Portland slag and composites cement concretes: engineering and durability properties

Abstract

The use of different cementitious main constituents is permitted within the BS EN 197-1 for use in concrete construction. The selection of cement types made depends on requirement of enhanced engineering and durability properties of concrete as well as exploiting potential for producing environmentally friendly concretes for practical applications. The main results of a laboratory experimental programme aimed at examining the performance of Portland-slag and composite cement (CEM II/B-S, CEM II/B-M, CEM V/A and CEM V/B) concrete mixes designed for equivalent 28-day compressive cube strengths of 40 and 50 N/mm 2 are reported in paper. The effect of up to 30-50% of ground granulated blast-furnace slag (GGBS) and its' combination with the silica fume (SF) and fly ash (FA) -within the BS EN 197-1 permitted limits-on fresh, engineering and durability properties have been established and its suitability for use in a range of practical applications was assessed.The loss of workability in all mixes was of a uniform nature and was found to be more for CEM V/B concrete mixes. Studies of hardened concrete properties, comprising bulk engineering properties (compressive cube and cylinder strength, flexural strength, drying shrinkage) and durability (initial surface absorption, carbonation rates) showed enhanced performance for Portland-slag and composite cement concrete mixes of equivalent strength, except resistance to carbonation.Keywords: Carbonation, drying shrinkage, durability, fly ash, ground granulated blast-furnace slag, initial surface absorption, mechanical properties, Portland cement, silica fume Bullet points:Lower w/c ratios did not have any influence on minimizing the early strength loss for equivalent 28-day strength concretes.Drying shrinkage results showed that the contribution of pozzolanic reactions for Portlandslag and composites cement concretes takes place after 14 days.Portland-composite cement concretes (PC+GGBS+SF) with higher w/c ratio showed improved pore structure.Carbonation resistance was observed to be linked with the loss of workability over time.

Cement-free Binders for Radioactive Waste Produced from Blast-furnace Slag using Vortex Layer Activation Technology

“…Blast-furnace slag (BFS) is usually treated in molten state, producing so-called granulated blast-furnace slag (gBFS), containing 3-5 wt. % of metal inclusions [3]. Granulated BFS usually contains certain amount of alumina, silica and calcium oxide, thus making it perspective source for production of construction materials.…”

Effect of Cyclic Carbonation on Chloride Ingression in GGBS Concrete

“…The use of ground granulated blast furnace slag (GGBS) is becoming more widespread due to its environmental credentials and pore modification properties (Bostanci et al 2015;Osborne 1999). It is also used in environments with high levels of chlorides due to its chloride binding capabilities (Dhir et al 1996;Luo et al 2003).…”

“…It is also used in environments with high levels of chlorides due to its chloride binding capabilities (Dhir et al 1996;Luo et al 2003). However, it is widely known that pozzolanic cements have a lower pH and subsequently lower resistance to carbonation (Bostanci et al 2015;Osborne 1999).…”

Efecto de la incorporación de ceniza volante y escoria de horno alto en el comportamiento electroquímico de concretos de cemento comercial

“…De igual manera, se ha comprobado en otras investigaciones que las resistencias disminuyen gradualmente a medida que el nivel de reemplazo aumenta. Esto puede ser atribuido al hecho de que el OPC es substituido por adiciones minerales, lo cual conduce a la reducción del contenido de CaO disponible, y en consecuencia la formación inicial de gel CSH se inhibe (Bostanci et al, 2015). Similares conclusiones son mencionadas por Ahmaruzzaman (2010) y Juenger y Siddique (2015), sobre la sustitución parcial de OPC por ceniza.…”

“…La literatura sobre concretos de cemento adicionado con escoria y ceniza pone de manifiesto la reducción en la resistencia a la carbonatación, respecto a concretos de OPC, incrementándose el efecto con el aumento del nivel del reemplazo (Bostanci et al, 2015;Dong et al, 2015). La razón expuesta es la reducción de portlandita disponible en la estructura de poro debido a su consumo por la reacción puzolánica en el sistema cementante.…”