Roller-compacted concrete

Extensive research has been conducted on the use of the following SWMs as highway C R materials (an alternative innovative way to recycle/reuse such wastes), soil stabilization material, roller compacted concrete, and road base stabilization materials. They include the following [1]. 

Fluorogypsum is not being used in any commercial applications however, it has been evaluated for use as a road base material, and in the production of impure plasterboard Phosphogypsum is a calcium sulfate hydrate that is pumped into ponds, eventually dewatered, and ultimately disposed of in large stockpiles called stacks. It has been recovered and reused with some success in stabilized road bases, unbound road bases, and roller-compacted concrete. It can be used for agricultural purposes, if the radium-226 concentration of the source material is less than 10 pCi/g... 

Chang WF (1988) A demonstration project roller compacted concrete utilizing phosphogypsum. Florida Institute for Phosphate Research, Publication No 01-068-072, Bartow, Florida, p 412... 

From 1984 Lowe was an independent consultant on dam engineering in Yonkers NY. He was the eighth Terzaghi Lecturer of the Society of Soil Mechanics in 1971, the second USCOLD Lecturer of the US Committee on Large Dams in 1982, and keynote lecturer on roller compacted concrete in 1988. He was a Fellow of the American Society of Civil Engineers ASCE, and member of the National Academy of Engineering. 

Roller-compacted concrete is developed and extensively applied to construct concrete dams in Japan. In order to control the consistency of fresh concrete, the VC test is carried out. The test is illustrated in Fig. 10.1. Fresh concrete after mixed is placed in the mold on the vibratory table, which vibrates vertically with 1mm stroke and 10 gal acceleration. The surcharge weight is 20 kg. During the vibration, time is measured by second, which is named VC value , until breeding water is observed at the surface of the mold. 

The use of plasterboard gypsum (PG) combined in mixtures with blast furnace slag, cement kiln dust (CKD), cement bypass dust (BPD) and power station mn-of-station ash (ROSA) was investigated to form a novel blended binder with pozzolanic properties. This novel binder had potential use to stabilise soils and to produce semi-dry roller compacted paste and roller-compacted concrete (RCC) for road foundation construction. 

The compressive strength of concrete is linked directly with the level of compaction. Therefore, concrete with zero slump should be compacted in different ways from conventional methods in which a vibrating table is used. These types of concretes are known as roller-compacted concrete (RCC) and usually contain low proportions of cement. 

A car park at the Lowdham Grange prison construction site in Nottingham was selected to evaluate the use of roller-compacted concrete (RCC) as the sub-base layer using Coventiy Binder. 

The results obtained with the concrete cubes samples from each truck indicated that the compressive strength was much lower than the laboratory strength of 10.8 MPa. However, the cube samples were compacted using a vibrating table attached to a hanuner drill and therefore, due to the size of the aggregates and the nature of the roller-compacted concrete, compaction was different in each set of moulds. As a result, these samples were less compacted than the RCC layer which was laid and compacted using a 3-tonne vibrating roller. 

Due to the slow strength development of the binder, roller compacted concrete (RCC) seemed to be the perfect way to lay the road base layer with acceptable compressive strength of 10-12 MPa at age of 28 days. 

Roller compacted concrete (RCC) is a dry concrete consolidated by the use of external vibrating rollers. Its initial consistency makes the main difference in comparison with ordinary concretes - its conventional slump value is equal to zero. The moisture content should be high enough that mixing is possible and the appropriate distribution of cement is feasible, but it should be sufficiently low to support heavy rolling and vibrating equipment. The aim of rolling is to decrease the porosity that should not exceed 3%, particularly when frost resistance must be ensured. 

Abdel-Halim, M. A. H., Al-Omari, M. A., Iskender, M. M. (1999) Rehabilitation of the spillway of Sama El-Serhan dam in Jordan, using roller compacted concrete , Engineering Structures, 21 497-506. 

Kokubu, K., Cabrera, J. G., Ueno, A. (1996) Compaction properties of Roller Compacted Concrete , Cement and Concrete Composites, 18 109-17. 

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