Ground Clay Brick Research Articles

Performance of ground clay brick in ASR-affected concrete: Effects on expansion, mechanical properties and ASR gel chemistry

The effects of ground clay brick (GCB) on alkali-silica reaction (ASR) expansion as well as on mechanical properties of ASR-affected concrete are investigated. Crushed red clay brick originated from demolished masonry was ground in a laboratory ball mill and replaced for portland cement at levels of 15% and 25% by weight in concrete mixes produced with alkali reactive sand. ASR expansion, compressive strength , flexural strength , and modulus of elasticity of the concrete mixes were evaluated. Effect of GCB on ASR gel chemistry was also studied on Pyrex glass-paste specimens using SEM/EDS (scanning electron microscope equipped with energy dispersive X-ray spectroscopy). The results indicate that GCB effectively reduces ASR expansion in concrete: associated cracking and loss on mechanical properties are also significantly reduced. SEM study suggests that GCB alters alkali silica gel chemistry thus resulting in a less expansive product.

Evaluación de la reactividad árido-álcali en diversos áridos silicatados. Alternativas para minimizar esta reacción

Siliceous aggregates are characterized for presenting certain chemical reactivity opposite to the calcium hydroxide liberated in the hydration of the Portland cement. The consequence of this reaction between the aggregate and the components of the intermediate concrete phase is the formation of gels very eager for water that can generate important disruptive pressures in the deeper structure of concrete. We have assessed the potential reactivity of several siliceous aggregates (granites, gneiss, hornfels, granites, quartzite and serpentine) by means of the accelerated method in concrete bars (normalized method) and the superficial reactivity method, observing by scanning electron microscopy (SEM) the formation of silica calcium alkaline gels. On the other hand, we explore the way of minimizing this disruptive reaction employing ground clay bricks and cement type CEM IV UNE-EN 197-1.

Use of Ground Clay Brick as a Pozzolanic Material in Concrete

Abstract This study investigates the suitability of using ground clay brick (GCB) as a pozzolanic material in concrete. Crushed clay brick originating from demolished masonry was ground in the laboratory and used as a cement replacement in paste and concrete. Hydration characteristics of paste mixtures were investigated for a better understanding in concrete application. The effect of ground brick replacement for cement on concrete’s mechanical properties and chloride ion penetration resistance, as a measure of durability, were also studied. Two replacement levels, 15 % and 25 %, were compared with the control (0 % GCB). The study on the cementitious pastes showed that the ground brick slightly increased the water demand for normal consistency, delayed the time of setting, reduced the temperature rise during hydration, and decreased the calcium hydroxide (Ca(OH)2) content. The tests on concrete showed that the mechanical properties (i.e., compressive, flexural and splitting tensile strengths, and modulus of elasticity) of concrete containing ground brick were comparable to those of the concrete without GCB. Furthermore, the GCB increased the resistance of concrete to chloride ion penetration. The study undertaken proved that, when it is finely ground, clay brick obtained from demolished masonry can be recycled as a pozzolanic cementitious material in concrete.

Comparative Performance of Ground Clay Brick in Mitigation of Alkali–Silica Reaction

This paper reports on a study of waste clay brick that was ground and used as a supplementary cementitious material (SCM) in a mortar. The effect of this ground brick, in comparison with other conventional pozzolanic materials (namely, a Class F fly ash, and a natural pozzolan), on the alkali–silica reaction (ASR) of the mortar was evaluated. The ground clay brick, fly ash, and natural pozzolan were introduced into the mortar as a cement replacement at a 20 or 35% level. Fly ash–natural pozzolan and fly ash–ground clay brick combinations were also employed as a cement replacement at a 35% level. These SCM-incorporated mortar samples were tested for ASR expansion, flexural and compressive strength, and rapid chloride permeability. The test results indicate that all the SCMs considered in this study reduced the mortar ASR expansion, rapid chloride permeability, and the ASR-associated strength loss. The finely ground waste clay brick demonstrated high potential to reduce the ASR expansion as well as the ASR-...

Effect of calcium formate as an accelerator on the physicochemical and mechanical properties of pozzolanic cement pastes

The aim of the present work is to study the effect of calcium formate (CF) as an accelerator on the properties of pozzolanic cement pastes. Three types of cements were used in this investigation. These cements were OPC and pozzolanic cements containing 80 mass% OPC and 20 mass% silica fume (SF) or 20 mass% ground clay bricks (GCB). The dosages of CF were 0.00, 0.25, 0.50, and 0.75 mass% of cement. The compressive strength, total porosity, and hydration kinetics such as free lime and combined water contents were investigated. The results obtained in this study showed that the addition of CF shortens the initial and final setting times and increases the compressive strength and combined water content as well as gel/space ratio at all ages of hydration. On the other hand, it decreases the total porosity. CF activates the liberation of Ca(OH) 2 of OPC pastes. The free lime content of pozzolanic cement in the presence of CF increases up to 7 days, then decreases at the later ages of hydration.

Use of ground clay brick as a pozzolanic material to reduce the alkali–silica reaction

The objective of this experimental study was to use ground clay brick (GCB) as a pozzolanic material to minimize the alkali–silica reaction expansion. Two different types of clay bricks were finely ground and their activity indices were determined. ASTM accelerated mortar bar tests were performed to investigate the effect of GCB when used to replace cement mass. The microstructure of the mortar was investigated using scanning electron microscopy (SEM). The results showed that the GCBs meet the strength activity requirements of ASTM. In addition, the GCBs were found to be effective in suppressing the alkali–silica reaction expansion. The expansion decreased as the amount of GCBs in the mortar increased.