THE EFFECT OF ADDITION SILICA FUME, SUPERPLASTICIZER, AND BONDING TO REACHING HIGH QUALITY LIGHTWEIGHT CONCRETE

In this research, a lightweight concrete mixture was made with foam and made use of the remaining broken rock from the Crusher Machine process, which was washed ashes. Other added ingredients used in the mixture are Silica Fume, Superplasticizer (Admixture Type F) and Bonding. This reseach uses a mix design from Circular Letter Number: 44 / SE / M / 2015 Concerning Design Guidelines for Mixing Light Material with Foam Mortar for Road Construction, Ministry of PUPR. Trial mix variations carried out are in proportion (SF 5%; BO 0.5%), (SF 10%; BO 0.5%), (SF 5%; BO 1%), (SF 10%; BO 1% ), as well as foam agents with variations 1:20 and 1:40. The treatment process (curing) of the test object is immersed in a water bath, and the testing of the compressive strength of the test object is carried out at the age of 7 days, 14 days and 28 days. By using stone ash, lightweight concrete was obtained with an average specific gravity of 1722 kg / m 3 to 1884 kg / m 3 . From the research results obtained the highest average compressive strength with the percentage of material that is in the variation of the SF 10% ; BO 0.5% and ratio foam (1) : water (40) only for K 190.6 kg/cm 2 or FC 15.82 MPa. In each specimen the value of quality efficiency with the most optimum weight variation at SF 10% ; BO 0.5% with a coefficient value of 10.03%.


INTRODUCTION
Concrete is one of the most important elements in building structures. Indonesia is an archipelago that is developing infrastructure development and almost all construction uses concrete. According to SNI 2847: 2013, concrete is a mixture of portland cement or other hydraulic cement, fine aggregate, coarse aggregate, and water with or without additives. The development of science and technology has led to the emergence of various kinds of innovations in the field of construction. The types of concrete in construction are very varied, can be reinforced concrete, prestressed concrete, mortar concrete, pre-cast concrete, and lightweight concrete.
Lightweight concrete based on unit weight (SNI 03-2847-2002) is concrete which has a density or unit weight <1,900 kg / m 3 consisting of cement, sand, water, foam agent, or other added materials. Lightweight concrete consists of two types, namely Autoclaved Aerated Concrete (AAC) and Cellular Lighweight Concrete (CLC), lightweight concrete with AAC type in its mixing using aluminum paste while for CLC lightweight concrete in mixing using foam.
Foam concrete material in cellular lightweight concrete is one of the construction materials that has been developed lately. The thing that should be considered in the VOLUME 19 │ NUMBER 1 │ JULY 2019 https://ejournal.worldconference.id/index.php/neutron E-ISSN: 2685-3272 | P-ISSN 1412-0860 manufacture of cellular lightweight concrete is the use of foam agents that function to trap voids in mortars, so that dry densities between 500 kg / m 3 -1600 kg / m 3 are obtained (Jitchaiyaphum, K, et. Al, 2011: 1157. The mixture in cellular lightweight concrete is cement, fine aggregate, water, foam agent and other added materials needed in its manufacture. Fine aggregate used is Abu Batu, which utilizes the results of the rest of the process of breaking the stone with a Crusher Machine. Additives Type F, Silica Fume and Bonding are other added ingredients to achieve highquality cellular lightweight concrete. Type F additives are used to obtain the desired level of consistency or specifications by reducing water weight by >12%. Bonding is a mixture of concrete adhesives that serves to increase the adhesion of concrete so that the concrete becomes solid and air cavities are reduced. Silica fume is a very fine pozolan material and partly consists of silica element, which is produced from a furnace as a by-product of the silicon metal industry (ASTM C 1240-93). Silica fume is physically finer than cement and chemically contains a high SiO2 element, which increases the strength of concrete when used as an additive to concrete.
In accordance with the description in the research background above, the writer can formulate the problem to be discussed : 1. Is using stone ash and foam agent able to produce lightweight concrete? 2. Is the addition of Silica Fume, Type F additives and bonding able to affect the quality and achieve high quality lightweight concrete? 3. What is the compressive strength produced in concrete with the addition of Silica Fume, Type F additives and bonding?

LITERATURE REVIEW
High quality lightweight concrete is concrete which has a specific gravity ranging from 350 kg/ m 3 -1900 kg / m 3 with compressive strength exceeding 6000 psi (40 Mpa). Lightweight Concrete Mixture Material According to the Ministry of Public Works and Public Housing Design Guidelines for Mixing Lightweight Mortar-Foam Materials for Road Construction, lightweight concrete using a mixture of Portland cement or other hydraulic cement, fine aggregate, foam, and water, with or without additives (admixture).
Fine Aggregate is an aggregate of not more than 5 mm in size, so it can be natural sand or sand from rock breaking resulting from rock breaking (stone ash). According to (SNI 03-6819-2002) the grains produced by fine aggregates must be hard and durable, must not contain mud, clay and loose material / more easily destroyed by more than 5%. Fine aggregate must be free from charcoal, wood objects and other unwanted impurities.
According to the Indonesian Industrial Standards (SII. 0013 -81) Cement is a hydraulic cement produced by smoothing clinkers which mainly consists of calcium silicates which are hydrolyzed together with additives which are usually used in casts. The composition of materials in cement consists of Silicondoxide (SiO), Aluminumoxide (AlO), Calciumoxide (CaO), Magnesiumoxide (MgO), Sulfurtrioxide (SO), Sodium Oxide (NaO).
Foam is a foam liquid containing vegetable protein or the like that can produce stable separate bubbles so as to produce a mixture of lightweight materials that meet technical specifications. Foam making material is foam agent and water, to make foam, mixing foam fluid and water using a foam generator and compressor.
According to the standard "Specification for Silica Fume fauna Use in Hydraulic Cement Concrete and Mortal" (ASTM.C.1240.1995: 637-642), silica fume is a smooth pozzolan material, where more silica composition is produced from higher kilns or residual production silicon or silicon iron alloy (known as a combination of micro silica with silica fume). The use of silica fume is always the same as High Range Water Reducer (Superplasticizer). Due to VOLUME 19 │ NUMBER 1 │ JULY 2019 https://ejournal.worldconference.id/index.php/neutron E-ISSN: 2685-3272 | P-ISSN 1412-0860 the use of water in concrete and the presence of silica fume which fills the pores and is pozzolanic, it causes the concrete to become impermeable, durable and of high strength.
According to ASTM C 494 and British Standard 5075, Superplasticizer is a highly effective water-reducing chemical additive. With the use of these additives obtained a mixture with a lower cement water factor at the same mortar viscosity value or obtained with a thinner viscosity with the same cement water factor, so that the compressive strength of concrete is higher. Superplasticizer also has a great influence in increasing workability.

