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Role of Water-Binder Ratio on the Porosity in Lime-Based Mortars
Abstract
In the present paper mortars with air lime and hydraulic binders (natural pozzolan and white cement) were manufactured using standard sand and different water-binder ratios (w/b). The influence of the w/b ratio on the open porosity and pore size distribution as well as on compressive strength at the age of three months was recorded. It seems that the pores that were mainly affected by high w/b ratio were different in different binding systems. In air lime mortars, pores with diameter larger than 500μm and those of 1-100μm are affected while in mortars with hydraulic binders pores of 100-500μm and 0.1-100μm are affected. Micro pores with diameter less than 0.1μm seem to be unaffected in all binding systems tested. In air lime mortars, strength decrease was not proportional to the increase of w/b ratio. On the contrary, in mortars with hydraulic binders both strength and porosity are changing proportionally to w/b variations.
... Currently, the wet grinding of lime-silica binder not is applied, because lime reacts with water to form calcium hydroxide, which has high water demand. Normal lime-silica binder must have a moisture content of at least 60 -70% for transport by hydro transport, while the binder becomes unsuitable, because excessive humidity of the silicate mixture obtained on its basis causes water separation during pressing and an uneven change in the volume of the raw brick (up to destruction) during its autoclaving [12]. ...
This article is devoted to the description of methods for improving the efficiency and production of autoclaved materials and lime, as well as an increase in safety in their production. The basis of the proposed technical and technological methods is a new method for the production of autoclaved materials. As part of the scientific work on improving the quality of autoclaved products, an additive (copper sulphate) was found, which makes it possible to slow down the lime hydration time in the binder for several hours, which makes it possible to apply the mechanical activation of lime-silica binder with wet grinding and improve working conditions in the workplace.
... Figs. 1 and 2 show the dynamic light scattering (DLS) pattern and the X-ray Diffraction (XRD) spectra of nano-CaCO 3 , respectively. The chemical composition and the physical properties of cement, Pozzolan, and nano-CaCO 3 are shown in Table I [25]- [27]. ...
Concrete with high levels of Pozzolan suffers from poor early age strength
development and an extended setting time and may therefore lead to construction delays thus
limiting its use in the concrete industry. The main objective of this study has been to evaluate the
effectiveness of calcium carbonate nano-particles (CCNPs) on improving the fresh and
mechanical properties of high volume natural Pozzolan (HVNP) cement mortars. At the beginning,
CCNPs have been synthesized in a simple and inexpensive way, and then the optimum content of
nano-CaCO3 has been determined based on the highest compressive strength achieved by ordinary
Portland cement mortar with different proportions of CaCO3 nanoparticles. In the end, the
determined optimum content has been used in order to evaluate the effect of nano-CaCO3 on the
properties of HVNP mortars containing 40% and 60% natural Pozzolan as partial replacement of
cement. Scanning electron microscopy (SEM) and X-ray diffractometery (XRD) techniques have
been used in order to investigate the microstructure, the properties, and the compositions of the
synthesized nano-particles and the cement-Pozzolan mortars. CCNPs have been synthesized
efficiently via the simple precipitation method and suitable sonication process has been used to
disperse CaCO3 nanoparticles. The results have indicated that nano-CaCO3 has increased the
compressive strength of the Pozzolan-cement mortars, and the best result has been obtained at an
optimum content of 1% nano-CaCO3. The addition of nano-CaCO3 to the HVNP mortar improved
its setting behavior; on the other hand, it has decreased its workability. However, this reduction in
the workability has been offset by an increase due to partial replacement of cement by HVNP.
Blending nano-CaCO3 with HVNP (40 and 60% replacement levels) has compensated for the low
compressive and flexural strength at early ages of HVNP mortars. Thus, it has proved to be an
effective way for improving the mechanical properties of high volume natural Pozzolan-cement
mortars. The XRD and SEM results have confirmed that nano-CaCO3 has improved the early
strength development and the microstructure of HVNP mortars by making it denser with less
pores.
This study aims to investigate the effect of ternary combination of silica fume, and glass and ceramic waste as a partial replacement of cement on selected properties of mortar in the presence of steel-polypropylene hybrid fibers. Thirteen mixtures have been made: one control mix and twelve mixes in which the cement has been replaced by constant proportion (30% of cement weight) of ternary combination of silica fume, and glass and ceramic waste. The steel fibers have been added in the proportion of 1% while polypropylene fibers have been applied in the percentages of 0.25%, 0.5% and 1% (by volume for both fibers types). The flow rate, the compressive and the flexure strength and the bulk density tests have been examined. The hardened tests have been carried out at age of 28 days. Results have showed that the flow rate values have been reduced after replacing cement with the combination of silica fume, and glass and ceramic waste. Moreover, it has been found out that the compressive and flexure strength values for all combination mixtures have been higher than that for control mixture. The enhancement ranges have been 31% to 62% for compressive strength and 3% to 25% for flexure strength. In addition, results have demonstrated that there has been no significant change in bulk density values for cement replacement mixtures related to the one for control specimens.
Abstract
The main purpose of this article is to investigate the possibility of improving expansive soils properties using different additives, cement, lime, and a combination of lime and cement. An experimental program has been carried out on expansive clayey samples taken from Irbid, Jordan. Cement, lime and cement-lime mixture have been added as percentages by dry weight of the soil at ratios of (3%, 5%, 8% and 12%). Different geotechnical properties including Atterberg limits, compaction test, unconfined compressive strength (UCS) and California bearing ratio (CBR) have been tested before and after using the additives. Free swelling and swelling pressure have been examined before and after after using the additives at no curing, after seven days curing and after 28 days curing. It is shown that, upon adding (cement, lime), the plasticity index and the swelling potential have decreased while the unconfined compressive strength (qu) and the maximum dry density (γd-max.) have increased. Also, the curing time increase is accompanied with a significant enhancement on the compressive strength (UCS) of the treated soil. It has also been noticed that the cement-lime mix (6% cement and 6% lime) has resulted in a noticeable improvement for the expansive soil used in this research over other additive percentages.
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