Composite Binder Containing Industrial By-Products (FCCCw and PSw) and Nano SiO2

Abstract

This article analyzes the integrated effect of industrial by-products (spent fluidized bed catalytic cracking catalyst waste (FCCCw) and paper sludge waste (PSw) generated in paper manufacturing) combined with nano-SiO2 (NS) on the properties of cement binder, when a certain part of the binder is replaced with the said by-products in the cement mix. Standard testing methods were used to analyze the physical and mechanical properties of cement-based materials. For structure analysis, we used X-ray diffraction (XRD), derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM). It was found that the replacement of cement by a combined additive of FCCCw, PSw and NS is important not only for ecological reasons (abatement of CO2 emissions and recovery of waste through secondary raw materials), but also in order to enhance the properties of cement-based binders. Presumably, higher amounts of calcium silicate hydrate (CSH) and calcium alumina silicate hydrate (CASH) in the compound binder are the result of the low content of portlandite and alite in the test specimens. The specimens modified with all three additives had the highest density (~2100 kg/m3), ultrasonic pulse velocity (UPV) (~4160 m/s) and compressive strength (~105 MPa), which was ~40% higher than in the control specimens. The average pore diameter of the complex binder decreased by 21%, whereas the median pore diameter decreased by 47%.

The Effect of Active Additives and Coarse Aggregate Granulometric Composition on the Properties and Durability of Pervious Concrete

“…With the reduced cement content and active additives added, the compressive strength of pervious concrete increased 6.3% and water permeability increased 3.5%. The effect of these additives on the properties and hydration of hardened cement paste was reported in research publications [ 66 , 67 ]. According to the published results, NS, FCCCw and PSw used together accelerate cement hydration by 4 h, increase the compressive strength by approx.…”

“…These results suggest that active additives (NS, FCCCw and PSw) reduced the dissolution of portlandite and other minerals. The explanation is that active additives accelerated the formation of CSH, which is more resistant to dissolution, and made the structure of the cement matrix denser [ 66 , 67 ].…”

“…These results suggest that active additives (NS, FCCCw and PSw) reduced the dissolution of portlandite and other minerals. The explanation is that active additives accelerated the formation of CSH, which is more resistant to dissolution, and made the structure of the cement matrix denser [66,67]. EDS analysis of areas S 1 and S 3 in PCO-C specimens showed that after the exposure to water flow, Ca content decreased 37%, the colour of the area S 3 had changed compared to the area S 1 prior to the washing, and the layer of cementitious matrix in this area reduced.…”

“…X-ray diffraction (XRD) patterns of FCCCw and PSw are presented in Figure 3 and Figure 4 , respectively. Y-type zeolite faujasite is the main crystal phase in FCCCw [ 66 ]. Calcite and CaO were the two main minerals identified in PSw.…”

“…The coarse aggregate with the same particle size distribution was used in PCO-C and PCO-1, but the composition of the binder was different. PCO-C composition contained only cement, and other compositions were mixed with a composite binder modified with active additives (NS, FCCCw, and PSw), which were developed in previous research works [ 66 , 67 ]. This binder described in previous papers was developed with the aim to use it in the manufacturing of pervious concrete for the following reasons: the complex application of 10% FCCCw, 2.5% PSw and 0.02% NS produced the best compressive strength results; the lowest level of portlandite was observed (portlandite is the most susceptible to dissolution in the presence of water); the highest levels of CSH and CASH were identified; the highest rate of hydration was observed.…”