Analysis of Cleanliness of Stone Ash on Organic Materials (ASTM C 40 -92)
Objective: Determine the levels of organic matter in the aggregates used in concrete mix. How to experiment levels of organic substances: The volume of stone ash + 200 grams was given a NOH solution of 3%, shaken for 10 minutes and allowed to stand for 24 hours. Treatment / curing in lightweight concrete that is immersed in a tub / curing tub and testing is carried out for 7 days, 14 days and 28 days. Concrete compressive strength value is determined when the concrete reaches the age of 28 days. The strength of concrete will increase rapidly until the age of 28 days, but after that the increase is not too significant. Generally at the age of 7 days the compressive strength reaches 65% and at the age of 14 days reaches 88% -90% of the compressive strength of the concrete age of 28 days.

Analysis of Ash
For the calculation of compressive strength of test specimens according to SNI 03-1974-2011 article 7, using systematic calculations can be written as follows: • Concrete Compressive Strength:

Target Concrete Specific Gravity, Foam & Slump Flow Test Specific Gravity
The target specific gravity is <1900 kg / m 3 , the target specific gravity foam (0.055-0.085 t / m 3 ), and the target flow mortar foam 180 + 200 mm.

Trial Mix Process and Manufacture of Test Objects
In this study the making of test specimens using cylinders 15cm x 30cm, with a total of 4 trial variations and each variation amounted to 9 test specimens.

Concrete Treatment of Test Objects (Curing)
Concrete curing / maintenance aims to maintain and guarantee the quality of the concreting. In this study the steps taken are as follows: Dismantling the test specimen is done ± 24 hours after making it; The specimen is immersed until the age of 7 days, 14 days and 28 days; The test object is taken / dried the day before the test day.

Concrete Compressive Strength Testing
Press test procedure: The test object is placed on a press machine sentries; The machine is running, press with a constant increase in load ranging from 2 to 4 kg / cm3 per second.      Based on the table above, the highest quality is found in 1:40 ratio variation (foam: water) using Silica Fume 10% and 0.5% Bonding which achieves quality K 191 kg / cm2 or FC 10.82 MPa. Based on the results of the trial obtained an average density or specific gravity above in accordance with the requirements of <1900 kg / m 3 , in the first trial with a foam ratio of 1:20 obtained an average of 1722 kg / m 3 and a second trial of foam ratio of 1:40 obtained an average of an average of 1884 kg / m 3 .

CONCLUSION
On the results of research and discussion that has been carried out several conclusions can be drawn as follows: 1. The use of ash stone material and foam agent (foam) in this study was able to produce concrete weighing <1900 kg / m 3 , as evidenced in the average results in the first trial mix with the ratio of foam: water (1:20) to get the result of specific gravity 1722 kg / m 3 and the second trial mix with a ratio of foam: water (1:40) yielding a specific gravity of 1884 kg / m 3 . 2. The addition of silica fume, superplasticizer (type f), and bonding can affect quality but do not reach the K-300 quality target. In this study the addition of optimum silica fume at a proportion of 10%, the more additions it will add to the strength of concrete.
The addition of type f in this study is optimum in the proportion of 0.6% because it can reduce water use by 12%. Whereas the addition of optimum bonding is in the proportion of 0.5% because if the bonding is mixed with foam / foam even though the proportion added does not really affect the strength of the concrete. 3. In this research, normal concrete with K-300 quality compared to lightweight concrete whose composition is cement, stone ash, silica fume, type f, and bonding. The results of normal concrete compressive strength obtained quality K 305.80 kg / cm 2 or FC 25.38 MPa, whereas for lightweight concrete obtained with a foam: water composition ratio (1:40), the proportion of silica fume use 10%, 0.5% bonding with compressive strength of K 190,6 kg / cm 2 or FC 15,82 Mpa. In each specimen the value of quality efficiency with the most optimum weight variation is SF 10% ; BO 0.5% with a coefficient value of 10.03%.

SUGGESTION
In order to produce research that will later become better in further research the authors suggest paying attention to the following matters: 1. There needs to be another trial and error in order to get the right lightweight concrete mixing and the quality to reach the desired target; 2. Use stone ash which has a uniform grain size and has a standard mud content by washing it first; 3. Add additives and admixture that can reduce more water so that the quality of concrete is in accordance with the target; 4. Pay attention to the moisture content test for the material because it affects the use of the amount of water in the concrete mixture; 5. Pay attention to the density foam to fit the requirements of 0.055 t / m 3 -0.085 t / m 3 .