CONSTRUCTION COST MANAGEMENT

USES OF EXCESS OR WASTE CONCRETE

Concrete is a very well-known, useful and costly material in the construction industry. It is widely used in all construction sites. Freshly produced concrete is soft, workable and can be molded into any desired shape. Concrete is produced at the site for specific purposes. But sometimes, it becomes excess for different reasons. It is under control when it is green or soft and we can use it as we desire but when it starts hardening, it starts controlling us. It becomes a great headache to Engineers, Contractors, Client and to all site people when there is excess concrete.

In most cases, it is found that excess concrete is dumped at the site or used for landfill or washed out. Being a costly material, it impacts the project budget and creates an environmental hazard too. Dumping of excess concrete is not a smart idea. It should not be dumped, it can be used.

what happens when excess concrete is dumped at the site?

As concreting works ends at the site, the excess concrete is dumped to the rear corner of the site. This is the most common practice of the construction site, and dumping excess concrete, the site people think that their job is done successfully. But after few months or later, when other activities are to start at that area, or the site is to be handed over to some other agency or if the client demands to clean the site, it becomes another project to break the hardened concrete which was dumped. Not only it is the wastage of materials but the loss of time, money and manpower. The broken lumps of concrete are not usable to any suitable work rather it has to be recycled or removed from the site with the extra cost of labor and transportation. Sometimes environmental and safety issues like housekeeping, dust, noise (due to concrete breaking) etc. are to face.

How concrete becomes waste?

Though it's easy to say that there will be no excess concrete or waste concrete at the site, it's quite impossible. Construction sites are an eventful place. The unforeseen events happen occasionally. There may be some unavoidable situation for which excess or waste concrete may generate. For example, presently most of the site the concreting operation is done with the concrete pump. If the concrete pump breaks down and concrete pipeline gets choked, wastage is inevitable. Because the pipeline is dismantled, the concrete in it needs to be cleared and it cannot be reused due to quality concern. So, the concrete becomes waste. Sometimes it may so happen that the bad weather condition does not permit to continue the concreting operation and the work has to stop in midway resulting excess concrete. However, it occasionally happens in the site but one has to be prepared for that and, there must be a good planning to utilize this waste concrete or excess concrete in other works.

What to do with the excess concrete?

Every bit of material is useful provided how you plan it to use. It can be used in different works for different purposes. It depends on good planning, coordination, communication, and skill. In many construction sites, it lacks planning for uses of excess materials and waste materials. Now the time has come, it cannot be avoided further. A suitable planning for uses of excess or waste materials should be implemented in every construction site. The following tips may help to deal with the excess concrete.

1. Calculation of exact quantity:
Excess concrete generates mainly due to mistakes in calculation. Before any concreting work, calculate the exact quantity of concrete is required. Recheck the calculation twice to confirm the exact quantity. In general practice 0.75% - 1% extra quantity is considered for wastage. Add the wastage quantity to exact quantity to get the required quantity. There should be no confusion among the site people about the actual quantity of concrete is required. Sometimes confusion and miscommunication lead to generate excess concrete. Now everyone who involved in concrete operation should be well versed that how much concrete is to be produced. This information should reach properly to the concrete production plant also. In practice, consumption of concrete is either little bit more than the required quantity or little bit less than required quantity. So, it should be controlled at the end of concreting work; the last batch of the concrete production should be adjusted as per requirement so that no excess concrete is made. Thus, avoiding excess production of concrete.

2. Beforehand Planning for excess concrete:
In a construction site, there are so many activities going on simultaneously. It may be some of the activity needs concrete such as P.C.C work, sunken slab filling or small structural casting like lintels, sunshades, stool column etc. Excess concrete can be utilized there provided grade of concrete should match or higher. Or excess concrete may be sent to another site where it may require but it should be planned beforehand.

3. Make some items which may require later on:

• Precast lintels - Generally, in building projects, many piece lintels are required for the doors, windows and other openings. Lintels can be made with left-over concrete which will be used there later on. For that, form-work with proper dimensions should be made ready beforehand. The number of forms to be made as per requirement and can be used repeatedly.

• Precast slabs - In building projects there are lots of use of precast slabs like kitchen counter, selves, pit covers, surface drain cover, electric trench covers etc. Precast slabs have many uses in a site. Excess concrete can be used here also.

• Precast paver block - It's the most useful item for every construction site. Paver block can be made in different size and shape as per need. It's weight should be less so that one can lift it easily. It is mainly used to pave the temporary path, floor of temporary site office, floor for labor's camp, temporary floor for material stacking, the landscape for garden etc. It has so many uses in a construction site.

• Precast kerb & channel - In road project these are widely used, even in building projects there must be some roads, both side of a road, kerb and channel blocks are used. It can made from excess or waste concrete.

• Concrete blocks - Another way to use excess or waste concrete for making concrete blocks of different sizes with proper lifting arrangement. 0.6m x 0.6m x 0.6m or 0.9m x 0.9m x 0.9m sizes are preferable. These concrete blocks are generally used for loading purposes for static pile load test. The pile load test agency hires it. Sometimes these are used to support the scaffolding work.

• Concrete planter - It's a go green idea. Nowadays, each construction site is environmentally conscious. To make the site clean and environment-friendly, waste reduction is one of the main aspects. Reduction of waste material not only saves the cost but reduces the environmental pollution. Excess or waste concrete may be used to make concrete planters with a lifting arrangement. It's a great idea. These planters can be used for site beautification or landscape designing. Regarding the size and design of the planter can be confirmed after discussion with the landscape designer or Architect.

• Concrete post - To make the concrete post with leftover concrete is another good idea. Concrete posts (0.15m x 0.15m x 2.5m length) with hooking arrangements for barbed wire are mainly used for the site fencing work.

4. Recycle of concrete - Recycling is the last choice when there is no other way. Hardened concrete can be recycled for use. Concrete obtained from broken pile heads, dismantling of old structures or renovation work has no way than recycle. Recycle process is not an economical affair as it involves a separate set up for a crushing unit. In recycling process concrete lumps are broken to usable sizes of aggregates in a crushing plant and aggregates are screened to different sizes for reused in concrete production. Still, many construction sites do not allow recycled aggregates in structural concrete production due to strength concern and other parameters. However, it can be used in sub-grade of the road work, concrete path work, precast concrete elements, production of lean concrete, P.C.C. work etc. where strength is not a great factor. Recycling is not beneficial for small project site so it should be planned accordingly.


NOTE: 
The above said precast items are generally used in the site but if it is excess or not in use can be sold.

SHARE

Green Environment

Hi, I’m Gobinda Burman (Green Environment). More than 27 years in the field of Building Construction industry, I’ve completed many high-rise building projects successfully. I have got the opportunity to learn and solve the critical practical problems related to building construction. I love to share my knowledge with those people who wants to build their own home and the budding civil engineers willing to build their career in this field..

• 
• 
• 
• 
•