Plum concrete
Contents |
[edit] Use of plum concrete
Civil design or engineering consultants use plum concrete to optimise the project costs in industrial projects.
Plum concrete, is where medium and large-sized stones are used as the aggregate. Plum concrete may also referred to as cyclopean or rubble concrete. The stone aggregates (plum) can be 150mm or 200 mm, or 300 mm or larger. The selection of plum size is based on the application, availability and engineering requirements.
This type of concrete maybe recommended for structures like gravity dams, barriers, bridges, or as mass concrete for machine foundations, retaining walls etc. Here the size of the plum would most likely be around 150 mm.
The uses of plum concrete are:
- For mass concreting where a high plain cement concrete (PCC) thickness is required due to strata.
- Under footing applications where the ground slope maybe between 1:10 to 1:50.
- In the construction of gravity dams, retaining walls, steep road slopes, bridge and culvert barriers.
- It is also used for road embankments, surface beds for water channels and machine foundations.
- For back filling deep or uneven sites
[edit] Properties of the plum concrete
The plum should be from trap rock (also know as Trapp or Trap), basalt or any other locally available stone. The stone should have at least 100 Kg/Sq mm minimum crushing strength. The stone should be hard, strong, durable, angular shaped, and with no seams, cracks or other structural defects.
The plum should be clean, and free from dirt, soil, organic or harmful materials. The process of plum batching should be carried out only after careful inspection of the materials.
The main difference between plum concrete and plain cement concrete (PCC) is that the filler materials used are large boulders, this helps bring costs down by up to 30% making it more economical.
[edit] Mix ratios of plum concrete
The specific application will help in decide the volume or ratio of plum required in the concrete. The plum to concrete ratio will be dictated by the engineering specification, however, when the plum is 150 mm, the plum volume is likely to be between 30% to 50% of finished concrete. When the plums are above 160mm, the volume of plum should be capped at 20% of the volume of finished concrete.
[edit] Preparation for plum concrete
The plum is added directly into the mixer or by spreading the plums over the wet mix followed by a further layer of concrete. When using the former method, the size of the plum should not be more than 1/3rd of the cross-section of the concrete mixer.
The specification of ingredients, mixing, placing, and testing should be as per IS456. Usually, M10 or M15 concrete is used.
The shuttering should be strong enough to avoid being damaged while stones are placed and concrete poured. The preparation of the working area and materials are as follows:
- Clean the working surface
- Remove any soft soil, dirt and other loose items, as these may affect the soil bearing capacity.
- Keep the surface moist by sprinkling water prior to pouring, this moisture is to ensure proper bonding.
- If needed Anti-termite treatment, can be spray applied.
It is recommended that a seven-day curing process is adopted to ensure full strength.
In summary, plum concrete can be utilised by civil design and engineering consultants for the strength and economic optimisation of projects, the specifics of this are dependent on suitable advice according to specific site conditions and particular project requirements.
[edit] Related articles on Designing Buildings
- Admixture, additive or agent.
- Admixtures in concrete.
- Architectural concrete.
- Cast-in-place concrete.
- Cellular concrete.
- Portland cement.
- Recycled concrete aggregate RCA.
- Reinforced concrete.
- Scabbling.
- Screed.
- Self-compacting concrete.
- Stratification of concrete.
- Testing concrete.
- The properties of concrete.
- The use of concrete structures to protect construction sites.
- Types of concrete.
Featured articles and news
One of the most impressive Victorian architects. Book review.
RTPI leader to become new CIOB Chief Executive Officer
Dr Victoria Hills MRTPI, FICE to take over after Caroline Gumble’s departure.
Social and affordable housing, a long term plan for delivery
The “Delivering a Decade of Renewal for Social and Affordable Housing” strategy sets out future path.
A change to adoptive architecture
Effects of global weather warming on architectural detailing, material choice and human interaction.
The proposed publicly owned and backed subsidiary of Homes England, to facilitate new homes.
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.