Ternary and quaternary blends as partial replacement of cement to produce hollow sandcrete blocks

A.O Sojobi,T.F Awolusi,G.B Aina,O.L Oke,M Oladokun,D.O Oguntayo

doi:10.1016/j.heliyon.2021.e07227

Abstract

Hollow sandcrete blocks constitute more than 90% of residential building construction in developing countries especially in West Africa. Over-reliance on dredged river sands and conventional ordinary Portland cement (OPC) contributes to environmental degradation and post-construction problems such as swelling and shrinkage-induced cracks prevalent in construction projects. The study investigates potential utilization of locally available materials such as laterite, calcite and calcined clay as ternary and quaternary blends to replace cement and quarry dust as 100% replacement of river sand with the aid of Taguchi-Response surface methodology approach. Optimum ternary blend of 24% calcined clay +1% calcite +75% OPC is recommended to achieve volume stability, higher compressive strength and higher flexural load capacity. Alternatively, ternary blends of 24% calcite +4% calcined clay +72% OPC can also be utilized. The improved mechanical properties were attributed to the Na- and Ca-rich aluminosilicates provided by the blended cements. Successful utilization of ternary and quaternary blended cements to produce stronger, durable and eco-friendly sandcrete blocks depends on utilization of high binder-to-aggregate ratio, optimal combination of the constituents, appropriate water-cement ratio and curing/production method. Partial and 100% replacement of river sand with granite dust is possible and contributes to reduction of environmental problems caused by river dredging as well as cleaner, ecofriendly construction. Ternary and quaternary blended cements is recommended to avert post-construction problems such as swelling and shrinkage-induced cracks prevalent in construction projects.

Highlights

Hollow sandcrete blocks are traditional materials that have been utilized in construction of residential buildings for several decades
Ternary blended cement derived from locally available pozzolanic materials is being explored as potential cement replacement while quarry dust is utilized as 100% replacement for river sand
The ordinary portland cement (OPC) utilized was obtained from the local market in Ado Ekiti while the quarry dust was obtained from Ijere in Ekiti State, calcined clay and laterite were obtained from Ire, Ekiti State and calcite from Auchi-Igara region of Edo State in Nigeria

Summary

Introduction

Hollow sandcrete blocks are traditional materials that have been utilized in construction of residential buildings for several decades. Sandcrete block is a composite material comprising a binding agent (cement) and fine aggregate. These conventional blocks utilize huge amount of ordinary portland cement (OPC) to achieve high compressive strength among other requirements. Sandcrete blocks are susceptible to water ingress during exposure to the environment even after plastering [5] To mitigate these shortcomings, ternary blended cement derived from locally available pozzolanic materials is being explored as potential cement replacement while quarry dust is utilized as 100% replacement for river sand. Replacement of OPC and river sand, partially or wholly, in production of hollow sandcrete blocks with local pozzolanic cementitious materials is desirable to achieve eco-friendly production, resource conservation and economic design

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