Laying foundation concrete is a critical phase in any construction project, forming the base that supports the entire structure. In Kenya, whether constructing a county hospital, a university lecture hall, or a retail shop in Nairobi, the quality and safety of foundation work determine the durability and safety of the building. This chapter addresses essential aspects of laying foundation concrete, focusing on personal protective equipment (PPE) and the key material, cement. Understanding the correct classes of PPE and the properties of cement ensures construction workers operate safely and produce strong, reliable foundations.

2.1 PPEs

Personal protective equipment (PPE) is the clothing and gear a worker wears to reduce exposure to hazards that remain after site controls such as barricades, shoring and machine guards are in place. Foundation concrete work exposes workers to wet cement, which is strongly alkaline and burns skin, cement dust, sharp reinforcement bar ends, heavy loads, deep trenches, noise and vibration from mixers and pokers. The Occupational Safety and Health Act, 2007 requires the employer to provide suitable PPE free of charge and the worker to wear it, and the contractor's site safety officer checks it daily.

Example: before the foundation pour for a maternity wing in Ol Kalou, the site foreman stops two labourers working in canvas shoes and issues them gumboots before they enter the wet concrete.

Head Protection

Safety helmets (hard hats) protect the head from falling objects such as stones, tools and bars dropping into the trench, and from knocks against formwork and starter bars. They are worn by everyone on site, including visitors. Helmets with chin straps are used where workers bend over trenches or climb in and out of excavations, so the helmet does not fall off.

Construction workers wearing safety helmets guiding the pouring of con (Source: substructure-1)

Worker wearing impact-resistant helmet on steel structure (Source: Wikimedia Commons)

• Fit and condition: The helmet's inner harness is adjusted to the head and the shell is replaced if cracked, deeply scratched or after a heavy impact.
• Colour coding: Many Kenyan sites use colours to identify roles, for example white for supervisors and yellow or orange for general workers.

Hand Protection

Wet cement and concrete cause chemical burns and dermatitis, while rebar ends, tying wire and rough aggregate cut and scratch the hands.

A pair of protective gloves (Source: Wikimedia Commons)

• Waterproof rubber or nitrile gloves: Worn when handling wet concrete, spreading, levelling and cleaning tools, because cement burns develop without pain at first.
• Leather or heavy-duty work gloves: Worn when carrying aggregates, formwork and cement bags.
• Cut-resistant gloves: Worn when cutting and tying reinforcement bars, where bar ends and wire are sharp.

Metal mesh cut-resistant glove (Source: Wikimedia Commons)

Foot Protection

Feet are at risk from dropped bars and blocks, nails in formwork, and prolonged contact with wet concrete.

A single safety boot for industrial use (Source: Wikimedia Commons)

• Safety boots with steel toe caps: Protect against falling and rolling objects and nails during formwork and steel fixing.
• Gumboots (rubber boots) with protective toe caps: Worn when standing in wet concrete during placing and compaction; trousers are worn over the boot tops so concrete cannot enter.
• Slip-resistant soles: Reduce falls on wet, muddy trench bottoms.

Eye and Face Protection

Cement splashes during mixing and placing, and chips fly when cutting bars or breaking out old concrete. Safety goggles or spectacles with side shields are worn for mixing, placing and cutting, and a face shield is added when using an angle grinder or disc cutter on reinforcement.

Respiratory Protection

Cement dust, released when bags are opened and emptied into the mixer, irritates the nose, throat and lungs, and dry cutting of concrete releases silica dust.

Person wearing a dust mask (Source: Wikimedia Commons)

• Disposable dust masks (FFP2 or N95): Worn by workers emptying cement bags and batching dry materials.
• Half or full-face respirators with particle filters: Used for prolonged dusty work such as dry cutting of concrete or blocks.

Person wearing a full-face respirator mask (Source: Wikimedia Commons)

• Powered air-purifying respirators (PAPR): Used only for heavy dust exposure or where a worker cannot get a good seal with a tight mask.

Person wearing powered air-purifying respirator (Source: Wikimedia Commons)

Body Protection

Overalls with long sleeves keep cement off the skin and protect against scratches. Where concrete admixtures, curing compounds or form-release oils are sprayed, chemical-resistant aprons or splash suits are worn as the product's safety data sheet requires.

Two people wearing chemical splash suits (Source: Wikimedia Commons)

High-visibility safety vest (Source: Wikipedia (High-visibility clothing))

High-visibility vests or jackets make workers visible to tipper, mixer and excavator drivers, especially when concrete is delivered by truck or dumper.

Hearing Protection

Concrete mixers, poker vibrators, compressors and disc cutters can exceed 85 dB(A). Earplugs or earmuffs are worn by workers operating or standing near this equipment for long periods.

Fall Protection

Workers in deep foundation excavations, on the edges of basements or on raised platforms over pile caps can fall. Guardrails and covered edges come first, and a full-body harness with a lanyard attached to a secure anchor is worn where those are not possible.

Worker fitting full-body harness on mannequin (Source: Wikimedia Commons)

Selection, Use and Care of PPE

1. Assess the task: Identify the hazards of each activity (batching, steel fixing, placing, compaction, curing) and choose PPE that matches them.
2. Check the fit: Helmets, gloves, boots and masks must fit the individual; poorly fitting PPE is removed by workers and gives no protection.
3. Inspect before use: Look for cracks, holes, worn soles, torn gloves and blocked filters, and replace damaged items at once.
4. Train the wearer: Show workers how to wear, adjust and remove PPE, especially masks and harnesses.
5. Use it throughout the task: PPE is worn for the whole operation, not only when the supervisor is present.
6. Clean and store: Wash cement off gloves and boots at the end of the day and store PPE in a dry, clean place away from sunlight and chemicals.
7. Record issue: Keep a PPE issue register signed by each worker, as evidence for the safety officer and for DOSHS inspections.

Chapter Summary

This chapter provided a comprehensive overview of laying foundation concrete, starting with the essential personal protective equipment required to ensure safety during the process. It then detailed the various tools and equipment used in concrete works, highlighting their specific roles. The classification of concrete was explained with emphasis on classes 15, 20, 25, and 30, each suited for different structural requirements. The batching of concrete materials covered the accurate measurement and selection of cement, fine aggregates, coarse aggregates, and water, critical for achieving the desired concrete quality. The process of fixing reinforcement bars was discussed to ensure structural strength and stability. Mixing of the batched materials was outlined to achieve a uniform and workable concrete mix. The chapter also described the proper placing of fresh concrete and the importance of thorough compaction to eliminate voids. Finally, curing was emphasized as a vital step to maintain moisture and promote the concrete’s strength development.