Silica Mortar Research Articles

Compressive strength, porosity, and density of mortar containing precipitated silica from Palm Oil Fuel Ash (POFA)

Palm Oil Fuel Ash (POFA) as an agro-industrial waste has potential applications in the construction industry. Using POFA to produce extracted precipitated silica is another step toward improving the performance of mortar and concrete with cost-effective biomass waste. This study investigates precipitated silica extracted from POFA as an additive for mortar. Mortar mixtures containing various percentages of precipitated silica (PS) and silica fume (SF) with 2%, 4%, and 6% by weight of cement were cast and studied. Compressive strength, porosity and density of the mortar at 28 days were tested to study the physical properties of the PCC-SP and PCC-SF mortars. The compressive strength of PCC-PS and PCC-SF mortars increased with the optimum 4% addition of silica. Precipitated silica mortar (PCC-PS) has lower strength, higher porosity, and similar density to the silica fume mortar (PCC-SF). However, the precipitated silica mortar has better strength, porosity, and density than the PCC mortar (control mix). The current findings suggest that the extracted precipitated silica can be used as a cost-effective additive from biomass waste to improve the performance of mortar and concrete.

Characterization of mechanical properties and microstructure of silica mortar and coral mortar based on nuclear magnetic resonance technology

It is crucial to use coral sand to replace traditional sand and gravel aggregates to produce coral aggregate concrete for island development and construction to minimize environmental damage to offshore islands and reefs. Coral sand particles are irregular in shape, porous, and break easily, resulting in substantial differences in engineering mechanical properties and the microstructure compared to land-based sand. Uniaxial compressive strength tests were carried out on coral mortar and silica mortar to determine the influence of the sand-cement ratio on the mortars’ compressive strength. Low-field nuclear magnetic resonance (NMR) technology was used to analyze the compressive strength of the two mortars at the microscopic scale. The optimum sand-cement ratio of coral mortar was determined. At the same mixture ratio, the compressive strength of coral mortar was lower than that of silica mortar. In the early hydration reaction, only one main peak occurred in the transverse relaxation time distribution of the silica mortar, but a secondary peak was observed in the coral mortar, and a transition peak appeared 84 hours later. The pore size range of the internal pores of the coral mortar was large, and the interval was continuous. The significantly higher proportion of harmful pores and very harmful pores resulted in the lower strength of the coral mortar than the silica mortar. The research results can provide a reference for using NMR to evaluate coral mortar.

Strength Properties of Nano and Micro Silica Mortar

Nano technology is increasingly being used in concrete industry, and in particular the use of nano silica particles in cementitious materials is becoming more popular to improver concrete properties. This paper deals with studying the influence of replacing a portion of cement by either nano silica, micro silica, or a combination of both on the strength properties (compression, tension and abrasion) of the cementitious mortars produced. Micro-silica particles are altered from 0, 5 and 10% while nano-silica particles are altered from 0, 0.5 and 1.0%. The paper reveals the method of mixing nano particles to prevent agglomeration and achieve a homogeneous mix so that the nano particles are well dispersed throughout the mortar matrix. Results indicate that incorporating both micro or nano particles improve the mortar matrix by making it denser with less internal voids hence preventing any transport of liquids throughout its matrix. In addition to the pozzolanic effect caused by using micro silica and nano silica which increases mechanical properties of the cement mortars.

Influence of aggregate and supplementary cementitious materials on the properties of hydrated lime (CL90s) mortars

Hydrated lime is a historic material currently used in conservation. It hardens slowly by carbonation slowing construction however, supplementary cementitious materials accelerate hardening enhancing strength. Hydrated-lime mortars with rice husk ash–RHA-; ground granulated blastfurnace slag–GGBS- and increasing amounts of two aggregates were studied. Increasing aggregate lowered strength as interfacial zones proliferate; it lowered hygric properties and raised water demand. Aggregate content/composition didn’t affect the high water retention. For the higher aggregate contents (90 days), limestone mortars are c.20% stronger than silica mortars while the (1:1) silica sand mortars are 56% stronger in flexion. Additions increased strength with little impact on hygric properties. GGBS increased strength c.six times. RHA increased strength with little impact on hygric properties due to its great specific surface and high water-demand increasing porosity. GGBS and RHA properties ruling hydrate production and the kinetics of the pozzolanic reaction are considered partially responsible for the mortar property variation.

Reducing dust formation of silica brick and silica mortar

Reducing dust formation of silica brick and silica mortar

A New Inorganic Cement Mortar For Sulfuric Acid Service★

Abstract Silicate cement mortars, consisting of a chemically inert solid filler containing a fluoride setting agent and a liquid sodium or potassium silicate binder, have been used for many years in acid-proof construction for high temperature, strong acid service. While silicate cements have performed well under unusually tough conditions, they are not without their shortcomings in sulfuric acid service. Instances of corrosive attack are explained by breakdown of the setting agent and hydrate or alum formation. A new material of construction, a silica cement mortar, has been developed which shows promise in sulfuric acid service. The binder is a silica sol instead of a solution of a sodium or potassium silicate which is alkaline. The setting agent permits an orderly gelation of silica resulting in a strong mortar. Unit cell dimensions are given for a number of sulfates and alums. Seven physical properties are listed and compared for sodium silicate mortar, potassium silicate mortar and silica mortar. The comprehensive strengths of these three materials after immersion in sulfuric acid are reported. 6.6.5

A STUDY OF THE WORKING PROPERTIES OF SILICA MORTARS*

AESRACTA method of testing the consistency of silica mortars is described which is a modification of the flow test for concrete and building mortars. The effect of added colloids and PH on the working properties is described. The use of colloids will produce marked improvements in mortars and will prevent settling out of the aggregate.

THERMAL EXPANSION OF SILICA MORTARS AFTER FIRING AT 950o, 1200o, and 1500oC1

The thermal expansion between 20°C and 950°C of silica mortars after being fired at 950°, 1200°, and 1500°C was compared with the expansion of the materials before firing. The mortars showed marked difference in expansion behavior after being fired to 1500°C, indicating that there was developed a large amount of tridymite The thermal expansion of the fired samples is less than that of the unfired samples.

THERMAL EXPANSION OF SILICA BRICK AND MORTARS1

Thermal expansion from 20 to 950°C and physical data of silica brick from various producing districts in the United States and Europe are presented. The variations in thermal expansion of brick from various parts of kilns are given for plants in the United States. The magnitude of variation of the thermal expansion of silica brick is quite small, the expansion ranging between 1.15% and 1.30% at the highest point of expansion. The expansion of the silica mortars varied between 1.30 to 1.52% depending upon variations in clay, quartzite, and bats. The variations in thermal expansion of silica mortars from various producing plants are also shown. Data on the effect of size of grain, clay content, and P.C.E. on the thermal expansion of mortars are given. An extensive bibliography on thermal expansion of silica brick appears with the paper.