Durability and chromatic behavior in cement pastes containing ceramic industry milling and glazing by‐products

Abstract

The decay in mortar and concrete induced by extremely aggressive agents is normally the result of the agent‐binder reaction. Cement composition and characteristics therefore determine the durability of the mortars and concretes of which they form part. The existing legislation envisages the use of different types of additions in cement, which have a direct effect on the durability of elements in buildings and civil works. This study addressed the inclusion of ceramic industry milling and glazing sludge as an active addition in cement. The reuse of this industrial waste is consistent with environmental policies that seek to reduce or eliminate spoil heaps by recycling industrial waste and byproducts as raw materials, in keeping with circular economy principles. The research conducted makes an innovative contribution to the valorization of this waste, and highlights the resistance of blended cement pastes to chemical agents, further to the Koch‐Steinegger method. Water‐induced decay in freeze/thaw situations was also studied. The processes involved were identified by analyzing the mineralogical variations detected with X‐ray diffraction, the morphological alterations observed with scanning electron microscopy and the mercury porosimetric findings on pore size distribution. The suitability of these binders for aesthetically demanding applications was also explored by measuring the color in pastes exposed to aggressive chemical agents. For the first time, a correlation was established between color parameters and the formation of the reaction products generated during chemical attack.

Durability of Ternary Cements Based on New Supplementary Cementitious Materials from Industrial Waste

“…The common denominator in all the pastes analysed was The pore system in the OPC exposed to aggressive media was refined more intensely than the systems in pastes M1 or M2, enhancing its durability and inducing higher Kock & Steinegger indices (see Section 3.3). That finding is consistent with prior accelerated testing for durability in cement-based materials bearing fly ash and either silica/alumina nanoparticles [52] or masonry industry sludge [4].…”

“…The diffractograms for the latter also contained lines for other crystalline compounds resulting from the reaction between hydration products and the sulphate and chloride ions in seawater. The Cl − ions diffusing through paste pores were partially retained by the phases bearing Al2O3, giving rise to calcium monochloraluminate hydrate or Friedel's salt (3CaO⋅AI2O3⋅CaCl2⋅AI2O3⋅10H2O) [59,60], from which ettringite may have formed via reaction with SO4 2− ions [4]. Brucite (Mg(OH)2) also formed as the product of the reaction between the Mg 2+ in the seawater and the OHions present in portlandite [61].…”

“…Given that cement susceptibility to such action depends on the chemical composition, crystalline or gelatinous nature and porosity of cement hydration products, those factors play a decisive role in the reactions with aggressive agents. The presence of calcium silicate or aluminate hydrates and especially portlandite is therefore a determinant in cement durability [4].…”

“…Along those lines, blending supplementary cementitious materials (SCMs) into cement or concrete is known to improve concrete structure durability [5]. Pozzolanic SCMs in particular favour durability due to their effect on pore system refinement and reduction of pore solution alkalinity and portlandite content in cement matrices [4,6]. In addition to those technical advantages, the use of SCMs carries social and environmental benefits associated with lower natural resource consumption and the valorisation of industrial byproducts, as well as a significant decline in CO 2 emissions.…”

“…Its filler effect likewise-identified would favour hydration, providing nucleation sites that would densify the cement matrix microstructure. Masonry and mixed C&DW ultrafines [19][20][21][22] comprise essentially SiO 2 , Al 2 O 3 and Fe 2 O 3 (SiO 2 + Al 2 O 3 + Fe 2 O 3 ≥ 84%), with pozzolanicity at least as high as fly ash and similar to that of other masonry materials, such as masonry [4,23] and fired clay sanitary ware [24] rubble. Further to research on mechanical behaviour, GRC has no adverse effect on new eco-cement performance at low replacement ratios (≤7%), whereas masonry ultrafines induce no significant decline in compressive or flexural strength at percentages of up to 25%.…”