Concrete production over the years has evolved from the traditional method of mixing cement, aggregates, and water to
the addition of chemical admixtures in conjunction with cement, aggregates, and water. The practice of adding chemical
admixtures as a component of concrete constituents is not new in many advanced countries. However, in many West
African countries, it is not widely known.
Ghana, a developing country is witnessing an increase in many infrastructure developments in recent years. Structures
including concrete roads, church buildings, industries, market facilities, and residential buildings are being constructed.
All these facilities depend on concrete for infrastructure development. However, the traditional method of formulating
concrete is a big problem for consultants and building contractors. The problem with the use of the traditional method of
concrete mix design has got to do with the achievement of the characteristic strength. Many times, builders struggle to
achieve the specified strength. For instance, this work came about after the contractor has struggled to achieve the specified
strength of 30MPa for the reinforced slabs and columns of a multi-story church building. The maximum characteristic
strength the contractor was achieving from the traditional method of concrete making was 20MPa. Investigations from the
site operations revealed that controlling the water required to achieve workable concrete was very problematic. This,
therefore, resulted in the excessive use of water to make the concrete workable. However, the studies of Šiler et al [1] have
revealed that the high content of water in concrete introduces pores and therefore causes a reduction in strength
performance. The difficulty in achieving the specified strength for the church building facility necessitated the need for
further solutions to achieve the characteristic strength.
The use of chemical admixtures in a form of superplasticizers has shown to be one good means to reduce excess water
while assuring good workability and achieving high-performance concrete [2]. SPs’ ability to reduce water means low
porosity and permeability and hence enhanced durability of concrete [3]. Superplasticizers are known to be organic
materials that are not biologically degradable and prone to microbial attacks. SPs are high-density molecular polymers
usually soluble in water [4]. The common types of chemical admixtures used in concrete include lignosulphonate (LS),
sulphonated naphthalene formaldehyde (SNF), sulphonated melamine formaldehyde (SMF) and polycarboxylate ethers
(PCEs) [5, 6]. LS are reported to have lower water-reducing and plasticizing ability as compared to SNFs, SMFs, and
PCEs. SNF, SMF, and PCEs have high range water reducing ability and are hence classified as superplasticizers.
Researchers have categorized LS, SNFs, and SMFs as second-generation chemical admixtures and the PCEs as newgeneration admixtures [3, 6].
Cement particles have charges on their surfaces which make them flocculate in contact with water [7]. Flocculation of
cement grains entrap water and therefore results in less water available for adequate hydration of cement. The introduction
of superplasticizers deflocculates the cement grains making water available for cement hydration whilst improving the
rheology of concrete. Second-generation superplasticizers including SNF can disassembly the flocculated cement particles
via electrostatic repulsion which is induced by the adsorbed superplasticizer molecules. The studies of Kapelko [8] used
SNF to modified concrete and his results indicated that concrete modified with SNF reduced the amount of mixing water
and decreased significantly the water-cement ratio. This resulted in an improved 28-days strength performance of the SNFbased concrete compared to the control concrete. Tkaczewska [9] studied the effect of different types of superplasticizers
on fly ash blended cement. His findings showed that the addition of SNF reduced the amount of water by 31% to reach the
same consistency as the control. The strength of the mortar mixtures containing SNF was also better than the normal mortar
mixture. Bouzoubaaˆ et al [10] performed investigations on super plasticized cement using SNF and normal portland
cement. Their investigation found out that the mortars made with the superplasticizer cement had shorter setting times and
higher compressive strengths than those made with the control Portland cement. The work of El-Gamal et al [5] also found
out that the addition of SNF to OPC pastes caused a notable improvement in the mechanical properties of the hardened
pastes during all stages of hydration. The improvement in the mechanical properties when SNFs are used is attributed to
the reduction in the mixing water lowering the water-to-cement ratio [5, 9, 10].
In this study, the main aim was to achieve a workable concrete mix design that could meet the specified design strength.
In achieving this, an SNF superplasticizer was used. The designed strength that guided the concrete mix design was C25/30
class of concrete strength. Slump flow and compressive strength were used to study the fresh and hardened state of concrete
properties respectively.
