Influences of PCE Superplasticizer on the Pore Structure and the Impermeability of Hardened Cementitious Materials

Abstract

The influences of polycarboxylate (PCE) superplasticizer on pore structure of hardened cement pastes (HCPs) and impermeability of hardened mortars were investigated. Cement pastes and mortars with different water to cement ratios (W/Cs) and varied superplasticizer dosages were prepared and cured for 7 days and 28 days respectively. Mercury intrusion porosimetry and alternating current impedance (ACI) were employed to characterize the pore structure of HCPs and the impermeability of hardened mortars. Results show that PCE significantly affects the pore structure of HCPs due to its impacts on the dispersion of cement grains in fresh cement pastes. The effects of superplasticizer on the pore structure are associated with W/C and curing age of cement pastes. At W/C of 0.29, increasing superplasticizer dosage results in obvious declines in total pore volume at early ages and reduces pore connectivity. By contrast, increases in total pore volume and higher pore connectivity are found when PCE is incorporated in the paste at W/C of 0.4. ACI reveals that the inclusion of PCE brings about a denser structure and enhanced impermeability of hardened mortars. It is believed that the enhanced impermeability is related to the reduced interfacial heterogeneity and the compacted interfacial zone when PCE is added.

Influence of Waste Fibers on the Total Porosity of Cementitious Composites

“…In addition, peak III and peak IV, which represent mezzo-and macro-capillary pores, are shifted upwards for the mixes with fibers compared to the reference mix, indicating increased connectivity of capillary pores or a greater proportion of large pores (Y. Zhang & Kong, 2014). Peak V, which represents entrained air, is also slightly higher for the fiber mixes than for the reference.…”

“…Peak I remains unchanged as it represents the intrinsic nature of C-S-H, i.e., it is not affected by the fibers nor the amount of superplasticizer (Y. Zhang & Kong, 2014), while peak II was significantly higher for the wGF10-6 mix. From the results presented, it is clear that the use of fibers, both factory-made and waste, leads to higher values of gel and micro-capillary pores.…”

Effect of nano clay and PCE on the buildability of ultra-fine dredged sand-based 3D printing materials

“…Meanwhile, it can also be seen from table 6 that the total porosity of AP2 is higher than that of NP2. This is mainly due to the low reactivity of NAC and its adsorption of a large amount of free water, which decreased the hrdration of cementitious material and increased the watercement ratio of 3DPM, thus playing negative role in the pore development of 3DPM [51]. Although the high water absorption of NAC led to the increase of cumulative intrusive pore volume of AP2, the volume of capillary pore of AP2 are less than those of NP2.…”

Synthesis, characterization, and performance of a novel polycarboxylate superplasticizer with a crosslinked topological structure

“…The adsorption behaviors and retardation effects of PCs were strongly determined by their charge characteristics, in the order of COO − > SO 3 − > N + . Zhang and Kong studied the influences of PCs on the pore structure of hardened cementitious materials and found that the incorporation of superplasticizer significantly reduces the average pore size . Perrot et al .…”

“…Zhang and Kong studied the influences of PCs on the pore structure of hardened cementitious materials and found that the incorporation of superplasticizer significantly reduces the average pore size. 18 Perrot et al reported that the impermeability of hardened cementitious materials was increased with the addition of PCs. 19 The authors demonstrated that PC reduced the cement paste permeability and did not influence the compressibility of the cement grain network.…”