TANZANIA - #likelafargeholcim

For building tips and information, follow us on

Tips for mixing and casting concrete slabs

Pouring a concrete slab

Casting a flat concrete slab may seem like an easy task, but there are some important details to remember that will make process safe and successful. One of the first things that contractors will learn on the job is how to pour a flat slab of concrete, whether it is for a floor, countertop or a base for an object.

Here are some things to consider before, during and after pouring concrete slabs. These tips will ensure that you don’t waste money or time during the process. Once you have built the wooden formwork and mixed the batch of concrete, remember the following points:

Safety is paramount

All contractors should wear appropriate safety gear when working with cement and concrete. Workers should have dust masks, goggles, gloves, boots and overalls. Appoint one employee to perform a quality check of the building materials and equipment before mixing the concrete. 

This will ensure that everything is in working order and that a high-quality batch of concrete is created. It will also ensure the safety of other contractors as faulty equipment, such as cement mixers, could lead to injury. This designated worker can also file safety reports and create quality checklists if needed.

Create a detailed batch report system

Before mixing the concrete, print out a detailed batch report that lists all the building materials needed and their quantities for each batch. When measuring out the sand, gravel, cement and water, put a tick beside each material. When adding the materials to the mixer, put another tick next to each item on the list.

This double-tick system will help you keep a detailed record of your building materials and see if there are any discrepancies or losses. It will also help you to accurately calculate how much concrete you will need to mix for the slabs. The batch report can be used for future reference so that you can easily recreate the slab with the correct quantities of materials.

Keep materials, tools and equipment nearby

It will help you to keep all of your building materials (sand, gravel, cement and water) near to the location where you will pour the concrete slabs. Also have all the necessary tools and equipment nearby. This will save time and effort when you need to quickly add some more materials to the concrete batch. It also makes it easier to carry heavy bags of cement or wheelbarrows of sand if they are stored close to the working site.

Pour multiple slabs from the same batch of concrete

If you are pouring several slabs at once, it is important to mix a large batch of concrete and use it to pour all the slabs, rather than mixing a small batch for each individual slab. This will ensure quality and consistency between all the slabs. Any variation in the ratios of wet and dry ingredients will easily be seen in the slabs. By mixing one batch of concrete, you will end up with identical slabs. 

Add materials to the mixer in the correct order

There is actually an ideal order in which building materials should be added to a cement mixer; sand and gravel go in first, followed by water and any admixtures. Next add any fibres and pozzolans. Lastly, the cement should be added gradually to the mixer.

The reason for following this order is simple; if you add cement first, followed by water, it can clump inside the mixer. Mixing the sand and gravel with water first ensures that all of the aggregates are wetted and dispersed. When the cement goes in last, it will combine nicely with the other materials to form a high-quality batch of concrete.

Some other points to remember

If you are hand-packing a stiff batch of concrete into a wooden form, make sure that the concrete goes into every edge and corner of the mould. If you are pouring a fluid mix of concrete, make sure that you release all the trapped air bubbles by tapping on the side of the formwork. 

If you are using steel rebar for reinforcing, make sure that it is suspended in the middle of the concrete batch and that no rebar stick out of the surface of the slab. These are some of the points to remember when pouring concrete slabs. Some of these details can be overlooked, which could affect the quality of the slab, so keep these tips in mind.

___

LafargeHolcim is a leading building materials and solutions company that has been operating in international markets for decades. We produce cement and aggregates for construction projects, ranging from small affordable housing developments to large-scale infrastructure projects such as high-rise buildings, dams and bridges. 

___

LafargeHolcim Tanzania has been supplying the country and neighbouring countries with our world-class Tembo cement brand for over 30 years. Our head office and fully-integrated plant are located in Mbeya, Southwest Tanzania.

___

At LafargeHolcim Tanzania, we believe customers come first. We listen to your specific requirements to supply and develop the best solutions for your needs. As the new leader in building materials, you can also rely on our cutting-edge research and development capabilities that have resulted in the finest materials for your construction projects, whether large or small.

___

Follow us on Facebook, Twitter, LinkedIn and Pinterest for the best tips on construction, handy projects and the latest industry news. See our Instagram channel for more insights into our products.

Tembo SupaSet cement used in construction of Wanging’ombe District Hospital

LafargeHolcim Tanzania is supplying Tembo cement for the construction of a new hospital. The Wanging’ombe District Hospital is currently being built under the supervision of the district engineer. Tembo SupaSet is being used to construct the foundations of the new healthcare facility. The Wanging’ombe District Hospital is located in Wanging’ombe – one of six districts …

Things to know about mortar for bricklaying

The two most common types of mortar used for bricklaying are cement and lime mortar. They have different properties and strength characteristics, so it is important for contractors to which one to use for a project. LafargeHolcim Tanzania manufactures a few cement products that are suitable for use as mortar in brickwork. These are Tembo …

Things to consider when pouring concrete during the rainy season

Construction projects are planned and executed all-year-round. This means that contractors need to build in some extreme weather conditions, from searing hot and dry temperatures to windy and rainy weather. These factors can all affect concrete and how it cures, but the rainy season can be particularly hard because it brings water and wind. Contractors …

How to prevent salt damage to your concrete structures

Salt is a natural mineral that can sometimes end up in your concrete mixture. It can either be present in the sand and aggregate or it can end up in the concrete if you are building in a seaside environment. It appears as white streaks or powdery crystals on the surface of cured concrete. The …

Inspection checklists for pouring concrete

All construction projects should be inspected at least once a day. This will ensure that the quality of the structure is up to standards and that the work is being done properly. An inspection is especially important when pouring concrete. There are a number of checks that should be performed to record the process and …

Building Materials Centre paving the future of Tanzania

The future holds many challenges for Tanzanians, especially in the infrastructure sector. Luckily, LafargeHolcim Tanzania understands these challenges and can help Tanzanians prepare to overcome them. We offer training programmes and free knowledge-sharing sessions at our Building Materials Centre in Dar es Salaam.  LafargeHolcim Tanzania shares the interests and concerns of the communities around us. …

Avoid these common construction mistakes

A building’s quality and resilience are not only affected by the materials used to construct it. Workmanship and building techniques also determine how well a structure will be completed. Poor concrete construction methods will result in a badly-built structure. Construction mistakes are made when contractors are not trained properly or when they are negligent. Poor …

Update your business space with concrete

Concrete is a wonderful building material. Not only is it perfect for the structure of buildings, but it can also be used in a decorative way. Business owners, restauranteurs and retailers should consider incorporating concrete into the interior design of their workspaces. This will modernise and improve the look and feel of the office, restaurant …