Pervious Concrete – Effect of Material Proportions on Porosity

Dhawal Desai

This paper describes the effect of size of aggregates and proportions of cement, aggregates, admixture and water on porosity of Pervious concrete which is the main feature of pervious concrete. Different sample blocks were made in lab with variations in mixture to see the porosity for final conclusion

Pervious concrete is a type of concrete with high porosity. It is used for concrete flatwork applications that allow water to pass directly through it, thereby reducing the runoff from a site and allowing groundwater recharge. The high porosity is attained by a highly interconnected void content. Typically pervious concrete has water to cementitious materials ratio (w/cm) of 0.28 to 0.40 with a void content of 18 to 35%.
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Utilization of Pulp Black Liquor Waste As A Cement Admixture

By H. H. M. Darweesh*, A. H. Abdel-kader2** and M. G. El-Meligy3**

Contact information: *Refractories, Ceramics and Building Materials Dept., 2**Taif University, Chemistry dept.,2, 3**Cellulose and Paper Dept. National Research Centre, Dokki, Cairo, Egypt.

The pulp black liquor waste (PBL), a byproduct from paper-making, is applied as a cement admixture in two types of cement, namely Ordinary Portland cement (OPC) and Portland limestone cement (LPC). The results showed that the water of consistency of cement pastes premixed with PBL was gradually increased with the concentration of PBL while the setting times (initial and final) were decreased. So, it can be used as an accelerator. The compressive strength increased slightly during the early ages of hydration but sharply during the later ages, particularly with those premixed with PBL. The combined water content and bulk density displayed the same trend as the compressive strength, whilst the apparent porosity decreased at all curing times. The IR spectra of cement pastes showed that the intensities of the different peaks of cement pastes with PBL are higher than those of the pure samples. The SEM images proved that the incorporation of PBL with cement did not affect the chemical composition of OPC or LPC hydrates, but it only affected the physical state, shape, size, morphology and crystallinity of the formed hydrates. The 2 wt. % of PBL is the optimum concentration.

PBL, OPC, LPC, combined water, bulk density, porosity, Strength, IR, SEM.
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Behavior of Concrete in Shear and Torsion with Different Types of Steel Fiber Using Constant Volume Fractions and Different Aspect Ratio

Kishor Sambhaji Sable (Faculty, Civil Engineering Department, Amrutvahini College of Engineering, Sangamner, Ahmednagar, Maharashtra, India)

Yogesh Ravindra Suryawanshi (M.E Civil (Structures), Amrutvahini College of Engineering, Sangamner, Ahmednagar, Maharashtra, India)

Mehetre Amol Jagganath (Faculty, Civil Engineering Department, Amrutvahini College of Engineering, Sangamner, Ahmednagar, Maharashtra, India)

In this modern age, civil engineering constructions have their own structural and durability requirements. Fiber Reinforced Concrete (FRC) is a composite material made primarily from hydraulic cements, aggregates and discrete reinforcing fibers. Fiber incorporation in concrete, mortar and cement paste enhances many of the engineering properties of these materials such as fracture toughness, flexural strength, resistance to fatigue, impact, thermal shock and spalling.

The SFRC is a composite material made of cement, fine and coarse aggregates and discontinuous discrete steel fibers. Recently developed an analytical model to predict the shear, torsional strength and bending torsion behavior of fiber reinforced concrete beam with experimental substantiation. However, very little work has been reported in combined torsion and shear. Similarly to beam with conversional reinforcement, the presence of shear may significance influence on torsional strength of fiber concrete beams. Present paper investigates the mechanical properties like as shear strength, and torsion strength of concrete with different types of steel fiber with constant volume fractions and different aspect ratio.

Key words: Aspect ratio, Fatigue, Flexural strength, Fracture toughness, Mechanical properties, Spalling, Volume fraction.
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Concrete Aggregates From Discarded Tyre Rubber

Kaushal kishore
Materials Engineer, Roorkee

The scarcity and availability at reasonable rates of sand and aggregate are now giving anxiety to the construction industry. Over years, deforestation and extraction of natural aggregates from river beds, lakes and other water bodies have resulted in huge environmental problems. Erosion of the existing topography usually results in flooding and landslides. Moreover, the filtration of rain water achieved by deposits of natural sand is being lost, thereby causing contamination of water reserves used for human consumption. Hence, to prevent pollution authorities are imposing more and more stringent restrictions on the extraction of natural aggregates and its crushing. The best way to overcome this problem is to find alternate aggregates for construction in place of conventional natural aggregates. Rubber aggregates from discarded tyre rubber in sizes 20-10 mm, 10-4.75 mm and 4.75 mm down can be partially replaced natural aggregates in cement concrete construction.

About one crore 10 lakhs all types of new vehicles are added each year to the Indian roads. The increase of about three crores discarded tyres each year pose a potential threat to the environment. New tyre is made of natural rubber (also called virgin rubber), styrene-Butadien Rubber (SBR), Polybutadienc Rubber (PBR), Carbon black, Nylon tyre cord, rubber chemicals, steel tyre card and Butyl rubber.
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Bitumen Modified With Styrene Butadiene Styrene thermoplastic For Roofing Application

Ms. Chinkal Patel – M.E. Chemical, GCPC , Gandhinagar
Prof. Rupande Desai – Asst. Professor of Rubber Technology, L. D. College of Engineering, Ahmedabad
Dr. P. J. Gundaliya – Asst. Professor of Civil Engineering, L. D. College of Engineering, Ahmedabad

In the Past, bitumen was used to waterproof roofs. The roof crack reflected through to the surface of each successive bitumen patch. The cracking problem solve if incorporated rubber in next round of patching. Roofing is a past or we also say that present waterproof barrier of environment & Human Effectiveness.

The primary reason for using bituminous rubber is that it provides significantly improved engineering properties over conventional grade bitumen.
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