregate.

scuffing, mixes are typically designed with polymer-modified binders. Fibers are often added to the mix to reduce drain down. Many states have a specification for open-graded friction courses and asphalt treated permeable bases that may be used in specifying mixes for porous asphalt pavements.” (U.S. Department of Transportation, 2015).

As shown by the Griffith criterion, tensile strength of brittle materials is theoretical 1/8 of the compressive strength. Typically, tensile strength of rock materials is about 1/10 to 1/8 of the compressive strength. Hence, rock fails easily under tension. In design, rock should be subjected to minimum tensile stress. Several methods are commonly used to test the tensile strength of rocks:

In order to produce High Performance Concrete, cement which containing as little C3A as possible should be used during manufacture process. This is because the lower amount of C3A, the easier to control the rheology properties on cement. Other than that, the cement-super plasticizer compatibility problems can also be reduced. Finally from strength point of view, this cement should be finally ground and contain an appropriate amount of C3S.

Airport and highway pavements should have sufficient quality and thickness to support airplane and highway loads respectively without failure (Mukabi & Ngaya 152). In addition, their surfaces should be firm and strong throughout the year and in any whether conditions. Both pavements must be stable enough to withstand adverse weather conditions as well as abrasion by traffic. To achieve these requirements, several factors of design and construction should be incorporated to guarantee a quality pavement.

Plastic increases the melting point of the bitumen and makes the road retain its flexibility during winters resulting in its long life. Use of shredded plastic waste acts as a strong “binding agent” for tar making the asphalt last long. By mixing plastic with bitumen the ability of the bitumen to withstand high temperature increases. The plastic waste is melted and mixed with bitumen in a particular ratio. Normally, blending takes place when temperature reaches 45.5°C but when plastic is mixed, it remains stable even at 55°C. The vigorous tests at the laboratory level proved that the bituminous concrete mixes prepared using the treated bitumen binder fulfilled all the specified Marshall mix design criteria for surface course of road pavement. There was a substantial increase in Marshall Stability value of the mix, of the order of two to three times higher value in comparison with the untreated or ordinary

The standard size of the specimen is 64mm X 12.7mm X 3.2mm with a V shaped notch in the middle. Occasionally specimen without notch can also be used.

The right consistency is achieved when you stop seeing dry patches in the mixture, and when not too much water is pooling or preventing the concrete from keeping its shape on the

7 Hardenability In Jominy Test .............................................................................. 8 Advantages & disadvantages of Jominy Test ................................................... 10 Testing Procedure .............................................................................................. 10 Uses of hardenability values ............................................................................. 13 Effects of alloying and microstructure .............................................................. 13 2.8.1 Carbon ................................................................................................... 14 2.8.2 Other alloying elements ......................................................................... 15 2.8.3 Boron ..................................................................................................... 15 2.9 Grain size........................................................................................................... 15 2.10 How to produce the result ................................................................................. 16 2.10.1 Contourplots .......................................................................................... 16 3 DESIGN PLAN OF JOMINY TESTING MACHINE ............................................. 18 3.1 Basic concept of the design ............................................................................... 18 3.1.1 Design standardization

The compression test shows the compressive strength of hardened concrete. The compression test shows the best possible strength concrete can reach in perfect conditions. The compression test measures concrete strength in the hardened state. Testing should always be done carefully. Wrong test results can be costly.

In the laboratory the dimensions of each concrete cube was measured using callipers. It was ensured that before each reading the calliper was zeroed to minimise any errors. The length, width and then depth was measured before proceeding to the next sample. 2 members measured the samples whilst 2 recorded the results. After all dimensions were recorded the mass of each cube was obtained using an analytical balance weighing the samples cured from 0 days up to 28 days.