Carbonation and chloride penetration of repair mortars with water treatment plant sludge and sugarcane bagasse ash sand

¹ Department of Civil Engineering, Federal University of São Carlos, Via Washington Luís, km 235, São Carlos, SP 13565-905, Brazil.
² Department of Materials Engineering and Construction, Federal University of Minas Gerais, Av. Presidente Antônio Carlos, 6627, Belo Horizonte, MG 31270-901, Brazil.
³ School of Computing, Engineering and Built Environment, Glasgow Caledonian University, Cowcaddens Road, Glasgow, G4 0BA, UK.

^* Corresponding author: a.klemm@gcu.ac.uk

Abstract

Water treatment plant sludge (WTPS) and sugarcane bagasse ash sand (SBAS) (wastes from water treatment and sugar/ethanol industries) can be used as replacements of natural sand in concrete. Thus, this paper aims to evaluate carbonation depth and chloride penetration of cementitious repair mortars produced with WTPS and SBAS. Three mortars compositions were analysed: plain reference sample (REF); sample with 3% of WTPS (3WTPS); and sample with 30% of SBAS (30SBAS). They were subjected to tests of accelerated carbonation and immersion in NaCl solution up to 84 days (12 weeks). The results showed that SBAS mortars had the best performance in relation to carbonation and chloride penetration tests. 3WTPS mortars had similar results to the reference sample. This is due to refinement of pores given by incorporation of fine waste materials making it difficult for aggressive agents to penetrate cement matrices. Therefore, 3WTPS and 30SBAS composites can be satisfactorily used in buildings repair services for more sustainable and durable construction.