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Conforms to BSS I 125 and ISI 774–1960

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Cutting The Cost Of Road Construction

Far from the bustle of the city, experts at the Central Road Research Institute near Okhla are quietly working on a number of projects. They have made commendable progress in many cases but are shy of talking of their achievement—not from a sense of false modesty but because of a fear that technical facts might be garbled and the layman misled into believing that something revolutionary has been done.

Of the notable jobs done at the Institute is one designed to cut the cost of road constructions. Broadly, it has been found that economies might be effected by introducing more inferior material, after processing, in road building. The common type of road is built with burnt brick as the base and broken granite forming the upper layer. The cost of construction depends among other things on the proximity of the quarry. Attempts had been made in the past to introduce inferior material broadly classified in the category of small stones, gravel, laterite and slate but the results had not always been satisfactory.

The CRRI has made tentative suggestions, after laboratory and field studies, on how inferior material could be effectively used for various types of roads. It has been found that soft aggregates even of poor quality can be used as the base in road construction, resulting, on a rough calculation in a saving of about Rs. 5,000 per mile. If the inferior aggregate is sufficiently hard it can be used as the base and the upper layer as well and the saving in this case would be about Rs. 13,000 per mile.

Pozzolanic Cement

Another important result of work undertaken at the Institute is a saving in the use of cement. After fundamental and applied research on the use of burnt clay as pozzolana (volcanic ash) a new building material, “reactive surkhi’’, has been cvolved. The findings show that if the right type of clay is burnt under controlled conditions it will yield “reactive pozzolana” which, when added to lime and sand, has three to four times the strength of mortar made with bazar surkhi, lime and sand.

According to experts at the Institute the two essential requisites for industrial production of this material are the location of the right types of raw clay and the necessary know-how for its controlled burning and grinding.

“Reactive surkhi’’ can be mixed with cement at the works by grinding the clinker and burnt clay together to produce “pozzolanic cement” which, it is claimed, is superior to, and perhaps cheaper than,ordinary cement. The material can also be mixed with lime and the product can be a substitute for cement in small bridges and culverts, single and double-storey masonry and building foundations.

A survey, which is not yet complete, has shown that the right type of clay is available in 11 States. For controlled calcination of clay to so “reactive surkhi’’ two types of kilns have been found suitable—a small rotary kiln with a capacity of 5 to 15 tons, and a batch type, down-draught kiln whose size could be adjusted according to available finances and the output required.

Highways Bill West Bengal Government have introduced in the State Assembly a new Highways Bill, which seeks to replace the 1952 Bengal Highways Act of 1925. The new Bill has more stringent provisions.

The objects of the measure are essentially to remove difficulties experienced by the Government in dealing with the numerous encroachments on the roadside lands throughout the State. Such difficulties had increased considerably in recent years because of instruction of many new roads.

Under the present Act road offences should go to the criminal courts. It was only after conviction that the court could pass order for removal of encroachments. Cases were not rare when criminal proceedings resulted in acquittal and the Government were then advised to go to civil courts. It is now proposed to end the time-consuming procedure and make it simpler.

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